Microwave Sintering Of Nanometer Alumina-zirconia All-ceramic Materials

Metal-ceramic restorations may lead to poor light transparence and black gingival margin. All-ceramic restorations can be used to prevent these problems. Now the most popular all-ceramic materials in used are those mainly consist of alumina or zirconia (ex: Vita In-ceram, Procera Allceram, Cercon). The sintering temperature of these materials is much higher than that of conventional ceramics. Expensive sintering oven and long sintering time is needed. All these lead to large cost and much time; Nanometer ceramic materials are believed to have high strength, good toughness and some other advantages. The conventional sintering method cannot control the growth of grain size and will cause nanometer materials to lose their good properties. It's necessary to study how to control the growth of grain size during the sintering process.In this study, microwave sintering was used to study the technology and fundamentals of nanometer alumina-zirconia all-ceramic composite materials. The properties of materials are tested, the results showed:1. The microwave sintering technology is constant and efficient. All-ceramic was successfully sintered using this heating system in combination with a suitable thermal insulator.2. The alumina dental ceramic sintered by microwave can reach 99% relative density at 1600℃ for 10 minutes preservation. Compared with traditional sintering, the sintering time is reduced greatly, heating efficiency is higher.3. Microwave sintering of alumina-zirconia nano-ceramic has lower sintering temperature, shorter preservation time, little grain size growth. It can save time and energy, so it will be an important technology to get high property dentalceramic in future. 4. The aid-heating materials is oxidated at high temperature, it will lead to thereduction of the heating efficiency. So aid-heating materials should be changedregularly.