The demand for high-energy-density sodium-ion batteries has driven research to increase the hard carbon(HC)plateau capacity(<0.1 V),but the plateau capacity-rate capability trade-off limits performance.We report a ...The demand for high-energy-density sodium-ion batteries has driven research to increase the hard carbon(HC)plateau capacity(<0.1 V),but the plateau capacity-rate capability trade-off limits performance.We report a way to regulate the closed pore structure and improve the rate capability of HC by the addition of graphene oxide using an emulsification process.In a non-emulsion system,graphene oxide not only shortens ion diffusion paths by inducing the formation of flakelike HC but also significantly improves the rate performance by serving as conductive bridges within the carbon matrix.The prepared graphene/phenolic resin carbon composite has reversible capacities of 362,340,319,274,119,86,69 and 48 mAh g^(−1)at current densities of 0.02,0.05,0.1,0.2,0.5,1,2 and 5 A g^(−1),respectively.When emulsification is introduced,the graphene oxide acts as a nano-confinement template,guiding the cross-linking of phenolic resin to form uniformly sized closed pores.This composite electrode material has the highest plateau capacity of 268 mAh g^(−1)at 20 mA g^(−1).展开更多
Mesoporous silica materials with high pore volume were successfully prepared by the chemical precipitation method, with water glass and a biodegradable nonionic surfactant polyethylene glycol （PEG）. The obtained mat...Mesoporous silica materials with high pore volume were successfully prepared by the chemical precipitation method, with water glass and a biodegradable nonionic surfactant polyethylene glycol （PEG）. The obtained materials were characterized by transmission electron microscopy （TEM）, scanning electron microscopy （SEM）, thermo gravimetric analyzer and differential scanning calorimetry （TG-DSC）, nitrogen adsorption-desorption measurements, and X-ray diffraction （XRD）. The results showed that the changes of the pore parameters depended on both the surfactant content and heat treatment temperature. When the content of PEG was 10wt% and the obtained PEG/SiO2 composite was heated at 600℃, the mesoporous silica with a pore volume of 2.2 cma/g, a BET specific surface area of 361.55 m^2/g, and a diameter of 2-4 μm could be obtained. The obtained mesoporous silica materials have potential applications in the fields of paint and plastic, as thickening, reinforcing, and flatting agents.展开更多
Through improving the aging process during synthesis of the support, γ-Al2O3 with large pore volume and high surface area was synthesized by a facile secondary reforming method. The synthesis parameters, such as the ...Through improving the aging process during synthesis of the support, γ-Al2O3 with large pore volume and high surface area was synthesized by a facile secondary reforming method. The synthesis parameters, such as the reaction temperature, the first aging temperature and the second aging temperature, were investigated. The textural properties of γ-Al2O3 were characterized by means of N2 adsorption-desorption isotherms, X-ray powder diffractometry （XRD）, scanning electron microscopy （SEM）, Fourier transform infrared （FTIR） spectroscopy and thermogravimetry （TG）. The experimental results indicated that AACH and amorphous A1OOH were the precursors of alumina, which were formed via precipitation from solutions after reaction of aluminum sulphate with ammonium hydrogen carbonate. The precursor nanocrystallites grew and re-assembled during the secondary reforming process, which resulted in an increased pore size and pore volume and a decreased bulk density. The as-synthesized γ-Al2O3 materials featured meso/macroporosity, large pore volume （2.175 cm^3/g）, high surface area （237.8 m^2/g）, and low bulk density （0.284 g/mL）.展开更多
The real pores in digital cores were simplified into three abstractive types,including prolate ellipsoids,oblate ellipsoids and spheroids.The three-dimensional spheroidal-pore model of digital core was established bas...The real pores in digital cores were simplified into three abstractive types,including prolate ellipsoids,oblate ellipsoids and spheroids.The three-dimensional spheroidal-pore model of digital core was established based on mesoscopic mechanical theory.The constitutive relationship of different types of pore microstructure deformation was studied with Eshelby equivalent medium theory,and the effects of pore microstructure on pore volume compressibility under elastic deformation conditions of single and multiple pores of a single type and mixed types of pores were investigated.The results showed that the pore volume compressibility coefficient of digital core is closely related with porosity,pore aspect ratio and volumetric proportions of different types of pores.(1)The compressibility coefficient of prolate ellipsoidal pore is positively correlated with the pore aspect ratio,while that of oblate ellipsoidal pore is negatively correlated with the pore aspect ratio.(2)At the same mean value of pore aspect ratio satisfying Gaussian distribution,the more concentrated the range of pore aspect ratio,the higher the compressibility coefficient of both prolate and oblate ellipsoidal pores will be,and the larger the deformation under the same stress condition.(3)The pore compressibility coefficient increases with porosity.(4)At a constant porosity value,the higher the proportion of oblate ellipsoidal and spherical pores in the rock,the more easier for the rock to deform,and the higher the compressibility coefficient of the rock is,while the higher the proportion of prolate ellipsoidal pores in the rock,the more difficult it is for rock to deform,and the lower the compressibility coefficient of the rock is.By calculating pore compressibility coefficient of ten classical digital rock samples,the presented analytical elliptical-pore model based on real pore structure of digital rocks can be applied to calculation of pore volume compressibility coefficient of digital rock sample.展开更多
Mesoporous silica with tuned pore volume and pore size was yielded with the controllable sol-gel process using inexpensive water glass as silica source and ammonia as an additive.The effects of the parameters of the s...Mesoporous silica with tuned pore volume and pore size was yielded with the controllable sol-gel process using inexpensive water glass as silica source and ammonia as an additive.The effects of the parameters of the sol-gel process have been examined.The results show that the mesoporous silica can be synthesized by controlling the weight ratio of ammonia to silica,concentration of water glass,gelating temperature and the final pH value.The major properties of the obtained mesoporous silica are large pore volumes and controllable pore sizes.展开更多
In this paper,a method composed of gelation of basic skeleton(first step)and skeleton reinforcement process(second step)was introduced to synthesize silica powder with high pore volume through the reaction between wat...In this paper,a method composed of gelation of basic skeleton(first step)and skeleton reinforcement process(second step)was introduced to synthesize silica powder with high pore volume through the reaction between water glass and sulfuric acid.No organic solvents were involved in the entire preparation process and the final product was collected by spray drying.The effect of concentration of base solution,gelation point p H value and skeleton reinforcement time on the BET specific surface area and pore volume of the prepared silica powder were investigated intensively.The results show that,a basic skeleton with good dispersibility and high porosity was obtained when the concentration of base solution was 0.1 mol·L^(-1) and the gelation p H value reached 6.5.Then the basic skeleton grew into a more uniform porous structure after 30 min skeleton reinforcement.Under these optimum conditions,silica powder prepared by skeleton reinforcement method had a BET specific surface area of 358.0 m^(2)·g^(-1),and its pore volume reached 2.18 cm^(3)·g^(-1),which was much higher than that of prepared by skeleton-free method(1.62 cm^(3)·g^(-1))and by direct gelation method(0.31 cm^(3)·g^(-1)).展开更多
Pore volume compressibility is an essential parameter in reservoir studies,as it plays a major role in recovery mechanisms.Over the past decades,many attempts have been made to establish a link between the pore compre...Pore volume compressibility is an essential parameter in reservoir studies,as it plays a major role in recovery mechanisms.Over the past decades,many attempts have been made to establish a link between the pore compressibility and the porosity and other mechanical properties of the rock.Some scholars introduced analytical correlations between pore compressibility and rock mechanical properties,while others developed empirical formulas for estimating pore compressibility based on a porosity calculated by comparing nonlinear models to laboratory data.In this study,pore volume compressibility is measured on 55 carbonate samples and then applied to derive an empirical relationship between pore compressibility and porosity at each stress step,which is useful for predicting pore compressibility based on initial porosity.We take the net stress effect into account and derive an empirical correlation based on net effective stress and initial porosity to predict pore compressibility.In the end,we compare the measured pore compressibility with that predicted by the derived correlation and other non-leaner models,which indicates that the newly proposed non-linear equation outperforms those available in literature。展开更多
THE mechanical response and deformation mechanisms of pure nickel under nanoindentation were systematically investigated using molecular dynamics(MD)simulations,with a particular focus on the novel interplay between c...THE mechanical response and deformation mechanisms of pure nickel under nanoindentation were systematically investigated using molecular dynamics(MD)simulations,with a particular focus on the novel interplay between crystallographic orientation,grain boundary(GB)proximity,and pore characteristics(size/location).This study compares single-crystal nickel models along[100],[110],and[111]orientations with equiaxed polycrystalline models containing 0,1,and 2.5 nm pores in surface and subsurface configurations.Our results reveal that crystallographic anisotropy manifests as a 24.4%higher elastic modulus and 22.2%greater hardness in[111]-oriented single crystals compared to[100].Pore-GB synergistic effects are found to dominate the deformation behavior:2.5 nm subsurface pores reduce hardness by 25.2%through stress concentration and dislocation annihilation at GBs,whereas surface pores enable mechanical recovery via accelerated dislocation generation post-collapse.Additionally,size-dependent deformation regimes were identified,with 1 nm pores inducing negligible perturbation due to rapid atomic rearrangement,in contrast with persistent softening in 2.5 nm pores.These findings establish atomic-scale design principles for defect engineering in nickel-based aerospace components,demonstrating how crystallographic orientation,pore configuration,and GB interactions collectively govern nanoindentation behavior.展开更多
To investigate the pore structure of graphene oxide modified polymer cement mortar(GOPM)under salt-freeze-thaw(SFT)coupling effects and its impact on deterioration,this study modifies polymer cement mortar(EMCM)with g...To investigate the pore structure of graphene oxide modified polymer cement mortar(GOPM)under salt-freeze-thaw(SFT)coupling effects and its impact on deterioration,this study modifies polymer cement mortar(EMCM)with graphene oxide(GO).The micro-pore structure of GOPM is characterized using LF-NMR and SEM.Fractal theory is applied to calculate the fractal dimension of pore volume,and the deterioration patterns are analyzed based on the evolution characteristics of capillary pores.The experimental results indicate that,after 25 salt-freeze-thaw cycles(SFTc),SO2-4 ions penetrate the matrix,generating corrosion products that fill existing pores and enhance the compactness of the specimen.As the number of cycles increases,the ongoing formation and expansion of corrosion products within the matrix,combined with persistent freezing forces,and result in the degradation of the pore structure.Therefore,the mass loss rate(MLR)of the specimens shows a trend of first decreasing and then increasing,while the relative dynamic elastic modulus(RDEM)initially increases and then decreases.Compared to the PC group specimens,the G3PM group specimens show a 28.71% reduction in MLR and a 31.42% increase in RDEM after 150 SFTc.The fractal dimensions of the transition pores,capillary pores,and macropores in the G3PM specimens first increase and then decrease as the number of SFTc increases.Among them,the capillary pores show the highest correlation with MLR and RDEM,with correlation coefficients of 0.97438 and 0.98555,respectively.展开更多
To enhance the electrochemical performance of lithium-ion battery anodes with higher silicon content,it is essential to engineer their microstructure for better lithium-ion transport and mitigated volume change as wel...To enhance the electrochemical performance of lithium-ion battery anodes with higher silicon content,it is essential to engineer their microstructure for better lithium-ion transport and mitigated volume change as well.Herein,we suggest an effective approach to control the micropore structure of silicon oxide(SiO_(x))/artificial graphite(AG)composite electrodes using a perforated current collector.The electrode features a unique pore structure,where alternating high-porosity domains and low-porosity domains markedly reduce overall electrode resistance,leading to a 20%improvement in rate capability at a 5C-rate discharge condition.Using microstructure-resolved modeling and simulations,we demonstrate that the patterned micropore structure enhances lithium-ion transport,mitigating the electrolyte concentration gradient of lithium-ion.Additionally,perforating current collector with a chemical etching process increases the number of hydrogen bonding sites and enlarges the interface with the SiO_(x)/AG composite electrode,significantly improving adhesion strength.This,in turn,suppresses mechanical degradation and leads to a 50%higher capacity retention.Thus,regularly arranged micropore structure enabled by the perforated current collector successfully improves both rate capability and cycle life in SiO_(x)/AG composite electrodes,providing valuable insights into electrode engineering.展开更多
The Micro pore volume in porous materials usually interests many researchers. However, there has been few, if not, direct method to determine it. A strategy of combining mercury porosimetry with pre adsorption is pr...The Micro pore volume in porous materials usually interests many researchers. However, there has been few, if not, direct method to determine it. A strategy of combining mercury porosimetry with pre adsorption is proposed in the present paper. The total pore volume in activated carbon is determined through direct measurements for the first time. The application scope of mercury porosimetry is also enlarged. Besides, the present experiments also confirmed the preference of adsorption to the smaller pores even in the range of meso and macro pores.展开更多
Pore volume of Cumulative water injection is one of the factors for evaluating water flood effect in a water flood oil field.In previous study,there were limited lab studies for evaluating oil displacement efficiency....Pore volume of Cumulative water injection is one of the factors for evaluating water flood effect in a water flood oil field.In previous study,there were limited lab studies for evaluating oil displacement efficiency.A method to characterize the distribution of pore volume of cumulative water injection is proposed in this paper,and it is verified by a five-spot water flooding streamline simulation model.The logarithmic relation between pore volume of cumulative water injection and water saturation is established by regression.An inflection point and limit point of cumulative water injection pore volume are identified.Current simulation model indicates inflection point appears after 2e5 pore volume(PV)injection,and limit point appears after 15e25 PV injection.Both inflection and limit point vary in different regions of reservoir.展开更多
In this paper,the heterogeneity of adsorption pores in middle and high rank coal samples were analyzed by using low temperature N2 and CO2 adsorption technology and fractal theory.The following results were achieved.1...In this paper,the heterogeneity of adsorption pores in middle and high rank coal samples were analyzed by using low temperature N2 and CO2 adsorption technology and fractal theory.The following results were achieved.1)According to the results of volume and surface fractal dimension,meso-pores can be classified into Mep-1,Mep-2,and Mep-3,respectively.Micro-pore can be classified into Mip-1,Mip-2,and Mip-3,respectively.2)Pore types play an important role in affecting the heterogeneity of meso-pores.The volume heterogeneity(VHY)of Mep-1 is simpler than that of Mep-2 and Mep-3 in type A samples.However,the VHY of Mep-1 becomes gradually larger than that of Mep-2 and Mep-3 from type A to type B and C.The VHY of open pore in the same diameter is higher than that of semi-open or closed pore.Meanwhile,the surface heterogeneity(SHY)of types A and B samples is significantly larger than that of type C,the SHY of semi-open or closed pores is more complicated than that of open pores.3)Coal rank mainly affects the heterogeneity of micro-pores.The heterogeneity of type A is always smaller than that of type B and C.The VHY of Mip-1 is more complicated than that of Mip-2 and Mip-3 in the same samples,and the sensitivity of the VHY of Mip-1 and Mip-2 to the degree of coal rank is smaller than that of Mip-3.Meanwhile,the SHY of Mip-1 and Mip-2 is simpler than that of Mip-3 in the same sample,the SHY of micro-pores remains stable as the pore size decreases,and the affect of coalification level on SHY decreases with the decrease in pore diameter.Full-scale fractal characterization has enabled quantitative characterization of adsorption pore properties and provided useful information with regards to the similarity of pore features in different coal reservoirs.展开更多
Acidizing treatment is considered as a significant process in the oil well stimulations to form wormholes in carbonate formation in order to enhance the reservoir fluid production.Obtaining the number of pore volumes ...Acidizing treatment is considered as a significant process in the oil well stimulations to form wormholes in carbonate formation in order to enhance the reservoir fluid production.Obtaining the number of pore volumes to breakthrough is an important objective in matrix acidizing,for it contributes to determining the wormhole characteristics such as type,shape,and size.Finding this number in experimental works requires a considerable amount of time,energy and cost.Therefore,this study aimed to establish an analytical method in which a reasonable result is achieved for the number of pore volumes to breakthrough.This purpose is accomplished by solely implementing acid and formation properties without performing any experimental works.The process of wormhole creation is done through developing a numerical model by utilizing the conservation of mass law method in which the carbonate core is considered as a closed system and the overall mass in the system as constant during the acid injection process.Furthermore,a constant number is added to the mathematical part of the model in order to eliminate the dimensionless Damk鰄ler number which is supposed to be calculated experimentally.The results of the numerical procedure of the model are further compared to four other experimental works,which led to calculating the average accuracy of this model that is shown to be 95.98%.This study puts forward a comprehensive numerical model to estimate the number of pore volumes to breakthrough with an acceptable accuracy rate merely through implementing known acid and core properties.展开更多
Acidizing in carbonate formations is an inevitable stimulation treatment method for oil and gas wells.In the limestone,acidizing stimulation makes capillary wormholes to increase fluids flow reservoir production.The p...Acidizing in carbonate formations is an inevitable stimulation treatment method for oil and gas wells.In the limestone,acidizing stimulation makes capillary wormholes to increase fluids flow reservoir production.The pore volume to breakthrough number is one of the main indexes for recognizing the wormhole structure.Therefore,finding the pore volume to breakthrough number is one of the main goals in the limestone acidizing.Obtaining this number is always required for experimental works,which needs time,energy and cost.The purpose of this research is to develop an empirical method to estimate an acceptable result for this number merely by implementing limestone core and acid properties without any experimental work.In order to create a wormhole,an empirical method is developed using the law of conservation of mass considering that the core of limestone as an isolated package and the overall mass is constant in this package in the acidizing period.Also,to develop the mathematical section,the Damk€ohler number is used.Since this number must be calculated experimentally,a constant number is created in the model to eliminate the Damkohler number.An average accuracy of 92.31%is obtained for the developed empirical model by comparing the results obtained from the other three experimental and numerical works.This study conclusively provides a thoroughly empirical method for estimating a high accuracy of the pore volume to breakthrough number by only using known physical properties limestone core and acid.展开更多
A new nano-assembly approach has been proposed for the preparation of macropore volume mesoporous aluminum oxide supports. Secondary nano-assembly and a frame structure mechanism for large pore volume mesoporous suppo...A new nano-assembly approach has been proposed for the preparation of macropore volume mesoporous aluminum oxide supports. Secondary nano-assembly and a frame structure mechanism for large pore volume mesoporous supports have been proposed. In a primary nano-assembly supersoluble micelle,aluminum hydroxide nanoparticles were precipitated in situ in surfactants with a volume balance (VB) less than 1,followed by secondary nano-assembly in linear and cylindrical shapes. The secondary nano-assembly of cylindrical aluminum hydroxides was calcined to form nano cylindrical aluminum oxides. For the formation of macropore volume mesoporous supports,we utilized a frame structure mechanism of mesoporous support,in which the exterior surface of the carrier may not be continuous. This macropore volume support has been used for the hydrotreatment of a residual oil catalyst,which possesses the following physical characteristics:pore volume 1.8―2.7 mL·g-1,specific surface area 180―429 m2·g-1,average pore diameter 17―57 nm,average pore diameter more than 10 nm (81%―94%),porosity 87%―93%,and crush strength 7.7―25 N·mm-1.展开更多
The effects of fly ash with different mixing volume and different particle sizes on pore solution of cement-based materials were studied. The pore solution was extracted by squeezing at scheduled ages. The particle si...The effects of fly ash with different mixing volume and different particle sizes on pore solution of cement-based materials were studied. The pore solution was extracted by squeezing at scheduled ages. The particle size distribution of fly ash was classified as smaller than 45 μm and 45～80 μm,and the mixing volume was classified as 10% and 20%. The concentrations of K+,Na+ and Ca2+ were measured using Inductively Coupled Plasma Emission Spectrometer (ICP),and the pH was measured by acid-base titration. The results indicate that the concentrations of various ions were prompted at the initial time of the hydration. With further hydration,ion concentrations of K+ and Na+ raise again and finally stabilized,but there is a certain decline on Ca2+ later on. It also shows that fly ash exhibited great effect on the hydration of cement,it can lower the concentration of Ca2+ and pH of the pore solution,but raise the concentrations of K+ and Na+. More importantly,ion concentrations of K+,Na+ and Ca2+ reduced with smaller particle sizes of fly ash.展开更多
The phenomenon of multiphase flow in porous media is confronted in various fields of science and industrial applications. Owing to the complicated porous structure, the flow mechanisms are still not completely resolve...The phenomenon of multiphase flow in porous media is confronted in various fields of science and industrial applications. Owing to the complicated porous structure, the flow mechanisms are still not completely resolved. A critical and fundamental question is the variation of pore structure and REV sizes among different types of porous media. In this study, a total of 22 porous samples were employed to systematically evaluate the pore-based architecture and REV sizes based on X-ray CT image analysis and pore network modelling. It is found that the irregular grain shapes give rise to large specific areas,narrow and thin throats in identical sand packs. The packs with more types of sands, or composited by the sands with larger difference in diameter, have larger specific area, smaller tortuosity and pore spaces.Based on the REV measurement through porosity solely, the REV sizes of sand packs are generally in the order of magnitude of 10^(-2) m L, while it is at least one order of magnitude smaller in rock cores. Our result indicates that the combination of porosity and Euler number is an effective indicator to get the REV sizes of porous samples.展开更多
It has presented a review of the results of the survey on the formation and behavior of submicropores (SMP) in mono- and poly-crystalline systems, condensed in the “open vacuum” and quasi-closed volume. The mechanis...It has presented a review of the results of the survey on the formation and behavior of submicropores (SMP) in mono- and poly-crystalline systems, condensed in the “open vacuum” and quasi-closed volume. The mechanisms, patterns and characteristics of these processes, depending on the physical and technological factors are reviewed.展开更多
A comprehensive analysis of the microstructure and defects of a thixomolded AZ91D alloy was conducted to elucidate their influences on mechanical properties.Samples were made at injection temperatures ranging from 580...A comprehensive analysis of the microstructure and defects of a thixomolded AZ91D alloy was conducted to elucidate their influences on mechanical properties.Samples were made at injection temperatures ranging from 580 to 640℃.X-ray computed tomography was used to visualize pores,and crystal plasticity finite element simulation was adopted for deformation analysis.The microstructure characterizations reveal a hierarchical cell feature composed of α-Mg and eutectic phases.With the increase of injection temperature,large cell content in the material decreases,while the strength of the alloy increases.The underlying mechanism about strength change is that coarse-grained solids experience smaller stress even in hard orientations.The sample fabricated at a moderate temperature of 620℃ exhibits the highest elongation,least quantity and lower local concentration of pores.The detachment and tearing cracks formed at lower injection temperature and defect bands formed at higher injection temperature add additional crack sources and deteriorate the ductility of the materials.展开更多
文摘The demand for high-energy-density sodium-ion batteries has driven research to increase the hard carbon(HC)plateau capacity(<0.1 V),but the plateau capacity-rate capability trade-off limits performance.We report a way to regulate the closed pore structure and improve the rate capability of HC by the addition of graphene oxide using an emulsification process.In a non-emulsion system,graphene oxide not only shortens ion diffusion paths by inducing the formation of flakelike HC but also significantly improves the rate performance by serving as conductive bridges within the carbon matrix.The prepared graphene/phenolic resin carbon composite has reversible capacities of 362,340,319,274,119,86,69 and 48 mAh g^(−1)at current densities of 0.02,0.05,0.1,0.2,0.5,1,2 and 5 A g^(−1),respectively.When emulsification is introduced,the graphene oxide acts as a nano-confinement template,guiding the cross-linking of phenolic resin to form uniformly sized closed pores.This composite electrode material has the highest plateau capacity of 268 mAh g^(−1)at 20 mA g^(−1).
基金the National Natural Science Foundation of China (No.20671010, 20236020, 20325621, 50642042).
文摘Mesoporous silica materials with high pore volume were successfully prepared by the chemical precipitation method, with water glass and a biodegradable nonionic surfactant polyethylene glycol （PEG）. The obtained materials were characterized by transmission electron microscopy （TEM）, scanning electron microscopy （SEM）, thermo gravimetric analyzer and differential scanning calorimetry （TG-DSC）, nitrogen adsorption-desorption measurements, and X-ray diffraction （XRD）. The results showed that the changes of the pore parameters depended on both the surfactant content and heat treatment temperature. When the content of PEG was 10wt% and the obtained PEG/SiO2 composite was heated at 600℃, the mesoporous silica with a pore volume of 2.2 cma/g, a BET specific surface area of 361.55 m^2/g, and a diameter of 2-4 μm could be obtained. The obtained mesoporous silica materials have potential applications in the fields of paint and plastic, as thickening, reinforcing, and flatting agents.
基金the financial support by the Natural Science Foundation of Liaoning Province of China (Grant No. 2013020122)the National Natural Science Foundationof China (Grant No. 21076100 and 51308045)the financial support by the PetroChina Company Limited (Grant No. 10-01A-01-01-01)
文摘Through improving the aging process during synthesis of the support, γ-Al2O3 with large pore volume and high surface area was synthesized by a facile secondary reforming method. The synthesis parameters, such as the reaction temperature, the first aging temperature and the second aging temperature, were investigated. The textural properties of γ-Al2O3 were characterized by means of N2 adsorption-desorption isotherms, X-ray powder diffractometry （XRD）, scanning electron microscopy （SEM）, Fourier transform infrared （FTIR） spectroscopy and thermogravimetry （TG）. The experimental results indicated that AACH and amorphous A1OOH were the precursors of alumina, which were formed via precipitation from solutions after reaction of aluminum sulphate with ammonium hydrogen carbonate. The precursor nanocrystallites grew and re-assembled during the secondary reforming process, which resulted in an increased pore size and pore volume and a decreased bulk density. The as-synthesized γ-Al2O3 materials featured meso/macroporosity, large pore volume （2.175 cm^3/g）, high surface area （237.8 m^2/g）, and low bulk density （0.284 g/mL）.
基金Supported by the National Natural Science Foundation of China(51474224)The Shenzhen Peacock Plan(KQTD2017033114582189)The Shenzhen Science and Technology Innovation Committee(JCYJ20170817152743178)
文摘The real pores in digital cores were simplified into three abstractive types,including prolate ellipsoids,oblate ellipsoids and spheroids.The three-dimensional spheroidal-pore model of digital core was established based on mesoscopic mechanical theory.The constitutive relationship of different types of pore microstructure deformation was studied with Eshelby equivalent medium theory,and the effects of pore microstructure on pore volume compressibility under elastic deformation conditions of single and multiple pores of a single type and mixed types of pores were investigated.The results showed that the pore volume compressibility coefficient of digital core is closely related with porosity,pore aspect ratio and volumetric proportions of different types of pores.(1)The compressibility coefficient of prolate ellipsoidal pore is positively correlated with the pore aspect ratio,while that of oblate ellipsoidal pore is negatively correlated with the pore aspect ratio.(2)At the same mean value of pore aspect ratio satisfying Gaussian distribution,the more concentrated the range of pore aspect ratio,the higher the compressibility coefficient of both prolate and oblate ellipsoidal pores will be,and the larger the deformation under the same stress condition.(3)The pore compressibility coefficient increases with porosity.(4)At a constant porosity value,the higher the proportion of oblate ellipsoidal and spherical pores in the rock,the more easier for the rock to deform,and the higher the compressibility coefficient of the rock is,while the higher the proportion of prolate ellipsoidal pores in the rock,the more difficult it is for rock to deform,and the lower the compressibility coefficient of the rock is.By calculating pore compressibility coefficient of ten classical digital rock samples,the presented analytical elliptical-pore model based on real pore structure of digital rocks can be applied to calculation of pore volume compressibility coefficient of digital rock sample.
基金Supported by the National Natural Science Foundation of China(20671010,20236020,20325621)
文摘Mesoporous silica with tuned pore volume and pore size was yielded with the controllable sol-gel process using inexpensive water glass as silica source and ammonia as an additive.The effects of the parameters of the sol-gel process have been examined.The results show that the mesoporous silica can be synthesized by controlling the weight ratio of ammonia to silica,concentration of water glass,gelating temperature and the final pH value.The major properties of the obtained mesoporous silica are large pore volumes and controllable pore sizes.
基金financially supported by the National Natural Science Foundation of China (21838003, 91834301, 21878092)the Shanghai Scientific and Technological Innovation Project (18JC1410600)+2 种基金the Social Development Program of Shanghai(17DZ1200900, 18DZ2252400)the Innovation Program of Shanghai Municipal Education Commissionthe Fundamental Research Funds for the Central Universities (222201718002)
文摘In this paper,a method composed of gelation of basic skeleton(first step)and skeleton reinforcement process(second step)was introduced to synthesize silica powder with high pore volume through the reaction between water glass and sulfuric acid.No organic solvents were involved in the entire preparation process and the final product was collected by spray drying.The effect of concentration of base solution,gelation point p H value and skeleton reinforcement time on the BET specific surface area and pore volume of the prepared silica powder were investigated intensively.The results show that,a basic skeleton with good dispersibility and high porosity was obtained when the concentration of base solution was 0.1 mol·L^(-1) and the gelation p H value reached 6.5.Then the basic skeleton grew into a more uniform porous structure after 30 min skeleton reinforcement.Under these optimum conditions,silica powder prepared by skeleton reinforcement method had a BET specific surface area of 358.0 m^(2)·g^(-1),and its pore volume reached 2.18 cm^(3)·g^(-1),which was much higher than that of prepared by skeleton-free method(1.62 cm^(3)·g^(-1))and by direct gelation method(0.31 cm^(3)·g^(-1)).
文摘Pore volume compressibility is an essential parameter in reservoir studies,as it plays a major role in recovery mechanisms.Over the past decades,many attempts have been made to establish a link between the pore compressibility and the porosity and other mechanical properties of the rock.Some scholars introduced analytical correlations between pore compressibility and rock mechanical properties,while others developed empirical formulas for estimating pore compressibility based on a porosity calculated by comparing nonlinear models to laboratory data.In this study,pore volume compressibility is measured on 55 carbonate samples and then applied to derive an empirical relationship between pore compressibility and porosity at each stress step,which is useful for predicting pore compressibility based on initial porosity.We take the net stress effect into account and derive an empirical correlation based on net effective stress and initial porosity to predict pore compressibility.In the end,we compare the measured pore compressibility with that predicted by the derived correlation and other non-leaner models,which indicates that the newly proposed non-linear equation outperforms those available in literature。
基金The National Natural Science Foundation of China(Grant No.12462006)Beijing Institute of Structure and Environment Engineering Joint Innovation Fund(No.BQJJ202414).
文摘THE mechanical response and deformation mechanisms of pure nickel under nanoindentation were systematically investigated using molecular dynamics(MD)simulations,with a particular focus on the novel interplay between crystallographic orientation,grain boundary(GB)proximity,and pore characteristics(size/location).This study compares single-crystal nickel models along[100],[110],and[111]orientations with equiaxed polycrystalline models containing 0,1,and 2.5 nm pores in surface and subsurface configurations.Our results reveal that crystallographic anisotropy manifests as a 24.4%higher elastic modulus and 22.2%greater hardness in[111]-oriented single crystals compared to[100].Pore-GB synergistic effects are found to dominate the deformation behavior:2.5 nm subsurface pores reduce hardness by 25.2%through stress concentration and dislocation annihilation at GBs,whereas surface pores enable mechanical recovery via accelerated dislocation generation post-collapse.Additionally,size-dependent deformation regimes were identified,with 1 nm pores inducing negligible perturbation due to rapid atomic rearrangement,in contrast with persistent softening in 2.5 nm pores.These findings establish atomic-scale design principles for defect engineering in nickel-based aerospace components,demonstrating how crystallographic orientation,pore configuration,and GB interactions collectively govern nanoindentation behavior.
基金Funded by the National Natural Science Foundation of China(Nos.5226804252468035)。
文摘To investigate the pore structure of graphene oxide modified polymer cement mortar(GOPM)under salt-freeze-thaw(SFT)coupling effects and its impact on deterioration,this study modifies polymer cement mortar(EMCM)with graphene oxide(GO).The micro-pore structure of GOPM is characterized using LF-NMR and SEM.Fractal theory is applied to calculate the fractal dimension of pore volume,and the deterioration patterns are analyzed based on the evolution characteristics of capillary pores.The experimental results indicate that,after 25 salt-freeze-thaw cycles(SFTc),SO2-4 ions penetrate the matrix,generating corrosion products that fill existing pores and enhance the compactness of the specimen.As the number of cycles increases,the ongoing formation and expansion of corrosion products within the matrix,combined with persistent freezing forces,and result in the degradation of the pore structure.Therefore,the mass loss rate(MLR)of the specimens shows a trend of first decreasing and then increasing,while the relative dynamic elastic modulus(RDEM)initially increases and then decreases.Compared to the PC group specimens,the G3PM group specimens show a 28.71% reduction in MLR and a 31.42% increase in RDEM after 150 SFTc.The fractal dimensions of the transition pores,capillary pores,and macropores in the G3PM specimens first increase and then decrease as the number of SFTc increases.Among them,the capillary pores show the highest correlation with MLR and RDEM,with correlation coefficients of 0.97438 and 0.98555,respectively.
基金supported by the National Research Foundation of Korea(NRF)grant funded by the Korean government(MSIT)(No.NRF-2021M3H4A1A02048529)the Ministry of Trade,Industry and Energy(MOTIE)of the Korean government under grant No.RS-2022-00155854support from the DGIST Supercomputing and Big Data Center.
文摘To enhance the electrochemical performance of lithium-ion battery anodes with higher silicon content,it is essential to engineer their microstructure for better lithium-ion transport and mitigated volume change as well.Herein,we suggest an effective approach to control the micropore structure of silicon oxide(SiO_(x))/artificial graphite(AG)composite electrodes using a perforated current collector.The electrode features a unique pore structure,where alternating high-porosity domains and low-porosity domains markedly reduce overall electrode resistance,leading to a 20%improvement in rate capability at a 5C-rate discharge condition.Using microstructure-resolved modeling and simulations,we demonstrate that the patterned micropore structure enhances lithium-ion transport,mitigating the electrolyte concentration gradient of lithium-ion.Additionally,perforating current collector with a chemical etching process increases the number of hydrogen bonding sites and enlarges the interface with the SiO_(x)/AG composite electrode,significantly improving adhesion strength.This,in turn,suppresses mechanical degradation and leads to a 50%higher capacity retention.Thus,regularly arranged micropore structure enabled by the perforated current collector successfully improves both rate capability and cycle life in SiO_(x)/AG composite electrodes,providing valuable insights into electrode engineering.
文摘The Micro pore volume in porous materials usually interests many researchers. However, there has been few, if not, direct method to determine it. A strategy of combining mercury porosimetry with pre adsorption is proposed in the present paper. The total pore volume in activated carbon is determined through direct measurements for the first time. The application scope of mercury porosimetry is also enlarged. Besides, the present experiments also confirmed the preference of adsorption to the smaller pores even in the range of meso and macro pores.
基金This work was financially supported by the National Basic Research Program of China(973)Program,‘study on water injection in fracture-cave carbonate reservoir’(2011CB201000).
文摘Pore volume of Cumulative water injection is one of the factors for evaluating water flood effect in a water flood oil field.In previous study,there were limited lab studies for evaluating oil displacement efficiency.A method to characterize the distribution of pore volume of cumulative water injection is proposed in this paper,and it is verified by a five-spot water flooding streamline simulation model.The logarithmic relation between pore volume of cumulative water injection and water saturation is established by regression.An inflection point and limit point of cumulative water injection pore volume are identified.Current simulation model indicates inflection point appears after 2e5 pore volume(PV)injection,and limit point appears after 15e25 PV injection.Both inflection and limit point vary in different regions of reservoir.
基金sponsored by the Major National Science and Technology Projects(No.2016ZX05044002003)the Fundamental Research Funds for the Central Universities(No.2017CXNL03)the Surface well placement optimization via the topology analysis of well spatial form(41402291)。
文摘In this paper,the heterogeneity of adsorption pores in middle and high rank coal samples were analyzed by using low temperature N2 and CO2 adsorption technology and fractal theory.The following results were achieved.1)According to the results of volume and surface fractal dimension,meso-pores can be classified into Mep-1,Mep-2,and Mep-3,respectively.Micro-pore can be classified into Mip-1,Mip-2,and Mip-3,respectively.2)Pore types play an important role in affecting the heterogeneity of meso-pores.The volume heterogeneity(VHY)of Mep-1 is simpler than that of Mep-2 and Mep-3 in type A samples.However,the VHY of Mep-1 becomes gradually larger than that of Mep-2 and Mep-3 from type A to type B and C.The VHY of open pore in the same diameter is higher than that of semi-open or closed pore.Meanwhile,the surface heterogeneity(SHY)of types A and B samples is significantly larger than that of type C,the SHY of semi-open or closed pores is more complicated than that of open pores.3)Coal rank mainly affects the heterogeneity of micro-pores.The heterogeneity of type A is always smaller than that of type B and C.The VHY of Mip-1 is more complicated than that of Mip-2 and Mip-3 in the same samples,and the sensitivity of the VHY of Mip-1 and Mip-2 to the degree of coal rank is smaller than that of Mip-3.Meanwhile,the SHY of Mip-1 and Mip-2 is simpler than that of Mip-3 in the same sample,the SHY of micro-pores remains stable as the pore size decreases,and the affect of coalification level on SHY decreases with the decrease in pore diameter.Full-scale fractal characterization has enabled quantitative characterization of adsorption pore properties and provided useful information with regards to the similarity of pore features in different coal reservoirs.
文摘Acidizing treatment is considered as a significant process in the oil well stimulations to form wormholes in carbonate formation in order to enhance the reservoir fluid production.Obtaining the number of pore volumes to breakthrough is an important objective in matrix acidizing,for it contributes to determining the wormhole characteristics such as type,shape,and size.Finding this number in experimental works requires a considerable amount of time,energy and cost.Therefore,this study aimed to establish an analytical method in which a reasonable result is achieved for the number of pore volumes to breakthrough.This purpose is accomplished by solely implementing acid and formation properties without performing any experimental works.The process of wormhole creation is done through developing a numerical model by utilizing the conservation of mass law method in which the carbonate core is considered as a closed system and the overall mass in the system as constant during the acid injection process.Furthermore,a constant number is added to the mathematical part of the model in order to eliminate the dimensionless Damk鰄ler number which is supposed to be calculated experimentally.The results of the numerical procedure of the model are further compared to four other experimental works,which led to calculating the average accuracy of this model that is shown to be 95.98%.This study puts forward a comprehensive numerical model to estimate the number of pore volumes to breakthrough with an acceptable accuracy rate merely through implementing known acid and core properties.
文摘Acidizing in carbonate formations is an inevitable stimulation treatment method for oil and gas wells.In the limestone,acidizing stimulation makes capillary wormholes to increase fluids flow reservoir production.The pore volume to breakthrough number is one of the main indexes for recognizing the wormhole structure.Therefore,finding the pore volume to breakthrough number is one of the main goals in the limestone acidizing.Obtaining this number is always required for experimental works,which needs time,energy and cost.The purpose of this research is to develop an empirical method to estimate an acceptable result for this number merely by implementing limestone core and acid properties without any experimental work.In order to create a wormhole,an empirical method is developed using the law of conservation of mass considering that the core of limestone as an isolated package and the overall mass is constant in this package in the acidizing period.Also,to develop the mathematical section,the Damk€ohler number is used.Since this number must be calculated experimentally,a constant number is created in the model to eliminate the Damkohler number.An average accuracy of 92.31%is obtained for the developed empirical model by comparing the results obtained from the other three experimental and numerical works.This study conclusively provides a thoroughly empirical method for estimating a high accuracy of the pore volume to breakthrough number by only using known physical properties limestone core and acid.
文摘A new nano-assembly approach has been proposed for the preparation of macropore volume mesoporous aluminum oxide supports. Secondary nano-assembly and a frame structure mechanism for large pore volume mesoporous supports have been proposed. In a primary nano-assembly supersoluble micelle,aluminum hydroxide nanoparticles were precipitated in situ in surfactants with a volume balance (VB) less than 1,followed by secondary nano-assembly in linear and cylindrical shapes. The secondary nano-assembly of cylindrical aluminum hydroxides was calcined to form nano cylindrical aluminum oxides. For the formation of macropore volume mesoporous supports,we utilized a frame structure mechanism of mesoporous support,in which the exterior surface of the carrier may not be continuous. This macropore volume support has been used for the hydrotreatment of a residual oil catalyst,which possesses the following physical characteristics:pore volume 1.8―2.7 mL·g-1,specific surface area 180―429 m2·g-1,average pore diameter 17―57 nm,average pore diameter more than 10 nm (81%―94%),porosity 87%―93%,and crush strength 7.7―25 N·mm-1.
基金supported by the National Fundamental Scientific Research Project (PR China),relevant to"Basic research in Environmentally Friendly Concrete (2009CB623201)"research Project 50802067 supported by National Natural Science Foundation of China
文摘The effects of fly ash with different mixing volume and different particle sizes on pore solution of cement-based materials were studied. The pore solution was extracted by squeezing at scheduled ages. The particle size distribution of fly ash was classified as smaller than 45 μm and 45～80 μm,and the mixing volume was classified as 10% and 20%. The concentrations of K+,Na+ and Ca2+ were measured using Inductively Coupled Plasma Emission Spectrometer (ICP),and the pH was measured by acid-base titration. The results indicate that the concentrations of various ions were prompted at the initial time of the hydration. With further hydration,ion concentrations of K+ and Na+ raise again and finally stabilized,but there is a certain decline on Ca2+ later on. It also shows that fly ash exhibited great effect on the hydration of cement,it can lower the concentration of Ca2+ and pH of the pore solution,but raise the concentrations of K+ and Na+. More importantly,ion concentrations of K+,Na+ and Ca2+ reduced with smaller particle sizes of fly ash.
基金supported by National Natural Science Foundation of China (Grant No. 52106213, 51876015)Shanxi Scholarship Council of China (2020-116)+1 种基金supported by the Key Laboratory of Ocean Energy Utilization and Energy Conservation of Ministry of Education (LOEC-201903)the Science Foundation of North University of China (XJJ201907)。
文摘The phenomenon of multiphase flow in porous media is confronted in various fields of science and industrial applications. Owing to the complicated porous structure, the flow mechanisms are still not completely resolved. A critical and fundamental question is the variation of pore structure and REV sizes among different types of porous media. In this study, a total of 22 porous samples were employed to systematically evaluate the pore-based architecture and REV sizes based on X-ray CT image analysis and pore network modelling. It is found that the irregular grain shapes give rise to large specific areas,narrow and thin throats in identical sand packs. The packs with more types of sands, or composited by the sands with larger difference in diameter, have larger specific area, smaller tortuosity and pore spaces.Based on the REV measurement through porosity solely, the REV sizes of sand packs are generally in the order of magnitude of 10^(-2) m L, while it is at least one order of magnitude smaller in rock cores. Our result indicates that the combination of porosity and Euler number is an effective indicator to get the REV sizes of porous samples.
文摘It has presented a review of the results of the survey on the formation and behavior of submicropores (SMP) in mono- and poly-crystalline systems, condensed in the “open vacuum” and quasi-closed volume. The mechanisms, patterns and characteristics of these processes, depending on the physical and technological factors are reviewed.
基金supported by the National Natural Science Foundation of China(Nos.51825101,52001202)the National Key Research and Development Program of China(No.2021YFA1600900)。
文摘A comprehensive analysis of the microstructure and defects of a thixomolded AZ91D alloy was conducted to elucidate their influences on mechanical properties.Samples were made at injection temperatures ranging from 580 to 640℃.X-ray computed tomography was used to visualize pores,and crystal plasticity finite element simulation was adopted for deformation analysis.The microstructure characterizations reveal a hierarchical cell feature composed of α-Mg and eutectic phases.With the increase of injection temperature,large cell content in the material decreases,while the strength of the alloy increases.The underlying mechanism about strength change is that coarse-grained solids experience smaller stress even in hard orientations.The sample fabricated at a moderate temperature of 620℃ exhibits the highest elongation,least quantity and lower local concentration of pores.The detachment and tearing cracks formed at lower injection temperature and defect bands formed at higher injection temperature add additional crack sources and deteriorate the ductility of the materials.
