Evaluation of Air Permeation Behavior of Porous <scp>SiC</scp> Ceramics Synthesized by Oxidation‐Bonding Technique

Dey, Atanu; Kayal, Nijhuma; Chakrabarti, Omprakash; Innocentini, M. D. M.; Chacon, Welton S.; Coury, José Renato

doi:10.1111/j.1744-7402.2012.02847.x

Cited by 38 publications

(42 citation statements)

References 35 publications

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“…As evident from the results in Table 4, for v s = 2 cm.s -1 , the pressure drop to the air flow for samples with a thickness of approximately 12 mm ranged from 25,423 to 189,029 Pa (250-1890 cm water column). Comparatively, these values are still significantly higher than those exhibited by commercial fibrous ceramic filter elements (1,000 to 2,000 Pa) operating in similar flow conditions 27,33 . Notably, however, the pressure drop exhibits an inertial contribution that is typically less than 5% in most compositions, which indicates the validity of Darcy's law to a velocity of up to 2 cm.s -1 .…”

Section: Resultsmentioning

confidence: 82%

Structural and fluid dynamic characterization of calcium carbonate-based porous ceramics

et al. 2013

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The aim of this work was to experimentally evaluate the use of calcium carbonate as a poregenerating agent in ceramic compositions. Compositions that contained 50% kaolin, 20% limestone, and different concentrations of quartz and feldspar were prepared by uniaxial pressing. Samples were heat-treated at a heating rate appropriate to induce calcium carbonate degassing, and they were then sintered at 800, 900, and 1050 °C. Tests of X-ray fluorescence, thermogravimetric analysis, porosimetry, and air permeation were performed. The composition (wt%) that contained 50% kaolin, 20% limestone, 20% feldspar, and 10% quartz and heat treated at 1050 °C (k 1 = 1.73×10 -13 m 2 and k 2 = 1.00×10 -8 m) showed the highest level of permeability among the investigated samples. Fluid dynamics simulations showed that the prepared samples would exhibit a pressure drop greater than the range desired for applications that involve the filtration of aerosols, but alternatively would be suitable as substrates for asymmetric membranes in microfiltration applications.

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Section: Resultsmentioning

confidence: 82%

Structural and fluid dynamic characterization of calcium carbonate-based porous ceramics

et al. 2013

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“…There are several ways of reporting the permeability of a porous body. In this work, permeability coefficients were retrieved from fitting of Forchheimer's equation, an empirical relationship well accepted in the literature to express the parabolic dependence of pressure drop (Δ P ) through a flat medium with the resulting superficial or face velocity ( v s ) of the fluid:

\frac{Δ P}{L} = \frac{italicμ}{k_{1}} v_{s} + \frac{italicρ}{k_{2}} v_{s}^{2}

…”

Section: Methodsmentioning

confidence: 99%

“…The great advantage of using coefficients k 1 and k 2 to represent the permeability of a ceramic investment is that they do not depend on the type of fluid and the velocity applied, but they are instead intrinsically related to features of the porous structure, such as the amount, size, and morphology of voids available for fluid flow. Any change in the processing variables that results in an increase in the interconnected porosity and pore size or the decrease in pore tortuosity and roughness will lead to higher values of k 1 and k 2 , even though with different intensity ranges . Therefore, the knowledge of k 1 and k 2 for different materials allows an easy comparison among them even if data were acquired in different flow conditions.…”

Section: Methodsmentioning

confidence: 99%

Microstructural, Physical, and Fluid Dynamic Assessment of Spinel‐Based and Phosphate‐Bonded Investments for Dental Applications

Innocentini

Chacon

Caldato

et al. 2013

Int J Applied Ceramic Tech

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This work reports the experimental evaluation of physical and gas permeation parameters of four spinel‐based investments developed with or without inclusion of sacrificial fillers. Data were compared with those of three commercial formulations. Airflow tests were conducted from 27 to 546°C, and permeability coefficients were fitted from Forchheimer's equation. Skeletal densities found for spinel‐ (ρs = 3635 ± 165 kg/m3) and phosphate‐bonded (ρs = 2686 ± 11 kg/m3) samples were in agreement with the literature. The developed investments were more porous and less permeable than commercial brands, and the differences were ascribed to the different pore morphologies and hydraulic pore sizes of ceramic matrices. The inclusion of both fibers and microbeads resulted in increases of total porosity (42.6–56.6%) and of Darcian permeability coefficient k1 (0.76 × 10−14–7.03 × 10−14 m2). Air permeation was hindered by increasing flow temperatures, and the effect was related to the influence of gas viscosity on ΔP, in accordance with Darcy's law. Casting quality with molten titanium (CP Ti) was directly proportional to the permeability level of the spinel‐based investments. However, the high reactivity of the silica‐based investment RP and the formation of α‐case during casting hindered the benefits of the highest permeability level of this commercial brand.

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“…Numerous studies of porous SiC ceramics have been performed in recent decades, including studies of technologies for making them with the use of different raw materials [5,6]. Despite this, there is little information on the kinetics of the sintering of these ceramics, and such information is important for controlling the formation of their porous microstructure.…”

Section: Introductionmentioning

confidence: 98%

Evaluating the Sintering Kinetics of Porous Sic Ceramics

Liu

Zhang

et al. 2015

Refract Ind Ceram

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Porous ceramics made by burning out a pore-former during the sintering process were investigated by stepwise isothermal dilatometry (SID), x-ray diffraction (XRD) phase identification, scanning electron microscopy (SEM), and mechanical-property analysis. SID data obtained by the Makipirtti-Meng method was analyzed and was found to fit well with data on shrinkage obtained by means of the rate equation proposed for use with this method. Kinetic parameters were evaluated and it was established that sintering takes place through two main mechanisms. These mechanisms are related to the generation and sintering of oxidation products and have activation energies of 55.4 and 325.4 kJ/mole. The sintering temperature greatly affects such properties of sintered specimens as open porosity and ultimate flexural strength. The results obtained in the investigation were well-supported by microstructural analysis of the sintered specimens.

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Evaluation of Air Permeation Behavior of Porous SiC Ceramics Synthesized by Oxidation‐Bonding Technique

Cited by 38 publications

References 35 publications

Structural and fluid dynamic characterization of calcium carbonate-based porous ceramics

Structural and fluid dynamic characterization of calcium carbonate-based porous ceramics

Microstructural, Physical, and Fluid Dynamic Assessment of Spinel‐Based and Phosphate‐Bonded Investments for Dental Applications

Evaluating the Sintering Kinetics of Porous Sic Ceramics

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