Effect of Microstructure on Wear of WC/Ni PTA Coatings

WC-Ni coatings were deposited onto steel substrates by the plasma transferred arc (PTA) weld-surfacing process. The wear performance has been evaluated by abrasion wear tests. The deposits were subsequently characterized using optical microscopy, scanning electron microscopy (SEM), and hardness testing. The microstructure consists of two kinds of carbide particles dispersed into the Ni-base alloy matrix. The analysis of the wear surfaces shows that the main wear mechanisms were preferential removal of one of the carbides by binder erosion and microcracking of the other. A variety of analyses were carried out to try to find a correlation with the wear test results. It is concluded that macro hardness, porosity, and the mean free distance between tungsten carbides are the main factors that correlate to the wear performance.