Modification of Inner Pores with Silicon Carbide Whiskers onto the Al2O3 Substrate by CVI Process

2005 ◽  
Vol 287 ◽  
pp. 212-219 ◽  
Author(s):  
W.S. Park ◽  
Doo Jin Choi ◽  
Hai Doo Kim
Keyword(s):  
Specific Surface ◽  
Surface Area ◽  
Specific Surface Area ◽  
Volume Fraction ◽  
Gas Permeability ◽  
Porous Alumina ◽  
Porous Ceramic ◽  
Chemical Vapor ◽  
Chemical Vapor Infiltration ◽  
Particulate Filter

In this study, SiC whiskers were grown in porous alumina substrate in order to enhance the filtering efficiency, performance, and durability by controlling pore morphology. This experiment was performed by chemical vapor infiltration (CVI) in order to obtain the whiskers on the inside of pores as well as on the surface of porous the Al2O3 substrate. The deposition morphology was changed remarkably with the deposition position and temperature. First, the mean diameter of whisker was decreased as the position of observation moved into the inside of substrate due to ‘the depletion effect’ and ‘the pressure effect’. Second, the deposition temperature caused the changes of the deposition type such as debris, whiskers and films and these changes of morphology affect the various properties. When SiC films were deposited, the gas permeability and the specific surface area decreased. However, the whisker showed the opposite result; a large specific surface area provides the absorption site and the whiskers in gas traveling path hinder the particles from easily flowing. Comparing with the normal pores (inter-grain open pores), the pores formed by the whiskers have relatively large volume fraction under the same pore size. Porous ceramic filters with whisker will be expected to increase the filtering efficient and gas permeability simultaneously. It is the main advantage of our whiskered filter. Therefore the porous alumina body which deposited the SiC whisker will be the promising material in order to apply to the particulate filter.

Design of Nanoporous Alumina Structure and Surface Properties for Dental Composite

2007 ◽  
Vol 361-363 ◽  
pp. 809-812 ◽  
Author(s):  
C. Azevedo ◽  
B. Tavernier ◽  
Jean Louis Vignes ◽  
Pierre Cenedese ◽  
Pierre Dubot
Keyword(s):  
Specific Surface ◽  
Surface Area ◽  
Specific Surface Area ◽  
Porous Alumina ◽  
High Specific Surface Area ◽  
Surface Reactivity ◽  
Dental Composite ◽  
Resin Composites ◽  
Dental Resin ◽  
Adsorption Sites

Recent studies showed that the particle size of fillers, using for the reinforcement of dental resin composites, should be as small as possible to provide the maximum surface area for bonding to resin monomer, and should be kept well dispersed so as to be functionalized by a silane. In the present study, porous alumina monoliths with high specific surface area, measured by the Brunauer-Emmett-Teller (B.E.T.) method, were obtained using a novel preparation method. Structure and surface reactivity have been investigated as functions of temperature and chemical treatments. The impregnation of the as-prepared material by Triméthyletoxysilane (TMES) stabilized alumina with high specific surface area at higher temperature. A FTIR study has described the effect of TMES treatment and temperature on the structure of the material. The use of allyldimethoxysilane (ADMS) as a probe molecule for measuring the surface reactivity, has allowed us to show that the treatment of samples with TMES and their reheating at 1300°C results in adsorption sites which give stronger chemical bonds. This preliminary study has, therefore, allowed us to optimize the structural and surface treatment of experimental fillers before their use in the reinforcement of resin composites or resin-modified glass-ionomer cements.

scholarly journals Structural and Morphological Quantitative 3D Characterisation of Ammonium Nitrate Prills by X-Ray Computed Tomography

Materials ◽  
2020 ◽  
Vol 13 (5) ◽  
pp. 1230
Author(s):  
Fabien Léonard ◽  
Zhen Zhang ◽  
Holger Krebs ◽  
Giovanni Bruno
Keyword(s):  
Computed Tomography ◽  
Specific Surface ◽  
Ammonium Nitrate ◽  
Surface Area ◽  
Specific Surface Area ◽  
Volume Fraction ◽  
Fuel Oil ◽  
X Ray ◽  
Oil Retention ◽  
X Ray Computed

The mixture of ammonium nitrate (AN) prills and fuel oil (FO), usually referred to as ANFO, is extensively used in the mining industry as a bulk explosive. One of the major performance predictors of ANFO mixtures is the fuel oil retention, which is itself governed by the complex pore structure of the AN prills. In this study, we present how X-ray computed tomography (XCT), and the associated advanced data processing workflow, can be used to fully characterise the structure and morphology of AN prills. We show that structural parameters such as volume fraction of the different phases and morphological parameters such as specific surface area and shape factor can be reliably extracted from the XCT data, and that there is a good agreement with the measured oil retention values. Importantly, oil retention measurements (qualifying the efficiency of ANFO as explosives) correlate well with the specific surface area determined by XCT. XCT can therefore be employed non-destructively; it can accurately evaluate and characterise porosity in ammonium nitrate prills, and even predict their efficiency.

Effect of Heat Treatment on Specific Surface Area of Si-C-O Fibers

2008 ◽  
Vol 368-372 ◽  
pp. 1639-1641
Author(s):  
Zeng Yong Chu ◽  
Rong An He ◽  
Hai Feng Cheng ◽  
Xiao Dong Li ◽  
Jun Wang
Keyword(s):  
Heat Treatment ◽  
Weight Loss ◽  
Specific Surface ◽  
Surface Area ◽  
Specific Surface Area ◽  
Treatment Time ◽  
Porous Ceramic ◽  
Ceramic Fiber

In this paper, effect of heat treatment on the SSA of Si-C-O fibers was investigated and morphologies of the treated fibers were studied using SEM. The results revealed that weight loss was proportional to the treatment time at 1573K and the specific surface area (SSA) increased sharply when the weight loss reached above 6wt%. A rough and porous ceramic fiber with SSA of 23.76m2/g could be obtained at the weight loss of 9.1wt%, as a result of the treatment at 1573K for 32h.

scholarly journals Effect of Mesopore Development on Butane Working Capacity of Biomass-Derived Activated Carbon for Automobile Canister

Nanomaterials ◽  
2021 ◽  
Vol 11 (3) ◽  
pp. 673
Author(s):  
Byeong-Hoon Lee ◽  
Hye-Min Lee ◽  
Dong Chul Chung ◽  
Byung-Joo Kim
Keyword(s):  
Activated Carbon ◽  
Specific Surface ◽  
Surface Area ◽  
Specific Surface Area ◽  
Pore Volume ◽  
Volume Fraction ◽  
Activated Carbons ◽  
Total Pore Volume ◽  
Working Capacity ◽  
Activation Time

Kenaf-derived activated carbons (AKC) were prepared by H3PO4 activation for automobile canisters. The microstructural properties of AKC were observed using Raman spectra and X-ray diffraction. The textural properties were studied using N2/77 K adsorption isotherms. Butane working capacity was determined according to the ASTM D5228. From the results, the specific surface area and total pore volume of the AKC was determined to be 1260–1810 m2/g and 0.68–2.77 cm3/g, respectively. As the activation time increased, the butane activity and retentivity of the AKC increased, and were observed to be from 32.34 to 58.81% and from 3.55 to 10.12%, respectively. The mesopore ratio of activated carbon increased with increasing activation time and was observed up to 78% at 973 K. This indicates that butane activity and retentivity could be a function not only of the specific surface area or total pore volume, but also of the mesopore volume fraction in the range of 2.8–3.8 nm and 5.5-6.5 nm of adsorbents, respectively. The AKC exhibit enhanced butane working capacity compared to commercial activated carbon with the high performance of butane working capacity due to its pore structure having a high mesopore ratio.

scholarly journals Development of the reference material of nanoporous zeolite

2020 ◽  
Vol 16 (1) ◽  
pp. 25-41
Author(s):  
E. P. Sobina
Keyword(s):  
Reference Material ◽  
Specific Surface ◽  
Surface Area ◽  
Specific Surface Area ◽  
Pore Volume ◽  
Gas Permeability ◽  
Experimental Studies ◽  
Metrological Traceability ◽  
Metrological Characteristics ◽  
Measuring Instruments

The article is devoted to the development of a reference material of the sorption roperties of nanoporous zeolite, which ensures metrological traceability of measurement results to the State primary measurement standard of units for specific gas adsorption, specific surface area, specific pore volume, pore size, open porosity and gas permeability coefficient of solid substances and materials GET 210-2019.The paper presents the results of theoretical and experimental studies on optimizing the conditions of sample preparation (thermal training) of the reference material using the thermogravimetric method and differential scanning calorimetry, coupled with mass spectrometric detection of the evolved gases (TG-DSC–MS analysis). The results of establishing the metrological characteristics of the reference material are described, including standard uncertainty due to the method of determining the certified value, as well as standard uncertainties from heterogeneity and instability. The GSO 10734–2015 reference material of the sorption properties of nanoporous zeolite (Zeolite SO UNIIM) has certified metrological characteristics: specific surface area (500–1200) m2/g; specific pore volume (0.10.5) cm3/g; the predominant pore diameter (0.4–0.9) nm; specific argon adsorption (0.001–20.0) mol/kg.The reference material is designed to calibrate measuring instruments and to control accuracy of results of sorption characteristics of nanoporous materials measurements; it can be used to certify appropriate measurement procedures, to test measuring instruments and reference materials for type approval and other types of metrological control. 

Chemical Vapor Infiltration of Carbon Fiber Felts from Methane: Influence of Surface Area / Volume Ratios

2006 ◽  
Vol 50 ◽  
pp. 107-114 ◽  
Author(s):  
W.G. Zhang ◽  
Yong Ping Zhu ◽  
K.J. Hüttinger
Keyword(s):  
Carbon Fiber ◽  
Surface Area ◽  
Fiber Volume Fraction ◽  
Volume Fraction ◽  
Polarized Light ◽  
Chemical Vapor ◽  
Chemical Vapor Infiltration ◽  
Initial Surface ◽  
Fiber Volume ◽  
Vapor Infiltration

Isothermal, isobaric chemical vapor infiltration of carbon fiber felts with fiber volume fractions of 7.1% and 14.2% were investigated at infiltration times from 20 to 120 hours, using a constant temperature of 1095 oC and a methane pressure of 22.5 kPa. Bulk densities and the density profiles as well as porosity at various densification stages were determined. Inside–outside densification was obtained in the most infiltrations, the gradients of densification along the infiltration depth decrease with increasing of residence time and infiltration times. Outside–inside densification occurs only in the felt with the lower fiber volume fraction at final infiltration stage and at longer residence times. Microstructure of the obtained matrix carbon was analyzed with a polarized light microscopy. Abruptly change from low/medium textured carbon to medium/high textured carbon are observed in both of the carbon fiber felts, whereas the thickness of the first lower textured layer is about 14 micros in the felt with a fiber volume fraction of 7.1%, whereas it is only 2 micros in the felt with a fiber volume fraction of 14.2%, which is caused by an increasing of initial surface area / volume ratio, [A/V], from 33 to 71 mm-1. Results are completely in agreement with the previous simulations studies on the influence of [A/V] ratios.

Porous ceramic monoliths assembled from microbeads with high specific surface area for effective biocatalysis

RSC Advances ◽  
2013 ◽  
Vol 3 (32) ◽  
pp. 13381 ◽  
Author(s):  
Tanja Yvonne Klein ◽  
Laura Treccani ◽  
Jorg Thöming ◽  
Kurosch Rezwan
Keyword(s):  
Specific Surface ◽  
Surface Area ◽  
Specific Surface Area ◽  
Porous Ceramic ◽  
High Specific Surface Area
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