定向凝固镍基高温合金表面微弧火花外延沉积MCrAlY涂层

Micro-arc Spark Epitaxial Deposition of MCrAlY Coating on Directionally Solidified Superalloys

在分析微弧火花沉积工艺产生的单熔体快速凝固过程的基础上,提出将微弧火花沉积用于制备具有定向凝固特征的防护涂层。结果表明:采用微弧火花沉积可在定向凝固高温合金表面获得超细的胞状柱晶结构、外延生长的MCrAlY涂层。与激光外延生长涂层相比,微弧火花外延涂层能够保持完全的柱状晶结构,而激光外延涂层表层通常会形成等轴晶层;另外,在组织均匀性、组织粗细、界面熔合区大小等方面微弧火花涂层具有明显的优势。

An attempt has been made to prepare epitaxial coating with characteristics of directional solidification on the basis of the analysis of the rapid solidification process of a single melt spot produced by micro-arc spark deposition. The results show that epitaxial MCrAIY coating with super-fine cellular crystallines can be prepared on directionally solidified superalloys. Compared to laser epitaxial growing coating, micro-arc spark coating remains fully columnar in the whole layer whereas laser coating tends to change to equiaxed at the top of the layer. In addition, micro-arc spark coating has advantages over laser coating in composition homogeneity, dendrite size, and interfacial fusion region.