US Patent 7399722 Alumina/zirconia ceramics and method of producing the same

Composite ceramics having a high strength, a high toughness and an excellent abrasion resistance, and a method of producing the same. The composite ceramics comprises 10 to 30 mass % of a zirconia crystal phase including Ce-stabilized zirconia crystal particles which contain CeO2 in an amount of 9 to 12 mol % and Y-stabilized zirconia crystal particles which contain Y2O3 in an amount of 2.8 to 4.5 mol %; and 70 to 90 mass % of an alumina crystal phase, the zirconia crystal phase having an average crystal particle size of not larger than 1 μm.