Nickel plating is a metallic coating of nickel , made by means of an electrolytic bath, which is given to metals to increase their resistance to oxidation and corrosion and improve their appearance in ornamental elements. There are two types of nickel plating: matte nickel plating and bright nickel plating.
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- 1 Manufacturing Engineering Nickel Plated
- 2 Components used in nickel plating
- 3 Nickel plating process
- 4 Sources
Manufacturing Engineering Nickel Plated
Matte nickel plating is done to give thick layers of nickel on iron , copper , brass and other metals (aluminum is a separate case) it is a very concentrated bath that allows working with currents of 8 – 20 amps per square decimeter, with which thick layers of nickel are achieved in reasonable times.
Components used in nickel plating
- Nickel sulfate
- Nickel chlorure
- Boric acid and moisturizer
Bright nickel plating is carried out with a bath of identical composition to the previous one, to which a brightener is added, which can be saccharin, for example. To get mirror quality the motherboard has to be mirror polished. The optimum working temperature is between 40 and 50 ºC, but it can be worked well at room temperature.
In nickel plating baths, a nickel anode is used that dissolves as nickel is deposited on the cathode. For this reason, the concentration of salts in the bath in theory should not vary and these baths can be active for a long time without the need to add salts.
If instead of using a nickel anode, an anode is used that does not dissolve in the bath ( platinum , lead …), the nickel salts will be converted by the effect of electrolysis gradually into their free acids, sulfuric and hydrochloric, with which will produce two phenomena, a decrease in pH (increase in acidity) and a decrease in the concentration of salts, this will lead to the progressive loss of efficiency of the bath.
For this reason, baths with an inactive anode cannot take advantage of all the nickel they contain in solution and when they have consumed approximately 50% of the nickel in dissolved salts, they become inefficient and their deposits are not good.
nickel plating process
Depending on the size of the pieces, various nickel plating methods are used. For small pieces, rotating drums are used and they are treated in bulk. Frame or hook nickel plating is applied when the piece to be treated is of a considerable size, and we want to avoid friction on the surface of the material.
The piece is hung on racks adapted to its geometry, its surface is cleaned to ensure a good deposition of the metal, and it is subjected to an electrolytic coating process in the middle with which a very good distribution of the coating is obtained and the large pieces are held on racks and immersed in nickel plating baths.