Research on laser remelting of plasma sprayed thermal barrier coatings
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摘要: 在GH536高温合金基材上等离子喷涂氧化钇部分稳定氧化锆(8YSZ)热障涂层后,采用连续CO2激光进行表面陶瓷层激光重熔,得到了表面形貌、组织结构符合质量要求的涂层。热震试验结果表明,在本试验的失效判据下,等离子喷涂及激光重熔试样的失效形式和机理不同,等离子喷涂试样为热震应力失效,激光重熔试样以热震应力和TGO应力共同作用形式失效。激光能量密度为4.0J/mm2时,激光重熔试样具有略高于等离子喷涂试样的热震寿命,当激光能量密度较高时,激光能量分布不均导致的组织及结构的不均匀,柱状晶粗化是能量密度较高的表征,扩展到喷涂态陶瓷层中的裂纹是激光重熔试样热震寿命降低的主要原因。Abstract: A CO2 continuous wave laser with defocused beam is used for laser remelting (LR) the surface of plasma sprayed (PS) thermal barrier coatings (TBCs) on GH536 superalloy substrate. The thermal shock tests are conducted to both PS samples and LR samples. With the different failure criterions,the mechanism of failure is discussed. It is indicated that the higher laser energy input is harmful for thermal shock lifetime of LR TBCs. The thin remelted thickness and improved laser beam quality are suggested for laser plasma compound preparation of TBCs.
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Keywords:
- laser remelting /
- thermal barrier coatings /
- plasma spraying /
- thermal shock test
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