Combustive Synthesis or Self-Propagating High-Temperature
Synthesis (SHS), is an energy-efficient combustion
method of producing metallic, ceramic and composite
materials from their constituent powders.
This thesis presents the results of an experimental and
numerical evaluation of the propagation velocity for the SHS
solid-solid reaction of titanium and carbon, as well as a
study of the ignition process for the reaction.
The experimental results show the dependency trend of
the wave propagation speed on various parameters: diameter
of the reactant compact, density of the compact, reactant
mixture composition, and dilution of the reactant mixture
with the inert product TiC. Conditions at which the reaction
ceases to propagate in a self-supporting manner are also
identified.
This thesis attempts to generalize the existing
experimental observations of the gasless SHS process by
means of a dimensional analysis, thus offering a mechanistic
framework within which future developments can be
correlated. The implementation of the new reaction kinetics
model of Kanury and some suitable dimensionless variables
permit the main factors affecting the process to be embedded
in a single key parameter, the Da number. This parameter
includes the overall effects of thermal properties,
stoichiometry of the reaction, carbon particle size, a
process constant, a compression effect and the diffusion of
one reactant through an intermediate complex. The study of
propagation covers a broad range of possible Da numbers that
could arise for different conditions found in experiments.
A section in numerical calculations of the preheated length
is included as well.
Comparison of the numerical and experimental results
for propagation are found to be in reasonable agreement,
thus validating the suitability of the analytical model.
The numerical study includes an examination of the
ignition problem for a stoichiometric mixture, using a
prescribed surface temperature boundary condition. For this
condition, an ignition threshold curve is determined above
which ignition will always occur and below which no ignition
is possible. / Graduation date: 1992
| Identifer | oai:union.ndltd.org:ORGSU/oai:ir.library.oregonstate.edu:1957/36787 |
| Date | 23 July 1991 |
| Creators | Hernandez-Guerrero, Abel |
| Contributors | Kanury, A. Murty |
| Source Sets | Oregon State University |
| Language | en_US |
| Detected Language | English |
| Type | Thesis/Dissertation |
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