Preparation And Coloring Behavior Of Dental Zirconia Ceramics

With the continuous improvement of people’s living standards and the intensification of the aging trend of the population,dental health and dental restoration issues are receiving more and more attention.3 mol%yttrium stabilized tetragonal zirconia（3Y-TZP）ceramic is the most commonly used biomaterial in dental restoration materials due to its excellent mechanical properties and good biocompatibility.With the increasing demand for dental aesthetics,it is necessary to color dental zirconia ceramics to ensure that the color of dentures is as consistent as real teeth.Therefore,coloring treatment is essential for the application of 3Y-TZP ceramics in dentistry.In this thesis,3Y-TZP powders were used as raw materials to prepare 3Y-TZP ceramic molding bodies by cold isostatic pressing and gel casting.The influence of the concentration of coloring solution on the crystal structure,microstructure,optical and mechanical properties of 3Y-TZP ceramics was studied by immersion coloring treatment of zirconia ceramics prepared by cold isostatic pressing.The specific content is as follows:The effect of different cold isostatic pressing pressures on the density of 3Y-TZP ceramic preforms was studied.The maximum density of 3Y-TZP ceramic preforms is 2.50g/cm3 when the cold isostatic pressure is 220 MPa within the range of 120～240 MPa;The preparation process of zirconia ceramics with 55 vol%solid content prepared by gel casting was optimized.It was found that when the p H of zirconia ceramic slurry was 4～13,the dispersant addition was 0.2～1.2 wt%,p H=12,and the dispersant addition was 1.0 wt%,the slurry had the best dispersibility.At this time,the absolute value of the Zeta potential of the slurry was 67.3 m V,and the viscosity was 233 m Pa·s.The effect of sintering temperature on the mechanical properties of zirconia preforms prepared by different molding methods after sintering was studied.It was found that the mechanical properties of zirconia ceramics were optimal when the sintering temperature was1475℃.At this sintering temperature,the density of cold isostatic pressing zirconia ceramics is 6.02 g/cm³,the Vickers hardness is 12.82 GPa,and the fracture toughness is 7.32MPa·m^1/2.The density of zirconia ceramics prepared by gel casting is 5.86 g/cm³,the Vickers hardness is 10.72 GPa,and the fracture toughness is 6.41 MPa·m^1/2.In contrast,the sintered properties of zirconia ceramics prepared by cold isostatic pressing are better than those prepared by gel casting.The zirconia ceramics prepared by cold isostatic pressing were soaked and colored,and the effect of Fe ion coloring solution concentration on the optical and mechanical properties of zirconia ceramics was studied.As the concentration of the coloring solution increases,the transmittance of the sample decreases,the color deepens,and the penetration depth of the coloring solution inside the ceramic increases.The Vickers hardness and fracture toughness of the samples treated by immersion and coloring are reduced.Especially,the Vickers hardness and fracture toughness decrease more obviously with the increase of coloring solution concentration.