Investigations on Material and Mechanical Properties, Air‐Permeation Behavior and Filtration Performance of Mullite‐Bonded Porous SiC Ceramics

Abstract

A theoretical relation between processing parameters and porosity (29-56%) of mullite-bonded porous SiC ceramics was derived and validated with experimental data. Porosity-dependent variation of fracture strength (9-34 MPa) and elastic modulus (7-28 GPa) was explained by the minimum solid area model. At room temperature, the Darcian, k 1 (1.2 9 10 À13 -1.6 9 10 À12 m 2 ) and the non-Darcian, k 2 (4.6 9 10 À9 -2.7 9 10 À7 m) permeability coefficients showed linear variation with porosity. Tests conducted up to 650°C indicated an increase in k 1 with temperature and a reverse trend for k 2 . Airborne NaCl nanoparticle filtration tests showed good performance of SiC ceramics with fractional collection efficiency of >99% at 46-56% porosity levels.*omprakash@cgcri.res.in

Fabrication and properties of mullite-bonded porous SiC membrane supports using bauxite as aluminum source

“…The most probable explanation for this is that excessive alkali metal oxides existed [25]. Because SiC oxidation can be accelerated at higher temperatures and/or longer reaction times [16][17][18][19][20], the optimum temperature for the fabrication of mullite-bonded porous SiC ceramics was 1400 1C. Therefore, the processing temperature and the holding time were fixed at 1400 1C and 3 h, respectively, in the following experiments.…”

“…Ding et al [16,17] fabricated porous mullite-bonded SiC ceramics, which demonstrate superior high-temperature mechanical properties and thermal shock resistance [15][16][17][18]. Alumina is considered as, in general, aluminum source for the fabrication of mullite-bonded porous SiC ceramics [16][17][18][19][20]. Bauxite is the major source of starting materials for Al 2 O 3 -based products [21][22][23].…”

Microstructure and gas permeation performance of porous silicon nitride ceramics with unidirectionally aligned channels

“…The gas permeation experiment of specimen was conducted by a laboratory‐made equipment described in previous work 16 . On basis of these data obtained in permeation experiment including inlet and outlet gas pressure and gas flow rate, the Darcian and non‐Darcian permeability coefficients of specimens, namely k 1 (m 2 ) and k 2 (m), were estimated by the Forchheimer equation suitable for compressible fluids 24,25 where P 1 and P 2 are the gas pressure (Pa) at the inlet and outlet of the sample respectively.…”

Permeability and mechanical integrity of porous biomorphic SiC ceramics for application as hot-gas filters

“…A review on this subject has been presented by Macdonald et al [44]. Most previous works assumed a monomodal and isotropic porosity and their applicability to bioSiC is questionable since it exhibits a complex anisotropic porous microstructure consisting of a SiC scaffold formed by a cluster of SiC grains and a multimodal pore size distribution inherited from the wood precursor, so that it is more difficult to model the gas flow forced to travel through these porous media instead of isotropic materials [45,46]. In particular, for a bimodal pore size distribution such as that observed in bioSiC for the axial direction, there is a difficulty in selecting the equivalent pore size d since the arithmetic mean will be biased towards the most abundant but smaller narrow channels thus underestimating the effective pore size.…”