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
| Identifer | oai:union.ndltd.org:ORGSU/oai:ir.library.oregonstate.edu:1957/37178 |
| Date | 10 January 1991 |
| Creators | Huque, Ziaul |
| Contributors | Kanury, A. Murty |
| Source Sets | Oregon State University |
| Language | en_US |
| Detected Language | English |
| Type | Thesis/Dissertation |
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