常压和低压环境下反应等离子喷涂Al/Fe2O3复合材料的合成机理(英文)

反应等离子喷涂(RPS)技术被广泛用于制备不同使用需求的高性能涂层材料。基于经典的铝热反应原理,采用反应等离子喷涂技术分别在近常压和低压环境下制备了Al-Fe₂O₃涂层,通过XRD、SEM和EDS等分析方法对所制备涂层的相组成和显微结构进行了表征。阐明了Al和Fe₂O₃在加热和反应等离子喷涂过程中的反应机理。DTA分析结果表明,氩气氛下长时间热处理产物主要为Fe、Al₂O₃和FeAl相。然而,在等离子喷涂过程中,低氧分压环境导致中间产物FeAl₂O₄铁尖晶石相的生成,由于近常压等离子喷涂过程的冷却速度极快,该相可以保留在最终涂层结构中。而低压反应等离子喷涂等离子体射流飞行距离长,还原性气氛和较长的反应时间将其进一步还原为FeAl相。

Synthesis Mechanism of Reactive Plasma Sprayed Al-Fe2O3 Composites Under Atmosphere and Low-Pressure Ambient Conditions

Reactive plasma spray (RPS) technique is frequently used to prepare high-performance coating materials with different application requirements. Based on the classical thermite reaction, the Al-Fe₂O₃ coatings were fabricated by RPS under atmosphere and low-pressure ambient. The phase compositions and microstructures of the obtained coatings were characterized by XRD, SEM and EDS. Moreover, the reaction mechanisms of thermite reaction of Al and Fe₂O₃ in sintering and RPS process were elucidated. The DTA analysis results indicate that the main sintering products are Fe, Al₂O₃ and FeAl phases under prolongated reaction condition with Ar gas protetion. However, low oxygen partial pressure leads to the formation of FeAl₂O₄ hercynite phase as an intermediate product during spraying. In atmosphere-reactive plasma spraying (A-RPS), such phase can be retained in the final coating under extremely fast cooling rate. Furthermore, it can also be continuously reduced to FeAl phase in the low pressure Ar-H₂ ambience due to the deoxidation effect and long in-flight distance of plasma jet.