研究了溅射Co-30Cr-6Al-0.5Y及Ni-30Cr-6Al-0.5Y涂层对TiAl金属间化合物抗高温氧化性能的影响。结果表明,在900℃～1000℃范围内,CoCrAlY、NiCrAlY涂层表面由于可形成粘附性良好的A1_2O_3膜,大大改善TiAl金属间化合物的抗氧化性能。在氧化过程中,CoCrAlY、NiCrAlY涂层中的Co、Ni向基体中扩散,从而在基体一侧形成两个扩散层,其中扩散层的外层分别为硬而脆的A1Co_2Ti、AlNi_2Ti三元金属间化合物。1000℃氧化时,CoCrAlY涂层中普遍存在的柱状晶结构和瘤状缺陷,导致Ti向外扩散,涂层表面出现TiO_2。而NiCrAlY涂层表面900℃氧化即出现少量TiO_2。
The effect of sputtered Co-30Cr-6Al-0.5Y and Ni-30Cr-6Al-0.5Y coatings on oxidation resistance of TiAl intermetallics was studied in static air at 900-1000℃. The uncoated TiAl alloys showed poor oxidation resistance due to the formation of porous mixed Al2O3+TiO2 scale. The CoCrAlY and NiCrAlY coatings could remarkably improve the oxidation resistance of TiAl due to the formation of protective Al2O3 layer. Two diffusion zones were formed with the inward diffusion of Co or Ni from coating into substrate. The outer diffusion layers were mainly composed of AlCo2Ti and AlNi2Ti ternary intermetallics respectively, which were hard and brittle. TiO2 appeared on the CoCrAlY and NiCrAlY coatings, which resulted in accelerated oxidation at 1000℃.
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