Suspension Plasma Spray process was used for deposition of pseudo-eutectic composition of aluminayttria- stabilized zirconia as a potential thermal barrier coating using Mettech axial III torch. Process variables including feed and plasma parameters were altered to find their effects on the formation of phases in the composite coating. The in-flight particle velocity was found to be the crucial parameter on phase formation in the resulting coatings. Low particle velocities below 650 m/s result in the formation of stable phases i.e., a-alumina and tetragonal zirconia. In contrast, high particle velocities more than 750 m/s favor the metastable c-alumina and cubic zirconia phases as dominant structures in as-deposited coatings. Accordingly, the plasma auxiliary gas and plasma power as influential parameters on the particle velocity were found to be reliable tools in controlling the resulting coating structure thus, the consequent properties. The noncrystalline portion of the coatings was also studied. It was revealed that upon heating, the amorphous phase prefers to crystallize into pre-existing crystalline phases in the as-deposited coating. Thus, the ultimate crystalline structure can be designed using the parameters that control the particle velocity during plasma spray coating.
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机译:使用Mettech轴向III焊炬,使用悬浮等离子喷涂工艺沉积了氧化铝共稳定的氧化锆的拟共晶成分,作为潜在的热障涂层。改变了包括进料和等离子体参数在内的工艺变量,以发现它们对复合涂层中相形成的影响。发现飞行中的粒子速度是所得涂层中相形成的关键参数。低于650 m / s的低粒子速度会导致形成稳定相,即α-氧化铝和四方氧化锆。相反,高于750 m / s的高颗粒速度有利于亚稳态c-氧化铝和立方氧化锆相作为沉积涂层中的主要结构。因此,发现等离子体辅助气体和等离子体功率作为影响颗粒速度的参数是控制所得涂层结构,从而控制所得性能的可靠工具。还研究了涂层的非晶部分。揭示了在加热时,非晶态相倾向于在沉积的涂层中结晶成预先存在的结晶相。因此,可以使用控制等离子体喷涂过程中粒子速度的参数来设计最终的晶体结构。
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