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为了进一步提高TiA1金的耐热腐蚀性能,分别采用等离子喷涂和等离子喷涂一激光重熔复合工艺在TiA1合金表面制备了纳米A1_2O_3-13%TiO_2(质量分数)陶瓷涂层,研究了两种涂层在850℃C下 75%Na_2SO_4+25%NaCl(质量分数)熔融盐中的热腐蚀行为,用扫描电子显微镜(SEM)和X射线衍射仪(XRD)对腐蚀后试样的微观组织以及物相进行了分析,并讨论了激光重熔处理对涂层耐热腐蚀性能的影响。结果表明,等离子喷涂陶瓷涂层的腐蚀情况较为严重,经过激光重熔后可以有效提高其耐热腐蚀性能。激光重熔试样具有较高抗热腐蚀性能的原因是:一方面激光重熔消除了喷涂层的层状结构和大部分孔隙,形成了均匀致密的重熔层,减少了热腐蚀过程中的腐蚀扩散通道;另一方面归因于激光重熔使亚稳相γ-A1_2O_3转变为稳定相α-A1_2O_3。
In order to further improve the hot corrosion resistance of TiAl alloy, ceramic coatings with nano-Al 2 O 3-13% TiO 2 (mass fraction) were prepared on the surface of TiAl alloy by plasma spraying and plasma spraying-laser remelting composite process respectively. The corrosion behavior of the samples was investigated by SEM and XRD at 850 ℃ for 75 ℃. The effects of laser remelting on the hot corrosion resistance of the coatings were also discussed. The results show that the plasma spraying ceramic coating corrosion is more serious, after laser remelting can effectively improve the heat corrosion resistance. The reason why the laser remelted sample has higher resistance to hot corrosion is that on the one hand, laser remelting eliminates the lamellar structure and most of the pores in the sprayed layer and forms a uniform and dense remelted layer, reducing the corrosion Corrosion diffusion channel; on the other hand due to laser remelting metastable phase γ-A1_2O_3 into stable phase α-A1_2O_3.