Preparation And Properties Of Diamond-like Carbon Films By Magnetron Sputtering

Diamond-like carbon(DLC)films have excellent properties such as low coefficient of friction,good biocompatibility,and high resistivity.DLC films prepared by various methods can effectively improve the wear resistance,biocompatibility,and insulation of materials.In the past three decades,many scholars and researchers have conducted in-depth research on the properties of DLC films,no matter from the preparation method or the design of the film layer structure,it provides new opportunities for the development and application of DLC films.DLC films shine in many fields.Although DLC films have been practically applied in many fields,DLC films still have many problems to be solved.For example,the large internal stress leads to poor adhesion between the DLC film and the substrate,the lower content of sp~3 hybrid bonds results in lower hardness of the DLC film,and the slower deposition rate leads to higher production costs.The DLC film was prepared on the die steel by pulsed magnetron sputtering in the experiment,and then the structural properties of DLC film were characterized by atomic force microscopy,Raman spectroscopy,step tester,Rockwell indentation tester and Vickers hardness tester.Aiming at the problem of poor adhesion between the substrate and DLC film base,a gradient transition layer is prepared to reduce the internal stress and improve the film base adhesion;for the problem of low hardness and slow deposition rate of DLC film,the hardness and deposition rate of DLC film were improved by optimizing the process parameters.Firstly,DLC film was prepared by preparing different gradient transition layers on the substrate,and the influence of different gradient transition layers on the bonding strength of DLC film and substrate film was studied.The results show that HF2 is the best binding force between DLC film and substrate prepared on Cr/CrN/CrNC/CrC gradient transition layer.At the same time,the gradient transition layer causes elements between film layers to diffuse each other,forming a structure similar to mechanical locking,which solves the problems of surface cracking and falling off of DLC film caused by the large difference in thermal expansion coefficient between DLC film and substrate and the poor surface bonding force between substrate and DLC film.Secondly,the hardness and deposition rate of DLC films were improved by exploring single factor experiments under different process parameters.Experiments show that the process parameters have an effect on the plasma activity,molecular mean free path,and sputtered C particle energy in the magnetron sputtering vacuum chamber during the preparation of DLC films.Thereby,the surface morphology and microstructure of the DLC film are improved,the surface is smoother,the microscopic cluster particles are more uniform and dense,and the sp~3 hybrid bond is improved.Through the exploration of sputtering current,deposition gas pressure and bias voltage,the highest hardness reaches 642 HV.Then,the deposition rate of the DLC film was increased to 14.62 nm/min by doping CH₄ with a hardness of 560 HV.