Study on the wear characteristics of Al-Ni-xCr composite coating prepared by low pressure cold spraying
The Al-based coating has well corrosion resistance,but its wear resistance is poor.In this pa-per,mixing Ni and Cr powders was designed to improve the wear resistance of the Al-based coating.A series of Al-Ni-xCr composite coatings with different Cr content were prepared by low pressure cold spraying.Their micro-morphology and composition were analyzed by means of metallography,scan-ning electron microscopy and X-ray diffraction.Their microhardness and wear curve were measured by microhardness tester and wear meter.Their wear mechanism was analyzed according to the microscopic characteristics.The results show that the low pressure cold spraying can achieve the co-deposition of Al,Cr and Ni metal powder.The Al-Ni-xCr composite coating is dense and uniform.Dendrite Ni pow-der has a higher deposition rate,while Cr powder shows a lower deposition rate.The Cr content in Al-Ni-70Cr coating is about 31 wt.%.With the increase of Cr content,the densification of Al-Ni-xCr com-posite coating increases.The wear resistance of Al-Ni-xCr composite coating is mainly related to Cr con-tent rather than Ni.Al-Ni-70Cr composite coating has the best wear resistance,and its wear rate is only 1/2 of that of Al coating.Its excellent wear resistance is attributed to the formation of a stable hard and high Cr-containing composite oxide film at the friction interface,which inhibits the wear process.
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