Coating processes Flashcards
What are the 2 main reasons for surface finishes?
Preservation/ protection- Prevent corroding, fading, oxidising or decaying. Or to prolong life.
Improving aesthetics- Colour, form, texture, reflectivity…
What is hot blackening?
When a thin layer of black oxide covers the surface of a metal to create a matt black abrasion resistant finish (wear resistant) .
What is the anodizing process?
When a negatively charged cathode is placed in with the positively charged anode (of the material which will be coated) in an electrolyte solution, hydrogen is released from the cathode and oxygen forms on the surface of the anode.
This creates an oxide layer on the anode which protects the material from corrosion.
What is enamelling?
The process of applying a thin coat of finely ground glass to the metal and heating until the glass melts and fuses with the metal.
What is a sacrificial protection of steel?
Iron can be protected from rusting if it’s in contact with a more reactive metal such as zinc.
Therefore, the reactive layer ‘sacrifices’ itself so the iron doesn’t rust even when there are scratches in the coating.
