To see the other types of publications on this topic, follow the link: Turning with sintered carbide.
Dissertations / Theses on the topic 'Turning with sintered carbide'
Create a spot-on reference in APA, MLA, Chicago, Harvard, and other styles
Consult the top 48 dissertations / theses for your research on the topic 'Turning with sintered carbide.'
Next to every source in the list of references, there is an 'Add to bibliography' button. Press on it, and we will generate automatically the bibliographic reference to the chosen work in the citation style you need: APA, MLA, Harvard, Chicago, Vancouver, etc.
You can also download the full text of the academic publication as pdf and read online its abstract whenever available in the metadata.
Browse dissertations / theses on a wide variety of disciplines and organise your bibliography correctly.
1
Ugwoha, Ezedimbu. "Performance of uncoated carbide tools in face turning of titanium base, Ti-6246 alloy and when drilling sintered nickel-base, RR1000 alloy." Thesis, London South Bank University, 2009. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.618691.
Full text
2
Prno, Peter. "Obrábění kobaltové slitiny UmCo50." Master's thesis, Vysoké učení technické v Brně. Fakulta strojního inženýrství, 2021. http://www.nusl.cz/ntk/nusl-444280.
Full textAbstract:
The diploma thesis deals with the topic of machinability of materials. The theoretical part describes the aspects according to which machinability can be evaluated. The material side of the thesis is focused on various types of difficult-to-machine materials. The cobalt alloy UmCo50 belongs to the group of difficult-to-machine materials and it is the subject of the experimental part. UmCo50 is an alloy for high temperature use. The primary aim of the thesis was to monitor the wear of the selected cutting tool when turning this alloy. Other aspects of the selected machining process were also monitored, such as force effects or the quality of the machined surface. Despite the fact that machinability of tested materials cannot be expressed in terms of the absolute value of a quantity, it is necessary to compare the various aspects of the machining processes by reference materials. However, certain conditions of this comparison must be met. Based on this, a comparison of tested and reference material was performed.
3
Jiang, H. "Tensile creep of sintered silicon carbide." Thesis, Swansea University, 1994. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.637429.
Full textAbstract:
Pressureless sintered silicon carbide is currently being evaluated for advanced aeroengine applications because it provides the best combination of strength retention and oxidation resistance at high temperatures. In the present work, tensile creep and creep fracture behaviour of sintered SiC has been investigated. Creep tests have been performed under constant stress and temperature ranges from 125 to 400 MPa and 1673 to 1873 K respectively. The sintered SiC exhibits primary dominated creep curves and little or no tertiary stage in all cases studied. It is established that the SiC displays a brittle-creep behaviour. The creep fracture behaviour has been studied by examining the fracture surfaces and longitudinal sections of failed test-pieces after creep exposure. It is concluded that creep fracture occurs by the formation and propagation of microcracks developed along the grain boundaries during creep deformation. All failures that have occurred immediately on loading are identified to be caused by pre-existing voids (large pores) which are the result from incomplete local sintering during manufacture.
4
Williams, T. "Development Of pressureless sintered silicon carbide-boron carbide composites for armour applications." Thesis, University of Surrey, 2016. http://epubs.surrey.ac.uk/810348/.
Full textAbstract:
Ceramic armour must offer protection against armour piercing threats at low weight and affordable cost. As a possible means of improving armour, a range of SiC-B4C composites have been produced and characterised. The degree of contact between the two phases has been quantified and shown to have a strong effect on the densification and microstructure in these materials. This understanding has enabled independent variation of microstructural parameters which are normally interrelated. These were; porosity, SiC:B4C mass ratio, B4C distribution in a SiC matrix and SiC grain size distribution. To assess effects of each of these parameters on ballistic performance V50 testing was carried out, using 7.62 mm armour piercing rounds. The amount of porosity is shown to have a slight effect on V50 and a marked effect on scatter in V50. The pore size distribution is also shown to be important; across a range of pairs of materials with similar total pore volumes but differing pore size distributions, larger pores consistently give lower V50. SiC:B4C mass ratio does not seem to greatly affect V50, potentially allowing application specific cost/weight balances at constant protection level. B4C distribution has a strong effect. In general, for B4C features with diameters ranging from 1 m to 100 m, the coarser features performed better. Using coarse B4C particles in a SiC matrix, a V50 of approximately 980 ± 20 m s-1 at a density of 3.00 g cm-3 was achieved reproducibly. This material is preferred due to a combination of relatively lower cost, reduced density and repeatability. Knoop indentation has been used to derive possible merit indices which could potentially be used to rank ballistic materials. These includes analysis of failure probability of indents and the indentation size effect. A preliminary study indicates ballistic impacts may affect SiC polytype composition.
5
Vargas-Gonzalez, Lionel Ruben. "Microstructural optimization of solid-state sintered silicon carbide." Diss., Georgia Institute of Technology, 2009. http://hdl.handle.net/1853/34691.
Full textAbstract:
In this work, the development of theoretically-dense, clean grain boundary, high hardness solid-state sintered silicon carbide (SiC) armor was pursued. Boron carbide and graphite (added as phenolic resin to ensure the carbon is finely dispersed throughout the microstructure) were used as sintering aids. SiC batches between 0.25-4.00 wt.% carbon were mixed and spray dried. Cylindrical pellets were pressed at 13.7 MPa, cold-isostatically pressed (CIP) at 344 MPa, sintered under varying sintering soaking temperatures and heating rates, and varying post hot-isostatic pressing (HIP) parameters. Carbon additive amounts between 2.0-2.5 wt.% (based on the resin source), a 0.36 wt.% B4C addition, and a 2050°C sintering soak yielded parts with high sintering densities (~95.5-96.5%) and a fine, equiaxed microstructure (d50 = 2.525 µm). A slow ramp rate (10°C/min) prevented any occurrence of abnormal grain growth. Post-HIPing at 1900°C removed the remaining closed porosity to yield a theoretically-dense part (3.175 g/cm3, according to rule of mixtures). These parts exhibited higher density and finer microstructure than a commercially-available sintered SiC from Saint-Gobain (Hexoloy Enhanced, 3.153 g/cm3 and d50 = 4.837 µm). Due to the optimized microstructure, Verco SiC parts exhibited the highest Vickers (2628.30 ± 44.13 kg/mm2) and Knoop (2098.50 ± 24.8 kg/mm2) hardness values of any SiC ceramic, and values equal to those of the "gold standard" hot-pressed boron carbide (PAD-B4C). While the fracture toughness of hot-pressed SiC materials (~4.5 MPa m1/2) are almost double that of Verco SiC (2.4 MPa m1/2), Verco SiC is a better performing ballistic product, implying that the higher hardness of the theoretically-dense, clean-grain boundary, fine-grained SiC is the defining mechanical property for optimization of ballistic behavior.
6
Maensiri, Santi. "Thermal shock resistance of sintered alumina/silicon carbide nanocomposites." Thesis, University of Oxford, 2001. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.365329.
Full text
7
Sallom, Zuhair Kamil. "Evolution of particle characteristics in sintered hard metal." Thesis, University of Leeds, 1989. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.236236.
Full text
8
Okeke, Christopher Igwedinma. "Threading and turning of aerospace materials with coated carbide inserts." Thesis, London South Bank University, 1999. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.297919.
Full textAbstract:
The first part of this study involve an evaluation of the performance of TiN and AlZ03 single layer coated cemented carbide tools when threading inclusion modified, 708M40T (En 19T) 817M40T (En 24T) and Jethete steels at high cutting conditions by monitoring tool wear, failure modes, post threading workpiece properties, micro and macro-surface alterations and subsurface microhardness variation of threaded surfaces. Test results show that flank wear was the dominant failure mode, increasing rapidly when machining at the top speed of 225 m min,l due to the high temperature generated which accelerates thermally related wear mechanisms. Tool life, surface finish, hardness variation and component forces during threading were influenced by the geometry of the cutting edge, shape of wear/length of wear along tool nose/cutting edge after threading. Formation of flake-like oxide debris on the worn inserts was found to increase with nickel content in the workpiece material. The Al20) coated carbide inserts with K05 - K20 substrate gave longer tool life, lower cutting forces, better surface finish! damages as well as minimum hardness variation after threading compared with the TiN coated VSX grade with P20-P30 substrates. This can be related to their superior hardness, density, transverse rupture strength as well as the unalloyed WC fine grained substrate (1/lm) in addition to the high hot hardness, excellent chemical stability and low thermal conductivity of the AlZ03 coating at elevated temperatures. A formula for tool rejection was also developed during this study based on the average flank wear (VBb) and growth in thread root (GTR) in order to establish a scientific basis for assessing wear of threading tools. The second part of this study involve single point turning of a nickel base, G263, alloy using rhomboid-shaped PVD coated (TiN/TiCN/TiN, TiAIN and TiZrN) carbide tools at high speed cutting conditions. The worn tool edges revealed adhesion of a compact fin-shaped structure of hardened burrs with saw-tooth edges. The compact structure also formed on the cut surface of the workpiece material. The use of coolant during machining tend to work harden the root of the burr thereby restricting tool entry at the cutting zone leading to the generation of excessive feed force which subjects the tool edge to premature fracture and consequently lower tool life. The serrated/saw-tooth like edges of the burr encourages abrasion wear on the tool flank face and the formation of shallow cavities/lateral cracks where fragments of hardened workpiece material are deposited causing deterioration of the machined surfaces. Tool life was generally influenced by the cutting conditions employed as well as the insert geometry. Increasing cutting conditions (speed, feed and depth of cut) led to chipping of the cutting edge and/or flaking of coating layers as well as notching and fracture of the cutting edge. These failure modes jointly contributed to lowering tool life during machining. The TiN/TiCN/TiN coated KC732 (Tool A) inserts with positive sharp edges gave overall performance at the optimum cutting conditions established under finishing operation. This is followed by the TiN/TiCN/TiN coated KC732 (Tool B), TiAlN coated KC313 (Tool C) and lastly the TiZrN coated KC313 (Tool D) inserts' with razor sharp edges. Under roughing operation, the ranking order of tool performance is the TiZrN coated KC313 (Tool D), TiN/TiCN/TiN coated KC732 (Tool A), TiAlN coated KC313 (Tool C) and lastly the TiN/TiCN/TiN coated KC732 {Tool B). The difference in tool geometry and coating materials contributed to the relative order of tool performance.
9
Lide, Hunter. "Processing-Structure-Property Relationships of Reactive Spark Plasma Sintered Boron Carbide-Titanium Diboride." Thesis, University of North Texas, 2019. https://digital.library.unt.edu/ark:/67531/metadc1538698/.
Full textAbstract:
Sintering parameter effects on the microstructure of boron carbide and boron carbide/titanium diboride composites are investigated. The resulting microstructure and composition are characterized by scanning electron microscopy (SEM), x-ray microscopy (XRM) and x-ray diffraction (XRD). Starting powder size distribution effects on microstructure are present and effect the mechanical properties. Reactive spark plasma sintering introduces boron nitride (BN) intergranular films (IGF's) and their effects on fracture toughness, hardness and flexural strength are shown. Mechanical testing of Vickers hardness, 3-point bend and Chevron notch was done and the microstructural effects on the resulting mechanical properties are investigated.
10
Lide, Hunter. "Processing-Structure-Property Relationships of Reactive Spark Plasma Sintered Boron Carbide-Titanium Diboride Composites." Thesis, University of North Texas, 2019. https://digital.library.unt.edu/ark:/67531/metadc1538698/.
Full textAbstract:
Sintering parameter effects on the microstructure of boron carbide and boron carbide/titanium diboride composites are investigated. The resulting microstructure and composition are characterized by scanning electron microscopy (SEM), x-ray microscopy (XRM) and x-ray diffraction (XRD). Starting powder size distribution effects on microstructure are present and effect the mechanical properties. Reactive spark plasma sintering introduces boron nitride (BN) intergranular films (IGF's) and their effects on fracture toughness, hardness and flexural strength are shown. Mechanical testing of Vickers hardness, 3-point bend and Chevron notch was done and the microstructural effects on the resulting mechanical properties are investigated.
11
Rubink, William S. "Processing-Structure-Property Relationships of Spark Plasma Sintered Boron Carbide and Titanium Diboride Ceramic Composites." Thesis, University of North Texas, 2018. https://digital.library.unt.edu/ark:/67531/metadc1157631/.
Full textAbstract:
The aim of this study was to understand the processing – structure – property relationships in spark plasma sintered (SPS) boron carbide (B4C) and B4C-titanium diboride (TiB2) ceramic composites. SPS allowed for consolidation of both B4C and B4C-TiB2 composites without sintering additives, residual phases, e.g., graphite, and excessive grain growth due to long sintering times. A selection of composite compositions in 20% TiB2 feedstock powder increments from 0% to 100%, was sintered at 1900°C for 25 minutes hold time. A homogeneous B4C-TiB2 composite microstructure was determined with excellent distribution of TiB2 phase, while achieving ~99.5% theoretical density. An optimum B4C-23 vol.% TiB2 composite composition with low density of ~3.0 g/cm3 was determined that exhibited ~30-35% increase in hardness, fracture toughness, and flexural bend strength compared to commercial armor-grade B4C. This is a result of a) no residual graphitic carbon in the composites, b) interfacial microcrack toughening due to thermal expansion coefficient differences placing the B4C matrix in compression and TiB2 phase in tension, and c) TiB2 phase aids in crack deflection thereby increasing the amount of intergranular fracture. Collectively, the addition of TiB2 serves as a strengthening and toughening agent, and SPS shows promise for the manufacture of hybrid ceramic composites.
12
Pabit, Edgardo L. "Grain boundary and triple junction chemistry of silicon carbide sintered with minimum additives for armor applications." [Gainesville, Fla.] : University of Florida, 2005. http://purl.fcla.edu/fcla/etd/UFE0012140.
Full text
13
Jin, Le [Verfasser]. "Ultra-low friction of sintered silicon carbide in aqueous tribological environment of mechanical seals / Le Jin." Aachen : Shaker, 2018. http://d-nb.info/1186590602/34.
Full text
14
Toller, Lisa. "Alternative binder hardmetals for steel turning." Licentiate thesis, Uppsala universitet, Tillämpad materialvetenskap, 2017. http://urn.kb.se/resolve?urn=urn:nbn:se:uu:diva-332451.
Full textAbstract:
The goal of this work is to understand how the wear and deformation mechanisms of hardmetalinserts change when the cobalt binder phase is replaced with a dierent metal or analloy. The focus is on inserts for steel turning. The work presented in this licentiate thesisconsists of the rst steps.Cobalt is the most common binder phase in hardmetal tools based on tungsten carbide asthe hard phase. Metallic cobalt powder, present during the manufacturing, has been associatedwith lung diseases and an increased risk for lung cancer if inhaled. Therefore it is importantto investigate alternative binders as one possible solution.This work studies binder phase alloys from the iron-nickel-cobalt system. These alloyscan be either austenitic, martensitic or a mixture of the two phases. By changing the binderphase composition to change the crystal structure it is possible to tailor the macroscopic mechanicalproperties of the material. It is also possible to tailor the composition in such a waythat the binder is transformation toughening, forming martensite as a response to mechanicaldeformation.The majority of inserts for steel turning are coated, and it is important to investigate if thehardmetals with alternative binder can be coated and if the coating adhesion is sucient forsteel turning.Four dierent alternative binder alloys and one reference with cobalt binder coated bychemical vapour deposition were investigated by scratch testing to determine the adhesion.The scratch test adhesion was sucient on all samples, but signicant variations in coatingadhesion were found.One alternative binder with 86wt%Ni and 14wt%Fe and a reference with cobalt binder manufacturedto mimic state of the art turning inserts were tested in steel turning. The alternativebinder grades had a lower resistance to plastic deformation and this was attributed to earlyaking of the coating due to a lower coating adhesion. Focused ion beam and scanning electronmicroscopy were used to study the deformation of the hard metal in the used cuttinginserts.
15
Nauyoks, Stephen Edwin. "Microstructure of nano and micron size diamond-SIC composites sintered under high pressure high temperature conditions." [Fort Worth, Tex.] : Texas Christian University, 2009. http://etd.tcu.edu/etdfiles/available/etd-10152009-102152/unrestricted/Nauyoks.pdf.
Full text
16
Berglund, Lina. "The Effect of Cooling Rate on Sintered Cemented Carbides." Thesis, KTH, Materialvetenskap, 2020. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-288541.
Full textAbstract:
Magnetic measurements are useful tools for quality control of cemented carbides. Previous work at Sandvik Mining and Rock Technology has shown that the coercivity increases with increased cooling rate during sintering for a specific grade. This study aims to investigate why the coercivity changes with the cooling rate and if this is true for other cemented carbide grades as well. Three different cemented carbide grades were sintered with different cooling rates and evaluated with coercivity, Cobalt-magnetic saturation and hardness measurements, and with microscopy and Electron Backscatter Diffraction analysis. It was found that the coercivity increased with increasing cooling rates for the previously studied grade, but not for the two other grades. It was expected that the increased coercivity would indicate a decrease in WC grain size, but the results showed that the WC grain size of the fastest and slowest cooling rate were the same. However, a change in size of the Co areas between the WC grains was found. The fast cooled sample showed smaller Co areas than the slow cooled sample. These Co/WC grain boundaries increase the coercivity. An increased fraction of hcp-Co/fcc-Co was also found for the fast cooled material which also increases the coercivity. No relationship between the hardness and the coercivity or the cooling rate was found. The contiguity for the different grades was also calculated. No significant difference in contiguity between the different cooling rates of each material was found but the contiguity values between the different materials differed. This is probably mainly dependent on the different binder contents of the materials.Magnetiska egenskaper är en viktig del av kvalitetskontrollen av hårdmetaller. Tidigare forskning hos Sandvik Mining and Rock Technology har visat att koerciviteten hos en hårdmetallsort ökar med ökad kylhastighet vid sintring. Målet med den här studien är att undersöka varför koerciviteten ökar med kylhastigheten och om detta även gäller andra hårdmetallsorter. Tre olika hårdmetallsorter sintrades med olika kylhastigheter undersöktes med mätningar av koercivitet, magnetisk mättnat i koboltfasen och hårdhet, samt med mikroskopi och Electron Backscatter Diffraction analys. Det visade sig att koerciviteten ökade med ökad kylhastighet för hårdmetallsorten som studerats tidigare, men inte för de andra två sorterna. En ökad koercivitet förväntas visa på en minskad WC-kornstorlek, men resultaten visar att det långsamt kylda och snabbkylda provet hade samma WC-kornstorlek. Däremot upptäcktes en ändring av storleken på Co-områdena mellan WC-kornen. Det snabbkylda provet visade en mindre storlek av Co-områdena jämfört med det långsamt kylda provet. Fler Co/WC-korngränser i det snabbkylda provet leder till en ökad koercivitet. Fraktionen av hcp-Co/fcc-Co-korngränser ökade också för det snabbkylda provet vilket också ökar koerciviteten. Inget samband mellan hårdheten och koerciviteten eller kylhastigheten upptäcktes. Beräkning av kontiguiteten för de olika sorterna genomfördes också. Ingen signifikant skillnad i koercivitet mellan de olika kylhastigheterna för the olika sorterna hittades, men kontiguiteten mellan de olika sorterna varierade. Det beror mest troligt på att dom olika sorterna har olika mängd matrismaterial.
17
Joshi, Kunal J. "OPTIMIZATION OF CUTTING CONDITIONS FOR SUSTAINABLE MACHINING OF SINTERED POWDER METAL STEELS USING PCBN AND CARBIDE TOOLS." UKnowledge, 2006. http://uknowledge.uky.edu/gradschool_theses/379.
Full textAbstract:
Powder metals are becoming a popular choice in the automotive and other manufacturing industries because of their ability to meet wide ranging product functional requirements without compromising the performance of the product. They offer various advantages, including weight reduction, near net-shape processing capability, and their ability to be sintered to achieve desired properties in the end-product. However, in order to satisfy the product design requirements during manufacturing, they need to be machined to the required tolerances. Machining of powder metals is quite different to machining of traditional metals because of their specific properties, including porosity. This thesis work deals with the finish machining of powder metal steels in automotive applications, for increased tool-life/reduced tool-wear. Tool-life is affected by a variety of factors such as tool grade selection, tool coating, cutting conditions and tool geometry including cutting edge geometry. This work involves optimization of cutting conditions for plunge cutting and boring operations of automotive powder metal components using PCBN and carbide tools. The cycle time of the process introduces an additional constraint for the optimization model along with the tool-wear criterion. Optimized cutting conditions are achieved for maximum tool-life.
18
Lawson, Thomas Ryan. "Micro-Raman spectroscopy and dry turning evaluations of nanostructured diamond films deposited on tungsten-carbide lathe inserts." Birmingham, Ala. : University of Alabama at Birmingham, 2008. https://www.mhsl.uab.edu/dt/2008m/lawson.pdf.
Full text
19
Radzevičiūtė, Joana. "Tekinimo plokštelių dėvėjimosi ir jį įtakojančių veiksnių tyrimas." Master's thesis, Lithuanian Academic Libraries Network (LABT), 2010. http://vddb.laba.lt/obj/LT-eLABa-0001:E.02~2010~D_20100618_133958-94110.
Full textAbstract:
Tekinimas yra vienas iš svarbiausių metalo apdirbimo būdų detalių gamyboje. Tekinimo įrankis turi ypač didelę reikšmę šiame procese, jis pjaunamąsias savybes praranda dėl pjaunančiųjų briaunų ištrupėjimo, pjaunančiojo pleišto plastinės deformacijos ir ypač dėl peilio darbinio paviršių dilimo. Norint parinkti optimalius pjovimo rėžimus ir įrankius, reikia nustatyti pagrindinius veiksnius, turinčius įtakos tam procesui. Tad gamybinėje įmonėje atlikti aliumininių detalių apdirbimo, smulkiagrūdžio karbido tekinimo plokštelėmis stebėjimai, norint išsiaiškinti pagrindinius veiksnius turinčius įtakos plokštelių nusidėvėjimui. Buvo pasirinktos trys plokštelės, kurios dirbo skirtingais režimais. Užfiksuoti plokštelių išdirbiai, bei nudilimo tipai pagal plokštelių viršūnių pakitimus. Iš gautų duomenų nustatyta, kad daugiausia įtakos plokštelių nusidėvėjimui turi abrazyvinis, difuzinis ir adhezinis dilimai.Turning is the most popular in metal working and cutting tool has big dispose in this work. The durability of the cutting tool depends of the tool accuracy, quality, of the setting parameters, of the cutting regime and the formation of motion. The cutting tool loses its quality for the following reasons: cracking of the cutting edges; plastic deformation of the cutting tool and most important cutting tool working edge attrition. In the production facility was during the observation after aluminum parts production, where they were processed fine grain carbide turning plates. For research the main factors for affecting the plates wear. Three plates were chosen, which worked in different operating modes. Was recorded plates output and types of wear, by geometry changing of plates head. From the data obtained revealed that the main influencing the wear plate wear is abrasive, diffuse, and adhesive wear.
20
Tamil, Alagan Nageswaran. "Textured insert for improved heat extraction in combination with high-pressure cooling in turning of superalloys." Licentiate thesis, Högskolan Väst, Avdelningen för avverkande och additativa tillverkningsprocesser (AAT), 2017. http://urn.kb.se/resolve?urn=urn:nbn:se:hv:diva-11738.
Full textAbstract:
Heat generated in a machining process is a common and critical obstacle faced in today's machining industries. The heat generated in the cutting zone has a direct negative influence on the tool life which, in turn contributes to increase the manufacturing costs. Especially, in machining of Heat Resistant Super Alloys, HRSA this is a very limiting factor. HRSA are capable of retaining their mechanical strength and hardness at elevated temperatures. This property is advantageous in the application in e.g. aero-engines but also a disadvantage, since it also lowers the machinability significantly. This work is an attempt to improve the heat transfer from the cutting zone, which would lead to an increase in the tool life. To achieve this goal, the cutting tool has been modified to create an improved interface between the coolant and tool in the high-temperature areas. Two generations of inserts have been designed and investigated. Firstly, an insert with surface texture features has been created with the purpose of increasing the available surface area for heat dissipation: First generation, Gen I. Secondly, a GenII was designed as a further improvement of Gen I. Here, several channel features on the rake face were added, reaching out from the contact zone to the near proximity of the cutting edge. This with the purpose of improving access of the coolant closer to the cutting edge. The experiments were conducted in facing operations of Alloy 718 with uncoated round carbide inserts. All experiments were carried out with high-pressure coolant assistance, with a pressure of 16 MPa on the rake face and 8 MPa on the flankface, respectively.The two generations of inserts, Gen I and Gen II, were experimentally evaluated by tool wear analysis in comparison with a regular insert. The results shows that the tool life increased significantly for the Gen I insert, compared to a catastrophic failure of the regular insert at the same conditions. Regarding the Gen II insert,an increase in tool life by approximately 30 to 40 percent compared to Gen I insert was observed.
21
Zhao, Yanan [Verfasser], Heinz [Akademischer Betreuer] Konietzky, Heinz [Gutachter] Konietzky, Jürgen [Gutachter] Knorr, and Guicheng [Gutachter] He. "Geomechanical aspects of Sintered Silicon Carbide (SSiC) waste canisters for disposal of high level radioactive waste / Yanan Zhao ; Gutachter: Heinz Konietzky, Jürgen Knorr, Guicheng He ; Betreuer: Heinz Konietzky." Freiberg : Technische Universität Bergakademie Freiberg, 2021. http://d-nb.info/1229692002/34.
Full text
22
Lacerda, Felipe Soares. "Contribuição à usinagem de peças de metal duro sinterizado." Universidade de Taubaté, 2015. http://www.bdtd.unitau.br/tedesimplificado/tde_busca/arquivo.php?codArquivo=767.
Full textAbstract:
A necessidade de se usinar materiais de alta dureza e garantir bom acabamento superficial é um desafio para as atuais indústrias metal/mecânica. Além disso, coloca-se também a necessidade de fazê-lo de forma técnica e economicamente viável. Diante desse desafio o torneamento duro surge como uma
opção. Com o uso dos parâmetros (velocidade de corte, avanço e profundidade de corte) e ferramentas adequadas o torneamento duro possibilita uma adequada rugosidade superficial e pode substituir a necessidade de retificação, simplificando e reduzindo custos no processo de fabricação. Para que seja possível alcançar tais resultados, é necessária a pesquisa e validação de parâmetros que permitam a
execução do torneamento de materiais de alta dureza. Por meio de ensaios, de desbaste interno, realizados com peças de metal duro H11N e com ferramentas de diamante, foram feitos testes preliminares com o uso da ferramenta de projeto de
experimentos (DOE), para selecionar os melhores conjuntos de parâmetros (velocidade de corte e avanço). Foi realizado um segundo grupo de testes, finais, para garantir estatisticamente os melhores resultados, as informações obtidas foram
rugosidade, desgaste e número de passes. Com a análise dos resultados preliminares obtidos utilizando a ferramenta estatística de projeto de experimentos (DOE), foi identificado alta quebra de ferramentas (54%). Com a realização de
micrografias, a possibilidade do problema estar relacionado com a estrutura do material e ou com o tamanho do grão foi descartada. Foram detectadas ainda, marcas na superfície usinada dos corpos de prova que são indicadores da existência
de vibrações durante o processo, o que justifica o número elevado de quebras das arestas de corte de forma prematura. Os testes finais não apresentaram quebra prematura de ferramentas, e sim uma vida maior que o esperado. Foi estabelecido parâmetros viáveis para o processo, velocidade de corte de 22,1 m/min e avanço de 0,09 mm/rev. Através da análise do desgaste foi possível estabelecer um critério
para troca de ferramenta, que foi o desgaste de flanco (Vb) de 0,2mm.The necessity of machining materials with high hardness to ensure a good surface finish is a challenge for metal mechanic industries these days. Furthermore, it has the necessity to achieve this goal in a technical way and be economically viable. An option to tackle this challenge is hard turning. Through the use of parameters (speed cutting, feed rate and cut depth) and adequate tools, the hard turning enables a good surface roughness and can replace the need for grinding, making the fabrication process simpler and reducing the cost. In order for these results to be achieved, research is required and validation of parameters, which allow the realization of turning materials with high hardness. Through trials of internal thinning, with pieces made of H11N material and diamonds tools, Design of experiments (DOE) preliminary tests were carried out to select the best parameters group (cutting speed and feed rate). Secondary tests were done to ensure statically the best results in this case, the data obtained was of roughness, wear and tool life. When analyzing the preliminary results obtained using the statistic tool, design of experiments (DOE), it was identified that a high breakage of tools was occurring (54%). Through micrograph tests, the possibility of the problem being with the material structure and grain size was discarded. Traces were detected in the machining surface on the machined piece, these are indicators of the chance of vibration during the process, which can justify the high premature tool breakage. The final tests didnt show premature tool breakage, they showed the life span of the tool was longer than what was expected. Viable parameters were established for this process, cutting speed of 22.1 m/min and feed rate of 0.09 mm/rev. Through the wear analysis it was possible to establish a criterion of tool change, it was flank wear (Vb) of 0.02mm.
23
Bamford, Erik. "Tool wear in turning of titanium alloy Ti–6Al–4V : Challenges and potential solutions for crater wear, diffusion and chip formation." Thesis, Uppsala universitet, Tillämpad materialvetenskap, 2016. http://urn.kb.se/resolve?urn=urn:nbn:se:uu:diva-306373.
Full textAbstract:
Titanium alloys are major materials used in the airplane industry, and prospects show that airplane production will double in the next 20 years. Consequently, the demand for cutting tools for machining of titanium alloys will increase. The primary problem when machining titanium alloys is their low thermal conductivity. Crater wear is the main factor limiting tool life, and is generally caused by thermal diffusion due to high temperatures in the tool-chip interface. This master’s thesis was performed in collaboration with Sandvik Coromant, with the prospect to increase knowledge of how diffusion and chip formation influences crater wear progression. The aim was to study tool wear of cutting tools when turning Ti–6Al–4V. This was done by testing two different rake face geometries, both coated and uncoated, at cutting speeds of 30–115 m/min. Diffusion was investigated to learn about the impact it has on crater wear. Chips were examined to investigate chip formation and shear strain. The coated modified rake face insert showed less crater wear only for the initial few seconds of machining. Uncoated inserts with a modified rake face showed higher diffusion rate and faster crater wear progression than did standard inserts. The standard inserts showed twice as long tool life as did the modified inserts. No significant differences in the chip formation mechanism were found between modified and standard inserts. Cracks were found within shear bands that were thinner than usual, which suggest that the generation of cracks allows less shear deformation.
24
Rosário, John Ferney Alvarez. "Avaliação da integridade da superfície no torneamento de um ferro fundido nodular com carboneto." Universidade de São Paulo, 2006. http://www.teses.usp.br/teses/disponiveis/3/3132/tde-05092006-131535/.
Full textAbstract:
Neste trabalho, estudou-se a integridade superficial durante o torneamento de um ferro fundido nodular com carbonetos, considerando a heterogeneidade microestrutural (fração volumétrica, tamanho e morfologia de grafita e dos carbonetos) e os efeitos dos parâmetros de corte (avanço, velocidade de corte e profundidade de corte), baseados num planejamento fatorial fracionário 24-1. Este texto apresenta, numa primeira parte, uma revisão baseada em referências bibliográficas clássicas da engenharia de superfícies, na tentativa de definir os conceitos que compõem a integridade da superfície. Posteriormente, descrevem-se os resultados de ensaios preliminares, realizados com a finalidade avaliar os níveis do processo e os efeitos desses parâmetros na integridade da superfície. Finalmente, realizaram-se os ensaios de usinagem em corpos-de-prova de ferro fundido nodular com carboneto, nos diâmetros de 80 mm e 140mm. Durante os ensaios de torneamento empregaram-se duas velocidades de corte (60 m/min e 180 m/min), dois avanços (0,1 mm/rev e 0,3 mm/rev) e duas profundidades de corte (0,2 mm e 0,3 mm). Após os ensaios de usinagem, foram realizadas: a avaliação das propriedades do material usinado (dureza e microestrutura), a análise de topografia da superfície usinada mediante avaliação da rugosidade, e a avaliação da influência dos parâmetros de usinagem na rugosidade. Encontrou-se uma dependência estatisticamente significativa da variação nas propriedades mecânicas dos corpos-de-prova em função da microestrutura, e mostraram-se os efeitos dessas variações em termos da integridade da superfície usinada.In this work, the surface integrity of a ductile cast iron with carbides was studied during turning operations, considering the microstructural heterogeneity (volume fraction, size and morphology of the graphite and carbides) and the effect of the machining parameters (feed, cutting speed and depth of cut), based on a fractional factorial design 24-1. This work presents, initially, a literature review based on classic works on surface engineering, as an attempt to define the main concepts of surface integrity. Later, the results of preliminary test are described, which were conducted in order to define the process levels and the effects of these levels on the surface integrity. Finally, turning tests were conducted on specimens of ductile iron with carbides, at diameters of 80 and 140 mm. Two cutting speeds (60 m/min and 180 m/min), two feeds (0,1 mm/rev and 0,3 mm/rev) and two depths of cut (0,2 mm and 0,3 mm) were selected during the tests. Machined specimens were analyzed in terms of the properties of the machined material (hardness and microstructure) and of the roughness of the machined surface. The effect of the machining parameters on the roughness was also studied. A statistically significant dependence was observed for the properties of the machined specimens as a function of the microstructure and the effect of these properties on the surface integrity is presented.
25
Zdařil, David. "Technologie výroby vybraného sortimentu nástrojů s aplikací vysoce produktivního výrobního zařízení." Master's thesis, Vysoké učení technické v Brně. Fakulta strojního inženýrství, 2020. http://www.nusl.cz/ntk/nusl-417150.
Full textAbstract:
The aim of this work is to analyze the issue of providing cutting tools for internal use in the company STERCH-INTERNATIONAL s.r.o. It is mainly the production and regrinding of end mills and drills for specific machining applications, whose benefit lies in increased efficiency and flexibility of production, which also brings a significant cost reduction.
26
Öhman, Sebastian. "Wear on Alumina Coated Tools and the Influence of Inclusions when Turning Low-Alloy Steels : Master Thesis - Chemical Engineering." Thesis, Uppsala universitet, Tillämpad materialvetenskap, 2016. http://urn.kb.se/resolve?urn=urn:nbn:se:uu:diva-302956.
Full textAbstract:
In this master thesis, performed at Sandvik Coromant Västberga (Stockholm), a comprehensive study has been made to investigate the wear on textured alumina (Inveio™) coated cutting tools when turning low-alloy steels. Specifically, wear studies have been made on tools’ rake faces when turning two separate batches of SS2541, after an initial turning time of 4 min. A particular focus has been given to elucidate what particular role the inclusions might have for the wear of the alumina coating onthe tools. Evaluation of tool wear has been made by employing several different analytical techniques, such as LOM, SEM, Wyko, Auger-spectrometry (AES), EPMA and XRD. The results shows that the arisen wear marks on both tested tool types may be divided into three separate and highly distinguishable wear zones, denoted here in thiswork as “wear bands”. Largest amount of wear tended to occur initially at the topmost part of the 3rd wear band. This was true for both tested tool types. This area demonstrated a characteristic 'lamellar' wear pattern, composed of narrow andstructured ridges. All the tools tested demonstrated the adhesion of workpiece materials of various composition that formed into smeared layers in these formed ridges. Depth-profiling Auger-spectrometry revealed that a significant amount of calcium was present in the machined alumina coating layers. This suggests that a reaction between the calcium-containing inclusions found in the steel and the aluminacoating layer had occurred during the performed turning tests.These results arecontradictory to the general belief that alumina is chemical inert during machiningand has previously, to the authors knowledge, not yet been published. Based on the results from this thesis and from a literature review concerning thebehavior of α-alumina during deformation, a new theoretical wear model has been developed. In this model, it is emphasised that the sliding of hard inclusions from the steel may activate pyramidal slip systems in the textured alumina coating. This causes a nano-crystallisation and/or amorphisation in the topmost part of the coating, which facilitates the further wear of these coated tools.I detta examensarbete, som har utförts vid Sandvik Coromant i Västberga (Stockholm), har en omfattande studie gjorts i syfte att undersöka slitaget på texturerad aluminiumoxid-belagda skärverktyg (Inveio™) vid svarvningen av låglegerade stålsorter. Förslitningsstudier har framförallt gjorts på verktygens spånsidor vid svarvningen av två separata batcher av stålsorten SS2541 efter en inledande ingreppstid på 4 min. Ett särskilt fokus har även ägnats åt att belysa vilken roll stålets inneslutningar kan ha för slitaget av aluminiumoxidbeläggningen. Utvärderingen av verktygsslitaget har gjorts med hjälp av flera olika analytiska tekniker, däribland LOM, SEM, Wyko, Auger-spektrometri (AES), EPMA samt XRD. Resultaten från detta examensarbete visar på att det uppkomna slitaget på de verktyg som har testats kan uppdelas till tre separata och mycket distinkta ”slitagezoner”. Dessa zoner har för detta arbete benämnts som ”nötningsband”. Störst förslitning framträdde initialt i den översta delen av det 3:e nötningsbandet på de testade skärverktygen. Detta område uppvisade ett karaktäristiskt ”lamell”-liknande utseende, bestående av smala och strukturerade åsar och skåror. Vidare uppvisade samtliga undersökta verktyg på förekomsten av påsmetat arbetsmaterial av varierande sammansättning i dessa bildade åsar. När de slitna verktygen undersöktes med djuprofilerande Auger-spektrometri påvisades det att en signifikant mängd kalcium fanns inuti aluminiumoxidbeläggningen. Detta tyder på att en reaktion mellan de kalciuminnehållande inneslutningarna (som finns inuti stålet) och aluminiumoxidbeläggningen har reagerat med varandra under bearbetningsförloppet. Dessa resultat är motsägande till den allmänna uppfattningen om att aluminiumoxid är kemiskt inert vid bearbetningen av stål. Därutöver har dessa resultat även, till författarens kännedom, aldrig tidigare publicerats. Baserat på de resultat som har erhållits från detta examensarbete, och från en omfattande litteraturstudie gällande deformationen av α-aluminiumoxid, har en ny teoretisk förslitningsmodell utarbetats. I denna modell betonas det särskilt att glidningen av hårda inneslutningar från stålet kan aktivera s.k. pyramidala glidsystem i den texturerade aluminiumoxidbeläggningen. Detta orsaker en nano-kristallisering och/eller amorfisering av den översta delen av aluminiumoxidbeläggningen. Denna omvandling tros kunna underlätta den fortsatta förslitningen av dessa belagda skärverktyg.
27
Pavézka, Vladimír. "Analýza dokončovacích způsobů obrábění." Master's thesis, Vysoké učení technické v Brně. Fakulta strojního inženýrství, 2011. http://www.nusl.cz/ntk/nusl-229963.
Full textAbstract:
This eleborate study is aimed at analysis of complete methods machining. There are characterized particular methods and their effect on the surface´s quality of machined area in this study. Concluding part of the study includes practical demonstration of machining by using cemented carbide-tipped tool and polycrystalline diamond and evaluation of this demonstration.
28
Koen, Devan. "Investigation of novel cooling methods to enhance aerospace component manufacturing practices." Thesis, Stellenbosch : University of Stellenbosch, 2011. http://hdl.handle.net/10019.1/18058.
Full textAbstract:
Thesis (MScEng)--Stellenbosch University, 2011.ENGLISH ABSTRACT: The aerospace industry actively pursues innovation, especially in materials and their use in new applications, to improve their aircraft as well as their competitive position. Ti-6Al-4V has been available now for more than 50 years. Yet, in the new generation of aircraft using structural composites, a dramatic increase in the proportion of Ti-6Al-4V will be seen along with emerging application in automotive and chemical industries. This material possesses superior material properties compared to conventional materials such as steel and aluminium, although it is at the expense of machinability. Researchers are therefore actively searching for improved cutting technologies to improve production rates for Ti-6Al-4V. At higher cutting speeds than the industry norm of 60 - 90 m/min, machining becomes a challenge, resulting in low productivity on titanium parts. The limiting factor in the machining of Ti-6Al-4V is high tool temperatures of the order of 1000oC, caused by its resistance to absorb heat and good mechanical strength at elevated temperatures. The result is extreme temperatures that are concentrated on the cutting edge of the tool. The challenge to improve the tool life is therefore focused on removing heat from the insert. Liquid nitrogen was identified as a good candidate as coolant with the additional advantage of being environmentally friendly. The research presented investigates the use of a gravity feed enclosed liquid nitrogen cooling system to improve the tool life of the cutting inserts. The liquid nitrogen is contained on the insert rake face by means of a tool cap. To improve the effectiveness of the cooling method, a polycrystalline diamond (PCD) insert was used. This insert has a considerably higher thermal conductivity that aids in cooling the cutting edge. Tungsten carbide inserts are used for benchmark testing. The round tungsten carbide inserts with conventional cooling performed exceptionally well for machining titanium compared to square inserts, yielding exceptional tool life improvements while significantly increasing the material removal rate. Positive results were recorded with the liquid nitrogen cooling system when used with the polycrystalline diamond cutting insert. A number of far reaching performance issues are identified relating to the design of the tool cap that hindered clear scientific outputs. From a research perspective, the project makes a contribution to the knowledge base in this field. Additionally a new approach in cooling was investigated, resulting in clear indications of design changes required.
AFRIKAANSE OPSOMMING: Die lugvaart industrie streef aktief innovasie na, veral op die gebied van materiale en hul gebruike, om hul vliegtuie en kompeterende posisie in die mark te verbeter. Ti-6Al-4V is al vir meer as 50 jaar beskikbaar. ‘n Drastiese verhoging in die aanvraag na Ti-6Al-4V deur die lugvaart, motor en chemiese industrieë word verwag wanneer die volgende geslag vliegtuie wat koolstofvesel as strukturele materiaal begin gebruik, in produksie gaan. Die materiaal het beter materiaaleienskappe as konvensionele materiale soos staal en aluminium, maar dit kom egter teen die prys van masjieneerbaarheid. Ti-6Al-4V se masjienering bo die industrie norm van 60 – 90m/min is ‘n groot uitdaging. Navorsers soek daarom deurentyd na verbeterde sny tegnologieë om die produksie tempo van Ti-6Al-4V te verbeter. Die beperkende faktor vir Ti-6Al-4V masjienering is die temperatuur wat genereer word. Die weerstand van die materiaal om hitte te absorbeer en sy goeie meganiese eienskappe veroorsaak dat temperature in die beitel 1000oC bereik. Hierdie temperature word egter op die snykant van die beitel gekonsentreer. Die uitdaging is dus om hierdie temperature in die beitel te beheer. Vloeibare stikstof is geïdentifiseer as ‘n goeie kandidaat vir verkoeling met die bykomende voordeel dat dit omgewingsvriendelik is. Die navorsing wat hier uiteengesit word, ondersoek die gebruik van ‘n geslote kamer beitelverkoelingstelsel wat deur gravitasie met vloeibare stikstof voorsien word om die beitel leeftyd te verbeter. Die oppervlak van die beitel word in hierdie konsep direk aan die vloeibare stikstof blootgestel. Om die effektiwiteit van die stelsel te verbeter word van PCD beitels gebruik gemaak. Die beitel se verbeterde hittegeleidingsvermoë help om die beitel se snykant koel te hou. Tungstenkarbied beitels word gebruik om ‘n standaard te stel vir eksperimentele analise. Die ronde tungstenkarbied beitels en konvensionele verkoeling het verstommend goed presteer vir Ti-6A-4V masjienering in vergelyking met vierkantige beitels. Die materiaalverwyderingstempo is aansienlik verhoog sonder om die beitel se leeftyd in te boet. Positiewe resultate is waargeneem met die vloeibare stikstof sisteem saam met die PCD beitels. ‘n Aantal verreikende uitdagings is geïdentifiseer wat suiwer wetenskaplike afleidings bemoeilik. Hierdie probleme kan almal aan die ontwerp van die toerusting toegeskryf word. Die werk lewer egter steeds ‘n bydrae tot die kennis in die veld. ‘n Bykomende benadering vir verkoeling is ondersoek wat duidelik ontwerp-veranderings aandui.
29
Gonçalves, André da Motta. "Usinabilidade do carbeto de tungstênio no torneamento com ferramenta de diamante." Universidade de São Paulo, 2009. http://www.teses.usp.br/teses/disponiveis/18/18146/tde-17042010-090833/.
Full textAbstract:
Este trabalho apresenta o estudo da usinabilidade do carbeto de tungstênio utilizando ferramenta de ponta única de diamante em máquina-ferramenta de ultraprecisão, em função de suas características de dureza e potencial uso para a fabricação de micromoldes. O carbeto de tungstênio foi submetido a testes de usinagem para a determinação dos parâmetros e condições de corte para a obtenção do regime dúctil. Com base nos resultados experimentais, concluiu-se que, para os avanços da ordem de 1 micrômetro/revolução, a profundidade de corte (AP) não influencia significativamente no resultado de rugosidade, e para avanços da ordem de 3 micrômetros, observou-se a formação de trincas na superfície usinada. Além disso, para profundidades de corte maiores que 2 micrômetros as ferramentas começaram a apresentar lascamento. Para avanços da ordem de 3 micrômetro/revolução a profundidade de corte influencia com grande significância no resultado de rugosidade. O torneamento do carbeto de tungstênio usando ferramenta de diamante mostrou-se uma opção viável à produção de superfícies em termos de qualidade óptica, porém, devido à alta dureza deste material (aproximadamente 4000HV) o torneamento mostrou ser um processo com condições limitadas para a produção em série de componentes em função da baixa taxa de remoção de material permitida. É possível que a retificação possa apresentar taxas de remoção maiores, mesmo assim garantindo a qualidade superficial atingida pelo torneamento, ou ainda, a retificação possa ser usada como um processo no desbaste do carbeto de tungstênio seguido do torneamento de ultraprecisão como a opção viável a produção em série de peças. Portanto, para obtenção de uma superfície de carbeto de tungstênio sem danos e com acabamentos da ordem de 10 nm, a profundidade e avanço não devem ser superiores a 2,00 \'mü\'micrômetros e 1,00 \'mü\'micrômetro/revolução, respectivamente, usando uma ferramenta de diamante nova com ângulo de saída 0 ou - 25 graus e uma máquina-ferramenta de alta precisão.The single point diamond turning of the Tungsten Carbide is presented. The motivation for this study is the material´s high hardness and potential application for micromolds. A Tungsten Carbide sample was subjected to tests for determination of cutting parameters to achieve the ductile regime of material removal. Based on experimental results it was concluded that for the feedrate of the order of 1 \'mü\'m/revolution, the depth of cut did not affect significantly the surface roughness and for federates of the order of 3 \'mü\'m/revolution, the dept of cut influenced results of roughness greatly. Moreover chipping of the cutting edge occurs for depths of cut of 2 \'mü\'m. The diamond machining of tungsten carbide tool using diamond proved to be a viable option for the production of surfaces in terms of optical quality, but due to the high hardness of this material (approximately 4000HV) showed to be limited for the production of components due to the low material removal rate. It is possible that the precision griding may provide higher material removal rates along with the acceptable surface quality. Therefore, to obtain a damage free surface in tungsten carbide with surface finishe in the order of 10 nm, cutting depth and feedrate should be smaller than 2,00 \'mü\'m and 1,00 \'mü\'m/revolution, respectively, using a new diamond tool with rake angle of 0 or - 25 degrees and precision high stiffness machine tool.
30
Sudo, Tadeu Tomio. "Uma contribuição ao estudo do torneamento com alta velocidade." Universidade de São Paulo, 2001. http://www.teses.usp.br/teses/disponiveis/18/18135/tde-15032016-134826/.
Full textAbstract:
O material, metálico ferro fundido cinzento, é muito utilizado industrialmente, principalmente na área automobilística. Usinagem com alta velocidade tem sido uma tendência atual para aumentar a produtividade, com a possibilidade de se ober ótima qualidade superficial, possivelmente eliminando processos subseqüentes. Aliado à questão de qualidade ambiental, as operações de usinagem têm-se voltado para usinagem a seco ou com mínima quantidade de lubrificante (MQL - minimal quantity of lubricant). Este trabalho estuda o torneamento com alta velocdidade de ferro fundido cinzento GG25 através de usinagem a seco e com MQL. Utiliza-se, em operação de faceamento, ferramenta de cerâmica mista (Al2O3+ TiC) e metal duro com cobertura (TiCN/Al2O3/TiN), usando velocidades de corte muito acima dos valores tradicionais. Comparativamente o desgaste é significativamente menor na cerâmica. O tipo de desgaste predominante é o desgaste de flanco. Os principais mecanismos de desgaste encontrados são abrasão mecânica e delaminação. O aumento do avanço diminui o desgaste de flanco. Existe uma razão entre a vazão de óleo e a vazão de ar na lubrificação MQL que viabiliza sua aplicacão com relação ao desgaste de flanco. Em todas as condições testadas, o sistema MQL mostra ser capaz de reduzir a rugosidade superficial Ra.The gray cast iron material is very used industrially, mainly in the automotive industry. High speed machining is the current tendency to increase the productivity, with the possibility of obtaining good surface quality, possibly eliminating subsequent operations. Due to regulations on the subject of environrnental quality, the machining operations have been turned to dry machining or minimal quantity of lubricant (MQL). This work studies the turning process at high speed of gray cast iron GG25 with dry machining and MQL techniques. The operation uses face turning with coated carbide (TiCN/Al2O3/TiN) and mixed alumina ceramic (Al203+ TiC) with cutting speeds much higher than the traditional recommended values. Comparatively, the wear is significantly smaller in the mixed alumina ceramic tools. The predominant type of wear is the flank wear. The main wear mechanisms are mechanical abrasion and delamination. The increase of feed values shows some reduction on the flank wear. It seems to exist an ideal ratio of oil to air in the MQL system, which makes possible its application for reducing flank wear on the tools. In all conditions tested, the MQL system shows to be able to reduce surface roughness (Ra).
31
Meliani, Hasnaa. "Fonctionnalisation d'outils de décolletage de précision par micro-structuration de surface." Thesis, Bourgogne Franche-Comté, 2020. http://www.theses.fr/2020UBFCD022.
Full textAbstract:
L’usure des outils de coupe représente un problème majeur qui compromet la productivité et la capacité à réaliser des pièces de haute qualité. L’objectif de ces travaux de thèse est d’améliorer la durée de vie des outils coupants en carbure de tungstène, revêtus ou non, et destinés à l’usinage de l’acier inoxydable et de l’aluminium. La méthode de fonctionnalisation adoptée est la structuration de surface par laser femtoseconde.Dans un premier temps, une étude expérimentale qui traite de l’interaction entre le laser et le carbure de tungstène a été réalisée. Pour la première fois, tous les paramètres d’interaction laser/carbure de tungstène ont été déterminés, comprenant les conditions de génération des ripples et de structuration en régime d’ablation athermique.Des structures à différentes échelles dimensionnelles ont été réalisées et testées sur un tribomètre de laboratoire de type fermé. Le but étant d’étudier le comportement au frottement et à l’usure de surfaces structurées en milieu lubrifié et de les comparer à une surface de référence. La mouillabilité des surfaces structurées a également été mesurée et les énergies de surfaces correspondantes ont été déterminées.Dans la deuxième partie expérimentale, des essais d’usinage, en coupe orthogonale et en chariotage, ont été effectués avec des outils structurés. Un panel de structures a été testé afin d’identifier les structures géométriques favorisant la performance de l’outil.L’étude fait clairement apparaître le rôle de la fonctionnalisation de surface par structuration laser femtoseconde dans l’amélioration de la durée de vie des outils coupants de l’ordre de 30% dans certains casTool wear is a major issue which compromises productivity and the ability of manufacturing high quality components. The main objective of this thesis is to improve the lifetime of coated or non-coated tools made of tungsten carbide and intended for stainless steel and aluminum machining. The functionalization method used in this work is surface structuring by femtosecond laser.At first, experimental study is conducted to investigate the interaction between femtosecond laser and tungsten carbide material. For the first time, all laser-matter parameters for generating ripples or athermal ablation structures on tungsten carbide is determined.Several structures at different dimensional scales are produced and tested on a closed-type tribometer. The purpose is to study tribological performances, both friction and wear, using structured surfaces in wet environment and to compare them to a reference surface. Wettability of structured surfaces is also measured and corresponding surface energies are determined.In the second experimental part, machining tests are conducted with various structured tools in orthogonal cutting and longitudinal turning configurations. A panel of structures is tested in order to identify the best geometrical structure which improves cutting tool performance.This study clearly shows the role of surface functionalization via femtosecond laser structuring in improving the lifetime of cutting tools by 30% in some cases
32
Piwonski, Michael. "Keramische Membranen auf Basis LPS-SiC: Schlickerentwicklung und Beschichtungsverfahren." Doctoral thesis, Saechsische Landesbibliothek- Staats- und Universitaetsbibliothek Dresden, 2005. http://nbn-resolving.de/urn:nbn:de:swb:14-1138049474013-12420.
Full textAbstract:
Die Filtration unter aggressiven Einsatzbedingungen, z.B. Einsatz in korrosiven Medien, Abgasfiltration, stellt besondere Anforderungen an das Filtermaterial. Sogenanntes "Liquid Phase Sintered Silicon Carbide" (LPS-SiC) erfüllt die Anforderungen sehr gut. Deshalb bestand das Ziel der Arbeit besteht darin, erstmals aus LPS-SiC asymmetrische keramische Membranen (grobporöses Substrat mit dünner, feinporiger Membran) herzustellen. Als Additivsystem fanden Yttriumoxid und Aluminiumoxid Verwendung. Es wurde Siliciumcarbid der Körnung F1200 auf Substrat der Körnung F500 abgeschieden. Dem Herstellungsverfahren kommt für die Qualität der Membran eine große Bedeutung zu. Daher wurden in dieser Arbeit folgende Beschichtungsmethoden untersucht, um die optimale Methode zu identifizieren: Tauchbeschichtung, elektrophoretische Abscheidung, Druckfiltration und Einsatz von Transfertapes (Transfertapes: Mischung aus Polyacrylatkleber und Pulver). Im Mittelpunkt stand dabei die Druckfiltration. Hierfür wurde eine neue Apparatur konzipiert und aufgebaut. Für die schlickerbasierten Methoden wurde ein wässriges System entwickelt, bei dem auf den Einsatz von organischen Hilfsstoffen verzichtet werden konnte. Die elektrostatische Stabilisierung konnte durch gezieltes Anlösen von Yttriumoxid, Ausfällen von feinskaligem Yttriumhydroxid und Belegung des Siliciumcarbids mit dem Yttriumhydroxid erreicht werden. Die Elektrophorese führte zu keinen befriedigenden Ergebnissen aufgrund des undefinierten spezifischen Widerstandes des Substrats (siehe Dissertation Jan Ihle, Bergakademie Freiberg 2004). Die Druckfiltration erwies sich als das geeignetste Verfahren. Mit ihr konnten ohne Einschränkungen hochwertige Membranen erzeugt werden. Druck und Zeit sind bei gegebenen Feststoffgehalt frei wählbar. Der Druck wurde zwischen 2*10E4 und 1*10E5 Pa variiert. Höherer Druck führte zu feineren Porengrößen (mittlere und maximale Porengröße). Mit der Druckfiltration konnten Membranen ohne makroskopische Defekte erzeugt werden. Sie führte im Vergleich aller Verfahren zu der geringsten Rauhtiefe der Membranen. Die Tauchbeschichtung ließ sich in diesem System nur über den Feststoffgehalt steuern. Membranen aus der Tauchbeschichtung wiesen makroskopische Fehler (große oberflächliche Poren) auf. Die Methode führte hinsichtlich Porengrößen und Rauhtiefe zu den schlechtesten Werten. Die Transfertape-Methode als neuartiger Ansatz erwies sich für das LPS-SiC System als noch nicht ausgereift. Das direkte Bekleben der Substrate war möglich. Hinsichtlich der Membrandicke sind aber Grenzen bei ca. 50 µm gesetzt. Darüber hinaus reißen die Membranen. Es wurden Schwankungen in der Entbinder- und Sinterschwindung verzeichnet. Weiterhin werden große Hohlräume im Substrat nicht von den Transfertapes abgeformt. Beide Effekte erhöhen die Spannungen beim Sintern, so dass bei geringeren Schichtdicken Risse entstehenSilicon Carbide (SiC) fulfills many requirements, e.g. a high robustness in terms of corrosion, which makes it a suitable Material for ceramic membranes. The aim of this work was to produce ceramic membranes out of porous liquid phase sintered Silicon Carbide (LPS-SiC). As additives Alumina and Yttria were used. The SiC based on commercial abrasive powders F1200 (Membrane) and F500 (Substrate). Different techniques of membrane formation were applied in order to find the optimum processing procedure: Dip Coating, Electrophoretic Deposition (EPD), Pressure Filtration and the usage of so called Transfer Tapes, a blend of Polyacrylate and ceramic powders). For the slip based methods a water based system was developed without the need of organic additives. A pure electrostatic stabilization was facilitated by solving Yttria with Hydrochloride Acid and precipitation, resulting in the coverage of the SiC particles with finely dispersed Yttria. The EPD was not successful due to a undefined specific resistance of the substrate. The pressure filtration turned out to be the best, most versatile method, leading to defect free membranes with the lowest measured surface roughness. The pressure ranged between 2*10E4 and 1*10E5 Pa. Higher pressure lead to finer pores. The Dip Coating was controlled only by the solids content. Membranes by Dip Coating showed macroscopic defects. As a new concept for ceramic membrane fabrication the Transfer Tapes needed further investigation. The direct gluing on the substrate was possible. The thickness of the membrane was limited to 50 microns in order to keep free of cracks. The Transfer Tapes exhibited pronounced fluctuations in the debinding and sintering shrinkage, leading to increased tension during sintering. Furthermore cavities, (e.g. big pores) were bridged. Both effects lead to increased tension during sintering
33
Marques, Armando. "Torneamento de Inconel 718 com aplicação de lubrificantes sólidos." Universidade Federal de Uberlândia, 2015. https://repositorio.ufu.br/handle/123456789/14776.
Full textAbstract:
Fundação de Amparo a Pesquisa do Estado de Minas GeraisThe nickel-based superalloys have a high mechanical strength which remains at elevated temperature, high creep and fatigue resistances and excellent oxidation resistance. This makes these alloys highly recommended for use in high temperature working environments such as mechanical components for the aerospace industry. However, these characteristics are major problems when machining them, as it promotes high heat generation in the flow zone, resulting in the development of high wear rates on the cutting tools. In order to reduce the problems caused by the high temperatures generated, the application of a cutting fluid, when possible, is essential to reduce friction at the chip-tool-workpiece interfaces and lower the temperatures in the cutting zone. Seeking to further increase in the efficiency of cutting fluids during machining of nickel alloys, this work presents a study of the influence of solid lubricants, graphite and molybdenum disulphide (MoS2) mixed to a vegetal based cutting fluid, applied by conventional method (flooding) and minimal quantity of fluid - MQF in turning of Inconel 718 with carbide and ceramic (mixed, whisker and SiAlON) tools. When turning with cemented carbide tools the addition of graphite to the cutting fluid provided the best results, while with ceramic tools MoS2 presented the best performance. The life of the carbide tool had an average increase above 200% in conventional flooding application of cutting fluid when compared to MQF, regardless the addition of solid lubricant. The addition of solid lubricants promoted an increase in the life of whisker and SiAlON tools. The flank wear was dominant for cemented carbide tools and SiAlON ceramics, while for whisker and mixed ceramics the notch wear was predominant. Attrition and diffusion wear mechanism were observed in all evaluated conditions. The addition of solid lubricant to the cutting fluid provided significant improvements in the surface roughness values for most of the evaluated conditions. However, there were no significant changes in the machining forces and cutting temperature. The residual stress was tensile and compression, depending on the fluid application method. Overall, the addition of solid lubricant showed no significant differences.
As superligas à base de níquel apresentam alta resistência mecânica que se mantém em elevadas temperaturas, altas resistência à fluência e à fadiga e excelente resistência a oxidação. Isso torna estas ligas altamente recomendadas para utilização em ambientes que trabalham a altas temperaturas, como por exemplo na fabricação de componentes mecânicos para a indústria aeroespacial. Entretanto, esta característica representa um grande problema quando elas são usinadas, pois promove elevada geração de calor na zona de fluxo, implicando no desenvolvimento de altas taxas de desgaste da ferramenta de corte. A fim de reduzir os problemas causados pelas altas temperaturas geradas, a aplicação de um fluido de corte, quando possível, é essencial, proporcionando redução do atrito na interface cavaco-ferramenta-peça e menores temperaturas na zona de corte. Na busca de aumentar ainda mais a eficiência dos fluidos de corte na complexa usinagem das ligas de níquel, este trabalho apresenta um estudo da influência dos lubrificantes sólidos grafite e bissulfeto de molibdênio (MoS2) misturado a um fluido de corte de base vegetal, aplicados pelo método convencional (jorro) e mínima quantidade de fluído MQF, no torneamento do Inconel 718, com ferramentas de metal duro e cerâmicas (mista, whisker e SiAlON). No torneamento com ferramentas de metal duro a adição de grafite ao fluido de corte proporcionou os melhores resultados, enquanto que no torneamento com ferramentas cerâmicas, foi o MoS2 que apresentou melhor desempenho. A vida da ferramenta de metal duro teve um incremento acima de 200% na usinagem convencional (jorro) quando comparado com a usinagem por MQF, sem considerar a adição do lubrificante sólido. A adição de lubrificantes sólidos promoveu um incremento na vida das ferramentas whisker e SiAlON. O desgaste de flanco foi predominante para as ferramentas de metal duro e cerâmica SiAlON, enquanto que nas cerâmicas whisker e mista o desgaste de entalhe foi predominante. Os mecanismo de desgaste de attrition e difusão foram observados em todas as condições avaliadas. A adição de lubrificante sólido ao fluido de corte proporcionou melhorias significativas nos valores da rugosidade para a maioria das condições avaliadas. No entanto, não se observou mudanças significativas nas forças e temperatura de usinagem. As tensões residuais foram de tração e compressão, dependendo do método de aplicação do fluido. No geral, a adição do lubrificante sólido não apresentou diferenças significativas.
Doutor em Engenharia Mecânica
34
Andrews, Anthony. "Electrochemical corrosion measurement of solid state sintered silicon carbide (SSiC) and liquid phase sintered silicon carbide (LPSSiC) ceramic materials." Thesis, 2006. http://hdl.handle.net/10539/1721.
Full textAbstract:
Student Number : 0405740V -
MSc (Eng) dissertation -
School of Chemical and Metallurgical Engineering -
Faculty of Engineering and the Built EnvironmentSilicon carbide ceramics have many attractive properties, one of which is their high degree of corrosion resistance. Even though corrosion is slow, it does occur. Standard procedures for corrosion testing such as the immersion method is limited due to the low corrosion rates of most of these materials: it does not elucidate the mechanism of corrosion, but only gives the rate and degree of dissolution. Electrochemical techniques offer the possibility to further elucidate corrosion mechanisms and establish the resistance stability of conducting or partially-conducting ceramic materials, thus enhancing the understanding of ceramic material behaviour. In conjuction with microstructural changes, the electrochemical corrosion behaviour of solid state sintered silicon carbide (SSiC) and liquid phase sintered silicon carbide (LPSSiC) have successfully been studied at room temperature in acidic and alkaline environments by using potentiodynamic polarisation measurements. Several hypotheses were proposed to assist in establishing the effect of silicon and carbon on the corrosion mechanisms of these materials. The effect of the secondary phase on the electrochemical corrosion of the LPSSiC was also investigated. Corrosion current densities of the LPSSiC materials were much lower than the SSiC materials in all test solutions. The SSiC materials showed pseudo-passive behaviour in HCl and HNO3, due to the formation of thin layer of SiO2 on the surface. The carbon in the SiC compound increased the corrosion current densities in all test solutions for SSiC materials. The electrochemical corrosion of LPSSiC is due to the dissolution of SSiC and not the oxides; the chemcial attack on the oxide phases is mainly by acid-base type of reactions, rather than electrochemical corrosion involving redox reactions.
35
Lin, Chih-Hsien, and 林志賢. "Effects of additives on characteristic properties of sintered boron carbide." Thesis, 2016. http://ndltd.ncl.edu.tw/handle/36p3z6.
Full text
36
Can, Antionette. "Densification, microstructure and properties of liquidphase sintered silicon carbide materials." Thesis, 2006. http://hdl.handle.net/10539/172.
Full textAbstract:
PhD - ScienceThe relationships between densification and microstructure, and between microstructure and mechanical and electrical properties of liquid phase sintered silicon carbide were studied in detail using hot pressing, gas pressure sintering and ultra–high pressure sintering techniques. Silicon carbide was sintered with 10 mass-% addition of the Y2O3-Al2O3 system, with various molar ratios. Hot pressing was carried out at 1925oC under 30 MPa, in argon, for half an hour. Materials were gas pressure sintered at 1925oC, under a final gas pressure of 80 bars (8MPa), in argon, for an hour. Ultra-high pressure sintering was done at ca. 1550oC, under 5.5 GPa pressure, for 15 minutes. The hot pressed and gas pressure sintered materials were subsequently heat treated at 1925oC and 1975oC. Most of the silicon carbide materials were sintered to a density around 99% of theoretical density. The heat treatment of the hot pressed materials resulted in an increase in density not changing the porosity. The densities of the heat treated hot pressed materials corresponded to the density of the gas pressure sintered materials. This resulted from the difference in composition of grain boundary phases – yttrium silicates in the hot pressed materials and yttrium aluminates in the gas pressure sintered and heat treated materials. The average silicon carbide grain size in the materials strongly depended on the densification method. In gas pressure sintered and heat treated materials the mean grain size was up to three times higher than that in the hot pressed materials. Grain growth appeared to be higher in the highest alumina-content materials. The heat treatment at 1975 °C resulted in more pronounced anisotropic grain growth. The ratio of the silicon carbide polytypes of sintered materials and materials heat treated materials at 1925oC, did not change significantly. In the materials heat treated at 1975oC Rietveld analysis revealed a decrease in SiC-6H polytype and an increase in amount of 4H and 15R polytypes, compared to the materials heat treated at 1925oC. This can be attributed to the increase in diffusion rates of aluminium into the SiC lattice at 1975oC. Segregation patterns were observed in the high yttria content materials, with Y2O3:Al2O3 molar ratios greater than or equal to two, after gas pressure sintering and heat treatments. This was suggested to be due to he poor wetting of the silicon carbide grains by the yttria-rich grain boundary phase. On heat treatment, the Vickers hardness of hot pressed materials was found to be increased from 20 to 26 GPa and elastic modulus from 318 to 338 GPa. In addition, the log of the electrical conductivity of liquid phase sintered silicon carbide (measured at 330oC) ranged from 10-8 to 10-3 with the changes in grain boundary phases observed after the heat treatments. The grain boundary phase composition also influenced the strength of the materials, The highest strength, 657 + 50 MPa, was measured for the hot pressed material containing the YAG phase. Indentation fracture toughness was mostly influenced by the SiC grain growth during heat treatments. The most significant increase in fracture toughness, the largest being from 3.7 MPa.m1/2 up to 5.6 MPa.m1/2, was observed in the higher alumina content materials after heat treatment at 1975oC. The increase in fracture toughness was attributed to the presence of a higher amount of platelet-like SiC grains within a broader grain size distribution. These elongated grains increased fracture toughness by increasing crack path deflection and crack bridging. The electrical properties were evaluated by Impedance Spectroscopy measurements between room temperature and 330oC. The LPS SiC materials can be classified into three groups with different electrical properties. This classification could be related to the grain boundary phases present in the materials. The materials with the lowest conductivity were all hot pressed materials, containing crystalline silicates and amorphous grain boundary phases. The materials with intermediate conductivity include gas pressure sintered materials and a hot pressed material, which contained crystalline aluminates (Y3Al5O12, YAlO3 and Y4Al2O9) in their grain boundaries. The materials with the highest conductivity only contained the aluminates, YAlO3 and Y4Al2O9. A pseudopercolation model of conduction was proposed, in which electrons move along a path which goes through the thinner intergranular layers, with largest nearest neighbour contact. The temperature dependence of the log of the conductivity of hot pressed and gas pressure sintered materials showed that the conduction mechanism in these liquid-phase sintered silicon carbide materials was variable range hopping conduction of electrons between defect sites. The non-Arrhenius behaviour, together with the observed wide range of peak frequencies, led to the conclusion that the effect of silicon carbide itself was not observed in the impedance spectra. The 1/T0.25 log conductivity dependence showed that the Cole-Cole arcs are due to insulating grain boundary phases rather than semiconducting SiC. In the Cole-Cole plots of the hot pressed and heat treated hot pressed materials only the effect of one phase could be observed. In the gas pressure sintered materials and the hot pressed material containing mainly YAG phase, the effects of two phases were seen in the frequency range measured. Ultra-high pressure liquid-phase sintered silicon carbide materials showed ultra-fine SiC grains, which were highly inter-grown. Segregated grain boundary “core-rim” structures, consisting of an inner core of nonequilibrium yttria and outer rim of equilibrium yttrium silicate were observed in materials containing 4 mass-% to 15 mass-% sintering additives. The hardness of ultra-high pressure sintered 10 mass-% materials increased with alumina-content, from 20 GPa – 22 GPa, and increased with decrease in sintering additive, up to 23 GPa (for the 4 mass-% material).
37
Rahman, Arif. "Bulk and nano-scale characterization of polymer derived silicon carbide and comparison with sintered silicon carbide." 2009. http://digital.library.okstate.edu/etd/Rahman_okstate_0664M_10502.pdf.
Full text
38
Liou, Pin-You, and 劉品佑. "Effect of additives of TiB2-riched mixture on characteristic properties of sintered boron carbide." Thesis, 2019. http://ndltd.ncl.edu.tw/handle/f4hpb7.
Full textAbstract:
碩士國立臺灣海洋大學
材料工程研究所
108
The research aims of fabricate the body of boron carbide(B4C) ceramic marterial by using pressureless sintering method preformed separately with mix sintered aids (TiB2, TiB2-ZrB2, TiO2, ZrO2) of various Zr/Ti ratio (0, 0.17, 0.36, 0.56 and 0.78) under distinct sintering temperatures (2200ºC, 2250ºC). The sintered ceramic bodies were subsequently carried out the measurement of density and Vickers hardness, the x-ray diffractometer (XRD) examination as well as scanning electron microscope (SEM). After XRD analysis, the results showed that the secondary phase((Ti, Zr)B2) formed in the sintered boron carbide bodies, regardless of the mixed sintered aids. This phenomenon is due to the lattice type of TiB2 is similar to ZrB2, and the atomic radius of Ti differs from that Zr by only 10% different; therefore, ZrB2 could dissolve into the TiB2 lattice to form a continuous solid solution. When boron carbide added with oxide sintered aids (TiO2, ZrO2) for pressureless sintering, the liquid phase is generated during high temperature, and the liquid phase fills the porosities and defects, increase the density and improve the mechanical properties of the sample; As for added boride sintering aid (TiB2, ZrB2), the powders will mutually diffuse and join each other, thereby improving the mechanical properties. Consequentially, when the B4C was calcined at the temperature of 2250 ºC with mixed oxide sintered aids (TiO2+ZrO2+C), the sintered boron carbide bodies can obtain the excellent densification (~97%) and hardness (~32 GPa). and show a great mechanical performance which is a useful ceramic material fabrication for the application of intended anti-ballistic armour. Keywords: boron carbide (B4C), mixed sintered additive, anti-ballistic armour.
39
Liu, Che-Yuan, and 劉哲原. "Study on the Mechanical Properties and Ballistic Performance of Liquid Phase Sintered Silicon Carbide." Thesis, 2015. http://ndltd.ncl.edu.tw/handle/03936140588285853546.
Full textAbstract:
博士國立臺灣大學
材料科學與工程學研究所
103
Ceramics exhibit excellent ballistic performance. However, many large cracks are formed after being hit by bullet for their brittle nature. The multi-impact protection ability of ceramics is thus limited. In the present study, a liquid-phase sintered silicon carbide (LSC) was prepared for the applications as ceramic armor. Its microstructure-ballistic performance relationships are established. The controlling factors for ballistic performance under single-hit and multi-hit are investigated. The design principles for ceramic armor are then proposed. More importantly, the factor controlling multi-impact performance is determined; direct experimental evidence is provided. In the present study, the SiC specimens doped with Al2O3 and Y2O3 is prepared by pressureless sintering. The microstructure is characterized and the ballistic performance is evaluated. For comparison purpose, the SiC specimens prepared by solid-state sintering were also prepared. For single-impact resistant, the kinetic energy from bullet correlates strongly to the hardness of ceramic armor. The hardness of solid-state sintered SiC (SSC) is higher; its performance against single impact is better than that of LSC. It can be related to the presence of two second phases, Y3Al5O12 (YAG) and Y4Al2O9 (YAM) after sintering at 1875 °C. Due to the formation of YAG and YAM, the hardness of LSC decreases from 23.2 GPa to 15.6 GPa. Compared with SSC specimens, the single-impact resistance of LSC specimen is 5-40% lower than that of SSC specimen. Due to the difference of CTE between the second phase and SiC matrix, residual stresses are generated. The presence of residual stresses encourages more crack deflection. The KIC value with the second phase increases from 2.7 MPa．m0.5 to 4.6 MPa．m0.5. The toughened LSC specimen disperses the shock wave energy from bullet impacts through intergranular fracture. The trauma area in LSC specimens is 25-60% smaller than that in SSC specimen. The liquid-phase sintered SiC thus exhibit better resistance against multiple impacts.
40
shing, Zheng shih, and 鄭世欣. "Sintering temperature and carbide content on the sintered microstructures and properties of Ni60-WC-Cr3C2." Thesis, 2016. http://ndltd.ncl.edu.tw/handle/67474230231085767383.
Full textAbstract:
碩士國立臺灣科技大學
機械工程系
104
In this study, sintered Ni60-WC-Cr3C2 composites with different carbide concentrations were processed at different temperatures. There are three parts in this study. In the first part, the specimens were analyzed by scanning electron microscope (SEM) to examine the densification behavior, and XRD and EDXA to examine the constituting phases. In the second part, Optimization of the hardness was achieved by plotting the broken-line graph of carbide concentration, temperature and hardness. In the last part, the optimized composite in the second part were tested by corrosion test, wherein a 70% acid was used. It was found the optimized composition and temperature is 30.0 vol% carbide sintered at 1150°C. The microstructural ananlysis indicted hardness is 899.9 kgf/〖mm〗^2, corrosion rate is 7.0 mg/〖cm〗^2．hr, porosity is 1.65%.
41
Zhao, Yanan. "Geomechanical aspects of Sintered Silicon Carbide (SSiC) waste canisters for disposal of high level radioactive waste." 2020. https://tubaf.qucosa.de/id/qucosa%3A74150.
Full textAbstract:
High-level radioactive waste (HLW) poses threat to the biosphere. Geological disposal is accepted as a safe way for HLW disposal. Waste canisters made of Sintered Silicon Carbide (SSiC) are proposed and geomechanical safety aspects relating to such SSiC canisters are investigated.
First part of the thesis reviews the state-of-the-art and demands for HLW disposal. The reason for considering Silicon Carbide (SiC) as canister material is explained. Especially in terms of corrosion and lifetime, ceramics and especially SiC is superior to metals or concrete. The only concern is its brittle behavior.
The second part of the thesis presents results on static and dynamic mechanical properties of SiC in general and in particular for SSiC based on literature review and own lab tests. Although strength values for SiC and especially SSiC are very high, the extreme brittle behavior has to be considered in case of impact or point-like loading.
The third and most extensive part of the thesis part contains numerical simulations, which consider most critical potential loading situations during transport and installation of the canisters underground. Both, pure elastic continuum and DEM based models are used considering the following loading situations (critical scenarios):
Freefall of canister during transport or installation (FF), Impact by falling rock block at disposal site (RF), Point loading due to accidental insertion of small stone below the canister (PL), Anisotropic earth pressure loading after disposal (EP).
Coating to protect the canisters against damage is investigated and preliminary parameters in terms of stiffness and thickness are recommended.
42
Huang, Yi-Lun, and 黃宜倫. "A study on chip breaker design of tungsten carbide inside-hole rough turning tools of the cutting force of turning medium carbon steel." Thesis, 2013. http://ndltd.ncl.edu.tw/handle/82539262420687626248.
Full textAbstract:
碩士國立宜蘭大學
機械與機電工程學系碩士班
101
The inner hole cutting forces by using lathe tool for medium carbon steels are well studied. The inner hole cutting forces with different trip's rake angles associated with different chip breaker widths are examined by dynamometer by using different feed rates and different cutting depths. The results show that the inner hole cutting forces for the lathe tool with rake angle are less than the lathe tool without rake angle. The cutting forces for the chip breaker within 1～3mm of the 25° rake angle lathe cutter are the smallest. Even the feed rate lower to 0.42mm/rev, the cutting force for the lathe cutter with 25° rake angle is less than the cutting force for the lathe cutter with 20° rake angle.
43
Yan-Fu, Lin, and 林焰福. "A Study on Chip Breaker Design of Tungsten Carbide Tools for Turning Medium Carbon Steel." Thesis, 2012. http://ndltd.ncl.edu.tw/handle/52334210606834730022.
Full textAbstract:
碩士國立宜蘭大學
機械與機電工程學系碩士班
100
The study mainly develops the sharp corner turning tool with a ladder-type chip breaker; the dynamometer to measure the three-dimensional cutting forces of the actual turning , to set the width and the side slope angle of chip-breaker, the tool is used to discuss the relationship between depth and feed in cutting, thus , improving the geometry and angle of chip-breaker, to reduce the cutting force and processing requirements to achieve better so that the cutting tool has the function of chip-breaker and reduces the cutting forces to improve the processing quality. We can, meanwhile, do a study to find out the best relations according to the width and depth of the chip-breaker. Finally, the chip-breaking machinability caused by the cutting tool can be discussed for the future tool design and analysis of manufacture and information for reference
44
Liu, Tzuan-Horng, and 劉醇鴻. "The tribological characteristics and turning performance of chromium carbide films deposited by unbalanced magnetron sputtering." Thesis, 2001. http://ndltd.ncl.edu.tw/handle/95029496588609317955.
Full textAbstract:
碩士國立成功大學
機械工程學系
89
The tribological characteristics and cutting performance of indexable inserts with chromium carbide films deposited by unbalanced magnetron sputtering were discussed in this thesis. At first, for complete understanding of properties and structures of chromium carbide films, the experiments of micro-hardness tester, scratch tester, SRV tester and SEM…etc were employed. Indexable inserts with chromium carbide films were applied to turning S45C medium carbon steel、copper and 6061 aluminum alloy. The influence of the thickness and the chromium content in chromium carbide films on wear resistance and cutting performance were discussed. The cutting performance also compared with commercial inserts with multi-layered coatings. The experiment results are shown as following : The higher the chromium content in chromium carbide films, the higher the hardness of the films. The chromium carbide films showed nearly equal or better wear resistance , and higher hardness after 600℃ heat treatments. In the turning experiment, we used the confirmation and analyses recommended by Taguchi method to optimize a condition for sputtering parameters. The most significant factor among the four factors in this experiment (bias voltage of the substrate, OES, flow rate of the argon gas and electric current of the target) is the OES parameters, so we focus the parameter in the later experiment . Due to it is very easy to adhere with steel，the tool life of chromium carbide coated inserts was shorter than commercial inserts but 0.7 times more than that of uncoated inserts on machining medium carbon steel. When turning copper, OES50-3(chromium content:68%, film thickness:3μm ) coated insert showed fantastically excellent performance, the tool life was 1.6 times more than that of uncoated insert .OES10-3 coated insert was found to reduce cutting force and the roughness of machined surface on turning copper and 6061 aluminum alloy .
45
Lin, Y. C., and 林炎成. "THE RESEARCH OF INFLUENCES OF ELECTRO-DISCHARGE ENERGY TO E.D. M. CHARACTERISTICS AND BENDING STRENGTH OF SINTERED CARBIDE." Thesis, 1995. http://ndltd.ncl.edu.tw/handle/45859038429652683986.
Full textAbstract:
碩士國立中央大學
機械工程研究所
83
Because the low thermal conductivity of sintered carbide, it is easy to crack at the surface during E.D.M.. It influences the life and presision of tool and mold severely. In experiments, we change the parameters of E.D.M. to examine the crack state and bending strength of materials due to electro-discharge Experiments show that the material removal rate is better at higher electro-discharge energy density during machining P and K kind sintered carbide, but the electrode wear rate increases. When machining P kind sintered carbide, the material removal rate is better, and the electrode wear rate is smaller.
46
Maseko, Thandazi Makhosazana. "Influence of carbon content and sintering temperature on the green and sintered properties of cemented carbide tool grades." Thesis, 2015. http://hdl.handle.net/10539/17636.
Full textAbstract:
A research study was done on four different cemented carbide cutting tool grades, which had different Co contents and different compositions of additional carbides such as TiC, TaC, NbC, Cr3C2 and TiCN. The tool grades were manufactured using the powder metallurgy process. The aims of the research were to investigate how carbon content and sintering temperature influences the material properties, and if possible to select the optimum parameters to yield the best sintered properties for each tool grade. The chemical analysis of the starting and milled powders with three different C contents were done using X-ray Fluorescence (XRF) and Inductively Coupled Plasma- Optical Emission Spectroscopy (ICP-OES), with phase identification and morphology done using X-Ray Diffraction (XRD) and Scanning Electron Microscopy (SEM) analysis. The milled and dried powders were pressed and sintered at three different sintering temperatures. Microstructural characterization of the sintered alloys included phase analysis, and measurement of the WC grain size, WC contiguity and Co binder mean free path. The hardness, toughness, coercivity, density, porosity and magnetic cobalt was determined using relevant standards. In general, as the C content increased, graphite formed in the alloys which resulted in lower hardness and toughness. The hardnesses of the different grades were affected in different ways and were dependent on the level of mixed carbides added and the Co content. It was also clear that as the Co content increased with the increase in C level, the hardness of the alloys decreased. The density for all the alloys decreased with an increase in C content. The porosity for all the alloys increased with an increase in C content. As the sintering temperature increased grain growth increased. However, with the addition of Cr3C2, which is a grain growth inhibitor, some alloys could be sintered at higher temperatures with limited grain growth. For all four tool grades the best material properties were obtained with the stoichiometric C content. With respect to sintering temperature, two grades showed the best properties at 1430°C while the other two grades had their best properties at 1510°C.
47
Rokebrand, Patrick. "Spark plasma sintered nanostructured ceramics for bio ceramic applications: Titanium carbide and titanium nitride in an alumina matrix." Thesis, 2013. http://hdl.handle.net/10539/12527.
Full text
48
Wu, Min-Han, and 吳旻翰. "A Study of Cutting Force in Turning Stainless Steels Using Tungsten Carbide Tool with A Chip Breaker." Thesis, 2013. http://ndltd.ncl.edu.tw/handle/74619532311406571298.
Full textAbstract:
碩士國立宜蘭大學
機械與機電工程學系碩士班
101
The main purpose of this paper is to study the cutting performance and cutting force in turning stainless steel using tungsten carbide tool with a chip breaker. Firstly, the tool tip is ground according to the tool specifications, then ground a groove and chip breaker rank angle in tip’s surface and measuring the groove size and chip brake angle by a tool maker. Finally turning the stainless steel, and measuring the cutting forces by a dynamometer. Comparing the different tool geometries, different tool chip breaker groove and brake angle, the chip breaker rake angle is 25°and the chip breaker width is 2 mm, the cutting force is the smallest.