Hardness and toughness of mullite-zirconia composites obtained by slip casting

L.B. GARRIDO, L. MARTORELLO, E.F. AGLIETTI, M.A. CAMERUCCI, A.L. CAVALIERI

MATERIALS SCIENCE AND ENGINEERING A-STRUCTURAL MATERIALS PROPERTIES MICROSTRUCTURE AND PROCESSING

Elsevier Science Ltd.

Lugar: New York; Año: 2006 vol. 419 p. 290 - 296

0921-5093

Mullite-ZrO2 composites were obtained by reaction-sintering of three alumina/zircon (wt. %) ratio (45.5/54.5, 51.7/48.3 and 35.1/64.9). Green compacts were made by slip casting of stabilized aqueous suspensions of alumina and zircon and reaction-sintered at 1450, 1550 or 1600 °C, 2h, or using a two step firing cycle: 1450 °C, 2h plus 1600 °C, 2h. The phase evolution was followed by XRD, the densification degree was calculated from densities and the microstructures were studied by SEM. Hardness, H and fracture toughness, KIC were measured by Vickers indentation. Effects of both the alumina/zircon ratio and the sintering conditions on the H and KIC and the microstructure were examined. Inter and intragranular mechanisms of fracture were observed. Mainly a phase transformation toughening was assumed although crack deflection and microcracking mechanisms can not be discarded