ZrO2 and its modified versions containing MgO and Y2O3 were selected a
s particulate reinforcement in order to achieve better mechanical prop
erties of mullite. Particulate composites up to 25 vol% ZrO2 and its m
odifications were pressed to 55% relative density at 300 MPa followed
by sintering at 1600 degrees C and 1650 degrees C for one hour. Studie
s were conducted on fracture toughness, transverse rupture strength, h
ardness, dielectric constant, microstructure and fractography. Composi
tes sintered at 1650 degrees C were found superior in properties than
those at 1600 degrees C. The maximum strength of mullite composites wa
s observed at a composition of 10 vol% ZrO2.