(1. 湖南科技大学 新材料制备及应用技术研究所，湘潭 411201；
2. 厦门理工学院 机械工程系，厦门 361024)
摘 要: 采用喷雾干燥和真空烧结技术制备MoSi2团聚颗粒，以MoSi2团聚粉末为原料，通过大气等离子喷涂法制备二硅化钼涂层，借助XRD、扫描电镜及能谱对团聚体粉末在等离子焰流中的熔化特性和涂层的组织结构进行研究。结果表明：团聚粉末在1 200 ℃真空热处理1 h后，粉末的流动性和松装密度分别提高55.6%和42.0%，适合等离子喷涂用。MoSi2颗粒经过高温等离子焰流后，粉末熔化充分，大多数团聚体粉末发生烧结过程，颗粒的平均粒度减小，形成较致密的球形颗粒。在喷涂过程中，部分四方相MoSi2(t)转变为六方相MoSi2 (h)或氧化形成了少量的Mo5Si3相，涂层中的富钼相呈“网状”组织结构。
关键字: MoSi2涂层；喷雾干燥；等离子喷涂；熔化特性
its melting characteristics in plasma arc
（1. Advanced Materials Synthesis and Application Technology Institute,
Hunan University of Science and Technology, Xiangtan 411201, China;
2. Department of Mechanical Engineering, Xiamen University of Technology, Xiamen 361024, China）
Abstract:The MoSi2 powder used for air plasma spraying was prepared by spray drying and vacuum sintering. By using MoSi2 powders as the raw powders, MoSi2 coating was prepared using air plasma spraying. The melting characteristics of MoSi2 powders in the plasma arc and the microstructures of the coating were studied by scanning electron microscopy (SEM) with energy dispersive spectroscopy (EDS) and X-ray diffraction (XRD). The results show that, when the powders are sintered at 1 200 ℃ for 1 h, the mobility and loose density of powders increase by 42.0% and 55.6%, respectively. Most MoSi2 particles occur during the sintering process, and the average particle sizes of the powders decrease after the MoSi2 powders pass through the high temperature plasma flame. MoSi2 particles are fully melted and the dense spherical particles are formed. Duri, ng air plasma spraying, part of the tetragonal MoSi2 (t) phase changes into MoSi2 (h) crystal structure or oxidize to form Mo5Si3 phase. The microstructure of molybdenum-rich phase in the MoSi2 coating is similar to the “mesh” structure.
Key words: MoSi2 coating; spray-drying; plasma spraying; melting characteristics
