scholarly journals Effects of particle grading composition of SiC on properties of silicon-bonded SiC porous ceramics

2021 ◽  
Author(s):  
Changzhi Zhao ◽  
Huajian Hu ◽  
Meizhen Zhuo ◽  
Chunying Shen
Keyword(s):  
Silicon Carbide ◽  
Particle Size ◽  
Pore Size Distribution ◽  
Pore Size ◽  
Single Particle ◽  
Packing Density ◽  
Bending Strength ◽  
Porous Ceramics ◽  
Argon Atmosphere ◽  
Coarse Powder

Abstract Silicon-bonded silicon carbide (SBSC) porous ceramics had been prepared by mixing two different particle size of SiC powder (coarse and fine) as aggregates for silicon carbide porous ceramics, adding metallic Si as the binder phase and firing at 1450 °C under argon atmosphere. Various combinations of SiC mixtures consisting of two different particle size and packing density were prepared, and the samples were investigated to understand apparent porosity, bending strength, pore size distribution, and microstructure. The result showed that mixing an appropriate proportion of SiC coarse and fine powders could not only improve the pore size distribution of SBSC porous ceramics but also significantly increase the bending strength compared with the single-particle size sample. The system had the highest free packing density when the ratio of coarse to fine SiC size was >2 and the coarse powder content was 60-70 wt%. The optimal bending strength, and apparent porosity were 37.53 MPa and 37.11% respectively when mixing 70 wt% of coarse powder (50.8 μm) and 30 wt% of fine powder (9.5 μm) and sintered at 1450 ℃ in an argon atmosphere. The material created had 100.3% increased bending strength, and 0.99% decreased porosity compared with the single-particle size sample (50.8 μm).

The Influence of Different Particle Size of Carbon Powders on the Preparation of Porous Silicon Carbide Ceramic

2011 ◽  
Vol 284-286 ◽  
pp. 1370-1374
Author(s):  
Fei Han ◽  
Yu Hong Chen ◽  
Sheng Wei Guo ◽  
Jian Jun Ma
Keyword(s):  
Silicon Carbide ◽  
Particle Size ◽  
Porous Silicon ◽  
Fracture Morphology ◽  
Porous Ceramics ◽  
Main Ingredient ◽  
Porous Silicon Carbide ◽  
Silicon Carbide Ceramic ◽  
Powdered Carbon ◽  
Mechanics Performance

On the preparation of porous ceramics with composite sintering auxiliaries Y2O3-Al2O3 , the main ingredient of SIC , and CMC as the porous agent . Having studied the C content of composite structure and mechanical properties , And analysised the composite fracture morphology with SEM . The results show that, when using different particle size of carbon powders mixed the porous silicon carbide ceramic sample size powdered carbon than a single sample of micro skeleton intact, the shapes of holes, and more rules are uniformly distributed, comprehensive mechanics performance is better.

Fabrication of Porous SiAlON Using Fe2O3 as Pore Former

2014 ◽  
Vol 804 ◽  
pp. 267-270
Author(s):  
Qing Wen Duan ◽  
Rong Zhen Liu ◽  
Hai Yun Jin ◽  
Jian Feng Yang ◽  
Zhi Hao Jin
Keyword(s):  
Particle Size ◽  
Porous Materials ◽  
Pore Size ◽  
Fracture Mode ◽  
Size Effects ◽  
Pore Diameter ◽  
Bending Strength ◽  
Thermal Reduction ◽  
Pore Former ◽  
Median Pore

Porous SiAlON ceramics were fabricated by carbo-thermal reduction nitridation method using Fe2O3 as pore former. Particle size effects of Fe2O3 were reported in this paper. The results showed that composites were composed by SiAlON, AlN and Iron Silicon phases. The median pore diameter of Sialon was affected by the composition and particle size of Fe2O3. The fracture mode of this material was intergranular. With the increase of Fe2O3 additions, the porosity of this materials increased. The bending strength of this material was reversely proportional to Fe2O3 particle size. The maximum bending strength of Porous materials with 30wt.% Fe2O3 additions (with a porosity about 65% and the pore size is about 1μm) could reach 22 MPa. The porous Sialon ceramics with a smaller pore size exhibited a higher bending strength.

scholarly journals COMPUTER SIMULATION OF RANDOM PACKINGS FOR SELF-SIMILAR PARTICLE SIZE DISTRIBUTIONS IN SOIL AND GRANULAR MATERIALS: POROSITY AND PORE SIZE DISTRIBUTION

Fractals ◽  
2014 ◽  
Vol 22 (03) ◽  
pp. 1440009 ◽  
Author(s):  
MIGUEL ANGEL MARTÍN ◽  
FRANCISCO J. MUÑOZ ◽  
MIGUEL REYES ◽  
F. JAVIER TAGUAS
Keyword(s):  
Computer Simulation ◽  
Particle Size ◽  
Pore Size Distribution ◽  
Pore Size ◽  
Size Distribution ◽  
Total Porosity ◽  
Size Distributions ◽  
Particle Size Distributions ◽  
Self Similar ◽  
Random Packings

A 2D computer simulation method of random packings is applied to sets of particles generated by a self-similar uniparametric model for particle size distributions (PSDs) in granular media. The parameter p which controls the model is the proportion of mass of particles corresponding to the left half of the normalized size interval [0,1]. First the influence on the total porosity of the parameter p is analyzed and interpreted. It is shown that such parameter, and the fractal exponent of the associated power scaling, are efficient packing parameters, but this last one is not in the way predicted in a former published work addressing an analogous research in artificial granular materials. The total porosity reaches the minimum value for p = 0.6. Limited information on the pore size distribution is obtained from the packing simulations and by means of morphological analysis methods. Results show that the range of pore sizes increases for decreasing values of p showing also different shape in the volume pore size distribution. Further research including simulations with a greater number of particles and image resolution are required to obtain finer results on the hierarchical structure of pore space.

scholarly journals Effect of Biochar Particle Size on Physical, Hydrological and Chemical Properties of Loamy and Sandy Tropical Soils

Agronomy ◽  
2019 ◽  
Vol 9 (4) ◽  
pp. 165 ◽  
Author(s):  
Sara de Jesus Duarte ◽  
Bruno Glaser ◽  
Carlos Pellegrino Cerri
Keyword(s):  
Particle Size ◽  
Pore Size Distribution ◽  
Pore Size ◽  
Size Distribution ◽  
Sandy Soil ◽  
Water Retention ◽  
Tropical Soils ◽  
Total Carbon ◽  
Loamy Soil ◽  
Physical Chemical

The application of biochar is promising for improving the physical, chemical and hydrological properties of soil. However, there are few studies regarding the influence of biochar particle size. This study was conducted to evaluate the effect of biochar size on the physical, chemical and hydrological properties in sandy and loamy tropical soils. For this purpose, an incubation experiment was conducted in the laboratory with eight treatments (control (only soil), two soils (loamy and sandy soil), and three biochar sizes (<0.15 mm; 0.15–2 mm and >2 mm)). Analyses of water content, bulk density, total porosity, pore size distribution, total carbon (TC) and total N (TN) were performed after 1 year of soil–biochar-interactions in the laboratory. The smaller particle size <0.15 mm increased water retention in both soils, particularly in the loamy soil. Bulk density slightly decreased, especially in the loamy soil when biochar > 2 mm and in the sandy soil with the addition of 0.15–2 mm biochar. Porosity increased in both soils with the addition of biochar in the range of 0.15–2 mm. Smaller biochar particles shifted pore size distribution to increased macro and mesoporosity in both soils. Total carbon content increased mainly in sandy soil compared to control treatment; the highest carbon amount was obtained in the biochar size 0.15–2 mm in loamy soil and <0.15 mm in sandy soil, while the TN content and C:N ratio increased slightly with a reduction of the biochar particle size in both soils. These results demonstrate that biochar particle size is crucial for water retention, water availability, pore size distribution, and C sequestration.

Preparation SiC Ceramic Composite Filtration Membrane Materials by Dry Pressing and Synchronous Sintering Method

2013 ◽  
Vol 690-693 ◽  
pp. 409-414
Author(s):  
Kui Fan Su ◽  
Li Ming Wang ◽  
Xiang Yun Deng ◽  
Jian Bao Li ◽  
Chun Peng Wang ◽  
...  
Keyword(s):  
Silicon Carbide ◽  
Particle Size ◽  
Pressure Drop ◽  
Pore Size ◽  
Ceramic Composite ◽  
Average Pore Size ◽  
Molding Pressure ◽  
Average Pore ◽  
Silicon Carbide Particle ◽  
Filtration Membrane

Silicon carbide ceramic composite filter membrane materials were prepared by dry pressure molding and synchronous sintering process at sintering temperature of 1300oC for 3h. and research the influence of on the molding pressure structure of SiC filtration membrane,effect of particle size on porosity, average pore size and filter pressure drop of filtration membrane, SEM was performed to examine the morphology, The porosity ,average pore size and filter pressure drop of filtration membrane were tested by Archimedes method ,bubble point method and filter pressure drop instrument. It is demonstrated that while the molding pressure (F) varied from 1MPa to 10MPa, the filter membrane material achieved preferable morphology and best performance when F equals to 5MPa. Under this modeling pressure, while silicon carbide particle size increased from 1 to 23μm, the pore ratio decreased from 48.0% to 36.2% and the average pore size increased from 0.35μm to 9.4μm, while the air gas velocity changed from 0 to 0.112m/s, the filter pressure drop increased, when the velocity is stable, the filter pressure drop reduced as the silicon carbide particle size.

Preparation, characterization, and sinterability of well-defined silica/yttria powders

1994 ◽  
Vol 9 (2) ◽  
pp. 436-450 ◽  
Author(s):  
Herbert Giesche ◽  
Egon Matijević
Keyword(s):  
Particle Size ◽  
Pore Size Distribution ◽  
Pore Size ◽  
Grain Growth ◽  
Spherical Particles ◽  
Sintering Process ◽  
Mixed Composition ◽  
Coated Particles ◽  
Wide Range ◽  
The Matrix

Dispersions of uniform submicron spherical particles consisting of silica cores and yttria coatings, or vice versa, were prepared by a precipitation technique. The overall size of the particles and the thickness of the shells could be varied over a wide range. Such powders were used to form green bodies by sedimentation, centrifugation, or pressure filtration, and the density and the pore size distribution of the resulting solids were evaluated. The green bodies were sintered and the changes in density, phases, and microstructure were followed with temperature. In general, the coated powders exhibited enhanced densification. On processing composite solids at temperatures <1000 °C, the formation of Y2Si2O7 took place, which caused a pronounced shrinkage of the samples. Powders of coated particles having the same silica/yttria ratios sintered at lower temperatures when the shell was composed of silica rather than of yttria. When either silica or yttria were in molar excess in the coated particles, the sintered products had a mixed composition of Y2Si2O7 and the component in excess. By terminating the sintering process before the grain growth started, the solids displayed a well-defined microstructure with a uniform distribution of areas of one phase in the matrix of the matter in excess. This property was mainly due to the uniformity of initial powders in terms of the particle size and the coating.

scholarly journals Environment-Friendly Preparation of Reaction-Bonded Silicon Carbide by Addition of Boron in the Silicon Melt

Materials ◽  
2021 ◽  
Vol 14 (5) ◽  
pp. 1090
Author(s):  
Maoqiang Rui ◽  
Yaxiang Zhang ◽  
Jing Ye
Keyword(s):  
Mechanical Properties ◽  
Silicon Carbide ◽  
Bending Strength ◽  
Sintering Temperature ◽  
Argon Atmosphere ◽  
Environment Friendly ◽  
Silicon Melt ◽  
Different Temperatures ◽  
Carbide Ceramics ◽  
Silicon Carbide Ceramics

Reaction-bonded silicon carbide ceramics were sintered by infiltration of Si and B–Si alloy under an argon atmosphere at different temperatures. The element boron was added to the silicon melt to form a B–Si alloy first. The mechanical properties of samples were improved by infiltration of the B–Si melt. The samples infiltrated with the Si-only melt were found to be very sensitive to experimental temperature. The bending strengths of 58.6 and 317.0 MPa were achieved at 1530 and 1570 °C, respectively. The sample made by infiltration of B–Si alloy was successfully sintered at 1530 °C. The relative density of the sample was more than 90%. The infiltration of B–Si alloy reduced the sintering temperature and the bending strength reached 326.9 MPa. The infiltration mechanism of B–Si alloy is discussed herein.

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