Sliding Wear Behavior of TiN/Ni-W Composite Coating

The sliding wear behavior of TiN composite coating with electric brush plating Ni W interlayer on 3Cr2W8V steel substrate has been investigated. The wear mechanisms of TiN/Ni W composite coating are analyzed based on observation of the worn coating surfaces with a scanning electron microscope. The results show that the mixed crystal Ni W brush plating interlayer crystallizes and precipitation strengthening occurs due to the temperature effects during the TiN deposition process. An interface diffusion layer is also formed between pallation. Moreover, the wear rates of the coatings initially increase with load increasing from 490 N to 980 N and then decreases as the load rises from 980 N to 1 470 N. This is mainly attributed to the change of the wear mechanisms of the coatings caused by a sharp load increase. Namely, the coatings are characterized by abrasive wear at relatively low load, while they are characterized by oxidation wear at extremely high load (above 1 470 N). Thelatter is usually accompanied by lower wear rate because of the friction reduction and wear resistant action of the resultant oxide film well bonded to the substrate.