Anodising
Anodising is an electrolytic passivation process. Anodising is done through positive and negative charge, the cathode's material is transferred to the anode creating a thicker oxide layer on the surface of the metal. This is so that it has increased corrosion resistance and wear resistance, and provides a better surface adhesive for paint primers.

The positive electrode called the anode is the material that is to be treated as it attracts all of the wanted material, and the cathode, the negative electrode attracts all of the unwanted material. The thickness of the oxide layer is determined by the amount of time you leave the anode in there for and the current per unit area.

Electro-plating
Electrolysis is used to electroplate objects. This is useful for coating a cheap metal with a more expensive one, such as copper or silver.

The negative electrode should be the object that you want to be electroplated.
The positive electrode should be the metal that you want to coat the object with
The electrolyte should be the solution of the coating metal, such as its metal nitrate or sulfate.

The object to be plated is connected to the negative terminal of the power supply, A piece of copper is connected to the positive terminal. The electrolyte is copper sulfate solution

Metals theory

Iron
Iron is converted from its ore by putting it into a furnace and removing the oxygen that is mixed within the ore, this is a process called smelting. This is done by putting the charcoal into the furnace which produces the heat you need to start the reaction by reacting with the oxygen from the ore. The impurities in the ore will form a later of slag. When removed, you are left with a greyish metal once it has cooled. Iron is often combined with carbon giving it a greater strength. By doing this, you are left with a combined material called steel.

Steel
Steel is an alloy of iron and a small amount of carbon. Carbon has  between 0.002% and 2.1%Carbon, Too little content of carbon content leaves the iron quite soft, ductile and weak. Carbon contents higher than those of steel make an alloyed that is brittle but not malleable. Also, alloying steel with other metals creates properties such as increased toughness and resistance to corrosion.

Carbon
Carbon can create Coal and diamond; they have different structures because of the pressure that is applied on them. The amount of carbon in steel increases the strength and hardness, but adding to much carbon can cause the metal to become brittle and break easily.

Iron & Carbon
Iron is normally soft and ductile, which alone, doesn’t make it a useful material to use. When you add carbon in a mixture with the iron, the characteristics are enhanced and the properties change, this can be good but bad in some ways. Increasing the amount of Carbon in the mixture can have different outcomes such as, The material will become a lot harder but the toughness reduces and can become brittle. Certain metals that have carbon in them can have their characteristics enhanced further by being heat treated, these include High carbon steel and medium carbon steel. The heat treating of the metal makes them become stronger, and harder.