The simultaneous control of crystal phase stability and one-dimensional growth has always been the major challenge for the preparation of tetragonal zirconia whiskers.In this study,we report a facile molten salt proce...The simultaneous control of crystal phase stability and one-dimensional growth has always been the major challenge for the preparation of tetragonal zirconia whiskers.In this study,we report a facile molten salt processing that utilizes CaF_(2) as a stabilizer and adsorbent to meet the phase and morphology requirements.The processes of stabilization,phase transition,ion adsorption and formation of special morphology involved in zirconia growth were investigated by XRD,IR,SEM,DTA-TG and TEM.By controlling the amount of CaF_(2)(15 wt%)added in the reaction precursor,tetragonal zirconia whiskers with a desired aspect ratio(>16)can be synthesized,which show single crystalline nature and[001]preferred direction.Ca ions doped at low temperature inhibit the occurrence of phase transition,which allows the tetragonal structure to be retained to room temperature.The inducement and pattern of whisker growth are supposed to be F-adsorption and screw dislocation elongation,respectively.The specific selectivity of surface adsorbed ions to certain zirconia crystal planes reduces or even inhibits the epitaxial growth rate in this direction,offering a viable avenue for the morphology modulation of inorganic nanomaterials.展开更多
Background The low-temperature resistance aging performance of Yttria-stabilized tetragonal zirconia polycrystal （Y-TZP） is the key effective factor that influences the long-term success rate of prosthesis. The obje...Background The low-temperature resistance aging performance of Yttria-stabilized tetragonal zirconia polycrystal （Y-TZP） is the key effective factor that influences the long-term success rate of prosthesis. The objective of this study was to test and compare the aging performances for resisting low temperature of Lava Frame, Cercon Smart, and Upcera Yttria-stabilized zirconia core materials, via analyzing the micro and the crystal phases of the materials, and measure the three-point bending strength and the fracture toughness. Methods The three zirconia green bodies were prepared as 60 test samples for three-point bending strength and as 60 test samples for fracture toughness. The test samples for three-point bending strength and fracture toughness were assigned to five groups and were treated respectively for 0, 5, 10, 15, and 20 hours to observe the micro and the crystal phases of the test samples. Then the three-point bending strength and fracture toughness were tested by X-ray diffraction （XRD）. Results The m phase content of Lava Frame was raised from 7.70% to 13.01%; the m phase content of Cercon Smart was raised from 4.95% to 8.53%; and Lava Frame is raised from 10.84% to 35.18%. The three-point bending strengths of the three zirconia core materials were higher than 1100 MPa and the fracture toughness was higher than 3 MPa.m^1/2. The three-point bending strength and the fracture toughness of Upcra zirconia decreased the most, followed by Lava Frame, and then by Cercon Smart. Conclusion The aging resistance sequences of the three zirconia core materials are, from strong to weak, Cercon Smart, Lava Frame, and Upcera.展开更多
The effects of Y_2O_3 adding methods (i.e.,co-precipitated and mixed) on the microstructure and properties of alumina-strengthened ytrria-stabilized tetragonal zirconia polycrystal (ASZ) were investigated. CYASZ and M...The effects of Y_2O_3 adding methods (i.e.,co-precipitated and mixed) on the microstructure and properties of alumina-strengthened ytrria-stabilized tetragonal zirconia polycrystal (ASZ) were investigated. CYASZ and MYASZ were made by different adding method of Y_2O_3,co-precipitated and mixed,respectively. The results show that CYASZ is of uniform microstructure with fine grain size,however,MYASZ is of inhomogeneous microstructure due to the inhomogeneous distribution of ytrria. Comparing with CYASZ,the density and the strength of MYASZ are decreased,but the toughness is changed only a little. Under sliding wear test,the wear resistance of CYASZ is better than that of MYASZ.展开更多
基金supported by the National Natural Science Foundation of China[grant numbers 51662016,51962014,52072162]the Key Research and Development Program of Jiangxi Province,China[grant number 20192BBEL50022]+3 种基金the Key projects of Youth Fund of Jiangxi Province,China[grant number 20202ACBL214006,20202ACBL214008]the Key Science Foundation of Jiangxi Provincial Department of Education,China[grant number GJJ180699]the Scientific Research Fund of Jiangxi Provincial Education Department(grant number GJJ160881)the Youth Science Foundation of Jiangxi Provincia Department of Education,China[grant number GJJ180740]。
文摘The simultaneous control of crystal phase stability and one-dimensional growth has always been the major challenge for the preparation of tetragonal zirconia whiskers.In this study,we report a facile molten salt processing that utilizes CaF_(2) as a stabilizer and adsorbent to meet the phase and morphology requirements.The processes of stabilization,phase transition,ion adsorption and formation of special morphology involved in zirconia growth were investigated by XRD,IR,SEM,DTA-TG and TEM.By controlling the amount of CaF_(2)(15 wt%)added in the reaction precursor,tetragonal zirconia whiskers with a desired aspect ratio(>16)can be synthesized,which show single crystalline nature and[001]preferred direction.Ca ions doped at low temperature inhibit the occurrence of phase transition,which allows the tetragonal structure to be retained to room temperature.The inducement and pattern of whisker growth are supposed to be F-adsorption and screw dislocation elongation,respectively.The specific selectivity of surface adsorbed ions to certain zirconia crystal planes reduces or even inhibits the epitaxial growth rate in this direction,offering a viable avenue for the morphology modulation of inorganic nanomaterials.
文摘Background The low-temperature resistance aging performance of Yttria-stabilized tetragonal zirconia polycrystal （Y-TZP） is the key effective factor that influences the long-term success rate of prosthesis. The objective of this study was to test and compare the aging performances for resisting low temperature of Lava Frame, Cercon Smart, and Upcera Yttria-stabilized zirconia core materials, via analyzing the micro and the crystal phases of the materials, and measure the three-point bending strength and the fracture toughness. Methods The three zirconia green bodies were prepared as 60 test samples for three-point bending strength and as 60 test samples for fracture toughness. The test samples for three-point bending strength and fracture toughness were assigned to five groups and were treated respectively for 0, 5, 10, 15, and 20 hours to observe the micro and the crystal phases of the test samples. Then the three-point bending strength and fracture toughness were tested by X-ray diffraction （XRD）. Results The m phase content of Lava Frame was raised from 7.70% to 13.01%; the m phase content of Cercon Smart was raised from 4.95% to 8.53%; and Lava Frame is raised from 10.84% to 35.18%. The three-point bending strengths of the three zirconia core materials were higher than 1100 MPa and the fracture toughness was higher than 3 MPa.m^1/2. The three-point bending strength and the fracture toughness of Upcra zirconia decreased the most, followed by Lava Frame, and then by Cercon Smart. Conclusion The aging resistance sequences of the three zirconia core materials are, from strong to weak, Cercon Smart, Lava Frame, and Upcera.
文摘The effects of Y_2O_3 adding methods (i.e.,co-precipitated and mixed) on the microstructure and properties of alumina-strengthened ytrria-stabilized tetragonal zirconia polycrystal (ASZ) were investigated. CYASZ and MYASZ were made by different adding method of Y_2O_3,co-precipitated and mixed,respectively. The results show that CYASZ is of uniform microstructure with fine grain size,however,MYASZ is of inhomogeneous microstructure due to the inhomogeneous distribution of ytrria. Comparing with CYASZ,the density and the strength of MYASZ are decreased,but the toughness is changed only a little. Under sliding wear test,the wear resistance of CYASZ is better than that of MYASZ.
