铌合金电子束表面熔覆层裂纹控制

Niobium alloy electron beam surface cladding silicide coating crack control

关键词:  电子束熔覆  裂纹  铌合金  硅化物涂层  正交试验

Key words:  electron beam cladding  crack  niobium alloy  silicide coating  orthogonal test

摘要:

在铌合金表面进行了电子束熔覆硅化物涂层试验.利用光学显微镜(OM)、扫描电镜(SEM)观察了涂层表面形貌,通过分析熔覆层表面的裂纹率以及裂纹的最大宽度,对熔覆涂层质量进行评价,研究了电子束熔覆参数对裂纹的影响.结果表明,裂纹倾向随着电子束束流、聚焦电流及扫描速度的增大呈先减小后增大的变化规律,通过控制电子束熔覆参数的合理匹配可以实现对涂层裂纹的控制.通过单变量试验和正交优化试验,筛选出了优化的熔覆处理工艺参数为:电子束束流为17 mA,聚焦电流为1885mA,扫描速度为540 mm/min.采用优化工艺参数获得的涂层的熔覆效果较理想,表面平整光滑无裂纹,晶粒致密均匀.

Abstract:

Electron beam surface cladding silicide coating on niobium alloy experiment has been investigated in this paper.Optical microscope and scanning electron microscope were applied to characterize the surface morphologies of silicide coatings.Through the analysis of cracking rate and maximum width of cracks on the surface cladding layer,the quality of cladding coating is characterized.The results of single variable tests reveal that different processing parameters have different influence on the cracks.By means of orthogonal tests,optimized electron beam cladding process parameters were developed.The optimized parameters were as follows:electron beam current=17 mA,beam focus current=1 885 mA,beam scanning speed=540 mm/min^-1.The silicide coating which was treated by electron beam surface cladding treatment with optimized processing parameters,performed good quality.There is no cracks on silicide coating surface,and the grains of coating were homogeneous and compacted.