Electroless Nickel Plated:
Electroless nickel plating is an autocatalytic process where a hard and corrosion resistant alloy of nickel and phosphorous is deposited onto a metallic surface via chemical reaction. Nickel is a yellowish coloured metal applied for corrosion protection and a cosmetic finish. To provide a good corrosion resistance, the nickel layer has to seal off product material from the environment, and therefore be pore-free. This means that the layer should be at least 20 µm (up to 40-50 µm) to guarantee a proper corrosion resistance. If the material has been given a copper undercoat, the applied layer of nickel can be thinner. The nickel layer can be applied in a matt, semi-bright or bright finish. After the product has undergone this process, it can also be chrome plated.
Mechanical Zinc Plated:
Mechanical zinc plating is a tumbling barrel process which applies a 3 – 80 µm thick zinc coating to a pre-treated steel surface (degreasing/descaling) by tumbling the parts with a mixture of zinc dust and ballotini (tiny glass beads). After the tumbling process, the zinc surface will be passivated by applying a chromate conversion coat or lubricated. Unlike electrolytic plating, the mechanical plating process avoids hydrogen embrittlement and therefore no weakening of the material occurs.
Chromium is a bluish-white coloured metal and is applied for decorative finishes and corrosion protection. With decorative chromium plating, a nickel layer is always applied first. The chromium layer that is applied over this nickel layer is thin and gives the product a different colour. To provide a good corrosion resistance, the nickel layer of the raw material has to be sealed off from the environment, and therefore be pore-free. This means that the layer should be at least 20 µm (up to 40-50 µm) to guarantee a proper corrosion resistance. If the material has a copper undercoat, this may result in a thinner nickel layer. With chromium plating, the nickel layer determines the shine.