In the advanced gas generator field, studies all over the world are seeking to develop ultra-high-temperature structural materials that will improve thermal efficiency in aircraft engines and other high-efficiency gas turbines. A 1% improvement of thermal efficiency would lead to a world-wide annual saving in energy costs of around $1000 billion [1]. Research is being vigorously pursued into the development of very-high-temperature structural materials that remain stable under use for prolonged periods in an oxidizing atmosphere at very high temperatures. For example, to improve the combustion efficiency of gas turbines, operating temperatures must be increased and, to achieve this, the development of ultra-hightemperature resistant structural materials is indispensable. Currently Nibase superalloys are the main thrust in this field, but these have melting points of less than 1673K, and their strength deteriorates sharply in the region of 1273K. For this reason, the development of turbine technology using advanced materials centred on ceramic composites has been vigorously pursued in recent years to overcome the heat resistance limitations of metals.