等离子球化制备球形CaF2/BaF2共晶粉末*

探究了使用大气等离子喷涂设备制备适合热喷涂使用的球形CaF2/BaF2共晶粉末的可能性。68%BaF2、32%CaF2粉末(质量分数)经过1 100℃真空烧结后,形成致密的块状氟化物共晶。机械破碎后的氟化物共晶经过等离子焰流重熔后得到了球形的氟化物共晶。使用F14-1流动性和松装密度测定仪测量球化前后粉末的流动性和松装密度。采用扫描电子显微镜,XRD表征球化前后粉末的形貌和物相组成。结果表明:球化后的粉末呈现较好的球形,球化后粉末的流动性和松装密度较球化前也有较大的改善:球化后共晶粉末的流动时间为55.20s/50g,松装密度为1.89g/cm3;另外,球化后共晶粉末还表现出良好的高温润滑性能:含有10%CaF2/BaF2共晶(质量分数)的镍基涂层在600℃和800℃的平均摩擦因数都小于0.3。

Plasma Spheroidization of CaF2/BaF2 Eutectic Powders

The preparation process of spherical CaF2/BaF2 eutectic powders through plasma spray technology is investigated.The fluorides were first prepared by combining 68% BaF2 and 32% CaF2 to melt under vacuum at 1 100 ℃.The solidified fluorides were then crushed into powders for subsequent processing through plasma spheroidization.The microstructure and cystallographic phase of spherical CaF2/BaF2 eutectic powders were determined by SEM and X-ray diffraction,while fluidity and apparent density were tested by F14-1flowmeter.Results show that the degree of sphericity of CaF2/BaF2 eutectic powders increases after spheroidizing,the fluidity and apparent density of spheroidal fluorides are 55.20 s/50 g and 1.89 g/cm3 respectively.In addition,spheroidal CaF2/BaF2 eutectic powders present good high temperature lubrication property,which can reduce the friction coefficient of Ni-based composite coating at high temperature.The friction coefficients of Ni-based composite coatings containing 10% CaF2/BaF2 eutectic at 600 ℃ and 800 ℃ are less than 0.3 in the experimental condition.