COLLOIDAL PROCESSING FOR PREPARATION OF LAMINATED COMPOSITES OF MULLITE WOVEN FABRICS OF SI-TI-C-O FIBERS/

A sol-gel-processed mullite powder and woven fabrics of Si-Ti-C-O fibe rs were formed into laminated composites (6 vol% woven fabrics). The g reen composites were hot-pressed to near full density at 1650 degrees C for 1 h at 39 MPa in a N-2 atmosphere. The strength and fracture tou ghness of the dense composites ( > 99% of theoretical density) were me asured at room temperature. The fracture toughness for monolithic mull ite (1.6 MPa m(1/2)) was increased to 3.9 MPa m(1/2) by the addition o f the woven fabrics. On the other hand, there was no significant diffe rence in the flexural strength between monolithic mullite and the comp osite.