高温扩散对超音速火焰喷涂NiCrBSi结晶器涂层组织与性能的影响

Effect of high temperature diffusion on microstructure and properties of HVOF sprayed Ni CrBSi mold coating

为提高超音速火焰喷涂Ni Cr BSi结晶器涂层的质量和使用性能,对喷涂后的涂层分别进行1000、1020、1040、1060℃的真空高温扩散处理,使用电子探针、扫描电镜和激光热导仪等仪器分析了涂层在扩散前后的组织和性能变化。结果表明:高温扩散对涂层的微观结构、显微硬度、摩擦磨损性能以及导热性能等都有一定影响。在经过1000℃以上的高温扩散之后,喷涂涂层的层状结构消失,组织缺陷减少,孔隙率降低。涂层的显微硬度下降,但硬度分布更为均匀。扩散之后涂层的耐磨性能提高,且在扩散温度为1020℃时提升效果最好。另外,高温扩散后涂层的导热系数明显提高,导热能力增强。

To improve the quality and properties of HVOF sprayed Ni Cr BSi mold coating,the vacuum high temperature diffusion was carried out at 1000,1020,1040 and 1060 ℃ respectively. The microstructure and properties of the coating before and after diffusion were studied by means of electron probe,scanning electron microscope( SEM) and laser thermal conductivity instrument. The results show that the thermal diffusivity has a certain effect on the microstructure,micro hardness,wear resistance and thermal conductivity of the coating. After high temperature diffusion over 1000 ℃,the lamellar structure of the sprayed coating disappears,and the microstructure defects decreases. The micro hardness of the coating decreases,but the hardness distribution becomes uniform. After diffusion,the wear resistance of the coating is improved,and the best effect is achieved when diffusion treated at 1020 ℃. In addition,the thermal conductivity of the coating is improved significantly after high temperature diffusion.