Abstract: To solve the problem of unknown molten status of particles before striking the substrate in supersonic plasma spraying process，individual particle heating and melting process in supersonic flow was studied using numerical methods，and particle broken and refining behavior was explored. After considering the phase transition inside the particle in the calculation，the temperature distribution at different time was more reasonable. The curve of particle melting interface changing over the heating time was obtained. Particles were completely melted at the time of 0.35ms，which was consistent with experimental results. When molten particles injected into high-temperature and high-velocity plasma jet，their diameter decreased sharply. The statistic at the distance of 100mm showed particles smaller than 5μm made up a significant proportion，which was more than 50% and consistent with the particle size distribution by particles collected experiment.

Key words: Supersonic plasma spray；Particle；Molten status；Broken refinement

摘要： 针对超声速等离子喷涂过程中颗粒撞击基体前熔化状态未知的问题，利用数值计算方法分析了单个颗粒在超声速气流中的加热熔化过程，并对颗粒的破碎细化行为进行了探究。计算考虑颗粒内部相变后，得到不同时刻颗粒内部的温度分布更加合理，通过分析得到了颗粒熔化界面随加热时间的变化曲线，其在0.35ms时完全熔化，这与实验分析结果相符。熔融颗粒在进入到高温高速等离子体射流中粒径会迅速减小，统计得到100mm处小于5μm的颗粒所占比例最大，超过了50%，与实验收集粒子的粒度分布一致。

关键词: 超声速等离子喷涂；颗粒；熔化状态；破碎细化