Nickel-tungsten alloy brush plating for engineering applications

The nickel-tungsten alloy coating has been developed for engineering application. It is of nanocrystalline structure (~ 2 nm crystallite size) and demonstrates excellent hardness and wear resistance. The coating is 60% nickel, 40% tungsten by weight. Due to high tungsten content in the alloy, it is thermally stable. Moderately elevated temperatures (200-500 °C) do not cause grain size growth and softening as the case of most other hard coatings (such as hard chromium, nickel phosphorus). Actually, the nickel-tungsten alloy coating can be further hardened by exposure to high temperature of 200-500 °C for a short period of time. Beyond the hardness and wear properties, the coating has been further characterized by XRD, electronic and optical microscopy, hydrogen embrittlement, salt spray corrosion, tribology, axial fatigue, and other testing.