Study On Properties And Applications Of Diamond-like Coatings Doped With Physical Vapor Deposition Elements

Diamond-like coatings(DLC)with excellent physical and chemical properties including high hardness,high wear resistance and good chemical inertness,have attracted great attention and been widely used.Due to the high internal stress of DLC coating,the adhesion between the coating and the substrate surface is low,therefore the thickness of DLC coating that can be deposited on the substrate surface is limited,which greatly restricts the further application of DLC coatings.Both the magnetron sputtering and the cathode arc technique were adopted in this thesis to deposit the Ti-DLC coating and Si-DLC coating on cemented carbide substrate.The Ti-DLC and Si-DLC coatings with different element doping ratios were obtained by changing the doping ratio of the two doped elements.The microstructure,thickness,adhesion and internal stress of DLC coatings were characterized by means of scanning electron microscopy(SEM)and Rockwell hardness indentation apparatus.When the Ti-DLC coating was deposited,Ti element content increased and the hardness and stress of the coating generally showed a downward trend as the sputtering power of the titanium target increased,while the coating thickness and strength showed a rising trend.When the Ti-DLC coating was deposited,Filmsubstrate adhesion is excellent with 8.5 at.% Ti,internal stress of the coating decreased from 4.5 Gpa of undoped coating to 2.1 Gpa,the coating still has high hardness and other excellent properties.It was found in the performance analysis of Si-DLC coating that when Si at.%= 3.5 at.%,coating stress decreased from 4.8Gpa to 3Gpa,Si-DLC coating performed best.According to the above analysis,when Ti = 8.5 at.%,the performance of the DLC coating is optimal,that is,the coating stress is smaller and the film-based bonding is better.According to the performance characterization and analysis of Ti-DLC coating and SiDLC coating,the optimum doping ratio of Ti and Si was obtained.The specimens and cutting tools with Ti-DLC coating and Si-DLC coating were prepared in the same proportion.The friction tests and cutting tests were conducted respectively.It was found in the friction and wear test that the friction coefficient of Ti-DLC coating was lower than that of Si-DLC coating.The wear rate of Ti-DLC coating calculated(3.58 × 10-68)8)3/)is also lower than that of SiDLC coating(4.62 × 10-68)8)3/),therefore the tribological performance of Ti-DLC coating is better.In the milling test of ZL108 aluminum alloy,cutting performance and service life of Ti-DLC coated tool is better than that of Ti-DLC coated tool.The chip produced in the cutting process by using Ti-DLC coated milling tool belongs to the ideal chip,which will not cause scratches on the machined surface and affecting the processing quality.