There are many kinds of all ceramic restoration system for clinical application in recent years, such as casting and hot pressing ceramic slip casting system, but because of the strength of the limitations of the long-term effect of posterior bridge repair of the poor. Only with the "zirconia ceramic steel" has the strength of 1 enough, can be safely used in posterior bridge, even Long bridge 2. Because of the high hardness and strong strength, the compact sintered zirconia ceramic can only be processed by carborundum cutters, and the processing cost is high and the time is long. To solve the above problems, now use the two times sintering of zirconia ceramics, and preliminary sintering ceramic body after molding by CAD / CAM amplification to cutting the desired shape, and then sintered to final sintering temperature of the material fully dense. Properties of zirconia ceramics during single sintering and two sintering process
The effects of two sintering processes on the sintering density, mechanical properties and microstructure of zirconia ceramics were investigated. Methods nano zirconia powder static pressure molding, using zirconia sintering furnace is a sintering and two step sintering of two kinds of heat treatment, sintered at different sintering temperatures of different sintering and sintering temperature sintering density, three point flexural strength, fracture toughness and hardness of the Vivtorinox measurement and analysis the specimen, and the fracture surface morphology was observed by scanning electron microscope. Results the density, three point flexural strength, hardness and fracture toughness of the sintered zirconia ceramics were different from those of the two sintering process compared with that of the first sintering process. The results showed that the sintering density of the zirconia ceramic sintered by Vivtorinox was different from that of the primary sintering. In the 900 / 1450 degrees C sintering temperature, sintering time two zirconia ceramic body the highest relative density (98.49%), the best mechanical properties, three point flexural strength, hardness and fracture toughness were Vivtorinox 1059.08MPa + 75.24MPa, 1377.00MPa + 16.37MPa and 5.92MPa + M1 / 2 0.37MPa M1 / 2. The two sintering makes the internal pores of zirconia ceramics increase slightly, some grains grow up and the sizes are uneven. Conclusion the two sintering process has certain influence on the properties of zirconia ceramics, but the properties of the materials can meet the clinical requirements.