Microstructure and properties of W-doped self-lubricated Ti(C,N)-based cermets

Abstract

Since wear usually occurs on the surface, it is not necessary to fabricate self-lubricated bulk materials. In the paper, Ti(C,N)-based cermets with self-lubricated gradient surfaces are prepared after carburizing treatment based on W-doped carbon-deficient cermets. The microstructures, mechanical properties and wear behavior of the W-doped self-lubricated Ti(C,N)-based cermets were investigated. The results showed that when W is added into the cermets, the carbon-deficient cermets were prepared. This carbon-deficient system hinders the inward immigraion of carbon atoms and thus changes the distribution of other elements in the cermets which results in the formation of a gradient layer enriched in graphite phase but deficient in Ni binder phase. Besides, with the increase of W content, the amount of graphite decreases. Moreover, the TRS and the hardness of cermets is enhanced due to the addition of W and the hardness of the graded cermets was obviously different along the depth direction. Compared with the self-lubricated bulk cermets without the addition of W, the self-lubricated cermets with 2 wt% W addition show the best tribological properties due to the lubricated effect of the gradient layer with high volume fraction of graphite as well as a superior tough substrate.