Title:preparation And Tribological Properties Of (TiAlCrMoW)N_x Multi-principal Element Nitride Coatings

The rapid development of the green processing manufacturing industry represented by high-speed dry cutting,there is an urgent need to improve the service performance of the tool coating in a wide temperature range.The multi-principal element nitride coating has more excellent room temperature mechanical properties and good high temperature stability,and is expected to be used as a tool protective coating to further improve the wide temperature range of service performance of the tool.However,there are few reports on the high-temperature tribological properties of multi-principal element nitride coatings.For this reason,this article prepared(TiAlCrMoW)Nx multi-principal element nitrogen by changing the nitrogen flow and substrate bias by multi-target sequential deposition.It has systematically studied(TiAlCrMoW)Nx coating microstructure and mechanical properties,high-temperature oxidation behavior and the evolution of tribological behavior in a wide temperature range,and correlated high-temperature tribological behavior with oxidation behavior,and clarified(TiAlCrMoW)Nx The high temperature friction and wear mechanism of the coating.The research results show that as the nitrogen flow rate increases from 4sccm to 16sccm,the N content in the prepared(TiAlCrMoW)Nx coating increases from 28.99%to 45.71%,and the coating changes from a two-phase mixed structure of BCC Me and FCC MeN to FCC MeN single-phase structure.As the nitrogen content of the coating increases,the hardness of the coating gradually increases,When the nitrogen flow is 12sccm,the hardness presents a maximum of 43.6GPa,and then the hardness decreases slightly.(TiAlCrMoW)Nx coating is oxidized at 700?.After oxidation,the oxide particles on the surface are composed of W and Mo oxides.The oxidation temperature increases from 600? to 700?,The size 600? to 700?,The size of the oxide particles decreases with the increase of nitrogen flow increase.The(TiAlCrMoW)Nx coating has a low friction coefficient during the room temperature friction process,and the coating prepared with a nitrogen flow rate of 12sscm shows the smallest friction coefficient of 0.21.As the substrate negative bias voltage increases from 60V to 120V,the N content in the prepared(TiAlCrMoW)Nx coating increases from 42.95%to 50.83%,and the phase structure of the coating changes from a two-phase mixed structure of BCC Me+FCC MeN converted to FCC MeN single-phase structure,and the coatings prepared under the negative bias voltage lower than 75V have higher hardness than 40GPa,and the hardness of the coatings shows a significant decline after 75V.Except for the coatings prepared with a negative substrate bias of 90V,the room temperature friction coefficients of the coatings are all below 0.37.After the negative bias voltage of the substrate exceeds 105V,the oxidation temperature of the prepared coating drops from 700? to 600?.At 700?,the number of oxide particles rich in W and Mo on the coating surface increased significantly.The friction coefficient of the two-phase mixed structure(TiAlCrMoW)Nx coating at 400? is significantly higher than that at room temperature.The change of friction coefficient is related to the change of crystal structure.At 600?,the friction coefficient fluctuates around 0.6.The friction behavior under high temperature conditions is related to the softening and oxidation behavior of the coating.