A fabrication technique for surface incorporation of ZrO2 was developed. Prefired mullite bodies with open porosities of 20-40% were infiltrated with a ZrOCl2 solution prior to firing. Mechanical properties of the surface modified mullite were improved. The flexural strength of the composite increased by 35-40% of that of mullite at room temperature, and had the same value at 1300°C as that of mullite. The fracture toughness of the surface layer of the composite was double of that of mullite.
