The Preparation Of Ni Base Tungsten Carbide Composite Coating Performance Study

Ni-WC composite coatings which has high hardness, excellent wear resistance, corrosion resistance, resistance to high temperature oxidation resistance and other aspects of the excellent performance, can be used for hard chromium plating and alternative products. This article through the electrical deposition method research and preparation a excellent performance can be used to replace of chromium plating Ni-WC composite coating, and reduce the pollution to the environment. The main conclusions are as follows:The preparation process of Ni-WC composite coatings were optimized by using the method of orthogonal design. The thickness,hardness, composition, abrasion performance, corrosion resistance and surface morphology of the composite coatings were also determined by using optical microscope, micro-hardness, X-ray diffraction(XRD), wear test apparatus, electrochemical workstations, scanning electron microscopy (SEM) and so on. At the same time, the range analysis of the experimental results were performed by using the range analysis method and the influence of various factors on the properties of Ni-WC composite coatings were obtained. The result shows that:Ni-WC composite coatings which have uniform thickness, high micro-hardness, wear and corrosion resistance, combinative ability were prepared by using the method of orthogonal design. The process parameters of mixing speed, WC concentration, electroplating temperature, and current density have an important influence on the electrodeposition process. The mixing speed of medium speed, WC concentration of30g/L, electroplating temperature of50℃and current density Dk of14A/dm2were the best electrodeposited preparation process, and the comprehensive properties of Ni-WC composite coatings were the best. The thickness, micro-hardness, surface abrasion rate, corrosion current and corrosive potential of the Ni-WC composite coating can be up to22.1μm,662.1HV0.1,0.0582mg·N-1·min-1,3.247x10-7A,-0.74V respectively. Coating substrate is nickel, with dispersion distribution WC particles. Through to the composite coatings surface morphology analysis, when WC particles scattered gradually into Ni substrate, the coating has excellent performance.Heat treatments for Ni-WC composite coatings prepared by electroposition at different temperatures were carried out. The changes of the microstructure and properties of the coatings were discussed by micro-hardness, XRD and wear test apparatus. The result shows, after heat treatment, the micro-hardness and abrasion resistant of coatings have relatively substantially improve in a certain temperature range. The temperature at500℃and the holding time of1h was the best heat treatment process. The micro-hardness of Ni-WC composite coating increased to1287HV0.1after the heat treatment, and the surface abrasion rate reduced to0.0547mg·N-1·min-1. In the heat treatment, insulation the extension of time will make the micro-hardness and abrasion resistant of coating reduced, therefore it must be the heat treatment process to strict control. Heat treatment process won’t make the structure of the coating, and the abrasion resistant of coating have a direct correlation with the micro-hardness.