Fabrication and Properties of 3D Mullite Fiber-Reinforced AI2O3 Matrix Composites Prepared by Sol-Gel Process

摘要

Fiber toughening is an effective method to improve the brittleness of ceramic materials. In this paper, three-dimensional mullite fiber reinforced alumina ceramic matrix (3D mullitef/Al203) composites were prepared by sol-gel process. Alumina sol was prepared by two ways in the inorganic aluminium salt method, and the alumina sol with good fluidity and high solid content was used as a precursor. The preparation process of alumina sol was studied by XRD and TGA-DSC. The results show that the sol is transformed into A1203 at about 1100°C, and the crystal phase is a-Al203 phase. The mechanical properties of the sample were analyzed by three-point bending test. The microstructure of the fractures was observed by scanning electron microscopy. The results show that with the increase of the immersion cycles, the density of composites increases continuously, and the toughening mechanism of continuous fiber extraction, interfacial debonding and crack deflection is fully utilized during fracture, which is characterized by ductile fracture behavior and achieved the purpose of toughening.