Diamond-like Carbon Film On Cemented Carbide Surface And Its Tribological Properties In Water Environment

WC cemented carbide as industrial teeth has a wide range of applications in the water environment.However,the complex and tough working environment could make WC cemented carbide serious wear in the water environment.Consequently,exploiting wear-resistant materials to reduce its wear of WC cemented carbide wold be becoming increasingly important.In this work,a hydrogenated a-C:H film,typical metal element doped Me/a-C:H films and rare earth element Ce in coordination with typical metal binary dopant(Me,Ce)/a-C:H carbon-based films were prepared by magnetron sputtering system on the surface of WC cemented carbide substrate.The microstructures and mechanical properties of the as-prepared carbon-based films were investigated systematically.The tribological behaviors of the as-prepared carbon-based films were investigated in ambient air and deionized water environment.The main findings were as follows:1.Hydrogenated a-C:H film constructed on WC cemented carbide substractes presented typical amorphous structure characteristics,the film could possess a smooth surface and relatively good mechanical properties.Although hydrogenated a-C:H film could have a relatively good tribological properties in the ambient air,it suffered from fastly wearing out due to sensitivity to water molecules in deionized water environment.2.In order to improve the performances of hydrogenated a-C:H films,Ti/a-C:H film and Cr/a-C:H film were prepared on WC cemented carbide substractes by exciting CH4 with metal Ti and Cr targets in magnetron sputtering system,respectively.As-prepared carbon-based films both showed typical amorphous structure characteristics.Ti element was existed with TiC nanocrystallites and uniformly dispersed in Ti/a-C:H film.Cr element was existed with Cr nanocrystallites and uniformly dispersed in Cr/a-C:H film.The metal Ti and Cr doping significantly improved the mechanical properties of DLC films,promoted the increase of hardness,elastic modulus and adhesive strength,and reduced the internal stress.Both in the ambient air and deionized water environment,two kinds of carbon-based films could show improved tribological properties compared to pure a-C:H films.3.Rare earth element could be a effective modifier,thus the rare earth Ce element with synergistic typical metal element Ti or Cr to further improve DLC films to construct(Ti,Ce)/a-C:H and(Cr,Ce)/a-C:H composite film on on WC cemented carbide substractes.The microstructures of the two carbon-based films were found to be amorphous,and Ti element was existed with TiC nanocrystallites and uniformly dispersed in Ti/a-C:H film,Cr element was existed with Cr nanocrystallites and uniformly dispersed in Cr/a-C:H film.,and the Ce element was dispersed in the two films with amorphous CeO2.The dopant rare earth element Ce promoted the hardness and elastic modulus of carbon-based films and the further enhancement of adhensive strength,and decrease of internal stress.Especially,the two kinds of rare earth modified carbon-based composite films could show much better tribological properties than that of other film systerm both in the ambient air and deionized water environment.