ceramics Flashcards
What is a ceramic
inorganic compound, of a metal and 1+= non metal
four most common elements in earth’s crust
O2, Silicon, Al, Fe
difference between traditional and new ceramics
traditional–clay based (e.g. pottery, bricks)
new–simpler in chemical composition (e.g. oxides, carbides)
what distinguishes glass from traditional and new ceramics?
glass is non crystalline (amorphous), ceramics are crystalline
3 mechanical properties of ceramic materials
brittle, no ductility, high hardness, low fracture toughness
3 physical properties of ceramics
electrical and thermal insulating, medium density (mostly below metals), high melting temperatures, thermal expansion lesser than metals generally
thermal expansion in ceramics generally is {lower, higher} than that of metals
lower
type of atomic bonding for ceramics
covalent and ionic
what does clay consist of, give an example clay
hydrous aluminum silicate
e.g. kaolinite clay
bentonite clay
french green clay
what’s glazing, as applied to ceramics
application of oxide surface coating, e.g. using alumina and silica, to a porous ceramic e.g. earthenware, to make produce more impermeable to moisture and more attractive
define oxide
compound containing oxygen, e.g. carbon dioxide
glazing makes a porous ceramic more {1} to moisture
impermeable
meaning of refractory
heat resistant (ceramics, and also to metals that are)
2 principal applications of cemented carbides
cutting tool inserts
rock drilling bits
drawing dies
dies for powder metallurgy
cemented carbides are ideal for applications where {1} is needed
1: hardness
define hardness
resistance to deformation, particularly permanent deformation e.g. scratching, cutting, abrasion
‘materials ability to withstand surface indentation/wear’
define toughness
materials ability to absorb energy and plastically deform without fracturing
one important application of titanium nitride
prolong tool life via thin coating on cutting tools
elements in Sialon
Si, Al, O2, N2
what material describes the following:
“An inorganic, non metallic material that cools to a rigid solid without crystallization”
glass
primary mineral in glass products
Silica
or SiO2, silicon dioxide
what’s the purpose of the additional ingredients added to glass?
increases fluidity in molten glass, during processing
retarding devitrification, tendency to crystalize from glassy state
reduces final products thermal expansion
increase chemical resistant
adds colour
alters index of refraction for optical applications
devitrification involves the transformation of …?
glass to polycrystalline state
graphite is composed of {1} in form of hexagonal {2} layers. {3} bonding exists between atoms in layers, the parallel layers are bonded by {4} forces, thus leading to highly {ani..} properties
1: carbon
2: crystalline
3: covalent
4: van der waal
anisotropic
