Study On Preparation And Properties Of In-situ Toughened Alumina Ceramic Matrix Composites

In situ transformed carbon fibers toughened alumina ceramic matrix compositeswere prepared by vacuum hot-press sintering, and in the sintering processpre-oxidized polyacrylonitrile fibers (below named as pre-oxidized PAN fibers) wereused as the precursors of the in situ transformed carbon fibers. The interface betweencarbon fibers and matrix, microstructure and toughening mechanisms of carbon fibers,as well as the properties of the composites were studied. The fabrication processes ofthe composites were also optimized. The results show that the surface layers of the insitu transformed carbon fibers display the obvious graphite lamellar structure with theobservation of TEM and the lamellar spacing is approximately0.3455nm and that theG line of graphite and the D line of turbostratic structure also exhibit respectively at1580cm-1和1360cm-1in Raman spectra. The additives obviously improve the interfacialbonding strength between carbon fibers and matrix. The flexural strength and fracturetoughness of the composite with3vol.%additive and20vol.%pre-oxidized PANfibers can reach to347.88MPa and8.22MPa·m1/2respectively,. The tougheningmechanisms are mainly fibers pulling-out, fibers bridging and crack deflection.