| Objectives To study experimental parameters of Salt-assisted solution Combustion Synthesis(SSCS),the 3mol% yttria-stabilized tetragonal polycrystalline zirconia(3Y-TZP)nano-powders which owned good properties were obtained by orthogonal test.Zirconia sintered bodies were gotten by powders molding and sintering.Compare the wear resistance between sintered bodies and two kinds of zirconia restorative material which were commonly used in clinic,provided experimental basis for improving the wear performance of zirconia restorative material versus human enamel antagonists.Methods With oxygen zirconium nitrate and urea as raw materials,3Y-TZP nanopowders were prepared via the SSCS and freeze drying method.Thermogravimetry differential thermal analysis(TG-DTA),x-ray diffraction(XRD)and transmission electron microscopy(TEM)were carried out on the ignition temperature of the precursors,the phase structure,the crystallite size,morphology,size distribution of the prepared 3Y-TZP nano-powders in order to select optimum process parameters.The effect of experimental conditions including the density of zirconium ion,the ignition temperature of the precursors,the molar ratio of metal ion to urea and molar ratio of metal ion to KCL on size of powders was studied by orthogonal test.Zirconia sintered bodies were gotten by powders molding and sintering.With natural tooth which were recently extracted as control group and three kinds of zirconia restorative materials(Upcera ST,Wieland and home-made 3Y-TZP)as experimental group,respectively make experimental group and control group grinding enamel.Using UMT-3 friction and wear testing machine to study friction and wear properties of the restorative materials.of three kinds of zirconia restorative materials in vitro experiment which was under simulative oral environment.The surface morphology and roughness of enamel and three kinds of porcelain pieces were analyzed using scanning electron microscope(SEM)photographs;the hardness of four kinds of specimens were tested by using the HVS-50 Z type automatic turret digital display vicars hardness instrument;the amount of weariness was measured by using the electronic balance(accurate to 0.001mg).The results were statistically analyzed by SPSS17.0 statistical software.Results 1 Through orthogonal test to investigate the optimum technological parameters of SSCS,the results were as follows: 0.085 mol/L zirconium ion,1 molar ratio of metal ion to urea,3 molar ratio of metal ion to KCl,and ignition temperature 400℃.The amount of urea and ignition temperature was major influence factors of powders grain size.The products were tetragonal polycrystalline zirconia and 2.9~9.0nm in crystalline size analyzed via XRD.The micrographs of nano-particles were sphericity,well dispersion and low-agglomeration.In addition,the particle size was 5.38 nm on the average which in keeping with the effect of XRD.In addition,the particle size was3.0nm on the average which in keeping with the effect of XRD.2 After friction and wear test,the morphology of enamel of Upcera ST,Wieland and control group had scratches and flake peeling under SEM,and fatigue wear occurred;The enamel surface of home-made 3Y-TZP had hemp dot of grinding material,and adhesive wear happened.The enamel wear loss of experimental group and control group was statistically analyzed by SPSS17.0.Wear loss was not exactly same(P=0.000,<0.05).The enamel wear loss of Wieland and homemade 3Y-TZP closed to one of control group.The results of surface roughness of experimentalgroup and control group were no difference by statistical analysis(P=0.051,>0.05).Their surface hardness were not identical which were analyzed by statistics(P=0.000,< 0.05).Conclusions 1 Salt-assisted solution Combustion Synthesis could prepare 3Y-TZP nanopowders which were 3 nm.2 By friction and wear test in vitro,the wear resistance of Wieland and home-made matched with the performance of enamel,and that of Upcera ST were higher than enamel’s. |
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