dt a level mock finishes

what do most metals have

they have a oxide layer which provides some barrier against the effects of the environments

what is the exemption to the oxide layer

steal, it has a layer that lets moisture to penetrate mate which leads to rust.

why are finishes applied

they are applied to metals to enhance the appearance and to help provide a barer against corrosion

cellulose and paints

they provide colour and texture, while providing a barrier against corrosion

but the metal needs to be cleaned and degreased, this is so the base and primer has a surface to grip on to

electro plating

involves using a metal to coat another usually a cheaper material to coat another, usually a cheaper material.

this is used as a protective layer and also for atheistic reasons

how dose electro plating work

the products and doner material are placed in a cylinder with electrolyte solution, as the direct current is applied the product attracts the doner metal and the product is electroplated.

what is dip coating polymers used for

coat hooks, out door play equipment frames

how dose polymer dip coating work

the metal was heater to 230 degrees

the hot product is dipped into a tank of fine polymer powered (which has air flowing through it so it acts like a liquid)

the heated metal allows the polymer to melt over the product

then it is cooled by air to allow the coat to set

what is metal dip coating

it is when a metal product is dipped into a tank of metal that is at its melting point.

product needs to be cleaned and degreased

what are examples of electroplating

tin plating - sheets of steel pass through a tank of steel at 320 degrease

zinc pleating - essentially the same but with zinc and 460, used for construction beams gates and animal pens

powered coating

it works by the product being negatively charged, and the polymer resin in the spray gun being positively charged (this causes an attraction between the two)

the product is then baked in an oven so the polymer melt

egs: washing machine bodies

varnishing

metal varnish gives a clear finish to protect the metal, it allows the metal to still be seen. mostly used for the more expensive metals.

metals need to be cleaned before applied, it is applied in a spray of brush

sealant

they are polymer based protective coating that protect the polished surface from decay and tarnish.

silicon base sealant are clear and used in the automotive industry

how are sealants applied

often applied with a cloth, then is left to cure for 15mins, then buffed with a clean cloth to shine.

anodising

makes the surface harder and more resistant to scratch, enhances the natural oxide layers gives it enhanced hardness and toughness

how dose anodising

The metal is hooked up to a positive electrical charge (making it the anode), while a separate plate is given a negative charge (cathode). Electrical current forces oxygen ions from the acid to bind with the metal surface, creating a microscopic,

cathodic protection

A method of preventing corrosion by connecting a more reactive metal (sacrificial anode) to the metal being protected. The reactive metal corrodes instead.