Studies on processing of layered oxide-bonded porous sic ceramic filter materials

Oxide-bonded porous SiC ceramic filter supports were prepared using SiC powder (d(50) = 212 mu m), Al2O3, and clay as bond forming additives and graphite as pore former following reaction bonding of powder compacts at 1400 degrees C in air. Reaction bonding characteristics, phase composition, porosity, pore size, mechanical strength, and microstructure of porous SiC ceramic supports were investigated. Mullite bond phase formation kinetics was studied following the Johnson-Mehl-Avrami-Kolmogorov (JMAK) model using non-isothermal differential thermal analysis (DTA) data. Compared to porous SiC ceramic filter supports having no needle-like mullite bond phase, materials processed by the mullite bonding technique exhibited higher average strength (22.1%) and elastic modulus (5.4%) at a similar porosity level of similar to 38%, with upper and lower bounds of their strength, modulus, and porosity being 39.1 MPa, 40.2 GPa, and 36.3% and 34.2 MPa, 31.3 GPa, and 33.0%, respectively. Spray coating method was applied for preparation of oxidation-bonded SiC filtration layer having thickness of similar to 150 mu m and pore size of similar to 5-20 mu m over the porous SiC support compacts using aqueous slurry made of fine SiC powder (d(50) = 15 mu m) followed by sintering. The layered ceramics thus prepared are potential materials for gas filter applications.

Automated summary

In this study, oxide-bonded porous SiC ceramic filter supports were prepared and their material properties and structure characteristics were investigated. Materials processed by the mullite bonding technique exhibited higher strength and elastic modulus at a similar porosity level. Spray coating method was applied for preparation of oxidation-bonded SiC filtration layer on the porous SiC support compacts.