(1. 蘭州理工大學 材料科學與工程學院，蘭州 730050；
2. 蘭州理工大學 省部共建有色金屬先進加工與再利用國家重點實驗室，蘭州 730050；
3. 蘭州理工大學 機電工程學院，蘭州 730050)
摘 要: 激光重熔是提高熱障涂層(TBC)陶瓷層致密度進而減少氧氣傳輸通道的有效途徑。本文將TBC陶瓷層表面進行激光重熔，通過1100 ℃高溫氧化實驗，研究重熔層對TBC熱生長氧化物(TGO)的影響規(guī)律，闡明了激光重熔對提高TBC抗高溫氧化性能的作用機理。結果表明：噴涂態(tài)TBC(AS-TBC)、重熔態(tài)TBC(LR-TBC)的TGO厚度及氧化增重均隨氧化時間的延長而增長。重熔層能消除部分噴涂缺陷，降低陶瓷層表面粗糙度，減少涂層與氧氣的接觸面積。經(jīng)過激光重熔的陶瓷層更加致密，促使層內粒子間隙愈合，而且重熔層的裂紋縮小甚至閉合提高了LR-TBC的應變容限，從而抑制了LR-TBC中氧通過孔隙與裂紋向黏接層的滲透，延緩了氧化中后期TGO的生長，使其直至氧化結束始終保持單一Al2O3層的TGO結構。最終，LR-TBC的拋物線氧化速率Kp相比AS-TBC下降了9.00%。
關鍵字: 激光重熔；熱障涂層；熱生長氧化物；高溫氧化
（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
