Дисертації з теми "Metallic stents"
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AL-Mangour, Bandar. "The use of cold sprayed alloys for metallic stents." Thesis, McGill University, 2012. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=107900.
Повний текст джерелаL'invention du stent coronaire, est un tube en treillis métallique conçu pour maintenir les artères ouvertes dans le traitement des maladies cardiovasculaires. Des résultats cliniques prometteurs ont été rapportés. Cependant, le succès à long terme des stents est problématique à cause des resténoses intra-stent et des fractures de stent par fatigue. Dans ce travail de recherche, il est proposé d'utiliser la technologie de pulvérisation dynamique des gaz à froid (CGDS) comme une alternative pour la fabrication de stents métalliques. En CGDS, de fines particules sont accélérées avec une vitesse élevée et subissent une déformation plastique à l'impact sur un substrat. La particularité du CGDS parmi les autres techniques de pulvérisation thermique est que la température des gaz dans le processus est bien en dessous du point de fusion de la matière. Par conséquent, les effets indésirables des températures élevées, telles que l'oxydation, la croissance du grain et les contraintes thermiques, sont absents. Comme la majorité des stents sont faits en acier inoxydable 316L et en alliage Co-Cr, cette étude porte spécifiquement sur le développement et la caractérisation de l'acier inoxydable et l'acier inoxydable 316L mélangé avec revêtements d'alliages Co-Cr produite par le procédé CGDS. Les techniques de microscopie électronique à balayage et à diffraction d'électrons rétrodiffusés ont été utilisées pour étudier les changements de microstructures de ces revêtements avant et après recuit. L'effet du type de gaz sur la microstructure des revêtements 316L et le rôle du post-traitement thermique à froid par pulvérisation dans la microstructure et les propriétés mécaniques et électrochimiques ont été également étudiées.
Mousselli, Jad. "On surface electropolishing for the development of metallic stents." Master's thesis, Université Laval, 2019. http://hdl.handle.net/20.500.11794/36574.
Повний текст джерелаCardiovascular diseases (CVD) are responsible for about one-third of all death cases in Canada. One of the solutions used to solve this problem is using a metallic device made of a mesh and called a stent. Stents are small devices that are implanted in narrowed blood vessels to restore blood flow and to avoid a heart attack or stroke and to treat brain aneurysms. An accurate surface control is needed to assure the cytocompatibility of the chosen alloy with its biologic environment. Metallic stents must satisfy precise conditions defined according to their final application. They need to respect strict requirements, in terms of mechanical properties, electrochemical interaction (corrosion) and cytocompatibility. The following alloys are traditionally used in biomedical applications and more precisely for cardiovascular applications: the alloy AISI316L is considered a reference in this field, but the alloy L605, a Co-based material, is gaining more and more importance, due to its high mechanical properties (high ductility and high ultimate tensile strength) and high corrosion resistance. The use of Titanium alloys is the new frontier for biomaterials in cardiovascular applications, it is considered as a new potential candidate for cardiovascular stents. Titanium alloys, shows a unique combination of high strength and high ductility (ultimate tensile strength and uniform deformation higher than 1000 MPa and 30%, respectively). Electropolishing is a pre-treatment step applied to these alloys to obtain chemically homogeneous surfaces, covered with a uniform and amorphous oxide layer, generally with a very smooth roughness. This process not only makes it possible to control the physical properties of the surface, but also the chemical ones. The electropolishing process has some changeable variables, such as current, voltage, electrolytic solution and temperature of electrolyte. By controlling them, it is possible to understand and improve the surface properties. This work is aimed at studying the effects of electropolishing changeable variables (current, voltage, electrolytic solution) on surface characteristics/properties (morphology, chemical composition and wettability) of those alloys used for the manufacture of stents.
Halwani, Dina. "Metal-tissue interactions in early stage biocorrosion of metallic stents." Birmingham, Ala. : University of Alabama at Birmingham, 2007. https://www.mhsl.uab.edu/dt/2007m/halwani.pdf.
Повний текст джерелаAdditional advisors: Peter G. Anderson, Brigitta C. Brott, Jack E. Lemons. Description based on contents viewed Feb. 4, 2008; title from title screen. Includes bibliographical references (p. 69-70).
Oikarinen, H. (Heljä). "Imaging of biliary carcinoma, fistula and primary sclerosing cholangitis and percutaneous metallic stenting in malignant biliary obstruction." Doctoral thesis, University of Oulu, 2001. http://urn.fi/urn:isbn:9514259173.
Повний текст джерелаDorri, Megan Mahrokh. "Study for the optimization of interfacial properties between metallic substrates and polymeric coatings by plasma-based surface modification methods to improve performance of vascular stents." Doctoral thesis, Université Laval, 2017. http://hdl.handle.net/20.500.11794/28229.
Повний текст джерелаOver the past 15 years, ischemic heart disease and stroke have remained the leading causes of death, worldwide. According to the World Health Organization, 15 million of the 56.4 million global deaths, in 2015, were caused only by ischemic heart disease or stroke. For the treatment of these diseases, surgical treatments have been introduced and improved to hold the blood vessels open. Among the surgical treatments, angioplasty with stenting is the most popular and the least invasive treatments. Stents, which are wire mesh tubes, prepare a mechanical support for blood vessels and hold them open to restore the blood flow. They are mostly made up of AISI316L stainless steel (SS316L), cobalt-chromium, and titanium alloys. More than half a century ago, when a stent first used, it has considerably evolved. However, release of potentially-toxic metallic ions and deterioration of mechanical properties due to corrosion, and decrease of polymeric coatings adhesion, in case of coated stents, still constitute major concerns in SS316L stents. In the case of SS316L stents, to circumvent the release of metallic ions, in the laboratory for biomaterials and bioengineering of Université Laval (LBB), a fluorocarbon (CFx) coating was previously investigated to isolate the stent completely from the biological environment. The coating also enables subsequent grafting of bioactive molecules to improve its integration in the body. The results were promising; however, the interface of SS316L/CFx needed to be modified to improve the adhesion of the CFx coating. In this Ph.D. research project, a new interface between the SS316L substrate and the CFx coating was created by plasma oxidation. The properties of this new interface, which was an oxide layer, was modified by varying the plasma-process parameters in order to preserve its properties after a 25% plastic deformation. This deformation is the maximum plastic deformation that imposes on a stent during its implantation. The new interface decreased the release of ions by decreasing the corrosion rate of the SS316L substrate by a factor of three. It was also found that the new interface produced an adequate adhesion of the CFx coating to the substrate after deformation as well as after immersion in an aqueous saline solution. The new oxide layer on SS316L was an amorphous oxide layer with an approximately 6 nm thickness, which was clearly distinguished from the polycrystalline microstructure of the substrate. The enhancement of the interface properties was ascribed to this nano-thick amorphous oxide layer, which was found to be more resistant to plastic deformation. This new oxide layer can be produced on bare-metal stents made of passivating metals. Moreover, it can create a favorable interface for coated stents, which have been used in drug-eluting stents, and also to improve stents integration in the human body.
Sullivan, J. H. "Metallic runoff from coated steels." Thesis, Swansea University, 2003. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.639132.
Повний текст джерелаMinata, Mauricio Kazuyoshi. "Próteses metálicas ou gastrojejunoanastomose no tratamento paliativo da obstrução gastroduodenal: revisão sistemática e metanálise." Universidade de São Paulo, 2018. http://www.teses.usp.br/teses/disponiveis/5/5168/tde-28092018-115210/.
Повний текст джерелаIntroduction: malignant gastric outlet obstruction is a frequent condition in advanced gastric and pancreatic neoplasms. Palliative treatment can be performed by endoscopic or surgical techniques. Palliation aims to relief symptoms and increase quality of life. Although surgical therapy is the established treatment, the complication rate of the procedure and the unfavorable clinical conditions must be considered. Despite the advances in the endoscopic treatment and the possibility to offer a minimally invasive therapy, complication rate and need of reintervention must be reminded. New technologies have been developed to minimize the complications related to the use of stents and require a detailed analysis. This systematic review aims to compare surgery and covered and uncovered stent treatments for gastric outlet obstruction. Methods: randomized clinical trials were identified in MEDLINE, Embase, Cochrane, LILACs, BVS, SCOPUS and CINAHL databases. Comparison of covered and uncovered stents included: technical success, clinical success, complications, obstruction, migration, bleeding, perforation, stent fracture and reintervention. The outcomes used to compare Gastrojejunostomy and stents were technical success, complications and reintervention. Patency rate could not be included because of lack of uniformity of the extracted data. Results: eight studies were selected, three comparing gastrojejunostomy and stents and five comparing covered and uncovered stents. The meta-analysis of surgical and endoscopic stent treatment showed no difference in the technical success and overall number of complications. Stents had higher reintervention rates than surgery (RD: 0.26, 95% CI [0.05, 0.47], NNH: 4). There is no significant difference in technical success, clinical success, complications, stent fractures, perforation, bleeding and the need for reintervention in the analyses of covered and uncovered stents. There is a higher migration rate in the covered stent therapy compared to uncovered self-expanding metallic stents in the palliation of malignant gastric outlet obstruction (RD: 0.09, 95% CI [0.04, 0.14], NNH: 11). Nevertheless, covered stents had lower obstruction rates (RD: -0.21, 95% CI [-0.27, - 0.15], NNT: 5). A subgroup analysis with studies that included only patients with gastric cancer showed similar results when compared with the analysis with all trials. Conclusions: in the palliation of malignant gastric outlet obstruction, covered stents had higher migration and lower obstruction rates when compared with uncovered stents. Gastrojejunostomy is associated with lower reintervention rates than stents
KASAI, KENJI, SADAYUKI SAKUMA, SHIGEKI ITOH, HIROSHI FUKATSU, MITSUHIKO HIROSE, TSUNEO ISHIGUCHI, SANJAY S. BAIJAL, and SUMIT ROY. "Esophageal Stenting with a Self-expandable Metallic Device: A Preliminary Study." Nagoya University School of Medicine, 1992. http://hdl.handle.net/2237/17522.
Повний текст джерелаBrikas, Marijus. "Microprocessing of silicon and metals with high pulse repetition rate picosecond lasers." Doctoral thesis, Lithuanian Academic Libraries Network (LABT), 2011. http://vddb.laba.lt/obj/LT-eLABa-0001:E.02~2011~D_20110324_161348-78636.
Повний текст джерелаDisertacijos tikslas yra ištirti didelio impulsų pasikartojimo dažnio pikosekundinių lazerių pritaikomumą medžiagų mikroapdirbimui, bei išaiškinti tokių lazerių spinduliuotės sąveikos su metalais ir siliciu ypatybes. Eksperimentiškai buvo ištirta abliacijos slenksčio ir akumuliacijos koeficiento priklausomybė nuo lazerio impulso trukmės siliciui ir metalams. Sukurtas ir eksperimentiškai patvirtintas modelis optimalioms fokusavimo sąlygoms surasti, siekiant maksimalios abliacijos spartos. Didelei impulso energijai, medžiagos nugarinimo efektyvumas mažėja dėl ekranuojančio plazmos poveikio. Įvairių impulso trukmių lazeriai buvo panaudoti silicio gręžimui bei pjovimui. Paviršiaus spektroskopijos metodais, nustatyta, kad pjovimo metu silicis yra legiruojamas anglimi iki 5 µm gylio iš atmosferoje esančio anglies dvideginio, o susidariusi silicio karbido fazė įtakoja lazerinio pjovimo kokybę silicio bandinio gylyje. Taikant didelio impulsų pasikartojimo dažnio pikosekundinius lazerius sudėtingos formos detalių gamybai, rasti sąryšiai tarp paviršiaus šiurkštumo bei proceso parametrų. Pjaunant lazeriu stentus iš Nitinolio, šilumos nukreipimas nuo ruošinio riboja galimą panaudoti lazerio vidutinę galią ir tuo pačiu pasiekiamą efektyvųjį pjovimo greitį; Vykdant sidabro ir aukso abliaciją pikosekundiniu lazeriu skystyje, generuojamos siauro dydžių skirstinio nanodalelės, kurios sudaro stabilius koloidinius tirpalus.
Brikas, Marijus. "Silicio ir metalų mikroapdirbimas didelio impulsų pasikartojimo dažnio pikosekundiniais lazeriais." Doctoral thesis, Lithuanian Academic Libraries Network (LABT), 2011. http://vddb.laba.lt/obj/LT-eLABa-0001:E.02~2011~D_20110324_161301-79480.
Повний текст джерелаThe objective of the thesis is to investigate applicability of high pulse repetition rate picosecond lasers for microfabrication and to clarify high repetition rate pulse interaction with metals and silicon. The ablation threshold and accumulation rate dependence on the laser pulse duration for silicon and metals has been experimentally studied. The model of optimal focus conditions for the maximum ablation rate was developed and experimentally confirmed. The material evaporation rate decreases duo to plasma screening for high pulse energies. Various pulse length lasers have been used for cutting and drilling of silicon. In this work key properties of laser radiation, radiation absorption, ablation and plasma formation are discussed. Surface spectroscopy methods have shown that laser cutting of silicon in the air leads to the cut surface doping with carbon atoms up to 5 µm depth from carbon dioxide in the atmosphere, and the resulting silicon carbide influences the laser cut quality. Testing of applicability of high pulse repetition rate picosecond lasers for the production of complex shapes, relationships between surface roughness and process parameters were determined. Heat abstraction from the workpiece, during laser cutting of stents from nitinol, limits the potential use of the average laser power and the effective cutting speed The silver and gold picosecond laser ablation in the liquid medium generates a narrow size distribution of nanoparticles, which form a stable... [to full text]
Hekkanen, Mikko. "Inclusion Rating of Clean Steels." Thesis, Örebro University, Department of Technology, 2009. http://urn.kb.se/resolve?urn=urn:nbn:se:oru:diva-7786.
Повний текст джерелаThe main part of this work has been a literature survey, reviewing scientifical reports forinformation on how steel cleanness is evaluated today, and also how the steel cleanness is related tothe fatigue performance of clean steels.
Taylor, Christopher James. "Metallic and organic coating development for high performance pre-finished steels." Thesis, Swansea University, 2009. https://cronfa.swan.ac.uk/Record/cronfa42304.
Повний текст джерелаRöttinger, Michael Heinrich. "Metall-Stent-Implantation bei Tracheomalazie Früh- und Langzeitergebnisse /." [S.l.] : [s.n.], 2001. http://deposit.ddb.de/cgi-bin/dokserv?idn=963428403.
Повний текст джерелаHill, Daryl P. "The influence of non-metallic inclusions upon the properties of linepipe steels." Thesis, Aston University, 1986. http://publications.aston.ac.uk/11902/.
Повний текст джерелаMorata, Royes Joan. "Wear resistance of heat-treated Advanced High Strength Steels and casting." Thesis, Luleå tekniska universitet, Institutionen för teknikvetenskap och matematik, 2020. http://urn.kb.se/resolve?urn=urn:nbn:se:ltu:diva-80526.
Повний текст джерелаGuo, Shuo. "Evaluation of deformed MnS in different industrial steels by using electrolytic extraction." Thesis, KTH, Materialvetenskap, 2017. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-217880.
Повний текст джерелаZhou, Haipo. "Modification of non-metallic inclusions to improve the fatigue properties of nitriding steels." Thesis, University of Canterbury. Mechanical Engineering, 1993. http://hdl.handle.net/10092/6768.
Повний текст джерелаEnglund, Hanna, and Henrietta Isaksson. "Regulation of Nitrogen Content in High Alloyed Stainless Steels during the AOD Process." Thesis, KTH, Materialvetenskap, 2019. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-254419.
Повний текст джерелаI slutskedet av AOD-processen blåses argon- och kvävgas genom stålsmältan. En pålitlig modell behövs för att reglera kvävehalten i stålsmältan under det här steget. Olika modeller undersöks med data från 31 charger av det duplexa rostfria stålet SAF2507 samlad från Sandvik Materials Technology (SMT). Undersökningen sker genom att titta på partialtrycket av kvävgasen och kvävehalten som uppnåddes för varje charge. Genom att beräkna kvävelösligheten i stålsmältan med olika modeller och sedan använda Sieverts lag, kan ett partialtryck för kvävgas räknas ut för varje charge och jämföras med datan. Mer exakta resultat är uppnådda med en justerad modell hämtad från J. Kijac et al. jämfört med den modell använd på SMT idag. Att ha i åtanke är att denna modell är baserad på teori med antagande om utspädd lösning, vilket inte är optimalt för höglegerade stål och ett förslag är att utveckla en modell med hjälp av ett mjukvaruprogram som baseras på äkta lösning såsom Thermo-Calc.
Schmiedt, Anja Bettina [Verfasser]. "Statistical modeling of non-metallic inclusions in steels and extreme value analysis / Anja Bettina Schmiedt." Aachen : Hochschulbibliothek der Rheinisch-Westfälischen Technischen Hochschule Aachen, 2013. http://d-nb.info/1047230615/34.
Повний текст джерелаBubenko, Clara, Karl Magnil, and Melker Olofsson. "An Investigation of Stainless Steels for Long-term Use in Liquid Sodium at up to 700°C." Thesis, KTH, Materialvetenskap, 2019. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-254324.
Повний текст джерелаDet svenska företaget Azelio har utvecklat en stirlingmotor som drivs av solenergi. Då tillgången på solenergi är begränsad till dagtid har Azelio också utvecklat en termisk lagringsenhet (TES). Den termiska lagringsenheten absorberar och lagrar solenergi och kan därmed förse stirlingmotorn med värme även under natten. Stirlingmotorn driver i sin tur en generator vilken producerar elektricitet under hela dygnet. Natrium används som värmeledningsfluid (HTF) mellan TES och stirlingmotorn, vid temperaturer över 600°C. Vid dessa temperaturer är natrium högreaktivt och fenomen såsom kryp och korrosion kan uppstå, vilka kan påverka egenskaperna hos omgivande material. Genom att jämföra högtemperaturstålet 253 MA med andra kommersiella stål, eftersöks en kvalificerad och prisvärd legering som kan motstå flytande natrium vid dessa temperaturer. Från en omfattande litteraturstudie skapades en lista med möjliga kandidater. Materialen analyserades sedan i huvudsak utifrån ingående legeringselements påverkan på dess egenskaper. Analysen visar på att 153 MA har några betydande fördelar jämfört med 253 MA, såsom en mer stabil mikrostruktur vid de angivna temperaturerna. Detta arbete rekommenderar därför 153 MA för vidare undersökning och testning.
Yin, Jiaqing. "Formation of Bainite in Steels." Doctoral thesis, KTH, Metallografi, 2017. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-207596.
Повний текст джерелаQC 20170523
Ånmark, Niclas. "Inclusion Characteristics and Their Link to Tool wear in Metal Cutting of Clean Steels Suitable for Automotive Applications." Licentiate thesis, KTH, Tillämpad processmetallurgi, 2015. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-164875.
Повний текст джерелаQC 20150422
Brisenmark, Emil, and Valencik Jane Jönsson. "Evaluation of the Effect of Non-Metallic Inclusions on the Corrosion Resistance of Stainless Steels and Nickel-based Alloys." Thesis, KTH, Materialvetenskap, 2020. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-277900.
Повний текст джерелаIcke metalliska inneslutningar (NMI) är små föroreningar som alltid finns i stål och andramaterial. NMI:er är mycket viktiga eftersom de kan negativt påverka olika egenskaper hos stål, beroende på deras komposition, morfologi och antal. I olje -och gasindustrin är en särskilt oroande egenskap som kan påverkas av NMI:er deras korrosionsmotstånd. I denna rapport undersöktes hur olika aspekter hos NMI:er, som storlek eller komposition, påverkade korrosionsmotståndet i rostfritt stål. För att utföra detta analyserades två olika stållegeringsprovbitar från pipelines med elektrolytisk extraktion, ett svepelektronmikroskop (SEM) och ett program som kallas ImageJ. Från resultatet framkom det att baraNiob-Titankarbider (NbTi-C) som fanns på en av provbitarna hade potentialen att vara farlig, då den orsakar gropar som är 1 till 12.5 gånger större än sin egen storlek. Det framkom också att storleken på inneslutningarna inte påverkade storleken på deras gropar.
Gutman, Lucie. "Selection of high-temperature abrasion resistant steels for the mining and processing industry." Thesis, Luleå tekniska universitet, Institutionen för teknikvetenskap och matematik, 2020. http://urn.kb.se/resolve?urn=urn:nbn:se:ltu:diva-80967.
Повний текст джерелаFacchini, Eugenia. "Analisi del surriscaldamento indotto nel corpo umano dalle onde a radiofrequenza durante la risonanza magnetica anche in presenza di stent e cavi metallici." Bachelor's thesis, Alma Mater Studiorum - Università di Bologna, 2021.
Знайти повний текст джерелаGram, Tove, and Amanda Vickerfält. "Characterization of non-metallic inclusions according to morphology and composition : A comparison of two different steels before and after turning." Thesis, KTH, Materialvetenskap, 2015. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-170024.
Повний текст джерелаHedberg, Petra. "Method to assess machinability of engineering steels using coated carbide tools." Thesis, Uppsala universitet, Tillämpad materialvetenskap, 2021. http://urn.kb.se/resolve?urn=urn:nbn:se:uu:diva-442898.
Повний текст джерелаEkengren, Jens. "Large and rare : An extreme values approach to estimating the distribution of large defects in high-performance steels." Doctoral thesis, Karlstads universitet, Avdelningen för maskin- och materialteknik, 2011. http://urn.kb.se/resolve?urn=urn:nbn:se:kau:diva-8226.
Повний текст джерелаÅström, August, and Morgan Sten. "Macro segregation in continuous cast HSLA steels : With correlation to impact toughness." Thesis, KTH, Materialvetenskap, 2019. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-254348.
Повний текст джерелаDenna rapport granskar makrosegringar i stränggjutet stål och eventuella kopplingar till slagseghet. Centrumsegringar och V-segringar undersöks för att undersöka vilken segringstyp som har störst effekt på slagseghet, vilket är syftet med denna avhandling. Förutom en litteraturstudie, hämtades Charpy-V data med SSAB’s medgivande från två olika stålsorter, kvalitet A och kvalitet B, med respektive dominant segringstyp. Datan som inhämtades erhölls från tre stycken Charpy-V tester för varje plåt, från ett närliggande område. Medelvärdet för dessa datapunkter användes i statistisk analysför att obeservera spridningen av datapunkter i olika charger av de två stålen. Dessutom, erhölls segringsbilder för respektive slab från SSAB. Resultaten visade att datapunkterna för kvalitet A, som hade centrumsegring som domiant segringstyp, var mer spridd än datan för kvalitet B. Således, är slutsatsen att centrumsegring är värre i relation till slagseghet eftersom en högre avvikelse leder till mindre förutsägbara egenskaper från en kunds perspektiv.
Laarich, Abdellatif. "Designing a Heat Treatment to Achieve Ductile Advanced High Strength Steels." Thesis, Luleå tekniska universitet, Institutionen för teknikvetenskap och matematik, 2020. http://urn.kb.se/resolve?urn=urn:nbn:se:ltu:diva-79754.
Повний текст джерелаAmeen, Ahamed. "Optimization of annealing parameters for SANDVIK 13C26 and 20C strip steels : By MODDE analysis and modified JMAK method." Thesis, KTH, Materialvetenskap, 2019. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-259336.
Повний текст джерелаProcessoptimering av en kontinuerlig glödgningsugn, RHF 125, för rekristallisationsglödgning av två Sandvik-stål, Sandvik 13C26 och Sandvik 20C, har genomförts. För att återskapa den kontinuerliga glödgningsprocessen som utförs den verkilga processen i valdes prover och olika kallreduktionshastigheter från pågående produktionslinjer. En experimentell värmebehandlingsmodell valdes med metoden 'Design of Experiments' med MODDE (från U-Metrics). Glödgningstemperaturen valdes till en temperatur under austeniseringstemperaturen för båda stålen och hålltider varierade från 30 s till 240 s. Mikroskopisk uppskattning av fraktionen rekristalliserat material utfördes med hjälp av Electron Back Scatter Diffraktion (EBSD), åtföljd av mekaniska testmetoder för att mäta hårdheten och sträckgränsen för stålproverna. De experimentella resultaten användes för att skapa en modell för att korrelera mellan de olika reduktionshastigheterna och glödgningsparametrarna för att uppnå högre grad av rekristallisation tillsammans med önskvärda mekaniska egenskaper. Dessutom utvecklades en modifierad Johnson-Mehl-Avrami-Kolomogrov-modell, baserad på hårdhetsvärden, för att bestämma transformationskinetiken genom att spåra evolutionen för rekristallisation. Modellen verifierades genom jämförelse med EBSD-mätningarna för Sandvik 13C26 bandstål. För 20 °C observerades inhomogen rekristallisation, vilket begränsade modellens användbarhet till stål som uppvisade homogent rekristallisationsbeteende och försumbar förändring i utskiljning och/eller förgrovning av sekundära faser.
Noftz, Maria Raili [Verfasser]. "Spätkomplikationen nach Implantation von selbstexpandierenden Metall-Stents bei Patienten mit maligner Ösophagusstenose : Möglichkeiten der Reintervention und Einfluss auf die Überlebenszeit / Maria Raili Noftz." Lübeck : Zentrale Hochschulbibliothek Lübeck, 2011. http://d-nb.info/1014186684/34.
Повний текст джерелаJubica, Jubica. "Characterization of Secondary Carbides in Low-Alloyed Martensitic Model Alloy Tool Steels." Thesis, KTH, Materialvetenskap, 2020. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-284449.
Повний текст джерелаDen ständiga utvecklingen av högpresterande stål för transport, konstruktion och energisektorn kräver bättre förståelse för materialets egenskaper vid tillverkning. Dessa martensitiska stål inkluderar många legeringselement vilket ger ökad hårdhet vid härdning och anlöpning. Att studera utskiljning av karbider är en utmaning eftersom de är närvarande endast i liten volymsfraktion. Karbidreaktionerna är komplexa till följd av så kallade metastabila karbider vilka endast är närvarande vid en del av utskiljningsförloppet. För att tydliggöra och förenkla karbidkarakteriseringen fokuserar detta arbete på modellegeringar med två huvudelement utöver järn och kol, molybden och vanadin. Detta görs för att fastställa effekten av molybden och vanadinkarbider på den totala hårdheten. I detta arbete studeras två modellegeringar, A och B, härdade och anlöpta vid 550 °C och 600 °C med samma vanadininnehåll men olika molybdeninnehåll. Materialens hårdhet utvärderas och jämförs vid dessa temperaturer. Ett mer detaljerat karaktäriseringsarbete görs för material A med hjälp av STEM-EDS för att förstå mikrostrukturen och analysera utskiljningarna. Simuleringar görs med TC-PRISMA för att stödja det experimentella arbetet, vilket inkluderar simulering av den sekundära karbidutskiljningen och predikterar karbidstrukturen i dessa stål. Resultaten visar att de små sekundärkarbiderna i martensiten bidrar till den ökade styrkan hos material A. Hårdheten vid 550 °C är högre än vid 600 °C för material A eftersom både utskiljningen av karbider är sker långsammare och även dislokationsåterhämtning.
Hall, Emily. "Modelling the influence of porosity on fatigue strength of sintered steels." Thesis, Uppsala universitet, Strukturkemi, 2019. http://urn.kb.se/resolve?urn=urn:nbn:se:uu:diva-398977.
Повний текст джерелаAlonso, Frank Micael [Verfasser], Sannakaisa [Gutachter] Virtanen, and Aldo R. [Gutachter] Boccaccini. "Functionalization of Steels and other Metallic Materials with Hydrophobic Layers - Influence on Wetting and Corrosion Resistance / Micael Alonso Frank ; Gutachter: Sannakaisa Virtanen, Aldo R. Boccaccini." Erlangen : Friedrich-Alexander-Universität Erlangen-Nürnberg (FAU), 2017. http://d-nb.info/1150964286/34.
Повний текст джерелаBurrows, Christopher John. "The irradiation resistance of oxide dispersion strengthened steels." Thesis, University of Oxford, 2015. http://ora.ox.ac.uk/objects/uuid:e464cc9c-5ac0-43cb-acd2-c09706176d9a.
Повний текст джерелаLin, Sen. "Deformation-Induced Martensitic Transformation and Mechanical Properties of Duplex and Austenitic Stainless Steels : A Synchrotron X-Ray Diffraction Study." Thesis, KTH, Metallografi, 2017. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-233334.
Повний текст джерелаChristopher, Petersson. "Erosion-Corrosion experiments on Steels in liquid lead and Development of Slow Strain Rate testing rig." Thesis, KTH, Kärnenergiteknik, 2019. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-261611.
Повний текст джерелаLai, Libang. "Low temperature embrittlement of duplex stainless steels : A study of alloying elements’ effect." Thesis, KTH, Materialvetenskap, 2020. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-289565.
Повний текст джерелаDuplexa rostfria stål (DSS), bestående av lika stor mängd ferrit- och austenit, har bredtillämpning inom t.ex. fordon, kemiteknik samt kraftverk på grund av kombinationen av utmärkta mekaniska egenskaper och korrosionsbeständighet. Försprödning vid låg temperatur begränsar emellertid tillämpningen av DSS över 250 °C. När driftstemperaturen varierar från cirka 250 till 500 ° C så kan DSS bli spröda på grund av fasseparation i ferritfasen. Fasseparationen är den främsta orsaken till lågtemperaturförstöring, och kinetiken för denna fasseparation uppnår den snabbaste hastigheten vid cirka 475 °C, så den kallas också '475 °C-försprödning'. Mycket forskning har utförts inom detta område, men problemet kvarstår. Mekanismen för fasseparation beror på förekomsten av ett blandningslucka i det binära järn-krom-systemet, och tidigare forskning har rapporterat att vissa legeringselement kan ha förmågan att fördröja fasseparationen. Målet med mitt examensarbete är att undersöka påverkan av olika legeringselement och välja ett som kan användas för att fördröja fasseparationen och därav mildra problemet med lågtemperaturförsprödning hos DSS. Detta arbete inkluderar litteraturundersökning av olika legeringselement som kan påverka mikrostrukturen och mekaniska egenskaper hos DSS i allmänhet. Därefter termodynamiska beräkningar för att identifiera effekten av de valda legeringselementen på fasjämvikt under värmebehandlingen. Vanadin valdes som ett potentiellt lämpligt legeringselement som kan tillsättas i DSS. Experimentella undersökningar utfördes på värmebehandlingsprocessen och effekten av V-legering. De huvudsakliga slutsatserna av examensarbetetär: tillsatsen av Al, Si, V, Nb och Ti beräknades av Thermo-Calc, de är alla ferritstabiliserande och V-tillsats verkar kunna vara effektiv på grund av dess kombination med de interstitiella elementen C och N. I den experimentella delen studerades vanadintillsatser i kombination med värmebehandling för att fördröja den hårdnandet och försprödningen. Enligt Thermo- Calc-beräkningar och experimentella resultat så kan prestanda förbättras desto merinterstitiella element som kombineras med V.
Arvidsson, Sofia, Lena Fransson, and Carin Lundgren. "Communication of Values : A Qualitative Study at Stena Metall." Thesis, Jönköping University, JIBS, EMM (Entrepreneurship, Marketing, Management), 2010. http://urn.kb.se/resolve?urn=urn:nbn:se:hj:diva-12368.
Повний текст джерелаPurpose: The purpose of this thesis is to investigate Stena Metall’s values and how they are communicated within the organization.
Background: In the Fall of 2008, the world was shocked by the worst financial crisis in decades. The crisis had deep effects on the Swedish economy, and many companies suffered heavily. The recycling and environmental service company Stena Metall experienced their first negative result in 30 years, and 900 employees had to leave the company. An action program, including an altered culture was established with the purpose to adapt the operations to the new business environmental conditions. Values, which are a part of the organizational culture, were decided to be an important part of the change. To implement these in the entire organization a well-structured communication process is needed. Within these subjects; values and communication, a qualitative study at Stena Metall has been conducted.
Method: To fulfill the purpose, a qualitative method has been used. Thirteen interviews were conducted to collect data from different levels of the organization. The interviews were designed differently based on the employee’s level of responsibility in the organization. The theoretical framework used when analyzing the empirical material includes earlier research in the areas of culture, with emphasis on values, and communication.
Conclusion: Two set of values have been identified, core values and aspiration values. The findings indicate a gap in the communicational process at Stena Metall. Part of the new information communicated about Stena Metall´s values is lost on its way from the management to the lower levels in the organization. The perception of what the values mean, both core and aspiration values, differs depending on level in the organization.
Valgimigli, Marco <1972>. "Correlazione tra i livelli circolanti di cellule staminali CD34+ e sviluppo di ristesosi binaria in pazienti sottoposti ad angioplastica coronarica con impianto di stent metallico tradizionale: studio prospettico osservazionale." Doctoral thesis, Alma Mater Studiorum - Università di Bologna, 2007. http://amsdottorato.unibo.it/146/.
Повний текст джерелаBoulnat, Xavier. "FAST high-temperature consolidation of Oxide-Dispersion Strengthened (ODS) steels : Process, microstructure, precipitation, properties." Thesis, Lyon, INSA, 2014. http://www.theses.fr/2014ISAL0139/document.
Повний текст джерелаThis work aims to lighten the understanding of the behavior of a class of metallic materials called Oxide-Dispersion Strengthened (ODS) ferritic steels. ODS steels are produced by powder metallurgy with various steps including atomization, mechanical alloying and high-temperature consolidation. The consolidation involves the formation of nanoparticles in the steel and various evolutions of the microstructure of the material that are not fully understood. In this thesis, a novel consolidation technique assisted by electric field called "Spark Plasma Sintering" (SPS) or "Field-Assisted Sintering Technique" (FAST) was assessed. Excellent mechanical properties were obtained by SPS, comparable to those of conventional hot isostatic pressed (HIP) materials but with much shorter processing time. Also, a broad range of microstructures and thus of tensile strength and ductility were obtained by performing SPS on either milled or atomized powder at different temperatures. However, SPS consolidation failed to avoid heterogeneous microstructure composed of ultrafine-grained regions surrounded by micronic grains despite of the rapid consolidation kinetics. A multiscale characterization allowed to understand and model the evolution of this complex microstructure. An analytical evaluation of the contributing mechanisms can explain the appearance of the complex grain structure and its thermal stability during further heat treatments. Inhomogeneous distribution of plastic deformation in the powder is argued to be the major cause of heterogeneous recrystallization and further grain growth during hot consolidation. Even if increasing the solute content of yttrium, titanium and oxygen does not impede abnormal growth, it permits to control the fraction and the size of the retained ultrafine grains, which is a key-factor to tailor the mechanical properties. Since precipitation through grain boundary pinning plays a significant role on grain growth, a careful characterization of the precipitation state was performed on consolidated ODS steels. The experimental data obtained by transmission electron microscopy, small angle neutron scattering and atom-probe tomography evidenced the presence of dense and nanosized particles in SPS ODS steels, similarly to what is observed in conventional ODS steels. This is of great importance since it proves that the precipitation is very rapid and mainly occurs during the heating stage of the consolidation process. Using a thermodynamic model, the precipitation kinetics of Y2O3 and Y2Ti2O7 were successfully reproduced at various consolidation temperatures. Both experimental and numerical findings agree with the rapid precipitation of nanoparticles that are then extremely stable, even at high temperature. Consequently, this model can be an efficient tool to design ODS steelsby the optimization of the precipitation state
Lundberg, Daniel, Filip Wilson, Hjalmar Gunnarsson, Leo Sjörén, Robin Xu, and Erik Djurberg. "Long term aging and creep exposure for advanced heat resistant alloys : A phase analysis." Thesis, Uppsala universitet, Institutionen för materialvetenskap, 2021. http://urn.kb.se/resolve?urn=urn:nbn:se:uu:diva-446407.
Повний текст джерелаBeltrami, Júlia. "Estudo de viabilidade de produção de um vergalhão de aço dual-phase com alto teor de silício via termodinâmica computacional." reponame:Biblioteca Digital de Teses e Dissertações da UFRGS, 2016. http://hdl.handle.net/10183/163461.
Повний текст джерелаWith the aging of reinforced concrete structures, their premature wearing became evident. Among the phenomena of greater severity to the structural stability of buildings is the corrosion of the steel rebar. To improve the performance of these structures, increase their service life and reduce maintenance costs, this work proposes the development of a rebar with better corrosion resistance, with a dual-phase microstructure. The main objective was to propose a viable production route, which adds the least possible cost, so as to obtain a competitive product. The thermodynamic simulation of the rebar manufacturing, from steelmaking to heat treatment and mechanical properties was carried out with the aid of computational thermodynamics using the FactSage software. The simulation consisted of three steps: 1) determining the temperatures A1 and A3 and the heat treatment windows; 2) calculating the mechanical properties from empirical models; 3) analyzing the behavior of inclusions during refining, solidification and hot-rolling. The study of the inclusion system is important because the simulated steels have high silicon content (from 1% to 2.5% by weight) and solid oxides may precipitate in the continuous casting molds. As a result of the study, it was found that the production of rebars with dual-phase microstructure and high silicon content is possible and the manufacturing route proposed is as follows: conventional electric steelmaking, with final adjustment of the silicon content after deoxidation and controlled addition of aluminum to obtain inclusions with 15% to 25% of Al2O3, refining slag rich in CaO, in order to obtain inclusions favorable to continuous casting and hot-rolling, and direct water quenching after the final rolling step (Thermex / Tempcore processes).
Ahlgren, Peters Adam. "A SIMULATION WITH FINITE ELEMENTS TO MODEL STEEL SHEET SLITTING : A Master Thesis in Engineering Physics." Thesis, Uppsala universitet, Tillämpad mekanik, 2019. http://urn.kb.se/resolve?urn=urn:nbn:se:uu:diva-385495.
Повний текст джерелаRothpfeffer, Caroline. "From wood to waste and waste to wood : aspects on recycling waste products from the pulp mill to the forest soil /." Uppsala : Dept. of Forest Soils, Swedish University of Agricultural Sciences, 2007. http://epsilon.slu.se/200783.pdf.
Повний текст джерелаBarguet, Laurianne. "Contrôle acoustique et vibratoire de la mécano-synthèse des matériaux composites à matrice métallique nanostructurés." Thesis, Le Mans, 2015. http://www.theses.fr/2015LEMA1027/document.
Повний текст джерелаDuring the ODS steel (Oxide Dispersion Strengthened) synthesis, the first stage consists in an active milling between original materials, which are metallic powder and oxide to obtain reinforced micro/nanoscale dispersions. This process, known as mechanical alloying, could be realized by balls milling composed by a cylindrical tank rotating around its main axis, within which steel beads are introduced. The grinding results from different combinations of collisions between beads and powders on the tank walls, that lead to morphological grain powder evolution (grain size and shape). The first part of this thesis proposes an ultrasonic method to characterize the metallic powder. An experimental method, which consists in acoustic probing for measuring linear acoustic parameters (longitudinal wave velocity and elastic modulus) of a slab of powder sample, appears to be suitable to follow different mechanical alloying stages. A dependence of the acoustic parameters on the morphological characteristics of metallic powder (grain shape and grain size distribution) is shown with the same sample preparation and the same confining pressure. In the second part, optimization process by identification of ball milling optimal rotation speed is researched in a first step. Correlation between acoustic or vibration signals and bead motion versus rotation speed, shows that acoustic and vibration energy are good indicators that can be used to find the optimal rotation speed. In a second step, acoustic and vibration measures are used to follow grain material properties evolution during a grinding (for a period of 176hrs) and to identify powder clogging mechanism on a milling tank
Röttinger, Michael Heinrich [Verfasser]. "Metall-Stent-Implantation bei Tracheomalazie : Früh- und Langzeitergebnisse / Michael Heinrich Röttinger." 2001. http://d-nb.info/963428403/34.
Повний текст джерелаGulapura, Hanumantharaju Arun Kumar. "Thermodynamic modelling ofmartensite start temperature in commercial steels." Thesis, 2018. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-221719.
Повний текст джерелаVan, der Merwe Ryno. "Corrosion characteristics of steels and metallic alloys used as construction materials in plants exposed to fluorine containing acids." Thesis, 2018. https://hdl.handle.net/10539/26652.
Повний текст джерелаThe two hydrofluoric acid (HF) storage tanks used for holding 70% technical grade HF product at the HF plant at Necsa started leaking in March 2012. An evaluation of the failure was conducted in the form of a corrosion failure analysis. It was confirmed that a higher than usual nitric acid (HNO3) content in the technical grade HF stream changed the corrosion mechanisms typically experienced within the HF storage vessels, which then caused the tanks to fail. Immersion type corrosion experiments were done to safely simulate the corrosive environment experienced by the mild steel, stainless steel and nickel alloys used on site, and to predict the change in corrosion rates and characteristics associated with the HNO3 contamination in the HF production plant circuit. Since the corrosion resistance of mild steel in HF is heavily dependent on the thickness of the protective scale on the steel, a series of planned interval corrosion tests (PICTs) was done to reproduce and then examine the oxidefluoride barrier on mild steel coupons in pure 70% HF prior to corrosion tests. These shorter PICTs were also done on the stainless steel and nickel alloys and showed that the prepassivation step had a surface cleaning effect when exposed for only 24 h. Eleven day corrosion tests were conducted to establish the effect of HNO3 concentration and temperature on mild steel corrosion in 70% HF, and to determine the change in corrosion rates and mechanisms associated with HNO3 contamination (0.1-1% HNO3) of the downstream HF products. The corrosion was characterized by analysing the corroded coupons for mass loss, apparent corrosion rates, acid consumptions, visual observations of scale formation and pits, as well as depth profiles from scanning electron microscopy and energy dispersive spectroscopy analyses. Linear relationships were frequently observed when analysing mass losses for the coupons over time, making it possible to define corrosion rates in terms of first order reaction kinetics. The harshest corrosive condition for mild steel in HF was determined to be 1% HNO3 in 70% HF at a constant temperature of 25ºC. The corrosion characteristics of alloys used in the HF plant, as affected by HNO3 impurities (in the range 50–10000 ppm) in the final HF acid product (70% Technical grade) were successfully established. Normalized SA516 Grade 70 mild steel and Monel 400 were found not adequate for use as construction materials in a plant where HNO3 contamination was >100 ppm. However, the corrosion resistance of SS 904 L was suitable under these conditions and was recommended for applications in HF solutions where the presence of an oxygen-containing acid (e.g. HNO3) is consistent. It was recommended that Alloy 31, Alloy 33 or Nirosta 4565S, with higher chromium content (>20 wt% Cr), should be considered for construction material of the HF plant when HNO3 contamination becomes unavoidable. However, if the continued use of mild steel at the plant cannot be avoided, other inhibition strategies tailored to the selective consumption of HNO3 in the HF product stream need to be investigated.
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