【摘要】 目的 利用紫外脉冲激光器对热障涂层（TBCs）进行激光上釉，能有效提升涂层的综合服役性能。方法选用纳米晶团聚与烧结破碎两种YSZ粉体，采用大气等离子喷涂（APS）在NiCoCrAlY黏结层的镍基高温合金基板上制备热障涂层。利用紫外脉冲激光对涂层表面进行上釉处理，分析上釉涂层的微观结构演变与特征元素含量，评价涂层的耐热腐蚀性能与抗弯曲涂层开裂能力。结果 激光上釉后，两种粉体APS涂层均未观察到明显热致垂直裂纹。纳米晶团聚粉体涂层的重熔质量最佳，厚度分布更均匀，表面形貌S_a提高约13.9%，平均晶粒面积减小约31.6%。在1 240℃、4 h、15 mg/cm~2的CMAS腐蚀条件下，纳米晶团聚粉体涂层的表面渗透占比降低42%。微观结构上，前者仅表层出现轻微颗粒分离，而后者则发生一定深度的明显降解。弯曲性能方面，纳米晶团聚粉体涂层抗弯强度为386 MPa，略低于烧结破碎型粉体涂层的583 MPa，但其开裂面积占比仅为20.48%(6 789 N载荷下)，显著低于后者的47.99%(6 571.8 N载荷下)，体现出更优的强韧性与裂纹扩展抗性。结论 纳米晶团聚粉体的激光上釉涂层在表面质量、抗CMAS腐蚀性能及损伤容限方面均表现出显著优势，展现出了更高的服役可靠性和应用潜力。更多还原

【Abstract】 Thermal barrier coatings(TBCs) serve as critical thermal protection materials for hot-section components in aero-engines and gas turbines(collectively referred to as two engines). To withstand increasingly severe thermo-mechanical coupled environments, ultraviolet pulsed laser glazing has been employed to effectively enhance the overall service performance of TBCs. In this study, two types of yttria-stabilized zirconia(YSZ) powders with different morphologies-nanocrystalline agglomerated and sintered-crushed-are selected to prepare TBCs via atmospheric plasma spraying(APS) onto nickel-based superalloy substrates with NiCoCrAlY bond coats. The coatings are subject to surface glazing with an ultraviolet pulsed laser. Scanning electron microscopy(SEM) is utilized to analyze the microstructural evolution and characteristic element distribution of the coatings before and after glazing. The coatings’ resistance to thermal corrosion is evaluated through CMAS corrosion tests, while their resistance to bending-induced cracking is assessed via bending tests. After ultraviolet pulsed laser glazing, significant differences are observed in the surface and cross-sectional morphologies between the two coatings. In terms of surface morphology, the areal average roughness(S_a) of the laser-glazed coating prepared from nanocrystalline agglomerated powders is 9.25 μm, approximately 13.9% lower than that of the coating prepared from sintered-crushed powders(10.73 μm), indicating a more uniform and denser laser-remelted quality. Furthermore, the glazed coating from nanocrystalline agglomerated powders exhibits finer grains and fewer defects in the remelted layer. Statistical results show that its average grain area is 4.54 μm~2, reduced by approximately 2.10 μm~2 compared with the 6.64 μm~2 of the glazed coating from sintered-crushed powders, representing a decrease of 31.6%. In the cross-sectional structure, neither of the APS coatings exhibits pronounced vertical cracks. However, the glazed coating from nanocrystalline agglomerated powders demonstrates a more uniform remelted layer thickness of approximately 1.7 μm, while the sintered-crushed powder coating, due to its irregular surface morphology, exhibits non-uniform absorption and melting of laser energy, resulting in an uneven remelted layer thickness ranging from 1 to 2 μm. Under CMAS corrosion conditions(1 240 ℃, 4 h, 15 mg/cm~2), the surface infiltration area ratio of the glazed nanocrystalline agglomerated coating is only 26.71%, significantly lower than the 69.32% of the sintered-crushed powder coating, with a difference exceeding 42 percentage points. Microscopically, the former exhibits only slight particle separation at the surface layer, while the latter shows significant localized degradation of approximately 3 μm. This particle separation phenomenon induced by CMAS attack can be attributed to the dissolution-reprecipitation mechanism between YSZ and CMAS. Specifically, CMAS initiates dissolution at the interface, leading to particle separation, and the fine-grained regions gradually transform into globular structures containing numerous small circular pores. Regarding bending performance, NA-TBC-LG exhibits a superior strength-toughness match. Its flexural strength is 386 MPa, slightly lower than that of SC-TBC-LG(583 MPa). However, during loading, the cracking area of NA-TBC-LG accounts for only 20.48% under a load of 6 789 N, whereas the cracking interface of SC-TBC-LG accounts for 47.99% of the total interface under a load of 6 571.8 N. In summary, the laser-glazed coating prepared from nanocrystalline agglomerated powders demonstrates significant advantages in surface quality, CMAS corrosion resistance, and damage tolerance. Its overall performance surpasses that of the traditional sintered-crushed powder coating, exhibiting higher service reliability and greater application potential.更多还原