(中南大學(xué) 粉末冶金國家重點(diǎn)實(shí)驗(yàn)室，長沙 410083)
摘 要: 用在空氣中氧化、氧炔焰超高溫?zé)g等方法對TaC涂層在不同溫度的氧化特征與氧化機(jī)制進(jìn)行研究。研究結(jié)果表明：TaC在508 ℃以上開始氧化，在508~690 ℃時(shí)氧化產(chǎn)物為六角Ta2O3固溶體，690~900 ℃時(shí)氧化產(chǎn)物轉(zhuǎn)化為斜方Ta2O5晶體，900~1 500 ℃時(shí)氧化產(chǎn)物為斜方Ta2O5，其形態(tài)為龜裂或多孔燒結(jié)態(tài)，未能形成對TaC的隔離保護(hù)膜；1 500 ℃氧化時(shí)出現(xiàn)部分Ta2O5液相與Ta2O5斜方相共存的現(xiàn)象；在氧炔焰超高溫2 300 ℃燒蝕時(shí)形成大量的Ta2O5熔體液膜，熔體與TaC的潤濕性很好。TaC涂層由低溫?zé)o熔體情況下界面反應(yīng)控制機(jī)制變?yōu)檠跬ㄟ^熔體溶解與擴(kuò)散的控制機(jī)制。
關(guān)鍵字: TaC涂層；氧化特征；氧化機(jī)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
