DEVELOPMENT OF HIGH-STRENGTH WHITEWARE BODIES

The effect of sillimanite sand as a replacement for quartz and alumina /cordierite glass-ceramic for feldspar was studied. Compositional vari ations were clue to the gradual incorporation of alumina in place of c ordierite glass-ceramic. Increased replacement of cordierite glass-cer amic by alumina (20%) increased the flexural strength by 100%, giving a value of 195 MPa. Elastic modulus, microhardness and fracture toughn ess also showed sharp increases compared with values for conventional triaxial whiteware compositions. Improvement in mechanical properties was attributed to the presence of sillimanite and alumina particles pr esent as fracture-resistant dispersoids in a viscous glassy matrix. In creased fracture behaviour is due to minimization of the glassy phase and limiting the size of Griffith's flaws. (C) 1996 Elsevier Science L imited.