Powder Metallurgy Questions Exams on “Self Propagating High Temperature Synthesis and Types”.
1. What is the fullform of SHS?
a) Standard pressure High-Temperature Synthesis
b) Standard pressure Heat-Temperature Synthesis
c) Self-propagating Heat-Temperature Synthesis
d) Self-propagating High-Temperature Synthesis
Answer: d
Clarification: Self-propagating High-Temperature Synthesis (SHS) is a novel material synthesizing technique developed in 1967 by A.G. Merzhanov, I.P. Boroviskaya and V.M. Shkirov at the Research Center of the USSR Academy of Sciences, USSR.
2. In ______, a self-sustaining reaction occurs by local ignition in a reactant mixture.
a) reaction sintering
b) SPS
c) SHS
d) activated sintering
Answer: c
Clarification: In self-propagating high-temperature synthesis (SHS), a self-sustaining reaction occurs by local ignition in a reactant mixture. A large number of materials including ceramic powders, including carbides, borides or nitrides as well as their composites in powder or whisker form can be synthesized using this process.
3. Spontaneous formation of product occurs in SHS.
a) True
b) False
Answer: a
Clarification: Spontaneous formation of product occurs in SHS due to the high-exothermic heat of reaction resulting from ignition of the reactants. This process is also called combustion synthesis, gasless combustions, and self-propagating combustion.
4. In SHS, _____ are the different classes of reactions recognized.
a) layer-wise combustion mode
b) propagation mode and simultaneous combustion mode
c) volumetric combustion mode
d) propagation mode and layer-wise combustion mode
Answer: b
Clarification: In SHS, two different classes of reactions have been recognized, (1) those processes in which layer-wise combustion occurs (propagation mode), and (2) those processes wherein volumetric combustion occurs (simultaneous combustion mode).
5. Conventional combustion processes differ from SHS reactions.
a) True
b) False
Answer: a
Clarification: Conventional combustion processes are generally volumetric and reactions occur in a volume, generating heat and the required products. SHS reaction occurs generally by the propagation of a combustion wave with a definite velocity through a reactant transforming it into products.