Effect of Laser Energy on Surface Quality and Properties of Electrodeposited Nickel-Cobalt-Tungsten (Ni–Co–W) Coating

Abstract

Ni–W-based coating is one of the most promising materials to replace hexavalent chromium coating, and Ni–W-based coating has excellent performance and good application prospects in many fields. W and Co are beneficial for the corrosion resistance of Ni–W-based coating. In this paper, laser irradiation was introduced into the electrodeposition system to improve Ni–Co–W coating. The effects of different laser energy densities (0,19.1,31.8,44.6, 57.3 and 70 μJ mm−2) on the surface quality, crystal phase, element content, mechanical properties and corrosion resistance of Ni–Co–W coating were studied. The results show that with the laser energy density increasing, the Co and W content increases first and then decreases, while the laser energy density is 31.8 μJ mm−2 and 57.3 μJ mm−2, the content reaches the highest respectively. Meanwhile, the laser energy density is 31.8 μJ mm−2, the Ni content is the lowest. The laser irradiated area temperature increasing makes hydrogen adsorption improved, residual tensile stress reduced and grain size refined. The surface quality is improved significantly because of laser irradiation, with the laser energy density is 19.1 ∼ 57.3 μJ mm−2. The micro-hardness, wear and corrosion resistance are optimized, with the laser energy density is 31.8 μJ mm−2.