scholarly journals Структура и механические свойства пористой диатомитовой керамики после деформации сжатием

2021 ◽  
Vol 47 (4) ◽  
pp. 11
Author(s):  
А.А. Скворцов ◽  
М.Н. Лукьянов ◽  
И.Е. Чебенева ◽  
А.А. Скворцова
Keyword(s):  
Mechanical Properties ◽  
Elastic Modulus ◽  
Porous Structure ◽  
Dynamic Modulus ◽  
Morphological Analysis ◽  
Pore Diameter ◽  
Porous Ceramics ◽  
Average Pore Diameter ◽  
Dynamic Elastic Modulus ◽  
Average Pore

This work is devoted to the study of the mechanical properties of porous ceramics based on diatomite. Based on the morphological analysis of the studied samples, the porous structure of ceramics (morphology and average pore diameter) was analyzed and the numerical value of the porosity of the samples (35...50%) was determined. The values of the static (70...115 GPa) and dynamic elastic modulus of the samples (37...50 GPa) were measured experimentally. The dependence of the dynamic modulus of porous diatomite ceramics on porosity is studied: the elastic modulus decreases with increasing porosity of the material. A decrease in the porosity of the material after deformation was also found. The formation of diatomite filaments after deformation of samples by compression at a rate of no more than 8 * 10-4 s-1 was detected.

Pore Structure and Mechanical Properties of ZrC/SiC Multi-Components Modified C/C Composites

2013 ◽  
Vol 833 ◽  
pp. 159-164 ◽  
Author(s):  
Xiu Qian Li ◽  
Hai Peng Qiu ◽  
Jian Jiao
Keyword(s):  
Mechanical Properties ◽  
Pore Diameter ◽  
Testing Machine ◽  
Average Pore Diameter ◽  
Flexural Properties ◽  
Matrix Interface ◽  
Polymeric Precursor ◽  
Average Pore ◽  
Fiber Matrix Interface ◽  
Injection Apparatus

The ZrC/SiC multi-components modified C/C composites were prepared by using a hybrid precursor containning polycarbosilane and organic zirconium-contained polymeric precursor as impregnant and C/C composites of low density as preform. The porosity, microstructure and mechanical properties of samples were characterized with mercury injection apparatus, scanning electron microscopy and universal electron testing machine respectively. The results show that the porosity and average pore diameter decrease firstly and increase subsequently with the increase of organic zirconium content of the precursor. When the content of organic zirconium is 50%, the porosity and average pore diameter reach minimum which were7.27% and 0.0795um respectively. The most probabilistic pore diameter shifted from 10-100um to 1-10um at the same time; Meanwhile, the flexural properties also increases and drops immediately as the content of organic zirconium in the precursor adds. When the content of organic zirconium is 25%, the flexural strength reaches maximum of 245.20MPa.The improved flexural properties is attributed to the proper bonding of fiber-matrix interface and the low porosity of samples.

How to tailor the porous structure of alumina and aluminosilicate gels and glasses

1996 ◽  
Vol 11 (2) ◽  
pp. 518-528 ◽  
Author(s):  
V. Vendange ◽  
Ph. Colomban
Keyword(s):  
Porous Structure ◽  
Pore Structure ◽  
Pore Size ◽  
Boron Oxide ◽  
Pore Diameter ◽  
Average Pore Diameter ◽  
Mesoporous Aluminosilicates ◽  
Average Pore ◽  
Impregnation Process ◽  
Size And Structure

Optically clear monolithic (OCM) gels of mesoporous aluminosilicates (average pore diameter 3.6 nm) and alumina (6 nm) have been prepared by slow hydrolysis-polycondensation of alkoxides and converted into OCM mesoporous glasses by heating. In order to change the properties, different ways of modifying the pore size and structure are proposed. We show that addition of boron oxide reduces the average pore diameter. A higher effect can be obtained by addition of a surfactant. In this case the mesoporous matrix becomes microporous (d < 2 nm). Another way of modifying the pore structure consists of introducing nanoprecipitates inside the porosity by an impregnation process. Modifications of the porous structure are different in alumina and aluminosilicates.

Microstructure and Mechanical Behavior of CaCu3Ti4O12 Ceramics Hollow Fiber Prepared via Dry/Wet Spinning Method

2020 ◽  
Vol 1010 ◽  
pp. 239-243
Author(s):  
Mohsen Ahmadipour ◽  
Tunmise Ayode Otitoju ◽  
Mohammad Arjmand ◽  
Zainal Arifin Ahmad ◽  
Swee Yong Pung
Keyword(s):  
Mechanical Properties ◽  
Tensile Strength ◽  
Hollow Fiber ◽  
Outer Layer ◽  
Pore Diameter ◽  
Hollow Fibers ◽  
Wet Spinning ◽  
Outer Diameter ◽  
Average Pore ◽  
Elongation At Break

Dry/wet method was used to prepare CaCuTi4O12 (CCTO) hollow fibers (HFs) and then the structural and physico-mechanical properties of HFs were characterized by XRD, FESEM, BET and tensile strength, respectively. The outer diameter and thickness of CCTO HFs were found to be 650 μm and 390 μm, respectively. A finger-like macrovoids and sponge-like was observed inside the membrane with a denser structure in the outer layer. It was observed that the crystallite size was increased from 28.5 nm to 37.0 nm while the average pore diameter was decreased from 34.65 nm to 29.16 nm in CCTO hollow fiber with 1.0 wt.% CCTO. In addition, the tensile strength of HFS was significantly improved from 4.84 MPa to 5.54 MPa and elongation at break was decreased from 6.97 % to 5.09 % which is ascribed to the reduction in porosity. All the results indicated the significant effect of CCTO content on properties of CCTO hollow fibers. The finding in this study could lead to a new direction to enhance the properties of HFS with potential application in membranes.

scholarly journals Predicting the Mechanical Properties of Bimrocks with High Rock Block Proportions Based on Resonance Testing Technology and Damage Theory

2019 ◽  
Vol 9 (17) ◽  
pp. 3537
Author(s):  
Yuexiang Lin ◽  
Limin Peng ◽  
Mingfeng Lei ◽  
Xiang Wang ◽  
Chengyong Cao
Keyword(s):  
Mechanical Properties ◽  
Elastic Modulus ◽  
Constitutive Model ◽  
Uniaxial Compression ◽  
Rock Block ◽  
Dynamic Elastic Modulus ◽  
Parameter Determination ◽  
Design Parameters ◽  
Damage Theory ◽  
Design And Construction

Block-in-matrix-rocks (bimrocks) are very complicated geological masses that cause many challenging problems during the design and construction of engineering projects, such as parameter determination and landsliding. Successful engineering design and construction depends on a suitable constitutive model and reliable design parameters for geological masses. In this paper, the vibration attenuation signal of welded bimrocks was obtained and studied using resonance test technology. Combined with a uniaxial compression test, a constitutive model was proposed to describe the mechanical behavior of welded bimrocks. On this basis, the relations between the dynamic elastic modulus and the physical parameters of bimrocks were established, which included macroscopic mechanical parameters and damage constitutive parameters. Consequently, a new technological process was proposed to provide quick identification of the mechanical properties of welded bimrocks. The results indicate that the dynamic elastic modulus is highly correlated with the rock block proportion (RBP) and uniaxial compression strength (UCS). It is an effective parameter to predict the strength of the bimrocks with high RBPs. Additionally, the proposed constitutive model, which is based on damage theory, can accurately simulate the strain softening behavior of the bimrocks. Combining the resonant frequency technology and the proposed constitutive model, the complete stress strain curve can be obtained in a rapid and accurate manner, which provides a further guarantee of the stability and safety of underground engineering.

scholarly journals Experimental Study on the Evolution Law of Mesofissure in Full Tailing Cemented Backfill

2020 ◽  
Vol 2020 ◽  
pp. 1-10 ◽  
Author(s):  
Yufan Feng ◽  
Guanghua Sun ◽  
Xuejian Liang ◽  
Chenyang Liu ◽  
Yue Wang
Keyword(s):  
Mechanical Properties ◽  
Pore Diameter ◽  
Failure Process ◽  
Hole Diameter ◽  
Fracture Density ◽  
Surface Porosity ◽  
Characteristic Parameters ◽  
Average Pore ◽  
Cemented Backfill ◽  
Lower Structure

To understand the mechanical properties of the backfill, to reveal the evolvement of micromechanical fissure of backfill, a uniaxial compression experiment was carried out for the full tailing cemented backfill. After loading, the microstructure of the specimens was observed by microscope and the pore characteristic parameters were analyzed. The results showed that the diameter of the initial damage hole of the backfill was mostly between 0 and 40 μm, the hole diameter increases gradually with the increase of pressure, and the hole diameter reached more than 5000 μm in the postpeak damage stage. The upper structure of the backfill specimen is compact while the lower structure is relatively loose. The cracks and interfaces between tailings particles and cement paste are mechanical weak surfaces, where the cracks are mainly generated and propagated. The tip of microfractures in the backfill is damaged by the influence of stress concentration. In the failure process, both surface porosity and fracture density decrease first and then increase, and the average pore diameter increases gradually. The results have guiding significance for the study of backfill mechanical properties and goaf filling design.

Added-value porous materials for controlled thymol release obtained by supercritical CO2 impregnation process

2019 ◽  
Vol 38 (5-6) ◽  
pp. 153-166 ◽  
Author(s):  
Stoja Milovanovic ◽  
Darka Markovic ◽  
Jasna Ivanovic
Keyword(s):  
Pore Diameter ◽  
Operating Time ◽  
Zero Order ◽  
Average Pore Diameter ◽  
Added Value ◽  
Average Pore ◽  
First Order ◽  
Supercritical Impregnation ◽  
Bioactive Substance ◽  
Environmentally Friendly Process

This study explores utilization of biodegradable and biocompatible polymers for controlled release of natural bioactive substance. For that purpose, poly(ε-caprolactone) (PCL) beads, cellulose acetate (CA) film, and poly lactic- co-glycolic acid (PLGA) flakes were impregnated with thymol by employing environmentally friendly process of supercritical carbon dioxide (scCO2) impregnation. At selected pressure and temperature, prolongation of operating time increased thymol loading. Pure scCO2 did not affect CA film with average pore diameter of approximately 3 µm, while it enabled change of PCL beads and PLGA flakes into foams with average pore diameter approximately 175 µm and 87 µm, respectively. Additionally to scCO2, thymol acted as a plasticizer increasing pore size of polymers up to three times. Kinetic of thymol release from selected samples was tested using phosphate buffer saline at 37°C and successfully described with Korsmeyer–Peppas, zero-order, first-order, and Higuchi models. The suggested method of PCL, CA, and PLGA supercritical impregnation led to development of porous, solvent free, added-value materials that release thymol in a controlled manner from 5 h to several days.

Preparation and Research of Porous Hydroxyapatite Whiskers/KGM Composite Bone Scaffolds

2013 ◽  
Vol 712-715 ◽  
pp. 415-419
Author(s):  
Ming Hua Huang ◽  
Qing Hua Chen ◽  
Li Lei ◽  
Duan Cheng Wang ◽  
Ting Ting Yan
Keyword(s):  
Compressive Strength ◽  
Degradation Rate ◽  
Pore Diameter ◽  
Sol Gel ◽  
Crosslinking Agent ◽  
Average Pore Diameter ◽  
Average Pore ◽  
Bone Scaffolds ◽  
Composite Bone

Sol-gel method and freeze-drying method were adopted to prepare the porous HAPw/KGM composite bone scaffolds and ammonia was used as a crosslinking agent. The porosity, average pore diameter, compressive strength and degradation rate in vitro were measured according to the related standard. The curves of each factor and lever affecting comprehensive properties were drew through the orthogonal design L9 (34) experiment. SEM and XRD were applied in characterization. The results show that the optimal preparation program of the composite scaffolds is KGM (2g), HAPw (4.5g), ammonia (0.1 ml) and the freeze temperature (-20 ° C); the prepared scaffolds are porous three-dimensional network structures; the porosity of optimal scaffold is more than 90%; the average pore diameter is between 200-300μm; the compressive strength is about 0.8Mpa and the degradation rate is about 50% within 9 weeks.

Mechanical Properties of Porous Si3N4 Ceramics

2013 ◽  
Vol 586 ◽  
pp. 166-169 ◽  
Author(s):  
Monika Kašiarová ◽  
Zuzana Vilčeková ◽  
Katarína Bodišová ◽  
Magdaléna Domanická ◽  
Miroslav Hnatko ◽  
...  
Keyword(s):  
Mechanical Properties ◽  
Elastic Modulus ◽  
Silicon Nitride ◽  
Porous Silicon ◽  
Trabecular Bone ◽  
Porous Ceramics ◽  
Porous Si ◽  
Depth Sensing ◽  
Bone Material ◽  
Polyurethane Sponge

Mechanical properties of porous silicon nitride prepared by two different processing routes have been studied. Depth sensing methods was used to measure the hardness and elastic modulus of experimental materials. The results were compared with the hardness and elastic modulus of trabecular bone in order to find out porous ceramics with properties close to that of trabecular bone. Material prepared by infiltration of polyurethane sponge exhibited properties close to the properties of bone and it is the potential material for further investigation in the bioapplication field.

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