Preparation And Properties Research Of DLC Coating On Low Alloy Carburized Steel

Diamond-like carbon film(DLC)is composed of diamond phase(sp3 carbon hybrid structure)and graphite phase(sp2 carbon hybrid structure).It has many excellent properties,such as high hardness,low friction coefficient,good light transmission performance,and stable chemical properties..Some key components of the diesel engine friction pair(such as piston pins)are subjected to periodic alternating mechanical and thermal loads,and adhesion and abnormal wear and tear often occur.In order to improve the friction and wear performance of the piston pin of the diesel engine,this study took 20CrMnTi steel piston pin as the object,and deposited four different DLC coatings on the surface of the piston pin.The specific work is as follows:(1)The plasma-enhanced chemical deposition method was used to deposit a pure DLC coating on the piston pin surface,and The DLC coating of W-doped DLC coating,Cr-doped DLC coating,and Cr-and Ti-doped DLC coating were deposited on the surface of the piston pin by magnetron sputtering.,Optimize the process parameters,shorten the deposition time(2)The three-dimensional profilometer,ultra-depth microscope,and scanning electron microscope(SEM)were used to observe the micro-topography of the coating,and the X-ray diffractometer was used to analyze the phases generated on different DLC coating surfaces.(3)The self-developed piston pin surface friction coefficient test instrument was used to test the friction coefficient of the smooth piston pin,pure DLC coated piston pin,and three doped metal DLC coated piston pins,and the wear marks were analyzed(4)The adhesion of four different DLC coatings and substrates were tested using a domestic scratch instrument,and the three methods of combining the acoustic emission method,the tangential friction change method and the microscopic observation method on the coating and substrate A comprehensive evaluation of the binding force of.The research results show:The three-dimensional morphology of several DLC coatings is similar,the surface is generally smooth and dense,there are very few protrusions and depressions,and the roughness comparison of DLC coatings doped with Cr is superior to other DLC coatings.During the phase analysis,it was found that a metal compound was formed on the surface of the DLC coating doped with metal;in the friction experiment,the friction coefficient of the piston pin coated with DLC was found to be better than that of the piston pin without coating,and in all among the DLC coatings,pure DLC and Cr-doped DLC coatings have the best friction performance.In the film-based adhesion test,it was found that the adhesion performance of metal-doped DLC coatings is better than pure DLC coatings.The DLC coating doped with Cr and the DLC coating doped with Cr and Ti are significantly better than the other two,and the DLC coating doped with Cr is slightly better than the DLC coating doped with Cr and Ti.In general,the DLC coating doped with Cr has good micro-morphology,excellent anti-wear and anti-friction performance,and strong bonding strength with the substrate.If it is used as a surface coating of the piston pin,it can solve the failure of the piston pin wear of the diesel engine to a certain extent.problem.