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研究了TC4合金表面激光熔覆WC-12Co/NiCrAlY复合涂层后熔覆层的组织结构、显微硬度、熔覆层深度等。实验结果表明,激光熔覆层在组织结构上分为熔化区、结合区、热影响区。由于涂层中不同部位成分、温度分布及冷却速度不同使初生相呈树枝状、块状、花瓣状及颗粒状等几种形态;实现了涂层与基体的良好冶金结合,熔覆层最高硬度可达1100 HV。利用SEM观察、显微硬度测试等分析手段,研究了激光功率、扫描速度、涂层成分、涂层厚度对熔覆层的显微硬度、熔覆层深度影响。结果表明:在其它条件不变时,随着能量密度的增加,熔覆层的显微硬度下降;随着涂层成分中WC-12Co相对含量的增加,熔覆层的硬度增加,但熔覆层的深度减小;激光能量密度大小对熔覆层中熔化区的深度有较大影响;随着涂层厚度的增加,熔化区的深度在减小。
The microstructure, microhardness and cladding depth of the laser cladding WC-12Co / NiCrAlY composite coating on TC4 alloy surface were studied. The experimental results show that the laser cladding layer is divided into the melting zone, the binding zone and the heat affected zone. Due to the composition of different parts of the coating, the temperature distribution and the cooling rate of different primary phase was dendritic, massive, petal-like and granular several forms; to achieve a good metallurgical coating and the substrate, the maximum hardness of the cladding Up to 1100 HV. The effects of laser power, scanning speed, coating composition and coating thickness on the microhardness and cladding depth of the coating were studied by means of SEM observation and microhardness test. The results show that with the increase of energy density, the microhardness of the coating decreases with the increase of the energy density. The hardness of the coating increases with the relative content of WC-12Co in the coating. The depth of the layer decreases; the laser energy density has a greater influence on the depth of the melting zone in the cladding; as the thickness of the coating increases, the depth of the melting zone decreases.