Geometric model of the pore structure of powder materials

1996 ◽  
Vol 34-34 (11-12) ◽  
pp. 675-679
Author(s):  
Yu. N. Kryukov
Keyword(s):  
Pore Structure ◽  
Geometric Model ◽  
Powder Materials

A novel fractal model for the prediction and analysis of the equivalent thermal conductivity in wood

Holzforschung ◽  
2021 ◽  
Vol 0 (0) ◽  
Author(s):  
Jingyao Zhao ◽  
Liangyan Guo ◽  
Yingchun Cai
Keyword(s):  
Thermal Conductivity ◽  
Pore Structure ◽  
Structural Parameters ◽  
Geometric Model ◽  
Fractal Theory ◽  
Wood Properties ◽  
Fractal Model ◽  
Equivalent Thermal Conductivity ◽  
Proposed Model ◽  
Aperture Distribution

Abstract This study proposes a new fractal model to improve the accuracy of equivalent thermal conductivity (ETC) prediction for wood and determine how the wood’s pore structure influences ETC. Using fractal theory and mercury injection porosimetry data, a fractal model for the geometry of the wood’s pore structure was built. The geometric model was then transformed into an equivalent thermal resistance model to calculate ETC. The calculations produced an explicit expression for ETC derived from the wood’s structural parameters including the minimum and maximum pore apertures, aperture distribution, porosity, and fractal dimension. The model also includes a probability factor. The simulated ETC produced by the model was validated by experiments and it was found to be in good agreement with these. These simulation results will be used to study the influence of several factors on ETC. The proposed model has the potential to be able to predict and analyzing other wood properties such as its electrical conductivity, diffusivity, and permeability and the model can likely also be used to analyze other porous materials.

The Factors which Influence on the Physical Phase of Phosphate Compounds Belonging to NZP Family

2013 ◽  
Vol 864-867 ◽  
pp. 702-705
Author(s):  
Yun Hua Huang ◽  
Peng Zheng ◽  
Lin Hua Zhu
Keyword(s):  
Chemical Composition ◽  
Pore Structure ◽  
Lattice Site ◽  
Sol Gel ◽  
Powder Materials ◽  
Hydrothermal Crystallization ◽  
X Ray Diffraction ◽  
X Ray ◽  
Phosphate Compound ◽  
New Type

A new type of phosphate compound with different chemical composition but the same framework belonging to NaZr2(PO4)3(NZP) family were synthesized by chelating sol-gel route. The factor that influence on the physical phase was investigated in this paper. The physical phase and pore structure of the synthesized powder materials were characterized by X-ray diffraction (XRD) and N2 adsorptiondesorption respectively. The results showed that the crystalline NZP family compounds CaZr4(PO4)6 and KZr2(PO4)3 which is occupied by Ca2+ and K+ respectively at lattice site of MIcan be prepared by sol-gel route followed with calcinations at 700-800°C for 2h, but when the gel precursor of CaZr4(PO4)6 was treated by hydrothermal crystallization at 160°C for 24h, the obtained powder was NH4Zr2(PO4)3 instead of CaZr4(PO4)6.

scholarly journals Utilization of Construction Waste Composite Powder Materials as Cementitious Materials in Small-Scale Prefabricated Concrete

2016 ◽  
Vol 2016 ◽  
pp. 1-11 ◽  
Author(s):  
Cuizhen Xue ◽  
Aiqin Shen ◽  
Yinchuan Guo ◽  
Tianqin He
Keyword(s):  
Mechanical Properties ◽  
Pore Structure ◽  
Composite Powder ◽  
Cementitious Materials ◽  
Small Scale ◽  
Powder Materials ◽  
Hydration Products ◽  
Construction Waste ◽  
Construction And Demolition Wastes ◽  
Composite Powder Material

The construction and demolition wastes have increased rapidly due to the prosperity of infrastructure construction. For the sake of effectively reusing construction wastes, this paper studied the potential use of construction waste composite powder material (CWCPM) as cementitious materials in small-scale prefabricated concretes. Three types of such concretes, namely, C20, C25, and C30, were selected to investigate the influences of CWCPM on their working performances, mechanical properties, and antipermeability and antifrost performances. Also the effects of CWCPM on the morphology, hydration products, and pore structure characteristics of the cement-based materials were analyzed. The results are encouraging. Although CWCPM slightly decreases the mechanical properties of the C20 concrete and the 7 d compressive strengths of the C25 and C30 concretes, the 28 d compressive strength and the 90 d flexural strength of the C25 and C30 concretes are improved when CWCPM has a dosage less than 30%; CWCPM improves the antipermeability and antifrost performances of the concretes due to its filling and pozzolanic effects; the best improvement is obtained at CWCPM dosage of 30%; CWCPM optimizes cement hydration products, refines concrete pore structure, and gives rise to reasonable pore size distribution, therefore significantly improving the durability of the concretes.

scholarly journals A Pore Scale Flow Simulation of Reconstructed Model Based on the Micro Seepage Experiment

Geofluids ◽  
2017 ◽  
Vol 2017 ◽  
pp. 1-8 ◽  
Author(s):  
Jianjun Liu ◽  
Yao Wang ◽  
Rui Song
Keyword(s):  
Pore Structure ◽  
Numerical Study ◽  
Geometric Model ◽  
Flow Simulation ◽  
Creeping Flow ◽  
Brinkman Equation ◽  
Reconstruction Method ◽  
Pore Scale ◽  
Effective Development ◽  
Reconstructed Model

Researches on microscopic seepage mechanism and fine description of reservoir pore structure play an important role in effective development of low and ultralow permeability reservoir. The typical micro pore structure model was established by two ways of the conventional model reconstruction method and the built-in graphics function method of Comsol® in this paper. A pore scale flow simulation was conducted on the reconstructed model established by two different ways using creeping flow interface and Brinkman equation interface, respectively. The results showed that the simulation of the two models agreed well in the distribution of velocity, pressure, Reynolds number, and so on. And it verified the feasibility of the direct reconstruction method from graphic file to geometric model, which provided a new way for diversifying the numerical study of micro seepage mechanism.

Electron microscopy study of shock synthesis of silicides

1993 ◽  
Vol 51 ◽  
pp. 1162-1163
Author(s):  
Kenneth S. Vecchio
Keyword(s):  
Shock Wave ◽  
Plastic Deformation ◽  
Close Contact ◽  
Microscopy Study ◽  
High Energy ◽  
Electron Microscopy Study ◽  
Powder Materials ◽  
Porous Powder ◽  
Wave Effects ◽  
Wave Passage

Shock-induced reactions (or shock synthesis) have been studied since the 1960’s but are still poorly understood, partly due to the fact that the reaction kinetics are very fast making experimental analysis of the reaction difficult. Shock synthesis is closely related to combustion synthesis, and occurs in the same systems that undergo exothermic gasless combustion reactions. The thermite reaction (Fe2O3 + 2Al -> 2Fe + Al2O3) is prototypical of this class of reactions. The effects of shock-wave passage through porous (powder) materials are complex, because intense and non-uniform plastic deformation is coupled with the shock-wave effects. Thus, the particle interiors experience primarily the effects of shock waves, while the surfaces undergo intense plastic deformation which can often result in interfacial melting. Shock synthesis of compounds from powders is triggered by the extraordinarily high energy deposition rate at the surfaces of the powders, forcing them in close contact, activating them by introducing defects, and heating them close to or even above their melting temperatures.

Correlation of Pore Structure and Permeability by SEM-Image Analysis

1990 ◽  
Vol 48 (1) ◽  
pp. 428-429
Author(s):  
C. A. Callender ◽  
Wm. C. Dawson ◽  
J. J. Funk
Keyword(s):  
Image Analysis ◽  
Pore Structure ◽  
Imaging System ◽  
Pore Space ◽  
Simulation Models ◽  
Image Analyzer ◽  
Imaging Data ◽  
Sem Images ◽  
Thin Sections ◽  
Rock Types

The geometric structure of pore space in some carbonate rocks can be correlated with petrophysical measurements by quantitatively analyzing binaries generated from SEM images. Reservoirs with similar porosities can have markedly different permeabilities. Image analysis identifies which characteristics of a rock are responsible for the permeability differences. Imaging data can explain unusual fluid flow patterns which, in turn, can improve production simulation models.Analytical SchemeOur sample suite consists of 30 Middle East carbonates having porosities ranging from 21 to 28% and permeabilities from 92 to 2153 md. Engineering tests reveal the lack of a consistent (predictable) relationship between porosity and permeability (Fig. 1). Finely polished thin sections were studied petrographically to determine rock texture. The studied thin sections represent four petrographically distinct carbonate rock types ranging from compacted, poorly-sorted, dolomitized, intraclastic grainstones to well-sorted, foraminiferal,ooid, peloidal grainstones. The samples were analyzed for pore structure by a Tracor Northern 5500 IPP 5B/80 image analyzer and a 80386 microprocessor-based imaging system. Between 30 and 50 SEM-generated backscattered electron images (frames) were collected per thin section. Binaries were created from the gray level that represents the pore space. Calculated values were averaged and the data analyzed to determine which geological pore structure characteristics actually affect permeability.

Author response for "Effect of lithofacies on pore structure of the Cambrian organic‐rich shale in northern Guizhou, China"

2020 ◽  
Author(s):  
Peng Xia ◽  
Hongnan Li ◽  
Yong Fu ◽  
Wenlang Qiao ◽  
Chuan Guo ◽  
...  
Keyword(s):  
Pore Structure ◽  
Author Response
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