Preparation And Property Study Of Diamond-like Carbon Coatings On The Cutting Edge Of The Cemented Carbide Tools

As one kind of tool materials cemented carbide has been widely used in the production of cutting tools,but onefold cemented carbide tools cannot meet the needs of modern manufacturing industry with the advance of science.The birth of coated tool solve the problems largely.It combines the advantages of base and coating so that it achieves the aims that the performances of tools have been improved.Diamond-like carbon is one kind of new materials which are similar to diamond in the aspect of proportis.It is befitting to be used to prepare coatings because of the advantages it has:low friction coefficient,high hardness and the abrasive resistance.Based on the discuss above the performances of the tools which are coated with DLC have been studied in this paper.The main research works are summarized as follows.(1)The simulation of coated tools was operated with the software Abaqus.The aim of the simulation is to study how the thickness of coatings influence the cutting process.The material model,the friction model,the chip separation criterion and the parameters of equations and materials are confirmed from literatures.The simulation was operated with the parameters after the creation of the cutting model.Afterwards the formation of chips,the stress distributions of tools,the comparison of the maximum distributions,the temperature distribution,the comparison of the maximum remperature and the cutting forces of tools were studied.The results show that coatings have obvious influence on stress and temperature and influence the cutting forces limitly.Referencing the results of the simulation,it can be summarized that in real manufacture the thickness of coatings should be designed to reduce the cutting temperature because the properties of DLC coatings will reduce in high temperature.(2)Diamond-like carbon coatings and transition layers which were made from pure metal were prepared on the surfaces of the YT15 tools using magnetron sputtering.The coatings were tested with optical profiler,SEM,EDS,Raman spectrum,sclermeter and surface performance tester.The results show that the transition layers are prepared successfully and the transition layers impact the performance of the tools differently.The results of Raman spectrum show that the differences of the elements of the transition layers impact the content of sp3 bonds limitedly.The tools with the transition layers which were made from Cu and Ag have a little more sp3 bonds.The results of hardness test show that the microhardness of the coatings were impacted finitely too.The results of bonding forces between coating and base show that the differences of the elements of the transition layers have important influence on this property.The tool with the transition layer which was made from W has the highest bonding force.It is concluded that the transition layers impact the performances between the coatings and the bases,and they have finite influence on the properties of the coatings.(3)The friction properties of the tools were tested by ball-plate rotating friction test.The results show that the friction coefficients of the tools are influenced largely by load and rubbing speed.The friction coefficients are low and verify placidly when the load is and the rubbing speed are low.The friction coefficients rise and verify sharply when the load and rubbing speed rise.The samples with Ti and W transition layers have higher abrasive resistance on different loads and rubbing speeds compared with other samples.The grinding cracks were observed by contourgraph.The results show that material transferred from friction ball to the coating.The transferred material influenced the friction process,wear mode and wear rate.The wear rate reduces with the reduction of loads and rubbing speeds when the coatings are unbroken and the wear rate rise sharply if the coatings are broken.The shape of the grinding cracks are observed by SEM.