Composite membranes have attracted increasing attentions owing to their potential applications for CO2 separation. In this work, ceramic supported polydimethylsiloxane （PDMS） and poly （ethylene glycol） diacrylate ...Composite membranes have attracted increasing attentions owing to their potential applications for CO2 separation. In this work, ceramic supported polydimethylsiloxane （PDMS） and poly （ethylene glycol） diacrylate （PEGDA） composite membranes were prepared. The microstructure and physicochemical properties of the compos- ite membranes were characterized. Preparation conditions were systematically optimized. The gas separation performance of the as-prepared membranes was studied by pure gas and binary gas permeation measurement of CO〉 N2 and H〉 Experiments showed that PDMS, as silicone rubber, exhibited larger permeance and lower separation factors. Conversely, PEGDA composite membrane presented smaller gas permeance but higher ideal selectivity for CO2/N2. Compared to the performance of those membranes using polymeric supports or freestanding membranes, the two kinds of ceramic supported composite membranes exhibited higher gas permeance and acceptable selectivity. Therefore, the ceramic supported composite membrane can be expected as a candidate for CO2 separation from light gases.展开更多
Al 2O 3-SiO 2-TiO 2-ZrO 2 supported membranes were prepar ed by Sol-Gel method. These composite ceramic membranes are level, even and no macro crack. There exist several crystalline phases such as Al 2O 3, TiO...Al 2O 3-SiO 2-TiO 2-ZrO 2 supported membranes were prepar ed by Sol-Gel method. These composite ceramic membranes are level, even and no macro crack. There exist several crystalline phases such as Al 2O 3, TiO 2(a natase), Al 2SiO 5, and ZrO 2 in these membranes. Changing the molar ratio of Al∶Si∶Ti∶Zr,the kinds and content of crystal phases of composite membranes could be different, which may lead to a variety of microstructure of membranes. The surface nanoscale topography and microstructure of membranes were investiga ted by XRD,SEM,AFM,EPMA. The effects of additives and heat treatments on the sur face nanoscale topography and microstructure of composite ceramic membranes were also analyzed.展开更多
Al2O3 ceramic powder was applied to modify the large pores defects on the surface of the porous metal Ti support,in situ oxidation method was a convenient method to prepare defect free ceramic/Ti composite membranes o...Al2O3 ceramic powder was applied to modify the large pores defects on the surface of the porous metal Ti support,in situ oxidation method was a convenient method to prepare defect free ceramic/Ti composite membranes on this basis.In situ oxidation conditions experimental results show that the best condition for preparing the TiO2-Al2O3/Ti composite membrane is under 800°C for 2 h,and the microstructure and pore sizes of the TiO2-Al2O3/Ti composite membranes are affected obviously.The thickness and composition of the TiO2/Ti composite membranes are determined by SEM and XRD completely.The pore size distribution of the composite membrane is measured by bubble pressure method,the most probable aperture is about 3.12μm,while the average pore size of defect free TiO2-Al2O3/Ti is about 3.23μm.After ultrasonic treatment,the slight weight change of membranes reveals no observable change,which indicates that TiO2-Al2O3/Ti composite membranes maintain a good stability.展开更多
The fabrication process of Sm2O3 doped CeO2 reinforced Ti3AlC2 nano composites including the nano particle dispersion process by a hetero-coagulation process was developed using in-situ synthesis and densification pro...The fabrication process of Sm2O3 doped CeO2 reinforced Ti3AlC2 nano composites including the nano particle dispersion process by a hetero-coagulation process was developed using in-situ synthesis and densification process of Ti3AlC2. The effects of Sm2O2 doped CeO2 nano particles on mechanical properties of Ti3AlC2 were investigated. It was found that the presence of 20SDC nano particles in Ti3AlC2 was very effective to improve the mechanical properties of Ti3AlC2 without spoiling the unique characteristics of Ti3AlC2temary carbide.展开更多
The MAX phase Ti3SiC2 has broad application prospects in the field of rail transit,nuclear protective materials and electrode materials due to its excellent electrical conductivity,selflubricating properties and wear ...The MAX phase Ti3SiC2 has broad application prospects in the field of rail transit,nuclear protective materials and electrode materials due to its excellent electrical conductivity,selflubricating properties and wear resistance.Cu–Ti3SiC2 co-continuous composites have superior performance due to the continuous distribution of 3 D network structures.In this paper,the Cu/Ti3SiC2(Ti C/Si C)co-continuous composites are formed via vacuum infiltration process from Cu and Ti3SiC2 porous ceramics.The co-continuous composites have significantly improved the flexural strength and conductivity of Ti3SiC2 due to the addition of Cu,with the conductivity up to 5.73×10^5 S/m,twice as high as the Ti3SiC2 porous ceramics and five times higher than graphite.The reaction between ingredients leads to an increase in the friction coefficient,while the hard reaction products(Ti Cx,Si C)lower the overall wear rate(1×10^–3 mm^3/(N·m)).Excellent electrical conductivity and wear resistance make co-continuous composites more advantageous in areas such as rail transit.展开更多
Textured Ti2AlC lamellar composites have been successfully fabricated by a new method in the present work.The composites exhibit high compressive strength of ca 2 GPa,fracture toughness of 8.5 MPa m1/2(//c-axis),flexu...Textured Ti2AlC lamellar composites have been successfully fabricated by a new method in the present work.The composites exhibit high compressive strength of ca 2 GPa,fracture toughness of 8.5 MPa m1/2(//c-axis),flexural strength of 735 MPa(//c-axis)and high hardness of 7.9 GPa(//c-axis).The strengthening mechanisms were discussed.The sintering and densification process was investigated and crystal orientation and microstructure were studied by electron backscattered diffraction techniques.The synthesis temperature is reduced to 1200?C by using high surface-to-volume ratio Ti2AlC nano flakes.The Lotgering orientation factor of Ti2 AlC and Ti3 AlC2{00 l}planes in the textured top surface reaches 0.74 and 0.49,respectively.This new route may shed light on resolving the difficulties encountered in large scale fabrication of textured MAX phases.展开更多
基金Supported by the National Basic Research Program of China （2009CB623406）, the National Natural Science Foundation of China （20990222） and the Natural Science Foundation of Jiangsu Province （BK2009021, SBK200930313）.
文摘Composite membranes have attracted increasing attentions owing to their potential applications for CO2 separation. In this work, ceramic supported polydimethylsiloxane （PDMS） and poly （ethylene glycol） diacrylate （PEGDA） composite membranes were prepared. The microstructure and physicochemical properties of the compos- ite membranes were characterized. Preparation conditions were systematically optimized. The gas separation performance of the as-prepared membranes was studied by pure gas and binary gas permeation measurement of CO〉 N2 and H〉 Experiments showed that PDMS, as silicone rubber, exhibited larger permeance and lower separation factors. Conversely, PEGDA composite membrane presented smaller gas permeance but higher ideal selectivity for CO2/N2. Compared to the performance of those membranes using polymeric supports or freestanding membranes, the two kinds of ceramic supported composite membranes exhibited higher gas permeance and acceptable selectivity. Therefore, the ceramic supported composite membrane can be expected as a candidate for CO2 separation from light gases.
文摘Al 2O 3-SiO 2-TiO 2-ZrO 2 supported membranes were prepar ed by Sol-Gel method. These composite ceramic membranes are level, even and no macro crack. There exist several crystalline phases such as Al 2O 3, TiO 2(a natase), Al 2SiO 5, and ZrO 2 in these membranes. Changing the molar ratio of Al∶Si∶Ti∶Zr,the kinds and content of crystal phases of composite membranes could be different, which may lead to a variety of microstructure of membranes. The surface nanoscale topography and microstructure of membranes were investiga ted by XRD,SEM,AFM,EPMA. The effects of additives and heat treatments on the sur face nanoscale topography and microstructure of composite ceramic membranes were also analyzed.
基金Projects(212006065,21666018)supported by the National Natural Science Foundation of China
文摘Al2O3 ceramic powder was applied to modify the large pores defects on the surface of the porous metal Ti support,in situ oxidation method was a convenient method to prepare defect free ceramic/Ti composite membranes on this basis.In situ oxidation conditions experimental results show that the best condition for preparing the TiO2-Al2O3/Ti composite membrane is under 800°C for 2 h,and the microstructure and pore sizes of the TiO2-Al2O3/Ti composite membranes are affected obviously.The thickness and composition of the TiO2/Ti composite membranes are determined by SEM and XRD completely.The pore size distribution of the composite membrane is measured by bubble pressure method,the most probable aperture is about 3.12μm,while the average pore size of defect free TiO2-Al2O3/Ti is about 3.23μm.After ultrasonic treatment,the slight weight change of membranes reveals no observable change,which indicates that TiO2-Al2O3/Ti composite membranes maintain a good stability.
文摘The fabrication process of Sm2O3 doped CeO2 reinforced Ti3AlC2 nano composites including the nano particle dispersion process by a hetero-coagulation process was developed using in-situ synthesis and densification process of Ti3AlC2. The effects of Sm2O2 doped CeO2 nano particles on mechanical properties of Ti3AlC2 were investigated. It was found that the presence of 20SDC nano particles in Ti3AlC2 was very effective to improve the mechanical properties of Ti3AlC2 without spoiling the unique characteristics of Ti3AlC2temary carbide.
文摘The MAX phase Ti3SiC2 has broad application prospects in the field of rail transit,nuclear protective materials and electrode materials due to its excellent electrical conductivity,selflubricating properties and wear resistance.Cu–Ti3SiC2 co-continuous composites have superior performance due to the continuous distribution of 3 D network structures.In this paper,the Cu/Ti3SiC2(Ti C/Si C)co-continuous composites are formed via vacuum infiltration process from Cu and Ti3SiC2 porous ceramics.The co-continuous composites have significantly improved the flexural strength and conductivity of Ti3SiC2 due to the addition of Cu,with the conductivity up to 5.73×10^5 S/m,twice as high as the Ti3SiC2 porous ceramics and five times higher than graphite.The reaction between ingredients leads to an increase in the friction coefficient,while the hard reaction products(Ti Cx,Si C)lower the overall wear rate(1×10^–3 mm^3/(N·m)).Excellent electrical conductivity and wear resistance make co-continuous composites more advantageous in areas such as rail transit.
基金financially supported by the National Key R&D Program of China(Nos.2017YFB0306201 and 2016YFB0701303).
文摘Textured Ti2AlC lamellar composites have been successfully fabricated by a new method in the present work.The composites exhibit high compressive strength of ca 2 GPa,fracture toughness of 8.5 MPa m1/2(//c-axis),flexural strength of 735 MPa(//c-axis)and high hardness of 7.9 GPa(//c-axis).The strengthening mechanisms were discussed.The sintering and densification process was investigated and crystal orientation and microstructure were studied by electron backscattered diffraction techniques.The synthesis temperature is reduced to 1200?C by using high surface-to-volume ratio Ti2AlC nano flakes.The Lotgering orientation factor of Ti2 AlC and Ti3 AlC2{00 l}planes in the textured top surface reaches 0.74 and 0.49,respectively.This new route may shed light on resolving the difficulties encountered in large scale fabrication of textured MAX phases.
