Rapid Preparation of Strong Machinable Si₃N₄-based Composites

Dense Si₃N₄/BN composite ceramics were fabricated by SPS at 1600~1650℃ for 5 minutes.Ex- perimental results indicate the SPSed Si₃N₄/BN composite ceramics maintains a considerably high bending strength,though it has a gradual decrease with increasing BN,caused by the aggregation of h-BN grains. The bending strength of sample was nearly 900 MPa when BN content got up to 30%,which could be highly machined by WC tool as well.SEM analysis suggests that microstructures of the materials are optimized dur- ing SPS process,which play a key role in the improvement of strength.