Effects of heating rate on the structure and properties of SiOC ceramic foams derived from silicone resin

Silicon oxycarbide ceramic foams were fabricated in a single step manufacturing process using in situ foaming of SiOC powders loaded silicone resin. The effects of heating rate on the porosity, compressive strength and microstructure of the ceramic foams were investigated. The porosity (total and open) increased firstly and then decreased with increasing heating rate. It was possible to control the total and open porosity of ceramic foams within a range of 81.9–88.2% and 62.4–72.5% respectively, by adjusting the heating rate from 0.25 °C/min to 3 °C/min while keeping the silicone resin content at 90 vol%. However, the compressive strength decreased with increasing the heating rate progressively, and the average compressive strength of the foams was in the range of 1.0–2.3 MPa. Micrographs indicated that the ceramic foams which cross-linked at a heating rate less than 1 °C/min had a well-defined open-cell and regular pore structure.