化学致密化处理对Al_2O_3/YSZ-Al_2O_3涂层抗高温氧化性能的影响

Effect of chemical densification process on high-temperature oxidation resistance of Al_2O_3/ YSZ-Al_2O_3 coatings

采用溶胶-凝胶热压滤法(TPFSP)可制备出具有空间网络结构的Al2O3/YSZ-Al2O3涂层。为进一步提高该涂层的抗高温氧化性能,本研究对该涂层进行化学致密化处理(PCD)。高温循环氧化结果表明,该涂层的抗高温氧化性能随PCD循环处理次数增加而增强,不过经12次PCD循环处理后,提高其抗高温氧化性能的作用效果发生衰减。高温循环氧化前后形貌分析表明,涂层表面的隆起随PCD循环处理次数增加而减少,复合涂层下的TGO层增厚及TGO层附近金属基体发生内氧化的程度也随PCD循环处理次数增加而减小,PCD对形貌的影响规律与其对氧化动力学曲线的影响规律相一致。

Al2O3/ YSZ-Al2O3 coatings with spatial-network structure have been prepared by thermal pressure and filtration of sol-gel paint（ TPFSP）. To further improve high-temperature oxidation resistance of the coatings,process chemical densification（ PCD） for different cycles was applied to the as-prepared coatings in this study. Cyclic high-temperature oxidation test demonstrates that their high-temperature oxidation resistance is improved with increasing cycles of the PCD. However,the impovement on high-temperature oxidation resistance decaies after 12 cycles of the PCD. Morphology of the coatings before and after cyclic high-temperature oxidation test shows that the number of bulges on the coatings decreases with increasing cycles of the PCD. At the same time,the thickness of thermally grown oxide（ TGO） layer under the coatings and the degree of internal oxidation of metallic substrate near the TGO layer also decreases with increasing cycles of the PCD. Morphology change of the coatings made by PCD agrees well with the change of cyclic oxidation kinetics curves.