This set of Ceramics Engineering Multiple Choice Questions & Answers (MCQs) focuses on “Spray Pyrolysis”.
1. Spray pyrolysis is also known as__________
a) spray drying
b) spray roasting
c) sol gel processing
d) solutionizing
View Answer
Explanation: Spray pyrolysis is also known as spray roasting as the metal salts can be dries and decomposed in a single step using higher temperature. Spray drying doesn’t decompose the salt solution directly. Sol gel processing includes highly viscous liquids while solutionizing is a heat treatment process.
2. What is the role of reactors in the spray pyrolysis equipment?
a) Atomization of solution
b) Sintering
c) Decomposition of metal
d) Evaporation of salts
View Answer
Explanation: Reactors in spray pyrolysis atomize the solution. They are arranged in series. The aerosol droplets undergo evaporation and solute condensation within the droplet in this chamber.
3. What is the temperature range of spray pyrolysis process?
a) Less than 300°C
b) Less than 1000°C
c) Greater than 300°C
d) Greater than 1000°C
View Answer
Explanation: Temperature range of spray pyrolysis process is generally greater than 300°C. This is so that the desired inorganic phase is formed by thermolysis and to get decomposition in single step.
4. Which step follows formation of microporous particle in spray pyrolysis process?
a) Atomization
b) Decomposition
c) Addition of fillers
d) Sintering
View Answer
Explanation: Sintering is the process that follows after formation of microporous particles. This is done to decrease porosity and make the particles compact for ease of further processing.
5. Droplet undergoes evaporation and solute concentration in the _________
a) outer layer
b) inner layer
c) grain boundary
d) grain
View Answer
Explanation: Droplet undergoes evaporation and solute concentration in the outer layer. The outer layer is exposed to the surrounding high temperature and it reaches a supersaturation limit. The outer layer has fine particle precipitates.
6. Which is the next step after precipitation?
a) Drying
b) Heating
c) Atomization
d) Decomposition
View Answer
Explanation: The next step after precipitation is drying. Drying is done so that the vapor diffuses through the pores in the precipitated layer. It is followed by heating and sintering.
7. If dense particles are required, we must first achieve homogeneous nucleation and growth in the droplet.
a) True
b) False
View Answer
Explanation: When there is homogenous nucleation and growth in droplet itself, there is saturation of fine particles of metal salts. On condensation, these saturated particles arrange themselves in such a way that there is no room left. So we get dense particles.
8. Drying of a droplet containing fine precipitates is quite different from that of a liquid droplet.
a) True
b) False
View Answer
Explanation: Fine precipitates provide a resistance to the mass transport of the solvent vapor. If the temperature of the drying chamber is too high, boiling of the solution may occur leading to inflation or disintegration of the droplet.
9. Which of the following solutions is preferable for sulphates?
a) Laboratory scale nitrates
b) Chlorides
c) Oxychlorides
d) Acids
View Answer
Explanation: A Laboratory scale nitrate is preferable solution for sulphates. Chlorides and Oxychlorides are used industrially because of their high solubility but are corrosive.
10. Which of the following salt solution is used to produce zirconia particle by spray pyrolysis?
a) Zirconyl hydroxychloride
b) Zirconium nitrate
c) Zirconium chloride
d) Zirconium silicate
View Answer
Explanation: Zirconyl hydroxychloride is used to produce zirconia particle by spray pyrolysis. Sometimes, Zirconyl chloride is also used as salt solution for the same.
Sanfoundry Global Education & Learning Series – Ceramics Engineering.
To practice all areas of Ceramics Engineering, here is complete set of Multiple Choice Questions and Answers.
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