Ceramics Flashcards
Ceramics are made up of ….. or ….. bonds.
Covalent, ionic.
The bonds in ceramics are d……l, which means the atoms are locked in place, so they cannot s….p, making ceramics such as silica h….d and b…..e
Directional, slip, hard, brittle.
What are bricks made from?
Baked moulding clay.
Name three properties of bricks…
- They are hard so difficult to scratch.
- They are brittle so they can break if handled carelessly.
- They are strong so can withstand a lot of force.
How is pottery made?
Shaping clay using hands or a spinner, and then baking it in a kiln to let the water escape, hardening the mould to produce a strong, but brittle material. It can then be coloured/glazed.
When force is applied to ceramics, they undergo e…..c strain. The stress concentration can be thousands of times greater than the a…..d stress. The crack d……s the tensile stress, concentrating it in a small area ….. the crack. The bonds are under a lot of s…..s, until they break so the crack moves.
elastic, applied, deflects, under, stress.
What are the cations in ceramics typically made from?
Alkalis or alkaline metals.
What are the anions in ceramics typically made from?
Halogen/oxygen ions.
To make ceramic very stiff and strong, the ions must be packed t……y
tightly.
Name three properties glass and ceramics have in common…
- Both are good thermal and electrical insulators.
- Both experience crack propagation.
- Both have high melting and boiling points.
Name two properties glass and ceramics don’t have in common…
- Glass is less hard, it is easily scratched compared to ceramics.
- Glass is amorphous, meaning while it is crystalline like solids the molecular arrangement is very random, making it more liquid-like.
Name four methods used when making ceramics.
Extrusion - The ceramic is shaped by squeezing it through a hole.
Jiggering - The material is placed onto a rotating mould.
Hot pressing - The powdered material is forced into a mould and pressed before it is heated to give the material shape.
Reaction bonding - For silicon nitride, the powder is shaped before it is heated with nitrogen gas, so the grains of silicon nitride can tightly fuse.
Silica can be crystalline, (i.e. - q…..z), or amorphous, (i.e. - g….s)
Quartz, glass.
How is glass made, and what structure does it have when finished?
At 1700 degrees celsius, silicon dioxide, sand, is melted until it sets through cooling, so the structure changes completely, giving the glass crystalline properties like solids, while also having the random molecular structure of liquids. Glass is amorphous.
What can be added to give a green tint to glass?
Iron or chromium based materials.
