Layered porous ceramic used for polymer-infiltrated-ceramic-network materials(PICNs) may be a promising candidate for dental restoration.The effect of sintering temperature of ceramic green bodies on mechanical and op...Layered porous ceramic used for polymer-infiltrated-ceramic-network materials(PICNs) may be a promising candidate for dental restoration.The effect of sintering temperature of ceramic green bodies on mechanical and optical properties of PICNs is unclear.The purpose was to fabricate PICNs and evaluate their mechanical and optical properties.Polymer-infiltrated layered silicates for dental restorative materials were prepared via infiltrating polymerizable monomers into partially sintered porous silicates and thermo-curing.Bending samples for flexural strength and fracture toughness were fabricated(sample numbers of n=15).Vickers hardness and elastic modulus were measured via nano-indentation(n=10).One-way ANOVA and Weibull statistics were used for statistical analysis.Optical property was characterized by spectral reflectance.Brittleness index was used to characterize the machinability of the materials.Microstructures and phase structures were investigated using scanning electron microscopy(SEM) and X-ray diffractometer(XRD),respectively.Flexural strength of polymer-infiltrated layered silicates varied from 91.29 to 155.19 MPa,fracture toughness ranged from 1.186 to 1.782 MPa·m^1/2,Vickers hardness ranged from 1.165 to 9.596 GPa,and elastic modulus ranged from 25.35 to 100.50 GPa.The formed glass phases at 1200 and 1300℃ showed influences on corresponding optical property,which could be observed from spectral reflectance.A kind of PICNs was fabricated by infiltrating polymerizable monomers into layered porous ceramic networks.Sintering temperature could have dramatic effects on the mechanical and optical properties of porous ceramics and PICNs.These kinds of materials possess similar properties to that of natural tooth and could be used for dental restoration.展开更多
A new type of polymer-infiltrated-ceramic-network composites (PICNs) was fabricated by infiltrating methacrylate-based monomers into partially sintered porous ceramics.The mechanical properties (flexural strength,flex...A new type of polymer-infiltrated-ceramic-network composites (PICNs) was fabricated by infiltrating methacrylate-based monomers into partially sintered porous ceramics.The mechanical properties (flexural strength,flexural modulus,elastic modulus,Vickers hardness,fracture toughness) were investigated and compared with that of the natural tooth and common commercial CAD/CAM blocks.Our results indicated that sintering temperature and corresponding density of porous ceramics have an obvious influence on the mechanical properties,and PICNs could highly mimic the natural tooth in mechanical properties.The biocompatibility experiments evaluated through in vitro cell attachment and proliferation of BMSCs showed good biocompatibility.The mechanical properties and biocompatibility confirmed that PICN could be a promising candidate for CAD/CAM blocks for dental restoration.展开更多
http://www.sciencedirect.com/science/journal/03787788/108Volume 108,Pages 1-470(1 December 2015)(1)Designing an optimal solar collector(orientation,type and size)for a hybrid-CCHP system in different climates,P10-22,b...http://www.sciencedirect.com/science/journal/03787788/108Volume 108,Pages 1-470(1 December 2015)(1)Designing an optimal solar collector(orientation,type and size)for a hybrid-CCHP system in different climates,P10-22,by Masood Ebrahimi,Ali Keshavarz Abstract:The purpose of this research is to determine the optimum orientation and size of a solar collector to be integrated with a basic-CCHP system.The basic-CCHP includes an internal com-展开更多
Ceramics used in the high temperature environment are inevitably subjected to sudden temperature change, which may lead to catastrophic thermal shock failure due to the intrinsic brittleness of ceramics. In this paper...Ceramics used in the high temperature environment are inevitably subjected to sudden temperature change, which may lead to catastrophic thermal shock failure due to the intrinsic brittleness of ceramics. In this paper, an experimental platform is designed to realize the in-situ observation during the thermal shock experiments. Experimental results show that all the cracks initiate from one of the edge midpoints and propagate to another one for square specimens. Such experimental observation is consistent with the maximum tensile stress zone with the maximum temperature gradient given by the finite element method(FEM). The different crack modes resulting from different heating rates after thermal shock experiments are observed and analyzed. Comparison between different clamping methods is conducted to study the effects of boundary conditions on the thermal shock experiments. Furthermore, in order to improve the thermal shock performance of alumina ceramics, crack arrest blocks are added near the edge midpoint. The thickness, shape and arrangement of the blocks are systematically investigated to understand the mechanism of improvement of thermal shock resistance.展开更多
基金financially supported by Beijing Municipal Science and Technology Commission(No.Z171100002017009)the National Natural Science Foundation of China(Nos.51532003,51221291,51328203 and 81671026)
文摘Layered porous ceramic used for polymer-infiltrated-ceramic-network materials(PICNs) may be a promising candidate for dental restoration.The effect of sintering temperature of ceramic green bodies on mechanical and optical properties of PICNs is unclear.The purpose was to fabricate PICNs and evaluate their mechanical and optical properties.Polymer-infiltrated layered silicates for dental restorative materials were prepared via infiltrating polymerizable monomers into partially sintered porous silicates and thermo-curing.Bending samples for flexural strength and fracture toughness were fabricated(sample numbers of n=15).Vickers hardness and elastic modulus were measured via nano-indentation(n=10).One-way ANOVA and Weibull statistics were used for statistical analysis.Optical property was characterized by spectral reflectance.Brittleness index was used to characterize the machinability of the materials.Microstructures and phase structures were investigated using scanning electron microscopy(SEM) and X-ray diffractometer(XRD),respectively.Flexural strength of polymer-infiltrated layered silicates varied from 91.29 to 155.19 MPa,fracture toughness ranged from 1.186 to 1.782 MPa·m^1/2,Vickers hardness ranged from 1.165 to 9.596 GPa,and elastic modulus ranged from 25.35 to 100.50 GPa.The formed glass phases at 1200 and 1300℃ showed influences on corresponding optical property,which could be observed from spectral reflectance.A kind of PICNs was fabricated by infiltrating polymerizable monomers into layered porous ceramic networks.Sintering temperature could have dramatic effects on the mechanical and optical properties of porous ceramics and PICNs.These kinds of materials possess similar properties to that of natural tooth and could be used for dental restoration.
基金This work was financially supported by the National Natural Science Foundation of China
文摘A new type of polymer-infiltrated-ceramic-network composites (PICNs) was fabricated by infiltrating methacrylate-based monomers into partially sintered porous ceramics.The mechanical properties (flexural strength,flexural modulus,elastic modulus,Vickers hardness,fracture toughness) were investigated and compared with that of the natural tooth and common commercial CAD/CAM blocks.Our results indicated that sintering temperature and corresponding density of porous ceramics have an obvious influence on the mechanical properties,and PICNs could highly mimic the natural tooth in mechanical properties.The biocompatibility experiments evaluated through in vitro cell attachment and proliferation of BMSCs showed good biocompatibility.The mechanical properties and biocompatibility confirmed that PICN could be a promising candidate for CAD/CAM blocks for dental restoration.
文摘http://www.sciencedirect.com/science/journal/03787788/108Volume 108,Pages 1-470(1 December 2015)(1)Designing an optimal solar collector(orientation,type and size)for a hybrid-CCHP system in different climates,P10-22,by Masood Ebrahimi,Ali Keshavarz Abstract:The purpose of this research is to determine the optimum orientation and size of a solar collector to be integrated with a basic-CCHP system.The basic-CCHP includes an internal com-
基金supported by the National Basic Research Program of China("973"Project)(Grant No.2015CB351900)the National Natural Science Foundation of China(Grant Nos.11222220,11320101001,11372155&11227801)the Tsinghua University Initiative Scientific Research Program
文摘Ceramics used in the high temperature environment are inevitably subjected to sudden temperature change, which may lead to catastrophic thermal shock failure due to the intrinsic brittleness of ceramics. In this paper, an experimental platform is designed to realize the in-situ observation during the thermal shock experiments. Experimental results show that all the cracks initiate from one of the edge midpoints and propagate to another one for square specimens. Such experimental observation is consistent with the maximum tensile stress zone with the maximum temperature gradient given by the finite element method(FEM). The different crack modes resulting from different heating rates after thermal shock experiments are observed and analyzed. Comparison between different clamping methods is conducted to study the effects of boundary conditions on the thermal shock experiments. Furthermore, in order to improve the thermal shock performance of alumina ceramics, crack arrest blocks are added near the edge midpoint. The thickness, shape and arrangement of the blocks are systematically investigated to understand the mechanism of improvement of thermal shock resistance.
