喷涂距离对超音速火焰喷涂 CoCrAlYTa 涂层组织性能的影响

采用超音速火焰喷涂技术制备CoCrAlYTa涂层,研究了喷涂距离对涂层相组成、孔隙率以及硬度、弯曲强度、高温抗氧化性能的影响。结果表明:喷涂距离在200～300 mm范围内时,随着喷涂距离的减小,涂层的致密度增加,孔隙率下降,显微硬度和弯曲结合强度增加,但相组成基本不变,主要由CoAl,AlCo2Ta和CoTa3相组成;涂层致密度越高,在高温氧化过程中,表面越易尽早形成连续氧化膜并促进涂层中Al元素的选择氧化,因此随着喷涂距离的减小,涂层的高温抗氧化性能逐渐增强。

The Influence of Spraying Distance on Structure and Properties of CoCrAlYTa Coating Prepared by HVOF

CoCrAlYTa coatings were prepared by HVOF process and the influence of spraying distance on phase structure, porosity, hardness,bending strength and high temperature oxidation resistance of as-prepared coatings were also investigated. The results revealed that with the decrease of spraying distance, the compactness of the coating was enhanced and the porosity of the coating decreased in 200 ~ 300 nm spraying distance. The micro-hardness and bending strength were also enhanced with the decrease of spraying distance. Spraying distance had no impact on the phase composition of the coatings and the coatings were all composed of CoAl, AlCo₂Ta and CoTa₃. The continuous oxide scale was easily formed and selective oxidation of Al was prone to being promoted for the more compact coatings during oxidation, which induced the oxidation resistance of the coatings increased with the decrease of spraying distance.