溶胶-凝胶法在3D-SiC陶瓷表面浸涂Al_2O_3薄膜的研究

以无机盐Al(NO_3)_3·9H_2O为先驱体、水为溶剂,加入不同浓度的胶溶剂HNO_3,采用溶胶-凝胶(Solgel)法制备了勃姆石(γ-AlOOH)溶胶.分别以溶液下降法和真空浸渍法在三维网络碳化硅陶瓷骨架(3D-SiC)表面浸涂γ-AlOOH溶胶,采用不同烧结制度在3D-SiC表面生成了Al_2O_3薄膜.采用X射线衍射仪(XRD)、红外光谱仪(IR)和扫描电子显微镜(SEM)分析了薄膜的物相和显微结构,并检测了薄膜的抗热震性.结果表明,采用真空浸渍法在3D-SiC表面浸涂加入浓度0.22mol/L HNO_3制备的γ-AlOOH溶胶能烧结形成致密平整的Al_2O_3薄膜.升高烧结温度,Al_2O_3晶粒长大,900℃时薄膜最致密且能观测到玻璃态显微结构.薄膜的抗热震性随烧结温度升高而提高.

Research of Al_2O_3 Film on the Surface of 3D-SiC Ceramics by Sol-gel Method

The preparation process of Al_2O_3 thin film is represented by the sol-gel method, in which Al(NO_3)_3·9H_2O is used as precusor, water and HNO_3 as solvent and peptizing agent, respectively. Dip-coating and vacuum impregnation methods are used to coat γ-AlOOH sol solution on three-dimensional silicon carbide sintered at different temperature to form Al_2O_3 thin film. X-ray diffraction(XRD), infrared spectrometry(IR), scanning electronic microscope(SEM) are used to study the mierostrueture and phase constitution of the film. The investigation clearly shows that the thin film which prepared from γ-AlOOH sol solution added 0.22mol/L HNO_3 with vacuum impregnation method, is coated on three-dimensional silicon carbide perfectly. The grain of Al_2O_3 increases with the sintering temperature increasing. The thin film is full density at 900℃, and the glass microstructure is observed. The thermal shock resistance of the Al_2O_3 thin film increases with the sintering temperature increasing.