Research On Material And Molding Technology Of Ceramic Bracket

With the improvement of living standard,Orthodontics have a great development in our country. To satisfy people's aspiration for beauty, bracket materials also have been optimized and improved continually. It has become a significant subject that exploring a kind of dental material with aesthetic feeling, excellent mechanical property and biocompatibility in Orthodontics. Therefore, research on bracket materials has mainly focused on the improvement of its strength while keeping its excellent biocompatibility and aesthetic feeling.In this paper, ZTA and 3Y-ZrO2 were taken as raw materials. The fabrication of tough bracket material with high strength and its preparation process have been investigated. The key point of this study was to get bracket with excellent mechanical properties with the method of hot pressure casting.As for the powder processing, ball milling with the aid of stearic acid was employed to treat ZTA and 3Y-ZrO2 powders. The effects of stearic acid on the surface property, polarity and mobility of ZTA and 3Y-ZrO2 powders were studied. FTIR spectroscopy was employed to analyze the effect of stearic acid coating on ZTA powders. The results show that powders after treatment have better dispersibility, covalent bonds are formed between the hydroxyl of ZTA surface and carboxyl of stearic acid, the polarity of ZTA powder is changed. Moreover, the flow ability is also improved.Green body has been improved by adjusting the fabricating technique and solving the problems occurred in the molding process. Thermal analysis method has been employed to study the weight-loss laws during the process of green body's debinding and make an appropriate degrease technologies. Samples are sintered after degreasing.Better sintering process was obtained by investigating the relative density, ratio of absorbing and bending strength of sintered sample. Both mechanical and physical properties were considered. Moreover, phase compositions and microstructures of the samples were observed by the method of Scaning electron microscope and X-ray diffraction, the mechanism of strength and toughening were discussed as well. The results show that the samples prepared by the above process exhibit excellent mechanical properties and especially that the highest bending strength of the modified 3Y-ZrO2 was 900MPa.