Preparation And Sliding Wear Properties Of Laser Cladding WC/Co-Cr Alloy Coating

With the development of industry technology recent years, the mechanical equipment must be work well in the environment that contain high temperature, high press, high velocity, highly automatic and other extremely aggressive environment, required the material has better wear properties, especially high temperature wear resistance, excellent thermal stability and other related properties that can lengthened the service life of the part. So only Co-based alloy coating can not meet the needs nowadays. Recent year’s research and application showed that added a hardness phase such as WC in the Ni-based alloy coating to strengthen its wear resistance. And not yet enough research the Co-based alloy coating added WC. Especially research on the WC/Co-Cr coating has rare reports. In this paper, WC/Co-Cr alloy coating was prepared by laser cladding. And its preparation process, organization, structure, and wear properties were discussed.Preparation of WC/Co-Cr alloy coating on the45#steel by cladding with Nd:YAG laser. Explored the laser current and the scan speed that influence macro quality of the coating. Select the better process parameters. The phase structure, morphologies and the composition of the coating were characterized by XRD, SEM and EDS, respectively. The results showed that the coating mainly composed by Co, WC, CrCo and Co7W6. A few phase Cr23C6, Cr7C3and other hard reticular distribution around the solid solution. With the increase of WC content in the cladding powder, more Fe elements diffusion to the WC/Co-Cr alloy coating. The element of Co, Cr, W and so on decrease from the coating to the substrate and gradient distribution. It’s metallurgical bond between the coating and substrate. When the added powder with15wt%WC, a regular arrangement of small organizations can be found, the coating surface hardness above1000HV. When the adding powder with20wt%WC, appears a lot of unmelted WC particles distributed in the coating.The coating with different components for the wear test at the room temperature. The results showed that with the coating WC content increases, the friction coefficient of the coating decrease, a slight increase in coating hardness, and the wear loss also decrease. When the WC content of20wt%, the friction coefficient is0.35, and the wear loss is0.1mg, but the coating crack appears more with the WC content increase, make it easier brittleness than low WC content. Considering, under the experimental conditions,15wt%WC powder content as the best content.The coating for high temperature wear test. The results are as follows. Keep the temperature of600℃and change the experiment load, the friction coefficient relations is μ100>μ300>μ400>μ200, The wear loss increased with the load increase above200N. Keep the load of200N and change the experiment temperature, the friction coefficient decrease with increasing temperature, while the WC/Co-Cr alloy coating wear weight loss decreased, the coating wear resistance was increased, friction pair abrasion has increased, and the weight loss and friction coefficient has consistent with the change. With increasing temperature, the wear mechanism from abrasive wear to oxidative wear changes.