Preparation And Friction Rules Of DLC Films Doped With CoCrFeNi

Diamond-like carbon（DLC）film is a solid self-lubricating material with excellent performance,which has been widely studied and applied by scholars.However,due to the defects of high residual stress and low film-based bonding force,it is usually necessary to introduce doping components to regulate the performance of the film to meet the application in harsh conditions.High-entropy alloys（HEAs）has high entropy effect,hysteresis diffusion effect,lattice distortion effect,cocktail effect and many other excellent physical and chemical properties.The study of modifying DLC film with CoCrFeNi high entropy alloy as doping component is still rare.Therefore,in this paper,DLC films with different amounts of CoCrFeNi were prepared,and their mechanical properties and friction and wear laws were analyzed.The results show that the number of sp² hybrid carbon atoms increases continuously.The I_D/I_G value at the surface of the film increases monotonically from 1.27 to 2.33 in Raman spectrum.The position of peak G moves monotonically from 1540 cm^-1 to 1558cm^-1.At the same time,the internal stress of the film decreases monotonically from 1.51GPa to 0.64 GPa.The hardness,elastic modulus and other mechanical properties do not change greatly when the CoCrFeNi target current is within 0.6 A,but as the current of the CoCrFeNi target exceeds 0.6 A,the mechanical properties of the films decreases due to the destruction of carbon structure.Therefore,proper doping can reduce the internal stress of DLC films on the premise of maintaining the original mechanical properties.The friction test of DLC films with different doping amounts shows that the friction coefficient and wear rate of the films decrease firstly and then increase with the enhance of doping amounts,and the DLC films with CoCrFeNi target current of 0.6 A shows the best tribological properties.It shows that the introduction of appropriate CoCrFeNi doped phases can effectively improve the friction and wear resistance of the films.In the process of friction,the increase of friction load promotes the graphitization of the film.Meanwhile,a transfer film can be formed at the friction interface,which is beneficial to friction.The density of the transfer film is positively correlated with the order of sp² hybrid bond on the surface of DLC film.A large number of the friction tests are carried out on the film with0.6 A CoCrFeNi target current,which has the best friction performance.The prediction models of wear depth,wear width and wear amount of the film with wear time and wear load are successfully established by the method of function fitting.Also,its accuracy is verified.