Y_(2)O_(3)对TC4激光熔覆镍基复合涂层组织及性能的影响

Effect of Y_(2)O_(3)on Microstructure and Properties of TC4 Laser Cladding Nickel-based Composite Coating

探究不同含量稀土氧化物Y_(2)O_(3)对钛合金TC4表面激光涂层的组织及摩擦磨损和抗高温氧化性能的影响。采用2 kW的光纤激光器,在TC4表面激光熔覆制备含0.2%、0.5%、0.8%、1.0%、2.0%、3.0%Y_(2)O_(3)粉末的Ni60A-50%Cr_(3)C_(2)涂层;利用SEM、XRD、EDS等对该涂层的组织和物相进行分析;通过显微硬度计测量该涂层的硬度;采用MMG-500三体磨损试验机进行摩擦磨损试验;利用WS-G150智能马弗炉进行抗高温氧化性试验。结果表明:Y_(2)O_(3)添加量为1.0%时,该涂层的组织及性能均优于其它Y_(2)O_(3)添加量,涂层没有缺陷、成形良好,涂层生成高硬度碳化物和金属间化合物,组织细密均匀。基体热影响区组织为针状马氏体,涂层结合区组织为平面晶和柱状晶,涂层中部和上表面组织为短小的胞晶和树枝晶,涂层显微硬度最大值为1604HV0.2,约是基体的4.6倍;涂层摩擦系数基本稳定在0.33左右,小于TC4基体的摩擦系数0.5~0.7,涂层的耐磨性较基体显著提高;恒温850℃氧化100h后涂层氧化增重为5.11 mg·cm^(-2),约为TC4基体氧化增重25.8 mg·cm^(-2)的20%,高温抗氧化性能显著提高。适量添加稀土Y_(2)O_(3)可改善TC4激光熔覆层的组织及性能。

The effects of different contents of rare earth oxide Y_(2)O_(3) on the microstructure,friction and wear and high temperature oxidation resistance of laser cladding coating on the surface of titanium alloy TC4 were investigated.A 2 kW fiber laser was used to prepare Ni60A-50%Cr_(3)C_(2) containing 0.2%,0.5%,0.8%,1.0%,2.0%,and 3.0%Y_(2)O_(3) powders.The microstructure and phase composition of the coating on the surface of TC4 were analyze by SEM,XRD and EDS.The hardness of the coating was studied by microhardness tester.The friction and wear tests were carried out by MMG-500 three-body abrasion tester,and the high temperature oxidation test was carried out by WS-G150 smart muffle furnace.Results show that,when the addition amount of Y_(2)O_(3) is 1.0%,the microstructure and properties of the coating is better than other addition amounts of Y_(2)O_(3).The coating has no defects,with good forming.The coating generates high hardness carbides and intermetallic compounds.The microstructure of the heat affected zone of the matrix is acicular martensite,the microstructure of the bonding zone of the coating layer is plane crystal and columnar crystal,and the microstructure of the middle and the upper surface of the coating layer is short cell crystal and dendritic cryctal.The maximum microhardness of the coating is 1604HV0.2,which is about 4.6 times than that of the substrate.The friction coefficient of the coating is basically stable at about 0.33,which is less than the friction coefficient of the TC4 substrate 0.5-0.7.The abrasion resistance of the coating significantly improves compared with the substrate.The oxidized weight gain of the coating after oxidation at a constant temperature of 850℃for 100h is 5.11 mg·cm^(-2),which is about 20%of the TC4 substrate's oxidized weight gain of 25.8mg·cm^(-2).The high temperature oxidation resistance significantly improves.The appropriate addition of rare earth Y_(2)O_(3) can effectively improve the microstructure and properties of TC4 laser cladding layer.