Ultralight SiC foams with improved strength from sucrose and silicon powder using magnesium nitrate blowing agent

The magnesium nitrate (MN) blowing agent reduced the time required for thermo-foaming and setting of silicon powder dispersions in molten sucrose by nearly half and quarter, respectively. The sucrose-silicon powder formulations were optimized at MN concentrations in the range of 2 to 6 wt% to achieve stoichiometric carbon-silicon composite foams. The reaction sintering of carbon-silicon composite foams produced open cellular SiC foams with density in the range of 0.168-0.08 g/cm3. A decrease in density, cell size and thermal conductivity and an increase in compressive strength of SiC foam were obtained by the use of MN blowing agent.