Electroless nickel plating

The method produces extremely even layers and provides good wear and corrosion protection. The process also provides good protection against the effects of several substances, such as caustic soda, mineral oil, varnish and molten PVC. Chemical resistance is good against alkali and various metal salts such as chlorides. Electroless nickel plating is offered with three different phosphorus contents that are important for corrosion protection and hardness. Higher phosphorus content gives lower hardness but better corrosion protection. Thanks to its phosphorus content, the electroless nickel has good friction properties. In general, however, friction is slightly higher for electroless nickel than for hard chromium plating. The hardness of an electroless nickel layer depends on the composition of the electroless nickel bath, the number of metallic reactions, the temperature of the heat treatment and the time. You can thus influence the process to achieve the specific result you are looking for. For example, the hardness can be increased from 450-500 Vickers (45-50 Rockwell C) at precipitation to 1000 Vickers (70 Rockwell C) by heat treatment to 400°C if this is done within 24 hours after the coating process. The hardness of electroless nickel-plated surfaces can be adversely affected by prolonged use in temperatures above 600 ˚C. Electroless nickel plating can thus be a good alternative to hard chromium. The coating normally has about one tenth of a percent elongation. When heated to 400˚C, it decreases to zero. Electrical resistance; Generally about 60 micro ohms/cm which can be reduced by heat treatment to 600˚C. Magnetism; Magnetism decreases with phosphorus content. Coatings with more than 8% phosphorus are non-magnetic. Melting point Approximately 890 ˚C. Coefficient of thermal expansion Approximately 13×10-6 cm/cm ˚C. Density Specific gravity 7.85 g/cm3, which increases with decreasing phosphorus content.