粉末粒度对喷涂二硅化钼涂层微观结构的影响

摘要

分别以2.5～15μm、15～30μm、30～54μm和54～74μm四种粒径的二硅化钼为热喷涂粉末,利用大气等离子喷涂技术制备了二硅化钼涂层,通过XRD和带能谱的SEM表征了涂层的微观组织结构.结果表明,喷涂过程中,喷涂粉末中部分四方相MoSi2 (t)转变为六方相MoSi2 (h),MoSi2中的Si含量出现了损失.随着喷涂粉末粒径的增大,MoSi2粒子在沉积过程中的氧化程度减弱,涂层中的Mo、Mo5Si3等富钼相和MoO3、MoO2等氧化产物的相对含量逐渐减少,而富硅相MoSi2逐渐增加.粉末粒度分别在30～54μm和54～74μm范围时,均可获得以MoSi2为主相的涂层.以粒径30～54μm的粉末制备的涂层组织较致密,内部出现了富钼相“网状”结构的组织.%MoSi2 coatings were prepared by air plasma spraying with MoSi2 particle size distributions of 2. 5 — 15μm, 15 — 30μm,30—54μm and 54—74μm. The microstructure of MoSi2 coatings and the oxidation behaviors during spraying course were investigated by means of XRD and SEM technology. The results showed that some MoSi2 (t) phase changed to MoSi2(h) crystal structure during the course of spraying, and the content of Si also reduced. With the increasing of powders size, the oxidation degree of MoSi2 particle during the spraying course gradually reduced. The rich molybdenum phases (Mo, M05 Si3) and the oxide molybdenum also reduced, but the rich disilicide phase(Mo-Si2) incriased. The main phase of the coating is MoSi2 when the powders size is belong to 30 — 54μm or 54 —74μm The coating is dense when the coatings were prepared with the size distributions of 30 — 54μm and the "mesh" micro-structure of molybdenum-rich phase was produced in the coating.