Preparation And Tribological Properties Of DLC/AlTiN Composite Coating

AlTiN coating is widely used in metal cutting tools because of its high hardness,good film adhesion and excellent resistance to high temperature oxidation.However,the coating has the high friction coefficient,poor toughness and high internal stress limited its application in harsh working conditions such as anti-friction protection.DLC?diamond-like carbon?coating has good self-lubricating performance,but it si not good for the binding force between this coating and Fe-based material.Through the multi-layer structure design,the characteristics and advantages of the two kinds of coating are combined,it is expected to improve the self-lubrication performance of the coating and the adhesion force of the film base.In this paper,the effects of substrate bias,N₂ flow,Ti-Al target current,Cr doping amount and other process parameters on the surface roughness,phase structure and tribological properties of AlTiN coating were studied by using two preparation processes of arc deposition and magnetron sputtering.The results show that the AlTiN coating prepared under different process parameters mainly exists in the phase of Ti₃AlN and grows in the directions of?110?,?200?and?220?.Tribological test results show that the friction coefficient of AlTiN coating is generally between 0.4 and 0.7,and the wear failure form of AlTiN coating is mainly abrasive wear due to the large surface roughness of the coating.On the basis of process optimization,the structure and tribological properties of DLC/AlTiN coating were studied.The results show that DLC/AlTiN coating surface is diamond-like structure,and the surface roughness is small.After a long time of friction,the coating with Id/Ig value at the wear mark increased,and the diamond structure changed to graphite structure to obtain a lower friction coefficient.DLC/AlTiN coating based on YT15 cemented carbide shows lower friction coefficient and wear rate.By depositing AlTiN coating,DLC coating and DLC/AlTiN composite coating on the surface of cemented carbide turning tool,The cutting experiments show that:at the same feed and cutting speed,the coated turning tool cutting temperature is lower,the surface roughness of coated turning tool processing sample is smaller,and the coating can effectively reduce the phenomenon of aluminum alloy cutting sticky knife,improve the workpiece surface processing quality.