Thermal explosion method was used to prepare porous NiTi shape memory alloy. The process of thermal explosion was investigated. The effect of process parameters on thermal explosion reaction and properties of products...Thermal explosion method was used to prepare porous NiTi shape memory alloy. The process of thermal explosion was investigated. The effect of process parameters on thermal explosion reaction and properties of products was analyzed. The results showed heating rate, green density, particle size of initial powder strongly affected combustion temperature, porosity and compressive strength of final products. The mechanism of thermal explosion and the microstructure of reacted products were studied by XRD and SEM photographs. The results showed the final products mainly comprised of NiTi, Ti2Ni and TiNi3 phases and their strength decreased with the increase of porosity.展开更多
TiO2 fibers were prepared via alternatively introducing water vapor and Ti precursor carried by N2 to an APCVD(chemical vapor deposition under atmospheric pressure) reactor at ≤200 °C. Activated carbon fibers(AC...TiO2 fibers were prepared via alternatively introducing water vapor and Ti precursor carried by N2 to an APCVD(chemical vapor deposition under atmospheric pressure) reactor at ≤200 °C. Activated carbon fibers(ACFs) were used as templates for deposition and later removed by calcinations. The obtained catalysts were characterized by scanning electron microscopy(SEM) ,transmission electron microscopy(TEM) ,Brunauer,Emmett and Teller(BET) and X-ray diffraction(XRD) analysis. The pores within TiO2 fibers included micro-range and meso-range,e.g.,7 nm,and the specific surface areas for TiO2 fibers were 141 m2/g and 148 m2/g for samples deposited at 100 °C and 200 °C(using ACF1700 as template) ,respectively. The deposition temperature significantly influenced TiO2 morphology. The special advantages of this technique for preparing porous nano-material include no consumption of organic solvent in the process and easy control of deposition conditions and speeds.展开更多
This paper reports the surface morphology and I-V curves of porous silicon (PS) samples and related devices. The observed fabrics on the PS surface were found to affect the electrical property of PS devices. When the ...This paper reports the surface morphology and I-V curves of porous silicon (PS) samples and related devices. The observed fabrics on the PS surface were found to affect the electrical property of PS devices. When the devices were operated under different external bias (10 V or 3 V) for 10 min, their observed obvious differences in electrical properties may be due to the different control mechanisms in the Al/PS interface and PS matrix morphology.展开更多
This investigation and morphology analysis of porous structure of some kinds of natural materials such as chicken eggshell, partridge eggshell, pig bone, and seeds of mung bean, soja, ginkgo, lotus seed, as well as th...This investigation and morphology analysis of porous structure of some kinds of natural materials such as chicken eggshell, partridge eggshell, pig bone, and seeds of mung bean, soja, ginkgo, lotus seed, as well as the epidermis of apples, with SEM (Scanning Electronic Microscope) showed that natural structures’ pores can be classified into uniform pores, gradient pores and multi pores from the viewpoint of the distribution variation of pore density, size and geometry. Furthermore, an optimal design of porous bearings was for the first time developed based on the gradient configuration of natural materials. The bionic design of porous structures is predicted to be widely developed and applied in the fields of materials and mechanical engineering in the future.展开更多
Gas hydrate is gradually considered as a potential energy resource. The presence of gas hydrate is commonly inferred from the appearance of “bottom simulating reflector”(BSR) on seismic section. Understanding the pr...Gas hydrate is gradually considered as a potential energy resource. The presence of gas hydrate is commonly inferred from the appearance of “bottom simulating reflector”(BSR) on seismic section. Understanding the properties of hydrate-bearing sediments and studying the AVO characteristics of BSR are of great significance. Although more and more domestic and international studies have been conducted on the subjects mentioned above, they are still in the primary stage and need a long way to go to be appled in practice, especially in the field of gas hydrate. Aiming at the identification of gas hydrate, we studied the characteristics of the AVO attributes based on the Biot's theory when the sediments were bearing gas hydrate or free gas. The AVO attribute crossplots obtained from seismic sections with the forward simulation by means of staggered-grid finite-difference were compared with that of theoretic models. The coincidence shows that utilization of AVO attribute crossplots is an effective way to recognize gas hydrate and free gas.展开更多
Modeling of solute transport is a key issue in the area of soil physics and hydrogeology. The most common approach (the convection-dispersion equation) considers an average convection flow rate and Fickian-like disper...Modeling of solute transport is a key issue in the area of soil physics and hydrogeology. The most common approach (the convection-dispersion equation) considers an average convection flow rate and Fickian-like dispersion. Here,we propose a solute transport model in porous media of continuously expanding scale, according to the combinatorics principle. The model supposed actual porous media as a combinative body of many basic segments. First, we studied the solute transport process in each basic segment body, and then deduced the distribution of pore velocity in each basic segment body by difference approximation, finally assembled the solute transport process of each basic segment body into one of the combinative body. The simulation result coincided with the solute transport process observed in test. The model provides useful insight into the solute transport process of the non-Fickian dispersion in continuously expanding scale.展开更多
A new type of heat storage materials combining high temperature molten salts phases change latent heat thermal storage materials, PCM with porous metals sensible heat thermal storage materials was developed. The proce...A new type of heat storage materials combining high temperature molten salts phases change latent heat thermal storage materials, PCM with porous metals sensible heat thermal storage materials was developed. The process was expressed as following: firstly, it is necessary to heat up the molten salts phases change materials to molten; and then the porous metals are put into the molten bath; after being held for 13 h, the composite heat thermal storage materials lumps are taken out of the molten bath and cooled to atmospheric temperature; the last step is to electrodeposit a layer metal coat on the surface of the material lumps. The new type of heat storage material integrates the advantages of both solid sensible heat thermal storage materials and high temperature phases change latent heat thermal storage materials. The metal base heat storage materials enjoy some favorable characteristics such as higher heat charge discharge rate, higher heat storage density and better mechanical strength.展开更多
Two-layer structure consisting of PS/PMMA-DR1 composite film planar waveguide layer on porous silicon cladding layer was fabricated in our experiment. The induced grating based on the third nonlinear optical propertie...Two-layer structure consisting of PS/PMMA-DR1 composite film planar waveguide layer on porous silicon cladding layer was fabricated in our experiment. The induced grating based on the third nonlinear optical properties was formed by interaction of two Nd∶YAG laser beams at 1064nm in the porous silicon/PMMA-DR1 waveguide. The diffraction efficiency of the first order diffracted light is measured to be about 0.2% of the total output.展开更多
Modern porous monoliths have been conceived as a new class of stationary phases for high performance liquid chromatography(HPLC) in classical columns in the early 1990s and later extended to the capillary format.These...Modern porous monoliths have been conceived as a new class of stationary phases for high performance liquid chromatography(HPLC) in classical columns in the early 1990s and later extended to the capillary format.These monolithic materials are prepared using simple processes carried out in an external mold(inorganic monoliths) or within the confines of the column(organic monoliths and all capillary columns).These methods afford macroporous materials with large through-pores that enable applications in a rapid flow-through mode.Since all the mobile phase must flow through the monolith,the convection considerably accelerates mass transport within the monolithic separation medium and improves the separations.As a result,the monolithic columns perform well even at very high flow rates.The applications of monolithic capillary columns are demonstrated on numerous separations in the HPLC mode.展开更多
文摘Thermal explosion method was used to prepare porous NiTi shape memory alloy. The process of thermal explosion was investigated. The effect of process parameters on thermal explosion reaction and properties of products was analyzed. The results showed heating rate, green density, particle size of initial powder strongly affected combustion temperature, porosity and compressive strength of final products. The mechanism of thermal explosion and the microstructure of reacted products were studied by XRD and SEM photographs. The results showed the final products mainly comprised of NiTi, Ti2Ni and TiNi3 phases and their strength decreased with the increase of porosity.
基金Supported by the National Natural Science Foundation of China （20307007, 50576081） and the Natural Science Foundation of Zhejiang Province （R 107532）, Program for New Century Excellent Talents in University （NCET-07-0761） and a Foundation for the Author of National Excellent Doctoral Dissertation of China （200747）.
基金Supported by the National Natural Science Foundation of China under Grant No 50376063, and the Institute of Engineering Thermophysics, Chinese Academy of Sciences.
基金Project (No. 20477006) supported by the National Natural ScienceFoundation of China
文摘TiO2 fibers were prepared via alternatively introducing water vapor and Ti precursor carried by N2 to an APCVD(chemical vapor deposition under atmospheric pressure) reactor at ≤200 °C. Activated carbon fibers(ACFs) were used as templates for deposition and later removed by calcinations. The obtained catalysts were characterized by scanning electron microscopy(SEM) ,transmission electron microscopy(TEM) ,Brunauer,Emmett and Teller(BET) and X-ray diffraction(XRD) analysis. The pores within TiO2 fibers included micro-range and meso-range,e.g.,7 nm,and the specific surface areas for TiO2 fibers were 141 m2/g and 148 m2/g for samples deposited at 100 °C and 200 °C(using ACF1700 as template) ,respectively. The deposition temperature significantly influenced TiO2 morphology. The special advantages of this technique for preparing porous nano-material include no consumption of organic solvent in the process and easy control of deposition conditions and speeds.
基金Project supported by the Natural Science Foundation of China (No.60225010) and the Key Project of Chinese Ministry of Education
文摘This paper reports the surface morphology and I-V curves of porous silicon (PS) samples and related devices. The observed fabrics on the PS surface were found to affect the electrical property of PS devices. When the devices were operated under different external bias (10 V or 3 V) for 10 min, their observed obvious differences in electrical properties may be due to the different control mechanisms in the Al/PS interface and PS matrix morphology.
文摘This investigation and morphology analysis of porous structure of some kinds of natural materials such as chicken eggshell, partridge eggshell, pig bone, and seeds of mung bean, soja, ginkgo, lotus seed, as well as the epidermis of apples, with SEM (Scanning Electronic Microscope) showed that natural structures’ pores can be classified into uniform pores, gradient pores and multi pores from the viewpoint of the distribution variation of pore density, size and geometry. Furthermore, an optimal design of porous bearings was for the first time developed based on the gradient configuration of natural materials. The bionic design of porous structures is predicted to be widely developed and applied in the fields of materials and mechanical engineering in the future.
文摘Gas hydrate is gradually considered as a potential energy resource. The presence of gas hydrate is commonly inferred from the appearance of “bottom simulating reflector”(BSR) on seismic section. Understanding the properties of hydrate-bearing sediments and studying the AVO characteristics of BSR are of great significance. Although more and more domestic and international studies have been conducted on the subjects mentioned above, they are still in the primary stage and need a long way to go to be appled in practice, especially in the field of gas hydrate. Aiming at the identification of gas hydrate, we studied the characteristics of the AVO attributes based on the Biot's theory when the sediments were bearing gas hydrate or free gas. The AVO attribute crossplots obtained from seismic sections with the forward simulation by means of staggered-grid finite-difference were compared with that of theoretic models. The coincidence shows that utilization of AVO attribute crossplots is an effective way to recognize gas hydrate and free gas.
文摘Modeling of solute transport is a key issue in the area of soil physics and hydrogeology. The most common approach (the convection-dispersion equation) considers an average convection flow rate and Fickian-like dispersion. Here,we propose a solute transport model in porous media of continuously expanding scale, according to the combinatorics principle. The model supposed actual porous media as a combinative body of many basic segments. First, we studied the solute transport process in each basic segment body, and then deduced the distribution of pore velocity in each basic segment body by difference approximation, finally assembled the solute transport process of each basic segment body into one of the combinative body. The simulation result coincided with the solute transport process observed in test. The model provides useful insight into the solute transport process of the non-Fickian dispersion in continuously expanding scale.
文摘A new type of heat storage materials combining high temperature molten salts phases change latent heat thermal storage materials, PCM with porous metals sensible heat thermal storage materials was developed. The process was expressed as following: firstly, it is necessary to heat up the molten salts phases change materials to molten; and then the porous metals are put into the molten bath; after being held for 13 h, the composite heat thermal storage materials lumps are taken out of the molten bath and cooled to atmospheric temperature; the last step is to electrodeposit a layer metal coat on the surface of the material lumps. The new type of heat storage material integrates the advantages of both solid sensible heat thermal storage materials and high temperature phases change latent heat thermal storage materials. The metal base heat storage materials enjoy some favorable characteristics such as higher heat charge discharge rate, higher heat storage density and better mechanical strength.
基金National Natural Science Foundation of China(60067001) West Glory Project of Chinese Academy of Science(2003XJDX) +1 种基金Excellent Youth Scholar Award Foundation of Xinjiang(XJEDU2004E02)
文摘Two-layer structure consisting of PS/PMMA-DR1 composite film planar waveguide layer on porous silicon cladding layer was fabricated in our experiment. The induced grating based on the third nonlinear optical properties was formed by interaction of two Nd∶YAG laser beams at 1064nm in the porous silicon/PMMA-DR1 waveguide. The diffraction efficiency of the first order diffracted light is measured to be about 0.2% of the total output.
基金Supported by grants of the National Institute of General Medical Sciences,National Institutes of Health(GM-48364),and the Materials Sciences and Engineering Division of the U.S.Department of Energy(DE-AC02-05CH11231).
文摘Modern porous monoliths have been conceived as a new class of stationary phases for high performance liquid chromatography(HPLC) in classical columns in the early 1990s and later extended to the capillary format.These monolithic materials are prepared using simple processes carried out in an external mold(inorganic monoliths) or within the confines of the column(organic monoliths and all capillary columns).These methods afford macroporous materials with large through-pores that enable applications in a rapid flow-through mode.Since all the mobile phase must flow through the monolith,the convection considerably accelerates mass transport within the monolithic separation medium and improves the separations.As a result,the monolithic columns perform well even at very high flow rates.The applications of monolithic capillary columns are demonstrated on numerous separations in the HPLC mode.
基金Supported by the National Natural Science Foundation of China under Grant No 10374089, and the Knowledge Innovation Program of Chinese Academy of Sciences under Grant No KJCX2-SW-W17.
