热循环氧化行为
( 1. 北京航空材料研究院 第五研究室， 北京 100095；
2. 沈阳航空工业学院材料系， 沈阳 110031)
摘 要: 采用电子束物理气相沉积方法（EB-PVD）在NiCoCrAlYHf粘结层上沉积YSZ热障层， 研究了该热障涂层1 100 ℃的循环氧化行为(每个循环为： 1 100 ℃保温30 min、 空冷5 min), 分析了粘结层和热生长氧化物的演化过程。结果表明： NiCoCrAlYHf 粘结层氧化初期由β-NiAl和γ固溶体组成， 186次循环氧化后β相/完全转变为γ固溶体。 NiCoCrAlYHf/EB-PVD热障涂层中的热生长氧化物包含Al2O3层和靠近热障层的尖晶石薄层。该热生长氧化物生长速度较快， 在粘结层的一些富Hf区域优先生长而呈现出明显的不均匀性；但其具有较大的失效临界热生长氧化物厚度， 失效时热生长氧化物均匀处的厚度约为10 μm。
关键字: 热障涂层； 热生长；氧化物； 循环氧化
（ 1. Laboratory 5, Beijing Institute of Aeronautical Materials, Beijing 100095, China;
2. Department of Materials Science and Engineering,
Shenyang Institute of Aeronautical Engineering， Shenyang 110031, China）
Abstract: The cyclic oxidation(30 min hold at 1 100 ℃, 5 min cooled in air) of electron beam physical vapor deposition(EB-PVD) yttria stabilized zirconia thermal barrier coatings(TBCs) on NiCoCrAlYHf bond coat at 1 100 ℃ was investigated. Attention was focused on the development of bond coat and thermally grown oxide(TGO). The result shows that the bond coat is composed of β -NiAl and γ solid solution at the initial stage of cyclic oxidation. The β phase is completely transferred to γ solid solution after 186 cycles. The TGO consists of an Al2O3 layer and a thin spinel layer in NiCoCrAlYHf/EB-PVD TBCs. This TGO has a big growth rate and grows irregularly because of selective growth at Hf-riched areas in the bond coat. But the TBCs has a larger critical thickness of TGO for failure. The thickness of TGO at uniform place is about 10 μm when the TBCs fails.
Key words: thermal barrier coating; thermally grown; oxide; cyclic oxidation
