Effects of the particle size composition of sintering additives on pore characteristics, flexural strength, and gas permeability of liquid-phase-bonded macroporous SiC

Yun Sung Il,남산,박상환 한국세라믹학회 2021 한국세라믹학회지 Vol.58 No.6

Macroporous SiC with unimodal pore-size distribution was fabricated using a liquid-phase bonding method with Al 2 O 3 – Y 2 O 3 –SiO 2 sintering additives at 1500 °C in Ar at for 1 h. The effects of the sintering additive particle size and content on the flexural strength, apparent porosity, gas permeability, and pore characteristics, such as average pore size and pore structure, were investigated. The pore size and porosity of the TA-SC specimens fabricated using relatively large sintering additive particles increased simultaneously, thus changing their pore structure. The pore structure of SA-SC mainly consisted of stacked cubic solid spheres, while the pore structure of TA-SC consisted of spherical pores with cubic stacking. The TA-SC specimens with higher porosity and larger pores exhibited higher flexural strengths than the SA-SC specimens. This can mainly be attributed to the difference in the pore structures of the SA-SC and TA-SC specimens, which directly affected the solid bonding area. The gas permeability of the SA-SC and TA-SC specimens varied from 2.5 × 10 –12 to 4.1 × 10 –12 m 2 depending on their porosity and pore size. The effect of the apparent porosity was more significant on the gas permeability than that on the average pore size, particularly for the porous SiC with the porosity of 33.5–39.7 vol% and the average pore size of 13.4–18.5 μm.

Effects of CO₂ miscible flooding on oil recovery and the alteration of rock properties in a carbonate reservoir

Han, Jinju,Han, Sunlee,Sung, Wonmo,Lee, Youngsoo Elsevier 2018 Journal of CO₂ utilization Vol.28 No.-

<P><B>Abstract</B></P> <P>This study experimentally investigated the impact of CO<SUB>2</SUB> miscible flooding on oil recovery and alteration of rock properties in two carbonate cores consisting of more than 98% calcite: Edwards white representing a homogenous medium mainly consisted of micropores, and Indiana limestone representing a heterogeneous medium mostly composed of macropores. Several methods were applied to investigate the alteration of rock properties by CO<SUB>2</SUB>-water-carbonate minerals interactions: 1) Core flooding to measure overall changes, 2) MICP and X-ray CT to analyze small pores and large pores, respectively, 3) SEM, PCM, and ICP to verify physical and chemical reactions.</P> <P>Oil recovery was higher in Edwards white than in Indiana limestone, since characteristic of Edwards white contributes to sufficient contact time and stable displacement between oil and CO<SUB>2</SUB>. From the analysis of the alteration of rock properties in homogenous sample, dissolution facilitates the enlargement of pore sizes. Therefore, fluid flow becomes more favorable. The precipitation is not critical determinant of alteration process, despite the high proportion of small pores. For heterogeneous sample, both dissolution and precipitation significantly affect to alteration of pore structure. Particularly, the precipitation seriously damaged to the main flow channels. These undesirable effects on fluid flow appeared at injection point, which was exposed to fresh CO<SUB>2</SUB> for a long time.</P> <P>This study suggests that pore structure analysis allows a more exact interpretation and judgment of the alteration of pore structure by dissolution and precipitation and can assist in designing injection plans, particularly near the injection area or in complex pore structure.</P> <P><B>Highlights</B></P> <P> <UL> <LI> Initial pore structure is crucial for CO<SUB>2</SUB> flooding in carbonate reservoirs. </LI> <LI> Quantitative pore analysis was performed using MICP and X-ray CT. </LI> <LI> Chemical and physical reactions affect flow characteristics and oil recovery. </LI> <LI> Dissolution and precipitation are simultaneously occurred in pore network. </LI> <LI> Alteration of rock properties is important in designing CO<SUB>2</SUB> EOR and CCS. </LI> </UL> </P>

Fractal Characteristics of Pore Structures in GGBFS-based Cement Pastes

Kim, Jiyoung,Choi, Young Cheol,Choi, Seongcheol Elsevier 2018 APPLIED SURFACE SCIENCE - Vol.428 No.-

<P><B>Abstract</B></P> <P>The present study evaluated pore surface fractal characteristics of high-strength cement pastes with different ground granulated blast-furnace slag (GGBFS) replacement ratios. Using the results of mercury intrusion porosimetry measurements, the surface fractal dimension in various pore-size ranges was calculated. Experimental results show that the fractal characteristics appeared in mesopores in range of 6–10nm and 10–25nm and larger capillary pores with sizes of more than 100nm. In larger capillary pores, as the GGBFS replacement ratio increased up to 65%, the surface fractal dimension and pore volume decreased, and they increased when the GGBFS replacement ratio increased from 65% to 80%. In contrast, higher GGBFS replacement ratios in mesopore regions resulted in an increased surface fractal dimension and pore volume. Furthermore, in the regions where fractal characteristics appeared, pore volume and the surface fractal dimension exhibited a proportional relationship. The ratio of the surface fractal dimension to the volume of larger capillary pores was strongly correlated with the compressive strength of the specimens.</P> <P><B>Highlights</B></P> <P> <UL> <LI> Pore surface fractal characteristics of GGBFS-based cement pastes were evaluated. </LI> <LI> Three pore-size ranges exhibited fractal characteristics. </LI> <LI> Pore volume and the surface fractal dimension were proportional. </LI> <LI> The ratio of the dimension to pore volume was correlated with compressive strength. </LI> </UL> </P>

Comparative Assessment of the Ability of Dual-Pore Structure and Hydroxyapatite to Enhance the Proliferation of Osteoblast-Like Cells in Well-Interconnected Scaffolds

조용상,이준섭,홍명화,이세환,Young Yul Kim,조영삼 한국정밀공학회 2018 International Journal of Precision Engineering and Vol.19 No.4

In this study, to compare the relative abilities of dual-pore structure and hydroxyapatite to enhance the proliferation of osteoblastlike cell in well-interconnected scaffolds, several types of scaffolds were fabricated using combined SLUP (Salt-Leaching Using Powder) and WNM (Wire-Network Molding) techniques: well-interconnected dual-pore scaffolds with hydroxyapatite particles, wellinterconnected dual-pore scaffolds without hydroxyapatite particles, and single-pore scaffolds with hydroxyapatite particles. To assess the characteristics of the fabricated scaffolds, their morphology, compressive modulus, water absorption, and in-vitro cell activity were measured. Consequently, it was found that while the hydroxyapatite (which is hydrophilic) provides some advantage for cell attachment, the cell attachment in the dual-pore scaffold with hydroxyapatite particles was similar to that of the dual-pore scaffold without hydroxyapatite particles. Moreover, regarding cell proliferation, we verified that the effect of the dual-pore structure was dominant compared with the existence of hydroxyapatite particles and co-existence of dual-pore structure/hydroxyapatite particles. However, the cell vitality of the dual-pore scaffold with hydroxyapatite particles was higher than that of the dual-pore scaffold without hydroxyapatite particles because of ions released by the hydroxyapatite particles.

콘크리트의 공극 특성에 관한 실험적 연구

이문환 ( Lee Mun-hwan ),정미경 ( Jung Mi-kyung ),오세출 ( Oh Se-chul ),서치호 ( Seo Chee-ho ) 한국구조물진단유지관리공학회 1999 한국구조물진단유지관리공학회 논문집 Vol.3 No.4

This study attempts to propose an evaluation considering the property of concrete pore which affects the deterioration of neutralization and the re-bar resistance of concrete. Understanding pore property of concrete in using extent, for practical using of concrete manufacturing condition, basic quality property and durability estimation etc, the results of the experiment are as follows. 1) The result of analysis pore property of every specimen with the method of area ratio, in limitation of 10^-6~10^-5m, the pore distribution ratio was maximum. It was high value as W/C was increased and the unit cement content was decreased. 2) In case of using admixture, the volume of pores was some increased as variation of mixing content. In high W/C range, it was very increased compared with plain concrete. 3) Concerned with compressive strength and volume of pores in hardened concrete, it is possible compressive strength estimation using the property of concrete pores. 4) Direct measurement of concrete pore property is difficult, the valuation of the dynamic modulus of elasticity using ultrasonic wave velocity was available. 5) Quantitatively evaluation of concrete structure durability by past result of pore distribution estimation, and it can be estimative scale of property study on the concrete materials.

Investigation on Pore-fracture of Coal and Its Influence Mechanism on Uniaxial Compression Failure Behavior

Yutao Li,Qingwei Guo,Yaodong Jiang,Bo Zhang,Xuehua Li 대한토목학회 2023 KSCE Journal of Civil Engineering Vol.27 No.5

Pore-fracture is an important component of coal, affecting the uniaxial compression failure behavior. However, it is difficult to effectively characterize the influence mechanism because of the complexity and randomness of components in coal. In this paper, scanning electron microscope (SEM), computed tomography (CT), indentation hardness and uniaxial compressiontests are conducted for specimens with high, medium and no bursting proneness to investigate it. The results indicate that distribution of three components (matrix, minal and pore-fracture) in specimens are extremely different, which is the embodiment of tectonic structure activity and geological condition of mineralization. The levels of bursting proneness of coal, the tectonic structure features, tectonic structure activities and external functions are related. 3-D reconstruction on the basis of CT images can visualize internal complex structure of specimens. The numerical simulation results demonstrate that distribution of pore-fracture, mechanical properties of matrix and minal are significant inducement of specimen’s failure difference in the identical loading mode. Main failure mode of specimens with high, medium and no bursting proneness are different, which proves that main failure mode of specimen correlates with its mechanical properties. The mechanical failure behavior of specimen under uniaxial compression is influenced by loading mode, mechanical properties of matrix and minal, pore-fracture feature and other considerations. The loading mode is extrinsic cause of mechanical failure behavior of specimens, also an inducing factor and could be intervened. Furthermore, mechanical properties of matrix and minal determine bearing capacity and ultimate failure mode of specimens. Primary pore-fracture seriously affects extension process and extension mode of secondary pore-fracture, and the internal damage development of specimens. Notably, coal composed by the convergence of matrix, minal and pore-fracture, all these are internal cause of mechanical failure behavior of specimens, which belong to basic factors and hard to be intervened.

Pore Size Distribution of Cement Mortar Prepared with Crushed Limestone Sand

Xudong Chen,Shengxing Wu,Jikai Zhou 대한토목학회 2016 KSCE JOURNAL OF CIVIL ENGINEERING Vol.20 No.2

Recently, the use of crushed sand obtained from limestone-quarried is growing especially in the countries where river sand is not quite available. In the paper, the results from an experimental investigation are presented, which evaluates the pore structure of mortar mixtures where fine aggregate is replaced by Crushed Limestone Sand (CLS). The behavior of pore structure of CLS mortar was compared to that of mortars prepared from Nature River Sand (NRS). A Mercury Porosimeter Intrusion (MIP) is adopted to study the behavior of pore size distribution. Both CLS and NRS mortar with four water-cement ratios and five sand-cement ratios are used to determine pore structure. An analytical model was established to compare changes in pore structure for different water cement ratio and volume of sand, and the model was based on the test results.

Pore Structure Modification and Characterization of Porous Cordierite with Chemical Vapor Infiltration (CVI) SiC Whisker

김익환,김준규,이환섭,최두진 한국세라믹학회 2008 한국세라믹학회지 Vol.45 No.2

The main purpose of this study is enhancing the filtering efficiency, performance and durability of filter by growing SiC whiskers on cordierite honeycomb substrate. The experiment was performed by Chemical Vapor Infiltration (CVI) in order to control pore morphology of substrate. Increasing the mechanical strength of porous substrate is one of important issues. The formation of“networking structure” in the pore of porous substrate increased mechanical strength. The high pressure gas injection to the specimen showed that a little of whiskers were separated from substrate but additional film coating enhanced the stability of whisker at high pressure gas injection. Particle trap test was performed. More nano-particle was trapped by whisker growth at the pore of substrate. Therefore it is expected that the porous cordierite which deposited the SiC whisker will be the promising material for the application as filter trapping the nano-particles. The main purpose of this study is enhancing the filtering efficiency, performance and durability of filter by growing SiC whiskers on cordierite honeycomb substrate. The experiment was performed by Chemical Vapor Infiltration (CVI) in order to control pore morphology of substrate. Increasing the mechanical strength of porous substrate is one of important issues. The formation of“networking structure” in the pore of porous substrate increased mechanical strength. The high pressure gas injection to the specimen showed that a little of whiskers were separated from substrate but additional film coating enhanced the stability of whisker at high pressure gas injection. Particle trap test was performed. More nano-particle was trapped by whisker growth at the pore of substrate. Therefore it is expected that the porous cordierite which deposited the SiC whisker will be the promising material for the application as filter trapping the nano-particles.

Review of Soil Structure Quantification from Soil Images

전현정,Daniel Gimenez,윤성원,박찬원,문용희,손연규,현병근 한국토양비료학회 2011 한국토양비료학회지 Vol.44 No.3

Soil structure plays an important role in ecological system, since it controls transport and storage of air, gas,nutrients and solutions. The study of soil structure requires an understanding of the interrelations and interactions between the diverse soil components at various levels of organization. Investigations of the spatial distribution of pore/particle arrangements and the geometry of soil pore space can provide important information regarding ecological or crop system. Because of conveniences in image analyses and accuracy,these investigations have been thrived for a long time. Image analyses from soil sections through impregnated blocks of undisturbed soil (2 dimensional image analyses) or from 3 dimensional scanned soils by computer tomography allow quantitative assessment of the pore space. Image analysis techniques can be used to classify pore types and quantify pore structure without inaccurate or hard labor in laboratory. In this paper, the last 50years of the soil image analyses have been presented and measurements on various soil scales were introduced,as well. In addition to history of image analyses, a couple of examples for soil image analyses were displayed. The discussion was made on the applications of image analyses and techniques to quantify pore/soil structure.

Review of Soil Structure Quantification from Soil Images

Chun, Hyen-Chung,Gimenez, Daniel,Yoon, Sung-Won,Park, Chan-Won,Moon, Yong-Hee,Sonn, Yeon-Kyu,Hyun, Byung-Keun Korean Society of Soil Science and Fertilizer 2011 한국토양비료학회지 Vol.44 No.3

Soil structure plays an important role in ecological system, since it controls transport and storage of air, gas, nutrients and solutions. The study of soil structure requires an understanding of the interrelations and interactions between the diverse soil components at various levels of organization. Investigations of the spatial distribution of pore/particle arrangements and the geometry of soil pore space can provide important information regarding ecological or crop system. Because of conveniences in image analyses and accuracy, these investigations have been thrived for a long time. Image analyses from soil sections through impregnated blocks of undisturbed soil (2 dimensional image analyses) or from 3 dimensional scanned soils by computer tomography allow quantitative assessment of the pore space. Image analysis techniques can be used to classify pore types and quantify pore structure without inaccurate or hard labor in laboratory. In this paper, the last 50 years of the soil image analyses have been presented and measurements on various soil scales were introduced, as well. In addition to history of image analyses, a couple of examples for soil image analyses were displayed. The discussion was made on the applications of image analyses and techniques to quantify pore/soil structure.