High-strength pseudobrookite-type MgTi2O5 by spark plasma sintering

Bulk polycrystalline MgTi2O5 has low coefficients of thermal expansion (CTE), high thermal shock resistance and high temperature stability. However, polycrystalline MgTi2O5 generally includes extensive internal microcracks and hence it has poor mechanical properties. In this study, dense MgTi2O5 samples with fewer microcracks were prepared by spark plasma sintering (SPS) of commercially available MgCO3 (basic) and TiO2 (anatase) powders at 1000-1200 degrees C for 20 min under 20-80 MPa in vacuum. The samples sintered above 1100 degrees C were composed of MgTi2O5 phase with trace intermediate MgTiO3. High relative density and flexural strength, 99.9% and 341.5 MPa, were obtained for the samples sintered at 1200 degrees C under 80 MPa. This strength value is, to the best of our knowledge, the highest value among pseudobrookite-type ceramics. The bulk CTE values of the samples were almost identical for all samples, similar to 10 x 10(-6) K-1 which confirms the fewness of microcracks. (C) 2016 The Ceramic Society of Japan. All rights reserved.