(1. 兰州理工大学 材料科学与工程学院，兰州 730050；
2. 兰州理工大学 省部共建有色金属先进加工与再利用国家重点实验室，兰州 730050；
3. 兰州理工大学 机电工程学院，兰州 730050)
摘 要: 激光重熔是提高热障涂层(TBC)陶瓷层致密度进而减少氧气传输通道的有效途径。本文将TBC陶瓷层表面进行激光重熔，通过1100 ℃高温氧化实验，研究重熔层对TBC热生长氧化物(TGO)的影响规律，阐明了激光重熔对提高TBC抗高温氧化性能的作用机理。结果表明：喷涂态TBC(AS-TBC)、重熔态TBC(LR-TBC)的TGO厚度及氧化增重均随氧化时间的延长而增长。重熔层能消除部分喷涂缺陷，降低陶瓷层表面粗糙度，减少涂层与氧气的接触面积。经过激光重熔的陶瓷层更加致密，促使层内粒子间隙愈合，而且重熔层的裂纹缩小甚至闭合提高了LR-TBC的应变容限，从而抑制了LR-TBC中氧通过孔隙与裂纹向黏接层的渗透，延缓了氧化中后期TGO的生长，使其直至氧化结束始终保持单一Al2O3层的TGO结构。最终，LR-TBC的抛物线氧化速率Kp相比AS-TBC下降了9.00%。
关键字: 激光重熔；热障涂层；热生长氧化物；高温氧化
（1. School of Materials Science and Engineering, Lanzhou University of Technology, Lanzhou 730050, China;
2. State Key Laboratory of Advanced Processing and Recycling of Non-ferrous Metal, Lanzhou University of Technology, Lanzhou 730050, China;
3. School of Mechatronics Engineering, Lanzhou University of Technology, Lanzhou 730050, China）
Abstract:Laser remelting is an effective way to improve ceramic coating compactness of thermal barrier coatings (TBC) and further decrease the channels of oxygen permeation. In this study, the TBC ceramic coating surface was modified by laser remelting, then isothermal oxidation tests were performed at 1100 ℃ to investigate the influence law of remelted layer on thermally grown oxide (TGO) of TBC, and clarify the mechanism of laser remelting on improving the TBC high-temperature oxidation resistance. The results show that TGO thickness and oxidation mass gain of the as-sprayed TBC (AS-TBC) and the laser remelted TBC (LR-TBC) increase with increasing isothermal oxidation time. The remelted layer eliminates part of sprayed defects, decreases the surface roughness of ceramic coating, and reduces the contact area between oxygen and TBC. The laser remelted ceramic coating with high compactness is beneficial to splats healing, and the cracks in the remelted layer improve the strain tolerance of the LR-TBC by narrowing and even healing. Thus, the permeated behaviors of oxygen through splats and cracks to bond coating are inhibited in the LR-TBC, and the TGO growth is postponed at the middle and final oxidation steps. That is contributed to TGO structure of the LR-TBC that keeps the single Al2O3 layer until the end of test. Ultimately, the parabolic oxidation rate (Kp) of the LR-TBC is decreased by 9.00% compared with that of the AS-TBC.
Key words: laser remelting; thermal barrier coating; thermally grown oxide; high-temperature oxidation
