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采用等离子喷涂工艺在TiAl基合金表面制备NiCoCrAl-Y2O3涂层,并用激光重熔工艺对涂层进行处理。用SEM、XRD对激光重熔前后的试样进行检测,分析了涂层的微观组织结构以及物相成分组成,同时对涂层进行高温氧化试验。结果表明,等离子喷涂后的涂层组织较致密,但仍存在孔洞等缺陷。激光重熔后涂层的组织结构进一步均匀、致密,晶粒得到细化。激光重熔过程中,涂层中Al元素上浮,并部分氧化生成Al2O3相。这两方面均可有效“阻碍”氧离子向内扩散和金属阳离子向外扩散,使重熔后涂层的高温抗氧化性能得到较大地改善。
The NiCoCrAl-Y2O3 coating was prepared on the surface of TiAl-based alloy by plasma spraying and the coating was treated by laser remelting. The samples before and after laser remelting were detected by SEM and XRD. The microstructure and phase composition of the coating were analyzed. At the same time, the coating was subjected to high temperature oxidation test. The results show that the coating after plasma spraying is dense, but defects such as voids still exist. The structure of the coating after laser remelting is further uniform and compact, and the grains are refined. In the laser remelting process, the Al element in the coating floats and partially oxidizes to form the Al2O3 phase. These two aspects are effective “impede” the inward diffusion of oxygen ions and the outward diffusion of metal cations, so that the high temperature oxidation resistance of the remelted coating is greatly improved.