C6.1.13 different materials Flashcards
What are ceramics?
Hard, non-metallic materials like brick, china, porcelain, and glass
Ceramics contain metals and non-metals, forming giant ionic lattices or giant covalent structures.
List three typical properties of ceramics.
- High melting points
- Hard and stiff, but brittle
- Poor conductors of electricity and heat
What is the primary component of ceramics that makes them unreactive?
Oxides
The compounds in ceramics are mostly oxides.
How is glass made?
By melting sand and allowing it to cool and solidify
Glass has an irregular giant structure without crystals and is usually transparent.
Describe the structure of glass.
Irregular giant structure without crystals
Glass is usually transparent.
What happens to clay when it is heated to very high temperatures?
Tiny crystals form, joined together by glass.
What is the purpose of a glaze on china and porcelain?
To form a smooth, hard, and waterproof surface.
What properties must be considered when choosing a material for an overhead electrical cable?
- Good conductor of electricity
- Lightweight
- Strong
- Resistant to corrosion
Which metal is the best electrical conductor among aluminium, copper, and steel?
Copper
What is the density of aluminium?
2.7 g/cm³
Why is aluminium chosen for overhead electricity cables instead of steel?
Aluminium is a better conductor and less dense than steel.
What types of materials are suitable for making electrical insulators?
Poor conductors of electricity, such as ceramics and polymers.
What is the electrical resistance of glass?
1.0
Which material has the highest compressive strength among glass, porcelain, and poly(propene)?
Porcelain
True or False: Poly(propene) has the highest tensile strength among the materials listed.
False
Why would porcelain be more suitable than glass for insulators where cables are fixed?
Porcelain has a higher compressive strength than glass.
What is the electrical resistance of poly(propene)?
0.03
Explain why glass has an advantage over porcelain for electrical insulators.
Glass must not contain bubbles or impurities, which could compromise its insulating properties.
Why is poly(propene) used for making ropes and crates?
It is tough and flexible.
What is the relative tensile strength of copper?
0.6
Fill in the blank: The primary purpose of electrical insulators is to prevent _______ from passing from the cable to the pylon.
electric current
