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Plating Specialists
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Diffused Nickel Plating
NiTEC Diffused Nickel Plating is a method of treatment carried out on electroless nickel plating, which has been used for several years by major oil companies worldwide, including Stena Offshore and Petrobras, on riser joints and end fittings for subsea flexible pipework.
It is an electroless nickel coating which is high in phosphorus (10-13%) and plated to 75 -100 microns. It is then heat treated to 605 - 610°C for 10 hours - diffusing the electroless nickel coating into the base metal by 3-5 microns, thus giving excellent corrosion resistance for the most demanding conditions. The diffusion process also allows a slight degree of flexibility of the component, without detrimental affect to the corrosion protection that the coating affords.
After electroless nickel plating, the parts have a bright, uniform, silver-grey finish to them. During heat treatment, as well as the diffusion of the nickel deposit into the steel at the substrate/deposit interface, the outer surface of the nickel oxidises, giving a green/brown colouration. The colour can vary if the atmosphere in the furnace changes. A blue/black colour would be obtained if a gas furnace was used for heat treatment.
Independent tests have been performed for NiTEC, including salt spray testing to ASTM B117. After 2000 hours of testing, none of the parts showed signs of corrosion and the tests were concluded. Results and testimonials are available from companies who have used the diffused nickel process.
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