扫描速度对激光熔覆NiCoCrAlY涂层组织及性能的影响

Effect of Scanning Speed on Microstructure and Properties of Laser Cladding NiCoCrAlY Coating

为了探究不同激光扫描速度下NiCoCrAlY涂层的组织性能,通过激光熔覆技术在IN718表面熔化沉积了NiCoCrAlY涂层,分析涂层的成形情况、微观结构,并测试硬度、摩擦磨损性能,建立了扫描速度、微观结构和涂层性能之间的动态关系。实验发现,不同扫描速度下的NiCoCrAlY涂层成形良好,凝固组织为垂直于固液分界面、定向及“外延式”生长的柱状枝晶组织、等轴枝晶组织。随着扫描速度的增加,涂层温度梯度增大,凝固速率加快,晶粒组织细化,涂层显微硬度有小幅度增大;同时,涂层的平均摩擦系数和磨损率呈现先减小后增加的变化趋势。结果表明,在12 mm/s扫描速度下获得的涂层耐磨性较优。

In order to explore the microstructure and properties of NiCoCrAlY coating under different laser scanning speed,the NiCoCrAlY coating was melted and deposited on the IN718 surface by laser cladding technology.The forming condition,microstructure,hardness,friction and wear properties of the coating were analyzed,and the dynamic relationship among scanning speed,microstructure and coating properties was established.The results show that the NiCoCrAlY coating has a good shape at different scanning speeds,and the solidification structure is columnar dendrite and equiaxed dendrite which is perpendicular to the solid-liquid interface and grows directionally and epitaxially.With the increase of scanning speed,the coating temperature gradient increases,the solidification rate increases,the grain structure is refined,and the coating microhardness increases slightly.At the same time,with the increase of the scanning speed,the average friction coefficient and wear rate of the coating first decrease and then increase.The results show that the wear resistance of the coating obtained at 12 mm/s scanning speed is better.