Tape casting of polysiloxane-derived ceramic with controlled porosity and surface properties

Abstract

Tape casting has been applied to produce porous hybrid and SiOC ceramic tapes using ceramic precursors and commercially available polysiloxanes as polymeric binders. SiC particles of two different mean sizes (4.5 or 6.5 μm) were used as inert fillers to prevent shrinkage and increase mechanical stability. Macroporosity was adjusted by varying the azodicarbonamide (ADA) content from 0 to 30 wt.%. Decomposition of the polysiloxanes at 600 °C resulted in the generation of micropores with high specific surface area (187–267 m2 g−1) and a predominant hydrophobic behavior. At 1000 °C mainly meso/macroporosity were observed (SSA: 32–162 m2 g−1) accompanied by increased hydrophilicity. The influence of ADA content, SiC size, and pyrolysis temperature on open porosity (2.5–37%), average pore size (<0.01–1.76 μm), surface characteristics, and flexural strength (10.5–121 MPa) were investigated. The porous tapes with different surface characteristics and controlled structure are highly promising for applications involving membrane processes, particularly microfiltration systems (0.1–10 μm).