MECHANICAL PROPERTIES OF SINTERED Si_N_4 FROM POWDER PRODUCED BY FLUIDIZED-BED DIRECT SILICON NITRIDATION

摘要

Si_3N_4 powder, produced by the fluidized-bed direct nitridation of silicon, was blended with water, compacted by pressure slip casting, and sintered under a pressurized nitrogen atmosphere. Compacts made from the powder showed roughly the same sinterability as those made from commercially available imide-process powder, yielding a hardness of Hv 1570, a fracture toughness of 7.2 MPa/m~(1/2), and a three-point bending strength of 1062 MPa, highest values attainable with Si_3N_4. The powder produced by the fluidized-bed direct nitridation may replace the Si_3N_4 powder from the other process, when water is used for preparing slips. A processing rout is proposed, which may realize a substantial reduction of total cost for producing sintered Si_3N_4 parts.