低压等离子喷涂NiCoCrAlYTa涂层的高温氧化行为  

High-temperature Oxidation Behavior of Low-pressure Plasma Sprayed NiCoCrAlYTa Coatings

作　　者：周宏明[1,2] 易丹青[1] 

机构地区：[1]中南大学材料科学与工程学院,湖南长沙410083 [2]中南大学粉末冶金国家重点实验室,湖南长沙410083

出　　处：《机械工程材料》2009年第5期18-21,25,共5页Materials For Mechanical Engineering

基　　金：中南大学博士后基金资助项目(76132017)

摘　　要：采用低压等离子喷涂技术在钴基高温合金K640表面制备了NiCoCrAlYTa合金涂层,利用XRD、SEM和EDS等研究了涂层的高温氧化行为。结果表明:该涂层在900℃的恒温氧化动力学曲线符合抛物线规律,氧化速率常数Kp为0.33×10-6mg2.cm-4.s-1;温度为1 050℃时,氧化初期的Kp值约为1.95×10-6mg2.cm-4.s-1,随着氧化时间的延长,氧化速率迅速降低;涂层在氧化过程中,表面先形成-θAl2O3,随着氧化时间的延长,-θAl2O3向-αAl2O3转变,且氧化温度越高转变速率越快,900℃氧化120 h后涂层表面仍存在-θAl2O3,而1 050℃氧化10 h后-θAl2O3就已基本完全转变;氧化过程中,基体与涂层之间发生互扩散;氧化后涂层中析出白色的颗粒状富钽相。The NiCoCrAlYTa coatings were deposited on Co-based high-temperature alloy （K640） substrate by low-pressure plasma spraying（LPPS）. The oxidation behavior of NiCoCrAlYTa coatings was evaluated by means of XRD, SEM and EDS. The results show that oxidation kinetic curves of the coating at 900 ℃ obeyed the parabolic law and the oxidation rate constant at 900℃ was 0. 33×10^-6mg^2·cm^-4·s^-1. The initial oxidation rate constant of the coating at 1 050 ℃ was 1.95×10^-6mg^2·cm^-4·s^-1 , and with the increase of oxidation time, the oxidation rate was decreased clearly. θ-Al2O3 was formed on the coating surface at the initial stage of oxidation. With the increase of oxidation time, θ-Al2O3was transformed into α-Al2O3 and the transformation rate increased with the increase of oxidation temperature. There was still θ-Al2O3 on the coating surface oxidized at 900 ℃ for 120 h. The transformation of θ-Al2O3 into α-Al2O3 was observed after the coating was oxidized at 1 050 ℃ for 10 h. Interdiffusion of elements between Co-based alloy and the NiCoCrAlYTa coating was observed during the oxidation process. White Ta-rich precipitates were observed during the oxidation process.

关 键 词：低压等离子喷涂 NICOCRALYTA涂层 氧化膜 氧化行为 

分 类 号：TG174.44[金属学及工艺—金属表面处理]