Questions and answers
Ceramics
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Questions: 81
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Question 16
Give examples (2) of equipment for crushing brittle raw materials
Hammer Crusher,, Jaw Crusher
Question 17
Give examples (3) of mills used in ceramic industry
Ball mill, Roller mill, Atritor mill
Question 18
Could you explain a term “calcination”
Calcination is a heat treatment in order to decompose the materials especially carbonate to its oxide state. It’s use only to simple oxides, is a endothermic reaction,
Question 19
Give an example (1 reaction) of solid state synthesis of mixed oxides
CaO + TiO2 -&rt; CaTiO3 (perovskite, ferroelectric)
Question 20
Give an example (1 reaction) of carbothermal synthesis of non-oxide ceramic powder
Si + C = SiC (???) Si3N4 + 3C ⇌ 3SiC + 2N2 (???)
Question 21
Obligatory requirement for self-propagating high-temperature synthesis (SHS) powder
exothermic reaction - the rate of heat losses from the closed system is slower from the rate of the heat evolution: borides, carbides, nitrides, silicides - ignition
Question 22
Give examples of chemical methods of ceramics powders manufacturing
Wet chemical methods: -spray frying; - freeze drying; - co-precipation; - pecchini method with critic acid; - hydrothermal methods; - SOL-GEL
Question 23
Description of spray-drying method fo ceramic powder
Spray-drying is a process of producing a granulates ,flowable powder of uniform bulk density. It is process by which fluid feed material is transformed in a dry powderby spraying the feed into a hot drying medium (gas) EVAPORATION -&rt; PRECIPITATION -&rt; DRYINGE -&rt; DECOMPOSITION
Question 24
Description of freeze drying method for ceramic powder
Freeze-drying is used to create a formable powder from a sprayed slurry mist. Freeze-drying creates softer particles with a more homogeneous chemical composition than traditional hot spray drying, but it is also more expensive.
Question 25
.List the reagents (3) in sol-gel method for ceramic powder production
- water - alkoxides - acid
Question 26
Principles of ceramic nanopowder production via gas-phase methods
EVAPORATION-CONDENSATION, DECOMPOSITION OF GASEOUS COMPOUNDS, REACTIONS BETWEEN GAS PHASES
Question 27
What does it mean: “rheology”
RHEOLOGY: hydrodynamics of dispersed systems: solid+liquid
Question 28
Parameters describing powder properties(3)
Particle size distribution, Apparent mean size, Specific Surface area (SSA)
Question 29
Why powder particles from agglomerates?
Because it wants to reduce the surface energy
Question 30
How water presence affect Hamaker’s constant of powder?
Water presence reducecs Hamaker's constant