(中南大学 粉末冶金国家重点实验室，长沙 410083)
摘 要: 用在空气中氧化、氧炔焰超高温烧蚀等方法对TaC涂层在不同温度的氧化特征与氧化机制进行研究。研究结果表明：TaC在508 ℃以上开始氧化，在508~690 ℃时氧化产物为六角Ta2O3固溶体，690~900 ℃时氧化产物转化为斜方Ta2O5晶体，900~1 500 ℃时氧化产物为斜方Ta2O5，其形态为龟裂或多孔烧结态，未能形成对TaC的隔离保护膜；1 500 ℃氧化时出现部分Ta2O5液相与Ta2O5斜方相共存的现象；在氧炔焰超高温2 300 ℃烧蚀时形成大量的Ta2O5熔体液膜，熔体与TaC的润湿性很好。TaC涂层由低温无熔体情况下界面反应控制机制变为氧通过熔体溶解与扩散的控制机制。
关键字: TaC涂层；氧化特征；氧化机理；活化氧化
mechanism of TaC coating
（State Key Laboratory of Powder Metallurgy, Central South University, Changsha 410083, China）
Abstract:The oxidized characteristic and oxidized mechanism of TaC coating at different temperatures were studied through oxidation in air, ultra-high temperature ablation by oxyacetylene torch and so on. The results show that TaC starts to be oxidized at above 508 ℃, TaC oxidation product is hexagonal Ta2O3 solid solution at 508−690 ℃. The solid solution transforms into the orthorhombic Ta2O5 crystal at 690−900 ℃. The oxidation product is orthorhombic Ta2O5 at 900− 1500 ℃ whose shape is chapped or porous sintered condition, and the isolation protective film to the TaC coating is not formed. The partial Ta2O5 liquid phase and the Ta2O5 orthorhombic coexist after oxidation on the surface of TaC coating at 1 500 ℃. The massive Ta2O5 melt fluid film occurs by ultrahigh temperature ablation of oxyacetylene torch at 2 300 ℃. With good wettability between Ta2O5 melt body and TaC coating, the oxidized mechanism of the TaC coating becomes into oxygen dissolution-diffusion control mechanism through the melt from the interface reaction control mechanism between oxygen and TaC coating without Ta2O5 melt at low temperature.
Key words: TaC coating; oxidized characteristic; oxidized mechanism; active oxidation
