低压等离子喷涂氧化铝涂层的特性

以细小的氧化铝为热喷涂粉末，采用低压等离子喷涂制备了沉积率高于50%，孔隙率低于2%的氧化铝涂层.研究了不同工艺下低压等离子喷涂氧化铝涂层的沉积率、相组成和显微结构，并对低压等离子功率和真空室压力工艺参数对涂层的影响进行了分析.研究结果表明，所制备的涂层以α-Al₂O₃和γ-Al₂O₃相并存；随着功率和压力提高，涂层的孔隙率有明显的降低，但压力达到23.7kPa时功率影响较小.此外，还对等离子焰流中的粒子温度和速度进行了计算.结果表明，在23.7kPa压力下保证粒子充分熔融的前提下使粒子具有较高的运动速度.

Characteristics of Low Pressure Plasma Sprayed Alumina Coating

LPPS (Low Pressure Plasma Spray) alumina coatings with deposition efficiency higher than 50% and porosity lower than 2% were elaborated using fine alumina powder as feedstock. Characteristics of alumina coatings prepared with different LPPS parameters, including deposition efficiency, phase composition and microstructure, were investigated. The effects of plasma power and chamber pressure on the LPPS alumina coatings were also studied. The results demonstrate that LPPS alumina coating consists of α-Al₂O₃ and γ-Al₂O phase. The porosity is evidently decreased with the increase of power and chamber pressure, but plasma power has insignificant influence on the porosity when the chamber pressure is as high as 23.7kPa. The particle temperature and velocity in plasma plume are obtained on the basis of empirical formula, which reveals that particles with high velocity in plasma plume are completely molten when the pressure is 23.7kPa.