(中南大學(xué) 材料學(xué)院,長沙 410083)
摘 要: 采用包滲法在Nb-10W合金基體上制備MoSi2涂層, 測試了涂層試樣的1 600 ℃靜態(tài)抗氧化和室溫至1 600 ℃循環(huán)抗氧化性能, 分析了硅化過程中涂層的形成機(jī)理、 涂層表面和截面的形貌以及氧化后涂層成分與結(jié)構(gòu)變化。 采用包滲法制備的硅化物涂層是通過反應(yīng)擴(kuò)散形成的, 該涂層為復(fù)合結(jié)構(gòu)： MoSi2相主體層； 以NbSi2相為主、 并含少量Nb5Si3相的兩相過渡區(qū)； Nb5Si3相擴(kuò)散層； 該涂層結(jié)構(gòu)表現(xiàn)出良好的高溫抗氧化和抗熱震性能； Si的擴(kuò)散是通過空位的反應(yīng)流動實(shí)現(xiàn)的, 空位在主體層與兩相過渡區(qū)界面處聚集成微孔帶, 氧化后微孔帶寬度增加； 致密的低硅化物擴(kuò)散層能有效地阻止裂紋向基體擴(kuò)展。
關(guān)鍵字: 鈮合金; 硅化物涂層; 二硅化鉬; 包滲法; 高溫抗氧化
XIANG Cai-wen, XU Liang-liang
（School of Materials Science and Engineering,
Central South University, Changsha 410083, China）
Abstract: The MoSi2 coating on the Nb-10W alloy was fabricated by pack cementation. The static at 1 600 ℃ and thermal cycling oxidation resistance properties from room temperature to 1 600 ℃ were tested. The formation mechanism, surface and cross-section morphologies of the coating were studied. The results show that the coating is multistructure including MoSi2 outer layer, two-phase zone with major NbSi2 and minor Nb5Si3, Nb5Si3 diffusion inner layer. The structure of the coating represent good high-temperature oxidation resistance and thermal shock resistance. The vacancy zone between the reservior layer and two-phase zone alleviates the heat stress to avoid cracking in the coating.
Key words: niobium alloy; MoSi2; silicide coating; pack cementation; high-temperature oxidation resistance
