31^st Materials Science and Engineering Conference: Advancement & Innovations

Porous Si₃N₄ bodies are of interest in various applications including bio and aerospace. Silicon nitride bodies were prepared with porosity and flexural strength of about 38% and near 180 MPa, respectively. The processing was via gel-casting method employing acrylamide (AM) and N,N'−methylene bisacrylamide (MBAM) for primary slurry, followed by coke bed sintering. The concentrations of APS and TEMED as initiator and catalyst, the sintering time and temperature were studied and optimized. Phase evolution and microstructure observation, as well as flexural strength and porosity of porous Si₃N₄ bodies, were investigated. It was found above, sintering process at 1650 °C with prolonged time had a significant effect on strength in a way that bodies with 33% porosity could experience 250 MPa. Development of the interlocking microstructure of fine β-Si₃N₄ grains was found to be the key factor for the increase of strength. Controlling the primary slurry components was also vital for maintaining the high strength. The results were explained with emphasis on potential applications.