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1
Singh, Rupali. "Mullite Ceramic from Diphasic Precursor Powder". Thesis, 2016. http://ethesis.nitrkl.ac.in/6927/1/RUPALI_SINGH_(612CR3009)__MtechR_2015.pdf.
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The use of mullite as a ceramic material proliferate from the field of conventional ceramic to the most advanced structural and functional area of ceramic due to its many advantageous properties. The properties of a sintered mullite ceramic are very much dependent on the type of processing route by which powder precursor was prepared.
In the present work, the stoichiometric diphasic mullite precursor powder was prepared by reverse addition technique using fume silica and aluminium nitrate nonahydrate as raw material. The effects of solution pH on the properties of the prepared powder have been investigated. The precursor powder made at ph-6, pH-8 and pH-10 were studied by TG-DSC analysis to know about the thermal decomposition behavior. Phase analysis of the precursor powder and calcined powder at different temperatures was done by XRD study. The presence of the different functional group in the precursor powder and calcined powder is confirmed by the FTIR study. The particle morphology, tendency of agglomeration and surface area, was investigated by microstructure analysis, particle size distribution and surface area analysis respectively. It was found that though the desired mullite phase formation is not very much affected by the variation of solution pH but the other properties are pH dependent.
The precursor powder formed at pH-8 exhibited better properties compared to the other batches. Therefore, the sintering study of the precursor powder in the presence of the different quantity of TiO2 additive is continued with that powder only. Samples made from different batches were sintered at three different temperatures i.e. 1450 ˚C, 1550 ˚C and 1650 ˚C under ambient atmosphere. The sintered pellets were characterized with respect to shrinkage, percent apparent porosity and bulk density. The phases formed in the sintered pellets were analyzed by X-Ray diffraction study. Morphology and microstructure were evaluated by FESEM.
2
Jani, P. "Development of CaF2 based Glass Ceramic". Thesis, 2010. http://ethesis.nitrkl.ac.in/1623/1/PJani.pdf.
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In the present work the glass of composition 40 % SiO2, 5 % Al2O3, 15 % Na2O, 5 % CaO , 12,5 % NaF , 21 % CaF2 and 1.5 % Sb2O3 (mol%) was prepared to investigate the crystallization of CaF2 in the parent glass matrix. To accelerate the crystallization and to develop the up conversion fluorescence property Er2O3 was doped in 0.5% , 1 % and 1.5 % (mol%). The casted glass was subjected to thermal treatment between 600 – 750oC. To observe the effect of rare earth on crystallization glass samples were examined in DSC. Spectroscopic property of the base glasses were studied using UV-Visible spectrophotometer. Phase authentication was carried out using X-Ray diffraction analysis.
3
Kumar, Vijay. "Phase formation process of citrategel derived hexagonal ferrite". Thesis, 2007. http://ethesis.nitrkl.ac.in/4147/1/Phase_formation_process_of_citrategel_derived_hexagonal_ferrite.pdf.
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It is now some 70 yrs since ferrites debuted as an important new category of magnetic materials. They were prized for a range of properties that has no equivalents in existing metal magnetic materials, and it was not long before full- fledge research and development efforts were underway. Today ferrites are employed in a truly wide range of applications, and have contributed materially to advance in electronics. Research too, continue apace, and the efforts of many man and women working in this field are yielding many highly intriguing results. New high-performance products are appearing one after another, and it would seem we have only scratched the surface of the hidden possibilities of these fascinating materials.
4
Patra, Sunil. "Synthesis and Characterization of $CaCu_3Ti_4O1_2$ AND Lanthanum Doped $CaCu_3Ti_4O1_2$ by Auto-Combustion Technique". Thesis, 2009. http://ethesis.nitrkl.ac.in/1526/1/sp_thesis.pdf.
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$CaCu_3Ti_4O1_2$ (CCTO) is a well known nonferroelectric material possessing high and nearly constant (room temperature to 300oC) dielectric constant at 1 kHz. It is being widely used in the electronic industries to manufacture electronic components such as multilayer capacitor (MLCC), DRAMs, microwave devices, electronic devices in automobiles and aircrafts. The properties like high permittivity of CaCu3Ti4O12 depend upon the particle size and powder morphology. The particle size and powder morphology of CaCu3Ti4O12 depend on the different processing parameters that are temperature, heating rate, duration and atmosphere. Several powder synthesis processes have been tried for the synthesis of CaCu3Ti4O12 among which solution combustion process have got enough emphasis now a days. CaCu3Ti4O12 synthesized using combustion synthesis techniques possess high purity and close control of powder morphology, which will result in the desired microstructure and dielectric behavior. Under this context the present study was carried out to evaluate the effect of different processing parameters on the phase purity, particle size, and powder morphology of CaCu3Ti4O12 and to study the effect of microstructure, sintering condition on the dielectric behavior of CaCu3Ti4O12. The study includes the optimization of different process parameters (ammonium nitrate, citric acid, pH) for synthesis of phase pure CCTO powder following solution combustion route. The optimization of process parameters were based on the phase purity, crystallite size and density. The optimized ratio for synthesis of CaCu3Ti4O12 was found to be 1:3:4:1.5:4 for CaCO3,CuO, TiO(NO3)2, citric acid and ammonium nitrate respectively at pH 1.The powder morphology, particle size, densification behavior and dielectric behavior of the sintered samples has been studied. Increasing sintering time found to enhance the density. The dielectric study showed its dependence upon sintering time, grain size and density. Dielectric property increases with increase in sintering time and density. An attempt has also been made to study the effect of lanthanum substitution at A site on the properties of CCTO ceramics.
5
Sahoo, Ganesh Kumar. "Synthesis and Characterization of BaTiO3 Prepared by Molten Salt Synthesis Method". Thesis, 2009. http://ethesis.nitrkl.ac.in/1525/1/ganesh.pdf.
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The study first optimized the different processing parameters e.g. salt systems, heat treatment temperature, holding time. By NaOH-KOH based salt system phase pure powder can be prepared at 175oC. NaCl-KCl based system produced phase pure powder at 700oC. LiCl-KCl based system failed to produce phase pure BaTiO3 powder. Crystallite size of the synthesized powder found to be varying 30-43 nm depending on the processing time and temperature. TEM analysis revealed that particle size in the range of 70-100 nm. It has been observed that NaOH-KOH system synthesized powder can be densified (98%) at a temperature 1225oC. Interestingly ultrafine grain size (200-500 nm) retained in highly dense sintered sample. In case of NaCl-KCl based powder only 91% density achieved, microstructure shows significant amount of porosity. Dielectric constant and loss factor of the sintered samples (εr =1400 and tanδ = 2% at 1 kHz) are on a par with BaTiO3 prepared via conventional sintered sample. NaOH-KOH salt based prepared sample showed almost flatten Curie peak and NaCl-KCl salt system prepared sample showed broad Curie peak with a Curie temperature of 115oC. The peak shift and broadening can be explained qualitatively from temperature dependence of volume fraction between surface cubic layer, bulk tetragonal layer, and gradient-lattice-strain layer (GLSL).
6
Patel, A. "Synthesis and Characterization of Multiferroic Composite (Barium Titanate Nickel Ferrite) by Solid State Route". Thesis, 2010. http://ethesis.nitrkl.ac.in/2005/1/comp_report.pdf.
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Both Barium titanate and Nickel ferrite were synthesized by Conventional ceramic processing method. Mixed oxide of BaCO3 and TiO2 for BaTiO3 and NiO and Fe2O3 for NiFe2O4 were calcined at 1000 oC for four hour and 900 oC for four hour respectively. Phases of particular compounds have been confirmed by XRD. For preparing multi ferroic composites the two separate powders are proved to be suitable. Composite (Four batches were prepared with composition 50:50, 60:40,70:30 and 80:20 ).
7
Mohapatra, Rohit. "Comparison of Physical Properties of Different Compositions of Alumina/Lanthanum Hexaaluminate Ceramic Composite". Thesis, 2010. http://ethesis.nitrkl.ac.in/1995/1/Rohit_final_Thesis.pdf.
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The aim of this study was to prepare four different composition of Alumina/Lanthanum Hexaaluminate powder. Four different compositions ranging from 10 to 80 vol % of Lanthanum Hexaaluminate were prepared. To prepare the Alumina-Lanthanum Hexaaluminate ceramic composite, stable aqueous Alumina slurry was needed to prepare. Thus, selection of electrolyte was made after comparing Darvan and tri-ammonium Cytrate. Darvan was chosen as an electrolyte to prepare stable aqueous Alumina slurry. The effect of pH on zeta potential was also studied.
After preparation of Alumina-Lanthanum Hexaaluminate ceramic composite powder, pellets of approximately 0.7gram for each composition were made by applying 4 Ton pressure for 120 seconds. The pellets were then sintered at 16500C in chamber furnace. The soaking time was kept for 4 hours. Then the bulk density, aparent porosity and strength were compared after calculation of dry weight, soked weight, suspended weight. The results revealed that bulk density increased with increasing vol % of LHA content and aparent porosity decreased with increasing vol% of LHA content. The strength also increased with increasing vol% of Lanthanum Hexaaluminate.
8
Bansal, Vinay. "Synthesis and Characterization of Sodium Potassium Niobate (Na0.5K0.5NbO3)–Nickel-Zinc Ferrite (Ni0.6Zn0.4Fe2O4)Composite". Thesis, 2010. http://ethesis.nitrkl.ac.in/2015/1/vinay_thesis_final.pdf.
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The present project dealt with the preparation of a multiferroic composite (Na0.5K0.5)NbO3-(Ni0.6Zn0.4)Fe2O4 in which the constituent materials (Na0.5K0.5)NbO3 [NKN] and (Ni0.6Zn0.4)Fe2O4 [NZFO] were prepared by coating method and combustion method respectively. These were mixed in required proportion and densified by conventional sintering process to form composite. Four compositions were prepared to form composite (1-x)(Na0.5K0.5)NbO3-x(Ni0.6Zn0.4)Fe2O4 [NKN-NZFO] ceramics, where x=0.01, 0.10, 0.15 and 0.20. XRD of the sintered and ground sample showed no reaction between individual phases and no secondary phase formation in the final product. SEM image shows that addition of NZFO significantly modifies the microstructure of the sintered sample. Grain size found to be 10-15 µm for 1% NZFO addition. The grain size reduced to 2-5 µm for higher NZFO addition. The dielectric constant and dissipation factor were studied as a function of frequency for ceramic composites
9
Kumar, Prashant. "Preparation and Densification study of Barium Zirconate (BaZrO3) nanopowders". Thesis, 2011. http://ethesis.nitrkl.ac.in/2621/1/Final_thesis.pdf.
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Barium Zirconate (BaZrO3) is a promising candidate for structural to electronic application. Different industry demands nano scale powder for the technology enhancement and hence, the preparation of BaZrO3 nano-powders and their sintering study through microstructure synchronization are the prime interest of this research. A typical combined wet chemical and calcination technique was employed to synthesis of 100nm BaZrO3 nano-powders. Elongated Barium carbonate (BaCO3) nano rod was prepared through wet chemical method, whereas, near spherical yttria stabilized zirconia nanoparticle was used to prepare this BaZrO3. Transmission electron microscope analysis (TEM), XRD and BET surface area confirmed the purity and morphology of developed nanoparticles. Prior to sintering, dilatometric study was conducted to understand the sintering behaviour this class of nanoparticles. A wide horizon of sintering profile optimized the sintering condition with consideration of relative density and microstructure. The nano powder was near to 98% dense at 1650oC for 2h. Field Emission Scanning Electron (FESEM) microscope study reveals the grain size is around 250nm. The developed perovskite BaZrO3 nano powders could be successfully used for different sectors.
10
Kundan, Paswan. "Sintering study of Mag-Al Spinel synthesized via combustion synthesis using glycine as fuel". Thesis, 2011. http://ethesis.nitrkl.ac.in/2623/1/final_thesis_kundan.pdf.
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The present work deals with the processing and sintering of phase pure Mag–Al spinel by auto-combustion process. Magnesium and aluminum nitrates have been used as the oxidizers and glycine as the fuel. Addition of glycine to the mixture of magnesium and aluminium nitrates results in a series of redox reactions to form a complex which subsequently crystallizes to form spinel at a lower temperature. Mag-Al spinel has been synthesized by varying metal to glycine ratio as 1:0.5, 1:1 and 1:2 and its effect on the spinel formation was studied. Variation of calcination temperature was done from 5000 C to 10000C for 1 hour and 2 hours and their XRD analysis were performed to identify the exact starting temperature for obtaining phase pure spinel. The phase pure Mag-Al spinel was formed at 700 °C, when using metal to glycine ratio as 1:2. However, the phase pure Mag-Al spinel formation took place at higher temperature in case of other metal to glycine ratios. Bulk density was achieved in the range 3.135 – 3.34. Apparent porosity in the range of (0 – 6.64) % was achieved.
11
Panda, Ashish Kumar. "Synthesis and Characterization of Calcium Phosphate-Alumina Composites". Thesis, 2012. http://ethesis.nitrkl.ac.in/3431/1/Ashish_Panda__Thesis.pdf.
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In the present study synthetic α-alumina and calcium phosphate based composites were processed and their mechanical properties were characterized. α-Alumina nano-powder was synthesized using reverse micelle method. Calcium phosphate nano-powders with different molar ratio starting from 1.8 to 1.1 was synthesized by precipitation method, using calcium nitrate (Ca(NO3)2.4H2O) and ammonium dihydrogen orthophosphate (NH4H2PO4) as precursor materials as source for calcium (Ca²+) and phosphate ((PO4)3-) ions respectively. Then 5, 10, 20 weight % of Calcium phosphate powder was mixed with alumina, consolidated and sintered at 1400°C for 4 hours. The synthesized composites, in form of pellets were characterized for bulk density, apparent porosity, hardness and flexural strength and its grain size and morphology were studied from SEM micrographs of sintered pellets.
The synthesized composites were found to have a bulk density in the range 3.092 – 3.76 g/cc, apparent porosity in the range 11-20% and hardness in the range 193.3 - 335 HV.
12
Lenka, Abinash. "Effect of calcination temperature on kaolinite for mullitisation of kaolinite and alumina mixture". Thesis, 2012. http://ethesis.nitrkl.ac.in/3486/1/FINAL.pdf.
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The present project work reports whether there is any effect of calcination temperature of kaolinite, on the mullitisation behavior of kaolinite and alumina mixture. Initially raw material characterization such as chemical analysis, DSC/TG analysis and XRD were carried out. Further in this experiment kaolinite was calcined at various temperatures (6000C, 10000C, 14000C) and calcined alumina powders were added in it, specimens were prepared by pressing and finally all the batches were fired at 16000C. The effect of calcination temperature was studied by performing different experiments, mainly physical properties such as apparent porosity & bulk density; mechanical properties and phase analysis by X-ray diffraction. Finally from the results it has been observed that there is always a significant impact of calcination temperature on the mullitisation behavior of kaolinite and alumina mixture. It has been found that the kaolinite that was calcined at higher temperature show some superior properties when mixed with alumina and fired, as compared to other batches. It shows higher amount of mullite content when fired along with other batches at 16000C, and also better mechanical and sintering properties. The batch that was made by mixing calcined alumina along with raw/uncalcined kaolinite show poor mechanical and sintering behavior.
13
Dhal, Amrit Abhishek. "Comparative study of properties of Barium Titanate synthesized by Solid State and Auto-combustion Method". Thesis, 2012. http://ethesis.nitrkl.ac.in/3528/1/amrit_thesis.pdf.
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Barium titanate is a well-known ferroelectric and piezoelectric material with high permittivity (more than 1000) and one of the most widely used ceramic materials in the electric industry, especially in multilayer ceramic capacitors (MLCC). The current trend in MLCCs to increase the number of active layers to 200-400 and to lower the dielectric thickness below 2-3μm. To achieve this objective, ultrafine and non-agglomerate powders are required. Preparation methods significantly influence the purity, stoichiometry, particle size or microstructure of the BaTiO3 powder, which in turn influences the dielectric property of the compound. So, present situation is in a need of such a synthesis route which can produce barium titanate of expected particle size with a high permittivity and depressed Curie peak. In the current work, two synthesis routes, solid state synthesis and auto-combustion synthesis has been discussed along with the comparative study of properties of the powder obtained from both the methods.
14
K, Rohan. "Programming and simulation of densification of ZTA nano-composite". Thesis, 2007. http://ethesis.nitrkl.ac.in/4191/1/Programming_and_Simulation_of_Densification_of_ZTA_nano-composite.pdf.
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Alumina is an important structural ceramics having wide application potential. However, its use in real life systems is limited due to its low fracture toughness resulting in catastrophic failure. Among the several measures that are being taken to overcome the draw- back, the addition of zirconia (platelet, particle, fiber) in the alumina matrix remarkably improves the toughness on account of stress induced transformation toughening. Al2O3–ZrO2 composite powder containing 15 mol% ZrO2 was prepared by sol-gel route using Aluminum nitrate (E-Merck, India) and zirconium oxychloride (E-Merck, India) as precursor. The sol–gel derived powder was properly characterized by X-ray Diffraction study (XRD). The analysis reveal the gel contained pseudoboehmite and amorphous Zr(OH)4 was decomposed in three and two stages respectively. The phase transformation of alumina during calcination followed the sequence of pseudoboehmite → bayerite → boehmite → γ- Al2O3 → θ-Al2O3 → α-Al2O3, while that of ZrO2 follows amorphous ZrO2 → t-ZrO2 → (t + m) ZrO2. Densification behavior of the sol gel precursor was studied through compaction of the powder at uniaxial press and subsequently sintered at muffle furnace. The relative density of the uniaxial pressed specimen depends on several factors; such as pressure, temperature, sintering profile and sample position during firing. An Artificial Neural Network (ANN) can predict the characteristics densification features of sintered specimens at any intermediate processing parameters. To evaluate this, simulation of relative density of ZTA Nano-composite has been carried out through MATLAB program. The simulation was focused on stepwise single layer to multilayered ANN theory. Herein, the project work is emphasized on the prediction of change in densification behavior with respect to change in processing parameters.
15
Jena, Preetam. "Synthesis and characterization of hydroxyapatite". Thesis, 2007. http://ethesis.nitrkl.ac.in/4251/1/Synthesis_and_Characterization_of_Hydroxyapatite.pdf.
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The current work deals with the synthesis and the subsequent characterization of HAP. The characterization involves analysis of X-ray diffraction, Scanning Electron Microscope, Particle size measurement, Thermogravimetric Analysis (TGA), Sintering and Pressing. In my project I have prepared HAP by the chemical precipitation method.. There was also an experiment undertaken in order to ascertain if there is any change in pH by changing the stages of pH correction XRD patterns were studied of calcined and pre calcined HAP powders. Then the HAP produced was divided into 36 diff 0.8 g batches which were sintered in 3 batches at 1000 0 C, 1100 0 C & 1200 0 C amd then their respective densities were studied. From all the studies made we found out that there is an improvement in crystallinity of HA after calcination. Thermal stability is only upto 1300C.
16
Khan, Nabid Anjum. "Enhanced phase stability of metastable tetragonal zirconia nanocrystals prepared through novel chemical routes". Thesis, 2007. http://ethesis.nitrkl.ac.in/4271/1/%E2%80%9CENHANCED_PHASE_STABILITY_OF.pdf.
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The present work deals with the synthesis and enhancement of metastable tetragonal zirconia nanocrystals through novel chemical routes. Nanocrystalline t-ZrO2 is a technologically significant material that finds extensive use as catalyst or catalyst support, oxygen sensor and structural components. In this work, ZrO2 nanoparticles are synthesized using both reduction and hydrolysis techniques. These techniques are known to result in the production of nanocrystalline materials. Also, promote the stabilization of t-phase of ZrO2 at the nano level at moderate temperature, which is one of the primary objective of this work. For reduction technique, the Zr-salts are reduced by the addition of strong (Sodium borohydride, NaBH4) and weak (Hydrazine hydrate, N2H5OH) reducing agents. However for hydrolysis technique, Zr-salts are hydrolyzed by adding ammonium hydroxide (NH4OH). In this process, geletion and precipitation occurred at low and high pH respectively with the addition of these agents. Here, the main objective is to stabilize the t-ZrO2 through geletion (low pH) and precipitation (high pH) route by using NaBH4 and N2H5OH and compare with the powders synthesized through hydrolysis process by the addition of NH4OH. It was observed that the crystallization temperature of t-ZrO2 for low pH is greater as well as broad range than the high pH ZrO2 samples. Stabilization of metastable t-ZrO2 is observed up to 600 °C for both pH in case of samples reduction by NaBH4. Stabilization of metastable tZrO2 is observed up to 500 °C for low pH in case of samples reduction by N2H5OH. Fully tZrO2 is seen for low pH sample, however mixture of t- and m- ZrO2 are observed for high pH sample up to 500 °C for the case of NH4OH. The as-prepared powders contain lots of water in the form of ZrO(OH)2.xH2O as studied from the IR analysis. From the XRD results it has been concluded that small crystallites (<25nm) stabilizes metastable t-ZrO2 upto moderate temperature. Low pH has better stability on metastable t-ZrO2 compared to high pH. Strong reducing agent (NaBH4) gives better stability on t-ZrO2 upto 600 °C compared to NH4OH. Reduction technique controls the crystallite size and slowly converts to m-ZrO2 as the calcination temperature increases. From the thermal as well as microstructural studies it was concluded that the stabilization of t-ZrO2 is dependent on the initial pH of the precursor, calcination temperature and also on the crystallite size of the ZrO2.
17
Kumar, Binit. "Multiferroic composites an overview". Thesis, 2007. http://ethesis.nitrkl.ac.in/4279/1/Multiferroic_composites__an_overview.pdf.
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Multiferroics, i.e. materials with magnetic and electric order coexisting, have been attracting much of interest the latest years. The interaction of magnetic and electric subsystems manifests itself as magnetoelectric (ME) effect that is interesting for practical applications such as the sensor techniques, microelectronics and magnetic memory systems. One of the most attractive substances for creation of new ME materials is the bismuth ferrite BiFeO3 due to its record high temperatures of electric (Tc ¼ 1083 K) and magnetic (TN ¼ 643 K) ordering. Noteworthy that the Giant ME effect at room temperature has been obtained for the first time in thin films of this material. In the bulk BiFeO3 samples the spatially modulated spin structure exists in which the magnetization vectors of antiferromagnetic sublattices change periodically from point to point with a period 620A ˚, incommensurate to the crystal lattice period (spin cycloid). The presence of spatially modulated spin structure results in zero value of the volume-averaged ME effect. A necessary condition for ME effect observation is the suppression of spin-modulated structure, that takes place in strong magnetic fields when the system undergoes the incommensurate–commensurate (IC–C) phase transition between spin-modulated and homogenous antiferromagnetic states. It has been noted in Ref. that there is a profound analogy between spatially modulated spin structures in multiferroics and spatially modulated structures in nematic liquid crystal (director vector waves). This periodic director vector structures in nematic liquid crystal arise in external electric field (flexoelectric effect ) and can be controlled with the electric field. The question arises whether the electric field can control spatially modulated structures in multiferroics in the same way as in liquid crystal.
18
Sharma, Antareep. "A comparative study between Direct Spinel Addition and In-Situ Spinelisation in a Low Cement High Alumina based Refractory Castable". Thesis, 2014. http://ethesis.nitrkl.ac.in/5506/1/110CR0615-4.pdf.
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Spinel containing castables are becoming widely popular due to their high slag resistance, spalling resistance, drying behavior and hot strength. Most of the steel plants today use Magnesia-Alumina spinel system (MgAl2O4). Spinel containing castables can be prepared by two methods: direct spinel addition and in-situ spinel formation. The latter option is cheaper but has a drawback of volume expansion during spinel formation, which may lead to cracking. On the other hand, the pre reacted spinel system is expected to show a better hot strength and mechanical behavior. This project is an attempt to study the properties of both such types and present a contrast between them. Also, the effect of two different types of cement, having different alumina composition, was observed.
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Adhikari, Prativa. "Effect of Different Nano-oxide Addition on Densification, Microstructure, Electrical and Mechanical Properties of Ba(Zr0.2Ti0.8)O3–0.5(Ba0.7Ca0.3)TiO3 (BZT–BCT) Ferroelectric Ceramics". Thesis, 2015. http://ethesis.nitrkl.ac.in/6728/1/Prativa_Mtech_2015.pdf.
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Piezoelectric ceramics are widely used as actuator, resonator, and spark igniter. Recently, much attention has been paid to prepare BZT-BCT piezoelectric ceramics because of its good dielectric, piezoelectric properties and environment friendly nature. However, piezoelectric ceramics based on BaTiO3 suffer from low reliability and poor mechanical properties such as strength and toughness. A novel method has been used to improve the mechanical properties of ceramics by reinforcement of matrix with stronger oxide (Al2O3, MgO, ZrO2, Stabilized-ZrO2) or nonoxide (SiC) particles. It is well known that electrical properties of ferroelectric ceramics generally degrade with non-ferrolecric additives and decrease in sinterability usually encountered with these refractory oxide additives. Use of nano-oxide additives may drastically reduce the amount of additive and in effect electrical property may not degrade much.
The aim of this work is to study the densification, microstructure, electrical and mechanical properties of BZT–BCT with nano oxide additives (Al2O3, MgO, and stabilized-ZrO2). BZT-BCT powders were prepared successfully by a conventional mixed-oxide method via planetary-milling technique. BZT–BCT composites were prepared by mixing high purity BZT–BCT powder and small amount (0.5-2.0 vol%) of oxides, i.e. Al2O3, MgO and ZrO2(3Y) separately. The flexural strength and hardness of BZT–BCT composites were increased significantly for all the three nano-oxide addition. It was found that nano-oxides addition improves densification and significantly modifies the microstructure. Though the relative permittivity and piezoelectric constant of the composites were decreased with the addition of nano-oxide, the decrement was sharp for MgO whereas it was least for Al2O3. Change in grain size, distribution of oxide particle and formation of secondary phases were used to explain the properties. 1 vol% Al2O3 added BZT-BCT will be useful for devices like low power transducers, where extremely high dielectric constant and high "d" constant required.
20
Abhinay, Sreeram. "Effect of Dispersant and Binder on Fabrication of BZT-0.5BCT Piezoelectric Wafers by Tape Casting Technique". Thesis, 2015. http://ethesis.nitrkl.ac.in/6878/1/S_Abhinay_M.Tech_(R)_Thesis_612CR3008.pdf.
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Recently, piezoelectric wafers/substrates have opened new opportunities for nondestructive evaluation (NDE) of structures in defence, aerospace and industrial sectors. Such wafers can be easily made by tape casting of slurries where dispersants and binders play a critical role. Generally, lead zirconate titanate (PZT) based compositions are used for piezo wafers/substrates. However, recent concern about environmental pollution from lead-based materials has generated renewed interest in developing lead-free ferroelectrics like Ba(Zr0.2Ti0.8)O3-0.5(Ba0.7Ca0.3)TiO3 [BZT-0.5BCT] having high dielectric constant (εr>3500) and piezoelectric properties (d33> 500pC/N). To date, there are no reports on the fabrication of BZT-0.5BCT wafers by tape casting and their electrical characterization.
The objective of the thesis is to develop a dense warpage free BZT-0.5BCT wafer/substrate with suitable dielectric and piezoelectric property. The BZT-0.5BCT powder was synthesized by solid-state reaction route. BZT-0.5BCT tapes were fabricated by a non-aqueous tape casting method. Tape casting slurries of BZT-0.5BCT powder were prepared using methyl ethyl ketone-ethanol (MEK-EtOH) (solvent), phosphate ester / polyvinyl butyral (PVB) (dispersant), PVB (binder), polyethylene glycol (PEG) and butyl benzyl phathalate (BBP) (plasticizer). The optimum amount of dispersant was determined from the minimum in slurry viscosity and sedimentation height. The role of the two dispersants (phosphate ester and PVB) in making stable slurry of BZT-0.5BCT powder vis-a-vis the final properties of the fired wafers was studied. It was confirmed that 1 wt.% phosphate ester is sufficient for effective dispersion of BZT-0.5BCT to get stable slurry and the amount was 0.5 wt.% when PVB was used as dispersant in place of phosphate ester. The role of the binder (PVB) on the fabrication of wafer was also studied. Variation of PVB content shows that at least 3wt% PVB required to get the workable green tape. Up to 3.5 wt% PVB (binder) addition, solid loading can be maintained at 65%. Improved dielectric (εr =1750 at 1 kHz), ferroelectric (Pr = 6.3 µC/cm2), and piezoelectric property (d33 =174 pC/N) were observed for wafers made without phosphate ester.
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Biswal, S. "Preparation of Hydroxyapatite Porous Scaffold". Thesis, 2010. http://ethesis.nitrkl.ac.in/1622/1/Siddhartha.final.pdf.
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The present work deals with the preparation and study of bioceramic scaffold using hydroxyapatite powder as the source material. Hap powder was prepared by Co-Precipitation technique using Ca(NO3)2.4H2O and (NH4)2HPO4 as raw materials. X-ray diffraction (XRD), Fourier Transform InfraRed (FTIR) spectroscopy and BET analysis were used to characterize the Hap powder and calculate its crystallite size, surface area and particle size. Polyethylene glycol (PEG – 600) was used as the pore former to produce the bioceramic scaffold. Bulk density, apparent porosity and compressive strength of the scaffold were calculated. Thereafter, characterization techniques like Mercury Intrusion Porosimetry and Scanning Electron Microscopy (SEM) were carried out to study the macro/micro pores and microstructure of the scaffold in detail. In the end, in-vitro bioactivity using SBF was done which was followed by a detailed SEM study of the SBF-treated scaffold which showed the growth of tissue over the scaffold surface.
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Saxena, K. "Synthesis and Characterisation of Lead Free Piezoelectric NBT-BT Ceramic". Thesis, 2010. http://ethesis.nitrkl.ac.in/1696/1/PROJECT-Kapil.pdf.
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This project dealt with the preparation of Lead-free piezoelectric ceramics (1- x)Bi0.5Na0.5TiO3 -xBaTiO3 that have been prepared by a conventional solid state reaction method , four different composition of (1- x)Bi0.5Na0.5TiO3 -xBaTiO3 were prepared in which x have values 0, 0.04,0.06,0.08. After the addition of BaTiO3 into Na0.5Bi0.5TiO3, the ceramics exhibit strong piezoelectric property at MPB, the ceramics with x = 0.06 exhibit optimum piezoelectric and dielectric properties. X-ray diffraction analysis of the different composition has been carried out to know about the phases. Dielectric measurement was carried out for different compositions. The samples were poled at a voltage 3-4 KV and the piezoelectric measurements were carried out. The micro-structural characterization was done by Scanning Electron Microscopy.
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Majhi, Manoj Kumar. "Effect of span length on bending strength and Weibull modulus of sintered alumina bar". Thesis, 2011. http://ethesis.nitrkl.ac.in/2658/1/manoj_thesis.pdf.
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The present study was undertaken to evaluate the bending strength of alumina both as a function of sintering temperature and span length. The fracture strength data was calculated on relatively a large number of samples for each data point (14). The strength data distribution was also used to evaluate the failure probability as well as the Weibull modulus which was correlated to the sintered density. It was observed that in the sintering temperature range of 1550 and 1600 OC the Weibull modulus showed that only one type of flaw behavior was operative in the sample and that the Weibull modulus increased with sintering temperature and decreased with increasing pan length. However at the highest sintering temperature 1650OC the Weibull statistics couldn’t be fitted to a single linear fit. This indicated that the data could be fitted to two different straight lines which implied that at 1650OC, two different flaw types controlled the sample failure.
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Rout, Sarat Kumar. "Synthesis, Electrical and Electrochemical Behavior of Lanthanum Strontium Cobalt Ferrite for SOFC Cathode Application". Thesis, 2015. http://ethesis.nitrkl.ac.in/6922/1/Sarat_phd_507CR004.pdf.
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Mixed ionic and electronic conductive (MIEC) perovskites, particularly La1-xSrxCoyFe1-yO3-δ, have been widely explored to replace the conventionally used LaSrMnO3 (LSM) materials for intermediate temperature SOFC applications. The B-site Co rich compositions have a fairly good electrical conductivity but because of its poor thermal and chemical compatibilities the iron rich composition (La1-xSrxCo0.2Fe0.8O3-δ) has usually been a preferred destination. The La-Sr variations on A-site have however a set of scattered data that needs to be optimized. In addition to the MIEC character, cathodes need a microstructural tailoring to enhance the oxygen reduction reaction sites. For this the cathode particles must have a considerably smaller size with high exposed surface area. In the present work La1-xSrxFeO3- perovskites with x=0.0-1.0, have been synthesized. Electrical conductivity and thermochemical stability study as a function of x showed La0.6Sr0.4FeO3- as a potential candidate for cathode application. Iron rich La0.6Sr0.4Co0.2Fe0.8O3-δ (LSCF) has been synthesized following solution combustion technique using citric acid and glycine as fuel. Different process parameters namely metal cation to fuel ratio (elemental stoichiometric coefficient), extra chelating agent and oxidant addition, and pH of the precursor solution has been optimized. It is seen that a fuel rich precursor solution favored the formation of high surface area (~30m2/g) LSCF powder. The effect of EDTA in reducing the calcination temperature and that of pH in powder homogenization helps in yielding fine powders. Infra-red spectroscopy (FTIR) study showed the purity of the well dispersed fine powder from the carbon residues. A correlation between the BET specific surface area, the crystallite size and SEM average particle size was established and was seen to be linked with the elemental stoichiometric coefficient. The influence of the processing parameters on the sintering, thermal expansion, thermal stability and electrical conductivity was studied. Thin electrolyte substrates were prepared from the in-house synthesized 8%-yttria stabilized zirconia (YSZ) and samarium doped ceria (SDC) powder. The chemical compatibility of LSCF powder with these electrolytes has also been studied and SDC was observed to be a better candidate in comparison to YSZ. Half electrochemical cells were prepared by screen printing the in-house prepared LSCF ink on YSZ and SDC substrates. For comparison half cells with SDC interlayer were also prepared with thin layer of LSCF electrode. Electrochemical study revealed that the polarization resistance of the half cells, apart from being influenced by the kind of electrolyte used and by the sintering temperature, are also influenced by the powder synthesis conditions. The improved electrochemical properties in case of LSCF electrode was attributed to its fineness at its powder synthesis level and the resulting microstructure. It has also been found that the electrode polarization of LSCF cathode is minimum with SDC electrolytes and maximum with YSZ electrolyte. The study also suggests the use of SDC interlayer on YSZ electrolyte as a potential solution for application of LSCF cathode with YSZ.
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Miss, Jyoti. "Characterizations of Substituted Co2Y and Zn2Y type Hexagonal Ferrite". Thesis, 2017. http://ethesis.nitrkl.ac.in/8788/1/2017_MT_Jyoti.pdf.
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Hexagonal ferrites are well known for their high-frequency microwave device applications. BaCo2Y and BaZn2Y type hexagonal ferrite are used for microwave antenna as they have good permeability and permittivity at high frequency. To modify the electrical properties of ferrites usually different substitution are applied in their crystal structure. In the present investigation, La-Zn is substituted for Fe in Co2Y ferrite, and La-Co is substituted for Fe in Zn2Y type ferrite. The ferrites with composition Ba2-xLaxZn2Fe12-xCoxO22 and Ba2-xLaxCo2Fe12-xZnxO22 where x equals to 0.0, 0.1, 0.3 and 0.5 were synthesized through conventional solid state reaction route. The phase formation behavior of the ferrites, changes in crystal structure parameters with substitutions were investigated using X-ray diffraction analysis. Accurate lattice parameters were evaluated through Rietveld refinement of XRD pattern. The electrical property of the ferrite was investigated on sintered ferrite. The microstructure of sintered ferrite was investigated by using Field Emission Scanning Electron Microscope (FESEM). The permittivity of the ferrite was measured on sintered pallet and permeability was measured on toroid specimen using LCR meter. All the electrical parameters were co-related with the crystal structure, microstructure, and densification behaviour of the ferrites.
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R, Vinaykumar. "Low Temperature Sintering and Characterizations of Co-Ti Substituted SrFe12O19 M-type Hexagonal Ferrites for High frequency Antenna Applications". Thesis, 2020. http://ethesis.nitrkl.ac.in/10209/1/2020_PhD_VKR_514CR6003_Low.pdf.
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The objective of the work was to sinter the Co-Ti substituted SrFe12O19 ferrite at 900oC using sintering additives and to use the low-temperature sintered ferrite for high frequency antenna substrate materials applications. SrCo1.5Ti1.5Fe9O19 ferrite was synthesized by two different routes; (a) sol-gel combustion and (b) solid-state reaction. Although the properties of the ferrite synthesized by sol-gel route were marginally higher than the ferrite prepared by solid state route, the ferrite synthesized by solid state route was used for low temperature sintering experiments due to its economical and simple processing technique. The different sintering additives like; (a) B2O3, (b) Bi2O3/+B2O3, (c) B2O3+CuO/ZnO, and (d) B2O3-Bi2O3-SiO2-ZnO (BBSZ) glass were used to study the sintering behavior of SrCo1.5Ti1.5Fe9O19 ferrite at 900oC. The 5wt% B2O3 sintering additive was proposed for the ferrite, which provides bulk density ~4.0 g/cc, equivalent ε~17 and μ~18, higher miniaturization factor (n=17.49) and good impedance matching (Zi=1.02). Bi2O3 or (Bi2O3+B2O3) additives were not so efficient like 5wt% B2O3 additive. The ferrite containing 5wt% Bi2O3 showed comparatively lower properties like; bulk density ~3.57 g/cc, ε~12.5, μ~13, n=12.74, and Zi=1.01. In the case of different combinations of B2O3+ZnO/CuO additives, 4wt% B2O3+6wt%ZnO (4B6Zn) composition was found efficient with respect to only higher bulk density achievement (~4.62 g/cc), as ε (~13) and n (~14.4) values were lower compared to 5wt% B2O3 added ferrite. The 5wt% BBSZ glass additive was found equally effective like 5wt% B2O3 additive, where the bulk density ~ 4.3 g/cc, n = 17.5 and Zi = 0.99 and about equivalent ε and μ (~17.5) were achieved. For comparison with SrCo1.5Ti1.5Fe9O19 ferrite, BaCo1.5Ti1.5Fe9O19 ferrite was also synthesized and low temperature sintered using 5wt% B2O3 and 5wt%. BBSZ glass additive. The BBSZ glass additive was found more efficient than B2O3 additive for BaCo1.5Ti1.5Fe9O19 ferrite. Finally, microstrip-fed cylindrical antennas based on low-temperature sintered SrCo1.5Ti1.5Fe9O19 and BaCo1.5Ti1.5Fe9O19 ferrites were designed, fabricated and characterized. BBSZ glass containing SrCo1.5Ti1.5Fe9O19 ferrite showed the antenna parameters; return loss ~ -34 dB, gain ~ 5.23 dB, VSWR ~ 1.05 and bandwidth (S11<-10dB) of 133 MHz at fr ~ 10.45 GHz. In the case of BBSZ glass containing BaCo1.5Ti1.5Fe9O19 ferrite, the return loss ~ -32 dB, VSWR ~ 1.03 and bandwidth of 98 MHz were found at fr ~ 8.91 GHz. The demonstrated results indicate that 5wt% B2O3 and 5wt%. BBSZ glass assisted low temperature sintered SrCo1.5Ti1.5Fe9O19 ferrite will be a better candidate for high-frequency antenna substrate material application.
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Mondal, Soumini. "Mg-Al Layered Double Hydroxide Nano-Carrier for Controlled Release of anti-inflammatory Drug". Thesis, 2016. http://ethesis.nitrkl.ac.in/6959/1/2016_Soumini_Mtech(r)_612CR3007.pdf.
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Layered double hydroxides (LDHs), have been known for many decades as a catalyst and ceramic precursors, traps for anionic pollutants, and additives for polymers. Recently, their successful synthesis on the nanometer scale opened up a whole new field for their application in nanomedicine. Here we report the efficacy of Mg1-xAlx (NO3) x (OH)2 LDH nanoparticles as a carrier and for controlled release of one of the non-steroidal anti-inflammatory drugs (NSAID), sodium salicylate. Mg1-xAlx (NO3)x(OH)2.nH2O nanoparticles were synthesized using co-precipitation method from an aqueous solution of Mg(NO3)2.6H2O and Al(NO3)3.9H2O. Salicylate was intercalated in the interlayer space of Mg-Al LDH after suspending nanoparticles in 0.0025(M) HNO3 and 0.75 (M) NaNO3 solution and using anion exchange method under N2 atmosphere. The shift in the basal planes like (003) and (006) to lower 2θ value in the XRD plot of intercalated sample confirmed the increase in basal spacing in LDH, which is because of intercalation of salicylate into the interlayer space of LDH. FTIR spectroscopy of SA-LDH nano hybrid revealed a red shift in the frequency band of carboxylate group in salicylate indicating an electrostatic interaction between cationic LDH sheet and anionic drug. Differential thermal analysis of LDH-SA nanohybrid indicated higher thermal stability of salicylate in the intercalated form into LDH as compared to its free state.DLS studies showed a particle size distribution between 30-60 nm for pristine LDH whereas salicylate intercalated LDH exhibited a particle size distribution between 40-80 nm which is ideal for its efficacy as a superior carrier for drugs and biomolecules.The cumulative release kinetic of salicylate from MgAl-LDH–SA hybrids in phosphate buffer saline (PBS) at pH 7.4 showed a sustained release of salicylate up to 72 h. The drug release kinetic closely resembled first order release kinetics through a combination of drug diffusion and dissolution of LDH under physiological conditions.The hemocompatibility tests performed on the samples showed that Mg Al LDH was compatible with human blood. Cytotoxicity of LDH-SA nanohybrid was determined using MTT assay, subsequently the DNA fragmentation test on human kidney cells. The results suggest that SA intercalated into LDH was much less cytotoxic than the bare SA on kidney cells.
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Anand, Rajan. "Electrophoretic deposition of hydroxy-apatite on Ti6Al4V". Thesis, 2012. http://ethesis.nitrkl.ac.in/3728/1/Rajan_Anand_thesis_108BM018F.pdf.
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In the present study, electrophoretic deposition of sintered and non sintered hydroxyapatite on Ti6Al4V has been carried out at a constant voltage of 30V for 5, 10 and 15 minute duration at different pH values of 1.5, 2.5 and 3.5 respectively for improving the property of coated layer. An uniform coating of hydroxyapatite (HAp) will results in a better cellular activity. As-received Ti-6Al-4V samples are polished by following the standard metallographic technique to prepare a scratch free surface. After coating under different processing conditions the surface are characterized by scanning electron microscopy (SEM) for morphological studies and x-ray diffraction technique for phase analysis. SEM images show that at lower pH value 1.5 and constant voltage 30V crack were not present at coating surface. Comparison between sintered (900˚ for 2 hrs) and non-sintered hydroxyapatite deposition and phase characterization analysis was done by XRD analysis. XRD analysis indicated that before sintering, some other compounds were present in HAp powder but after sintering they were not oxidized. The presence of chemical elements on the deposited surface was assessed by EDS.
(Keywords: Ti6Al4V, Electrophoretic deposition, Hydroxyapatite, XRD, SEM, EDS )