Studies On Physical And Mechanical Properties And Preparation Of The Zirconia-toughened Ceramics For Dental Application

Ceramic as a kind of prosthetic material has excellent natural appearance and the best biocompatibility, excellent corrosion resistance and abrasive resistance. The metal materials can not be compared with ceramics, especially In aesthetic characteristics. Now the porcelain-fused-to-metal (PFM) restoration is the most commonly used ceramic restorations. However, the metal substructures of the PFM restorations generally result in poor biocompatibility and poor aesthetics because of the precipitation of metal ions and low transmittance. These shortcomings can be completely overcome by the application of all-ceramic restorations, which have natural appearance and the best biocompatibility. With the increasing of aesthetic demands, all-ceramic restorations will become the main method of fixed prosthodontics. It is generally accepted that the mechanical shortcomings of ceramic materials including their inherent brittleness and lower strength limit the application of all-ceramic restorations. Recent developments have attempted to develop dental material which exhibit excellent aesthetic characteristics, the best biocompatibility and higher fracture strength and toughness.The key idea of this study was to make zirconia-toughened ceramics with excellent fracture strength and toughness for dental application. It Is commonly used of 3mol% yttria-stabilized zirconia-toughened ceramics In abroad, and only a partuses zirconia-toughened ceramics stabilized by two types of stabilizer. The ZrOi-CeOaA^OyMgO ceramic is used in this study. We hope to integrate the advantages of every type of stabilizer to greatly improve the toughness of zirconia-toughened ceramics.Compared with 3mol%Y2O3 stabilized zirconia-toughened ceramic, the process parameters and fundamental characteristics of the ZrCK-CeC^/YiCh/MgO ceramic were investigated. Different testing ways Including X-ray diffractometry (XRD), scanning electron microscopy (SEM), and mechanical tests were used in this study. By changing the sintering method and adjusting sintering temperature, the influence of sintering temperature and method on phase contents, microstructure of the samples, and the relationship with mechanical properties of the zirconia-toughened ceramics were then investigated. The results show that:The compound stabilizer of CeO2/Y2C)3/MgO has good stabilizing effect on zirconia ceramic and It makes sintering temperature of zirconia ceramic lower than before.The ZrOi-CeOoA^Os/MgO ceramic is found to have superior mechanical properties, including single-edge notch bend fracture toughness and static three-point flexure strength, and toughening effect of microcracks, phase transformation and the effect of grain evulsions are beneficial for Improving mechanical properties of the materials. It is suitable for the standard of dental post in mechanical properties.Uniformly dispersed (Y, Ce, Mg)- ZrOi powder was prepared by chemical coprecipitation, and high density ZrOj ceramic which was stabilized by compound stabilizer was prepared by means of appropriate technique.Sintering temperature has dominant effect on the mechanical properties of zirconia toughened ceramic. In terms of sintering temperature and bending strength, the best sintering temperature of 3mol% yttria-stabilized zirconia should be about 1570癈.The sintering temperature of zirconia ceramic has a close relationship with their microstructures. It Influence mechanical properties through the grain size and pore contents.The result of mechanical test shows that the CeCK/^Os/MgO stabilized dental zirconia ceramic post has good mechanical properties.