A theoretical and experimental study of self-propagating high-temperature synthesis of titanium carbide
| Autor: | Huque, Ziaul |
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| Rok vydání: | 1991 |
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| Druh dokumentu: | Thesis/Dissertation |
| Popis: | Self-propagating high-temperature synthesis (SHS) is a new method of producing advanced ceramic materials and offers an attractive alternative to conventional methods of materials processing. An experimental investigation was carried out to determine the SHS reaction wave propagation speed in a vertical cylindrical compact made from a mixture of titanium and graphite powders. Ignition was accomplished by radiatively heating the top surface of the cylinder by resistively heated tungsten heating coils. Syntheses were carried out in inert argon environment and under atmospheric pressure. Propagation speeds were determined by analyzing the temperature distribution with time at two locations at known axial distance. Effects of various system parameters, such as, density and diameter of the initial compact, different mixing ratios of the reactants and dilution with product, on reaction propagation speed were determined. A numerical model was also developed to predict the propagation speed. A two-dimensional formulation was adopted with both radiative and natural convective heat loss from the periphery of the cylindrical compact using constant values of properties and kinetic parameters. Two different kinetic models describing the reactions involving solids are employed to calculate the wave speed using a finite difference scheme. The calculated results were compared with the experimental data. Trends of the results with Kanury kinetic model were found to be in better agreement with the experiments. Results showed no significant effect of heat loss on the propagation speed within a practical range of compact diameter. Quenching conditions of the reaction for titanium rich and carbon rich cases and also for the case of dilution with the product were identified. Variation of propagation speed with sample initial density showed a maximum value at densities between 2.1 gm/cm³ and 2.2 gm/cm³. During the synthesis, the samples were found to expand axially. Hence the final product obtained was highly porous with densities below 50% of the density of TiC. Graduation date: 1991 |
| Databáze: | Networked Digital Library of Theses & Dissertations |
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