Microstructure,oxidation behavior and tribological properties of AlCrN/Cu coatings deposited by a hybrid PVD technique

Achieving high hardness and low friction at elevated temperatures for nitride-based hard coatings has substantial scientific interest and application significance.In this study,AlCrN/Cu coatings were deposited by a hybrid PVD technique combining arc evaporation from an Al_(60)Cr_(40) target and magnetron sputtering from a Cu target in a mixed Ar and N_(2) atmosphere.The microstructure,oxidation behavior,and tribological properties of the coatings were investigated.AlCrN/Cu coatings show a dual-phase structure of(Al,Cr)N solid solution and Cu metallic phase.Excessive sputtering power of the Cu target induces the disintegration of interlayer interfaces of the nano-multilayered geometry,accompanied by a decline in hardness from above 30 GPa to 22.7 GPa.Moreover,the formation of fine CuO grains on the coating surface is conducive to reducing the friction coefficient of AlCrN/Cu when exposed to air at high temperatures.The AlCrN/Cu coating with a sputtering power of 0.5 kW obtains a friction coefficient of 0.39±0.05 after pre-oxidation at 800℃,distinctly lower than that of AlCrN,which exhibits a friction coefficient of~0.65.The further transformation of CuO to cubic Cu(Al,Cr)_(2)O_(4),which stems from the solid-state reaction of CuO,Al_(2)O_(3),and Cr_(2)O_(3),would cause a rise in friction coefficient and wear loss.The mechanism of oxidation and tribological behavior of the AlCrN/Cu coatings related to the temperature and Cu content was discussed.

Friction and wear properties of AlCrN coating by cathodic arc ion plating

AlCrN coating was prepared on the surface of TiC-based cermet cutting tool with cathodic arc ion plating,and the surface-interface morphologies,compositions of chemical elements,and phases were analyzed by scanning electron microscope(SEM),energy dispersive spectrometer(EDS),and X-ray diffraction(XRD),respectively.Bonding strength of the coating-substrate interface was measured with scratching test,and the wear mechanism and friction coefficient of TiC-based cermet cutting tool and AlCrN coating were investigated with friction and wear testing machine.The results show that the interface binding of AlCrN coating is metallurgical mode,and its binding strength is 83 N.The average friction coefficient of TiC-based cermet cutting tool under the load of 6 N is 0.8409,while that under the load of 8 N decreases by about 11%,and the wear mechanism of TiC cermet cutting tool is fatigue wear,abrasive wear,and oxidation wear.The average friction coefficient of AlCrN coating is 0.6363 under the load of 6 N,and the change is relatively stable,decreasing by about 25%than that of TiC-based cermet cutting tool;when the load increases to 8 N,the average friction coefficient of AlCrN coating decreases by 9%.The wear mechanism of AlCrN coating is abrasive wear and oxidation wear,showing lower friction coefficient and good wear resistance.