Coating and surface treatments Flashcards
What are the types of metal coating?
Dip Coating Power Coating Enamelling Paint Oil finishing Galvanising Electroplating
What happens in Dip Coating?
1) Metal is heated to high temperatures (250°C)
2) It’s then dipped into a polythene in powder form
3) Air is blown in to ensure an even coating on the hot metal
What happens in powder coating?
1) The metal is electrically charged
2) Paint in powder form is sprayed from a gun and attracted to the metal
3) The charge created an even coating
4) It is then heated until the power melts and produces ‘run free’ paint.
What happens in enamelling?
Powdered glass is heated and melted before being fused into the metal.
What does enamelling produce?
A material glass like in appearing that is usually coloured
What is galvanising?
The process of applying a coat of zinc to steel or iron to protect it from rust.
What is annealing?
When you heat and cool a metal slowly to remove stress and make it softer
What is normalising?
When you heat metal and cool it at room temperature to reduce hardness and increase ductility
What is case hardening?
When an alloy’s surface is hardened by adding carbon, heating and quenching
What is tempering?
When steel/ cast iron is heated and cooled in air to increase toughness and reduce hardness and brittleness.
What is hardening?
When you heat and then cool the metal rapidly by submerging it in liquid or oil.
