Performance Research Of AlCoCrFeNi High Entropy Alloy Coating

As a conventional front suppression weapon,artillery has played an important role in modern warfare.With the increasing of muzzle velocity and range of projectile,the more and more severe erosion and wear of gun barrel in the process of firing has become an urgent problem for gun designers to solve.AlCoCrFeNi high entropy alloy has excellent mechanical properties and corrosion resistance.The preparation of AlCoCrFeNi high entropy alloy on Cr Ni3Mo VA steel surface of as a coating has a certain innovative significance for improving the service performance of gun barrel.In this paper,the AlCoCrFeNi high entropy alloy coating was deposited on the Cr Ni3Mo VA steel surface by ESD.The wear tests were carried out on the samples under different conditions.The microstructure,phase composition,mechanical properties and the influence of temperature on the mechanical properties of AlCoCrFeNi coating were systematically investigated by means of SEM,EDS,XRD and nano-indentation.The conclusions were summarized as following:AlCoCrFeNi high entropy alloy coating is composed of a single BCC.The coating thickness is about 40±20μm,showing the dendritic structure.The hardness of the coating is 7.36 GPa,and the Young’s modulus is 180.2 GPa.At room temperature,the stable friction coefficient of AlCoCrFeNi coating is 0.5-0.6,and the wear rate is 2.70×10^-4mm³/（N·m）.The friction coefficient and wear rate of the coating are reduced by about35.3%and 62.4%,respectively,compared with the substrate.At 300℃,the stable friction coefficient of AlCoCrFeNi coating is 0.4-0.5,and the wear rate is 1.15×10^-4 mm³/（N·m）.The coefficient of friction and wear rate of the coating are reduced by about 18.2%and36.8%,respectively,compared with the substrate.The wear rates of AlCoCrFeNi coatings at 300℃,600℃and 800℃are 8.4×10^-4mm³/（N·m）,0.528×10^-4 mm³/（N·m）and 3.42×10^-4 mm³/（N·m）,respectively.The coating showed the lowest wear rate at 600℃.Meanwhile,the stable friction coefficient of AlCoCrFeNi coating is 0.42-0.45 at 300℃and 800℃,and 0.46-0.49 at 600℃.The wear mechanism of AlCoCrFeNi coating at room temperature and 300℃is abrasive wear and a small amount of oxidation wear.At 600℃and 800℃,AlCoCrFeNi coatings exhibited significant oxidation wear,and at 800℃,the surface fatigue spalling occurred.A compact oxide film mainly composed of Al₂O₃ and Cr₂O₃ was formed on the worn surface.