| Ni-W alloy coatings with excellent hardness, wear resistance and appearance produced by electrodeposition were introduced in this dissertation. This process is promising for replacing the chrome plating; because most of its performances have surpassed those of chrome coatings, including current efficiency, wear resistance and other performances.Pulse plating and one additive were both utilized to improve the performances of Ni-W alloy coatings. It was found that reasonable current parameters for pulse plating could enhance the hardness, wear resistance, appearance and sedimentation rate of Ni-W alloy coatings. The additive could effectively improve the appearance of alloy coatings; reduce the internal stress and cracks of alloy coatings.The influences for contents and surface images of alloy coatings caused by the changes of electrolyte contents and plating parameters were investigated. Through XRD analysis it was found that the structure of alloy coatings changed from crystal to mixed crystal and then to amorphism with the increasing content of W in the alloy coatings. The amorphous mechanism of alloy coatings was explained.The heat treatment performance of alloy coatings was investigated; the hardness of alloy coatings would be remarkably increased through the appropriate heat treatment process. The hardening mechanism was also discussed.The frictional and wear performances of alloy coatings under different conditions were investigated on the ball-pan frictional and wear tester, and those of chrome coatings were also investigated for comparison. The wear mechanism of coatings were analyzed by the technology of surface micro-analysis and principles of tribology. Experimental results showed that the excellent performances of anti-plastic deformation and anti-adhesive wear were exhibited during the experiments for Ni-W alloy coatings. Frictional performances of alloy coatings were superior to those of chrome coatings under dry sliding, high speed or heavy load conditions.
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