Expansionless oxidation-bonded SiC microfiltration membrane by controlling the oxidation of SiC particle mixtures

Abstract

Oxidation bonding is a technique used to produce porous SiC ceramics at low temperatures. The oxidation behavior of SiC particles depends on various factors, including the oxidation environment, temperature, time, particle size, and impurities. The key properties required for a porous ceramic membrane are a controlled pore morphology, high strength, and high permeability. In this study, SiC powders with different particle sizes (0.55 and 7 μm) were used to fabricate porous ceramic membranes. First, the oxidation behavior of the SiC powders was evaluated. Then, the feasibility of using their mixture to create supports for microfiltration applications was analyzed. Through this study, not only were the ideal conditions for fabricating microfiltration supports quantified but also the conditions where specimens could be made with zero size change. Finally, a membrane fabricated from a powder mixture composed of 92% of the 7 μm powder and 8% of the 0.55 μm powder and sintered at 1450°C was proposed, which had a 37% porosity, 1.42 μm pore size, 49.6 MPa flexural strength, and L cm -2 min -1 bar -1 air permeability.

A reverse particle grading strategy for design and fabrication of porous SiC ceramic supports with improved strength

“…After sintering, as presented in Fig. 9 (c), the diameter of supports slightly increased to ~31.05 mm and the size of channels decreased to ~3.95 mm, which was mainly attributed to the expansion behavior of SiC particles induced by the surface oxidation [36]. In addition, the shapes of green body, sintered body and their channels were well kept.…”

“…It was obvious that the mass loss decreased from 1.85% to 1.56% with the increasing W16 content. The change in mass loss could also evidence the relatively low level of oxidation behavior of coarse grains [36][37][38]. It was easier for small-sized particles to be oxidized due to their large specific surface area compared with large-size particles [36].…”

“…This process requires higher fracture energy, which is conducive to the increase of bending strength [43]. However, when the content of W16 increased to 30 wt%, the resistance of crack declined because the number of neck connections in the route of crack decreased, which can be to some degree attributed to the less oxidation degree of coarse SiC particles [36]. wt% and (f) 30 wt%, and (g) schematic illustration of the route of crack growth in various supports.…”