Effect Of Forming Process Of Nanometer Zirconia On Its Mechanical Properties

Objectives Orthogonal experiments were carried out to discuss the process parameters of self-made nanometer zirconia in the molding process.The powders were cold-isostatically pressed by dry pressing,and the zirconia ceramic was obtained after microwave sintering.Compared with the two commonly used clinical repair materials,to provide experimental basis for improving the material properties,prepared with good mechanical properties and wear resistance of zirconia porcelain.Methods The yttrium-stabilized tetragonal nanostructured zirconia(3Y-TZP)powder obtained by salt solution combustion method was used as raw powder.The effect of PVA mass percentage(A),particle size distribution(B),and dry compression molding pressure(C)on the density of the green body was investigated using orthogonal experiments.After the dry pressing of the initial green body through 200 MPa cold isostatic pressing,using Archimedes method to determine the relative density as an indicator to screen out the best 3Y-TZP powder molding process parameters.Dry pressing combined with cold isostatic pressing,microwave sintering,and clinical commonly used Upcera,Wieland two kinds of repair materials to do mechanical properties and friction and wear performance comparison.The surface hardness of each group of porcelain was measured by Vickers hardness tester.Bending strength is measured with a universal testing machine.The sem observation of fracture surface microstructure.The data were compared by one-way ANOVA.Friction and wear testing machine(MMW-1)simulated oral environment,in vitro study compared the friction and wear properties of three groups of materials.The microstructure of the worn surface was observed using a scanning electron microscope(SEM),and the electronic balance was used to measure the mass loss before and after friction and wear.All experimental data using SPSS17.0 statistical software for statistical analysis.Results 1 The mass percentage(A)of PVA and the pressure(C)during the dry-press molding are the most important factors.The optimum process conditions are: A: 14wt%;B: 6: 3: 1;C: 120MPa;White relative density of up to 64.92%.Scanning electron microscopy,after adding dispersant PVA powder was spherical,highly dispersed,low agglomeration.2 on the mechanical properties of the test,Upcera,Wieland and self-made 3Y-TZP three groups of the surface hardness values are statistically different,the surface hardness of Wieland> Upcera> homemade porcelain group.Three groups of flexural strength by statistical analysis,the bending strength values are not exactly the same(P = 0.000,<0.05).Among them,the self-made porcelain group and the Wieland group flexural strength close to greater than the Upcera group.3 After the friction and wear test,the wear amount of the three groups of specimens was not statistically the same(P = 0.000,<0.05)by SPSS17.0 software statistical analysis.Among them,Upcera and homemade porcelain group wear close to,greater than the Wieland Group.Scanning electron microscopy showed that the wear mechanism of Wieland porcelain was mainly fatigue wear.The wear mechanism of Wieland porcelain was fatigue wear with abrasive wear.The wear mechanism of self-made porcelain was abrasive wear with adhesion wear.Conclusions 1 Dry pressing combined with cold isostatic pressing can be prepared with a relative density of 64.92% of the green body.2 The mechanical properties and friction and wear properties of the self-made ceramic block are close to those of the Upcera block,and there is still a certain gap between the self-made ceramic block and the Wieland block.it is a promising all-ceramic repair material.