摘要
表面处理是提高钛合金抗冲蚀性能的重要途径。采用激光氮化涂层过程中同步送Al粉的方法，在Ti6A14V合金表面制备了一层均匀的TiN／Al复合涂层，涂层内没有微观裂纹和孔洞。研究结果表明：激光扫描速度对复合涂层的微观结构、硬度及抗冲蚀性能有着重要的影响。随着激光扫描速度的增加，复合涂层的厚度降低。在复合涂层最表面存在一层平均厚度大约为2～3μm的连续的氮化物陶瓷层，涂层内部存有大量的枝状晶组织。复合涂层的微观硬度和抗冲蚀性能明显高于Ti6A14V合金基体。当激光扫描速度从240mm／min升高到720mm／min时，涂层表面的微观硬度从1600HV01降低到1200HV0.1，而且涂层的冲蚀失重也逐渐降低。这主要是因为随着激光扫描速度的降低，由于反应时间的增加，导致涂层中TiN硬质相的含量也在增加。
Surface treatment is an important approach to improving the erosion resistance of Titanium alloy. A one-step in situ method was developed to synthesize uniform Al metallic matrix composite coatings reinforced with TiN on Ti6Al4V alloy. Using this method, Al powder and nitrogen gas were simultaneously fed into the feeding nozzle during the laser nitriding process, and crack- and pore-free coatings were made. Experimental results show that the laser scanning speed has an important influence on the microstructure, micro-hardness and erosion resistance of TiN/Al composite coatings. With the increasing speed of the laser scanning, the thickness of the composite coatings decreases. A very thin continuous layer with the thickness of approximately 2 to 3 μm can be found at the coating surface. Some massively dendritic structures including the coarse primary dendrites and secondary dendrites branching from the primary dendrites can be found in the upper zones of the composite coatings. The microhardness and erosion resistance of composite coatings fabricated at the laser scanning speed in the range from 240 mm/min to 720 mm/min are higher than those of the Ti6Al4V alloy substrates. When the laser scanning speed increases from 240 mm/min to 720 mm/min, the micro-hardness at the coating surface decreases from 1 600 HVoA to 1200 HV0.1. Moreover, with the increasing speed of the laser scanning, the erosion resistance of coatings gradually decreases. This phenomenon can be largely attributed to the increasing content of TiN in the coatings resulting from the decreasing speed and the increasing reaction time of the laser scanning.
出处
《中国表面工程》
EI
CAS
CSCD
北大核心
2016年第4期125-131,共7页
China Surface Engineering
基金
国家自然科学基金(51575183)
关键词
激光氮化
复合涂层
抗冲蚀性能
laser nitriding
composite coming
erosion resistance
