等离子喷涂粒子的直径对冲击速度以及涂层构建的影响

The Influence of the Particle's Diameter on the Impacting Velocity forming of Plasma Spraying Coating

采用数值计算和SEM分析的方法,研究了等离子喷涂粒子直径对其冲击速度以及涂层构建的影响。采用纳米氧化铝(粉末直径d≈20nm)悬浮液大气等离子喷涂技术(SPS)制备了有纳米结构的涂层。结果表明,粒子的密度对其在等离子喷涂流场中的速度影响不太明显,粒子直径对冲击速度以及涂层构建有明显影响,流场中的粒子直径的减小,粒子越难克服流场边界的阻力,冲击变形越小;可增大涂层中有纳米结构的比例,获得精细的涂层结构,涂层表面粗糙度下降。粒子直径<45 nm,将不能克服流场边界的阻力,不能沉积到基材表层,沉积效率下降。获得精细纳米氧化铝涂层最佳的流场中的粒子的直径为300～500 nm。

The nanoeale alumina powders（d ≈20nm） were dispersed in distilled water or ethanol and injected by a peristaltic pump into plasma under atmospheric conditions. Scanning electron microscopy（SEM） and theory analyses were performed to study the effect of that diameter of particle＇ s on forming of plasma spraying coating. The results showed that the diameter of particle＇ s have a significant influence on the impacting velocity. With the particles＇ size decreasing, the part.ides in the flow to overcome the resistance to border more difficult, the impacting deformation smaller, in a nano-coating increased the proportion of the strueture, access to the fine eoating structure, eoating the surface roughness decline. The diameter of partieles decreased to below 45 nm would not be able to overcome the resistance of the flow border, and could not be deposited to the substrate surface. The optimized concentration of nano-alumina suspension is between 300 nm and 500 nm to get fine nano-Al2O3 coating.