Microstructure And Properties Of WC Containing Coatings Prepared In Situ By Laser Alloying On TC4 Titanium Alloy Surfa CE

TC4 alloy material composition is Ti-6Al-4V,is better than high strength,corrosion resistance and high temperature resistance and other excellent properties,are widely used in aerospace,defense,automotive and Marine industries?engine components,camshaft,fasteners,valves,etc.?,but the wear-resisting performance is poorer,limits its further application,improve the titanium alloy wear resistance,and its surface hardness is of great significance to broaden its range of application.In this study,WC?carbon content 0.1%?,Ni and Si mixed powder were used as raw materials,and the coating containing WC,Ni and Si was successfully prepared in situ on the surface of titanium alloy by laser alloying technology.The effect of adding a small amount of Cr/Co with different WC content and different laser power on the microstructure and properties of TiNi based coating was studied.The experimental results of the influence of different laser power on the microstructure and performance of WC coating show that:when the power is 1600W and 1700W,the coating hardness is equivalent to about945HV,but when the power is 1800W,the hardness decreases slightly.When the power is 1700W and 1800W,the friction coefficient of the coating is relatively close?fluctuates from 0.22 to 0.33?.The friction and wear experiment is more stable and the sample wears more when the laser power is 1600W and 1800W.The experimental results of the influence of WC content on the microstructure and properties of TiNi coating show that the coating with higher WC was prepared with the appropriate laser alloying parameters and was uniformly dense,with a small amount of microscopic cracks,and bonded with TC4 matrix in metallurgy.The coating structure is mainly composed of Ti,Ti5Si3,WC and TiNi.The average hardness was950HV,nearly 2 times higher than that of TC4 substrate?320³60HV?.The average friction coefficient of the coating is 0.2,which is 1.2 times lower than that of the substrate?0.44?.The average wear of 0.308mg decreased by 1.1 times compared with that of matrix?0.67mg?,which significantly improved the wear resistance of TC4.The experimental results of the influence of a small amount of Cr/Co on the microstructure and properties of the coating show that the coating with higher WC is uniformly dense,without cracks and is metallurgical bound to TC4 matrix.The composite phases of Ti₅Si₃,TiNi,TiC and Ti₂Co were precipitated,which enhanced the wear resistance and hardness of the alloy layer.The average hardness of the coating is about918HV,the average friction coefficient of the coating is 0.3,and the average wear is 0.388mg.That is to say,the hardness and wear resistance were slightly reduced.The group with more chromium and cobalt elements added significantly improved the defects?holes,cracks,etc.?in the coating and made the tissue more fine and even.