(中南大學(xué) 粉末冶金研究院 粉末冶金國(guó)家重點(diǎn)實(shí)驗(yàn)室，長(zhǎng)沙 410083)
摘 要: 為提高C/C復(fù)合材料在高溫富氧環(huán)境中的抗氧化性能，采用兩步刷涂+化學(xué)氣相沉積法在C/C復(fù)合材料表面制備含Si3N4、MoSi2、TaC等添加劑的ZrB2-SiC基多層復(fù)合陶瓷涂層。利用XRD和SEM等分析測(cè)試手段研究涂層的物相組成和微觀結(jié)構(gòu)，并分析討論涂層在900和1500 ℃的等溫抗氧化機(jī)理。結(jié)果表明：利用兩步刷涂+化學(xué)氣相沉積法制備的ZrB2-SiC基復(fù)合陶瓷涂層整體厚度約為200 μm。Si3N4、MoSi2可很好地促進(jìn)ZrB2-SiC基氧阻擋層的高溫?zé)Y(jié)，使涂層致密化，并提高涂層在900 ℃的抗氧化性能；與之相比，TaC則不能很好地發(fā)揮致密化作用，對(duì)涂層在900 ℃時(shí)抗氧化性能的提高有限。在900 ℃時(shí)，ZrB2-SiC基陶瓷涂層的氧化過(guò)程主要受氧在涂層孔隙等缺陷中的擴(kuò)散所控制，添加劑主要通過(guò)改變涂層的致密化程度來(lái)影響涂層的抗氧化性能。在1500 ℃氧化過(guò)程中，涂層抗氧化性能惡化，但致密的化學(xué)氣相沉積SiC封填層的引入可顯著改善涂層在1500 ℃時(shí)的抗氧化性能，涂層表面生成了完整的含有ZrO2和ZrSiO4等高熔點(diǎn)顆粒的SiO2玻璃態(tài)氧化膜，為基體提供有效的氧化防護(hù)。
關(guān)鍵字: C/C復(fù)合材料；ZrB2-SiC基涂層；添加劑；抗氧化機(jī)理
（State Key Laboratory of Powder Metallurgy, Powder Metallurgy Research Institute, Central South University, Changsha 410083, China）
Abstract:To improve the anti-oxidation performance of C/C composites under high temperature and oxygen enriched environment, ZrB2-SiC based ceramic coatings with Si3N4, MoSi2 and TaC addition were prepared by two-step slurry painting+chemical vapor deposition (CVD). Phase composition and microstructure of the as-prepared coating were investigated by using X-ray diffractometry and scan electron microscopy, and the isothermal anti-oxidation mechanism at 900 ℃ and 1500 ℃ were also analyzed and discussed. The conclusions are as follows, the thickness of the as-prepared ZrB2-SiC based composite ceramic coating is about 200 μm. The densification and the anti-oxidation properties of the coating can be improved by the addition of Si3N4 and MoSi2, effectively. While the anti-oxidation properties of the coating can not be improved by the addition of TaC effectively at 900 ℃. At 900 ℃, the oxidation process of ZrB2-SiC ceramic coating was mainly controlled by the diffusion of oxygen in pore and other defects in the coating. The anti-oxidation property of coating can be improved by the addition by affecting the density of coating. In the oxidation process of 1500 ℃, the oxidation resistance of the coating decreases. The introduction of the compact structure of CVD SiC sealing layer can improve the oxidation resistance significantly. At 1500 ℃, in oxidation process, SiO2 glassy oxide film with ZrO2 and ZrSiO4 on the coating is generated, this can provide effective oxidation protection for the substrate.
Key words: C/C composite; ZrB2-SiC based coating; additive; anti-oxidation mechanism
