Silicon nitride foams from emulsions

Si3N4 foams with open cells were developed by emulsification of an aqueous powder suspension containing an alkane phase (70 vol% of octane or decane), using a surfactant as emulsion stabilizer. 5 wt% of Y2O3 and 5 wt% of MgO were used as sintering additives, and the samples were pressureless sintered at 1600 degrees C in N-2. Ceramic foams, mainly based on alpha-Si3N4, with total porosity ranging from 70 to similar to 77 vol%, average cell size of similar to 31 mu m for octane and similar to 55 Inn for decane, and compression strength ranging from similar to 5 to similar to 20 MPa were produced. (C) 2014 Elsevier B.V. All rights reserved.