COLLOIDAL PROCESSING FOR PREPARATION OF LAMINATED COMPOSITES OF NEW-ZEALAND KAOLIN WOVEN FABRICS OF SI-TI-C-O FIBERS

New Zealand kaolin compacts and laminated kaolin/Si-Ti-C-O woven fabric (16-17 vol%) compacts were formed by filtration and the doctor blade method using aqueous kaolin suspensions containing polyacrylic ammonium and methyl cellulose. The kaolin suspensions, with 10-37 vol% solids at pH 6-8, showing non-Newtonian flow expressed by a power law equation of S=K gamma over dot(n) (S is the shear stress, gamma over dot the shear rate, and K and n (0<n<1) are constants), were formed into green compacts of 51-54% of the theoretical density (TD). The kaolin compacts and laminated composites were hot pressed to 96-98% TD at 1350-1500 degrees C under a pressure of 39 MPa in N-2 atmosphere. The flexural strengths of hot-pressed kaolin and composites were 210 and 180 MPa, respectively. The composite fractured via delamination in the Si-Ti-C-O fabric layers.