抄録
A sintered SiC fiber reinforced SiO_2-mullite composites were fabricated by impregnation of the fiber tows into matrices slurry and hot pressing. In order to control the nature of residual stress in the composites, the matrix of three levels of Al_2O_3 content in SiO_2-mullite were prepared. Tyranno SA fiber was selected for the reinforcement because of high-temperature phase stability. The obtained composites had well dense structure, and both mullite and glassy SiO_2 phases were found in the matrices. Volume fraction and morphology of the mullite were dependent on the extent of super saturation of Al_2O_3 in the under cooled liquid. Interfacial chemical reaction between fiber and oxide matrix due to fabrication process was not observed. The nature of thermal residual stress in the composites was controlled by Al_2O_3 content in SiO_2-mullite hypereutectic oxide material, which was analyzes by finite element method (FEM) and by measuring interfacial shear stress with fiber push-out test. Three-point flexural strength of the composites at room out in the fracture surface. The highest flexural strength of the SiO_2-3.7 mol.% Al_2O_3 matrix composite will be caused by the highest compressive residual stress in the matrix.
