TiB_2增强Ni/Al冷喷涂层的组织结构

Microstructure of TiB_2 reinforced Ni/Al cold sprayed coatings

在不同的冷喷温度条件下,采用冷喷涂技术制备含不同TiB_2陶瓷含量的Ni/Al-TiB_2涂层,其中Ni/Al-TiB_2喷涂粉末为机械混合制成。采用扫描电镜(SEM)表征Ni/Al-TiB_2粉末、冷喷涂层及热处理后涂层的形貌,通过X射线衍射技术(XRD)分析Ni/Al-TiB_2粉末和冷喷涂层物相结构,采用能谱分析仪对热处理后涂层成分元素进行分析。结果表明,冷喷涂层截面组织结构致密,孔隙率低,尤其是在冷喷温度为450℃条件下涂层孔隙率更低。冷喷涂层的物相与粉末相同,主要为TiB_2、Ni和Al三相。在650℃热处理10 h后涂层中孔隙率增加,涂层中原位生成了Ni Al3和Ni Al金属间化合物,并且涂层与基体界面之间生成了Fe Al3金属间化合物,从而提高了涂层与基体之间的结合力。

The mixture of Ni,Al and TiB_2 powders with different mass ratio of TiB_2 was prepared by mechanical mixing method and then the Ni /Al-TiB_2 coatings were fabricated by cold spraying using the mixed powders at different spraying temperatures.Morphology of the Ni /Al-TiB_2 powders,the cold-sprayed coatings with and without heat treatment were studied by scanning electron microscopy（SEM）,composition of the powders and the phases of the cold-sprayed coatings were examined by X-ray diffraction（XRD） and EDS analysis.The results show that the microstructure of the coatings is dense with low porosity,especially the cold-sprayed coatings at the spraying temperature of 450 ℃.The phases in the spraying powders and in the coatings are the same with the main phases of TiB_2,Ni and Al.The porosity of the coatings is increased after heat treatment at 650 ℃ for 10 h,and Ni Al3 and Ni Al intermetallic compounds in-situ generated in the coatings.Meanwhile,Fe Al3 intermetallic compound forms at the interface of the coatings and substrate to increase the bonding strength of the coatings after the heat treatment.