Thermal and mechanical properties of aluminum titanate-mullite composites

The thermal and mechanical properties of aluminum titanate-mullite composit es prepared by a gel-coated powder processing method, namely a mullite prec ursor gel coating aluminum titanate particles (containing 2.5 wt% MgO), wer e investigated. A microstructure with both elongated and equiaxed mullite g rains was observed in the composite samples. Both the mechanical strength a nd the thermal expansion coefficient increased with the mullite amount. The mechanical strength showed a strong dependence on the grain size of alumin um titanate with an exponent of -3. Inhibition of aluminum titanate grain g rowth due to the presence of the mullite phase enhanced the mechanical stre ngth of the composites. The thermal shock resistance tended to decrease as the mullite content increased. The thermal stability of aluminum titanate w as improved in the present composite system.