金属间化合物NiAl-Ta-Cr高速火焰喷涂工艺及涂层特性

Production and Characterization of NiAl-Ta-Cr Intermetallic Coatings Sprayed by High Velocity Oxy-Fuel

采用高速火焰(HVOF)热喷涂工艺制备了金属间化合物NiAl-Ta-Cr涂层。研究了喷涂距离、氧气流量以及燃气流量等工艺参数对涂层组织结构和性能的影响。用光学显微镜观察涂层的组织结构并测定涂层的孔隙率,用LECOTC316气体抽提仪检测涂层的氧含量。结果表明,氧气流量、喷涂距离等工艺参数对涂层性能的影响比较明显。随着喷涂距离的增加,涂层的氧含量降低;O/H比率越大,涂层的氧含量越高,而孔隙率降低,沉积率越高。涂层经1100℃,4h真空热处理后,变得更加均匀和致密,孔隙率降低,但涂层的硬度有所降低。涂层经1100℃,100h高温氧化处理后,在涂层表面生成了连续的氧化铝氧化层,硬度比真空退火后略有下降。

Intermetallic NiAl-Ta-Cr coatings were sprayed by the HVOF process. The effects of the spray parameters （including spray distance, oxygen and fuel flow rate etc.） on the microstructure and properties of coatings were investigated. Metallographic investigations and porosity measurements of the coatings were carried out by optical microscopy. The oxygen content of the coatings was measured by the LECO TC316 gas extract equipment. The results show that both the oxygen flow rate and the spray distance can significantly influence the properties of the coatings. The oxygen content in the coatings decreased with increasing the spray distance. A high O/H ratio led to a high degree of oxidation, a low porosity and more deposition. The coatings showed a homogeneous and dense structure, less porosities, and lower microhardness after heat-treated in a vacuum furnace at 1100℃ for 4 h. A continuous Al2O3 oxide scale formed on the surface of the coatings after the heat treatment at 1100℃ for 100 h. However, the microhardness of the coating slightly decreased as compared to that after vacuum annealing.