Properties of Mechanical Activation Combustion Synthesied High α-Content Silicon Nitride Powders and Sintered Bulk Ceramics after Iteration Reactions

摘要

Effect of iteration times on mechanically-activated combustion synthesis of high α-content Si_3N_4 powders was investigated. Properties of the as-synthesized powders such as α-content (C_α) as well as specific surface area (A_s) were examined. Results showed that both of C_α and A_s became higher after iteration reactions. The mechanical properties of the sintered bulk ceramics from as-synthesized powders were also tested to reveal the sinterability of the powders. Results showed that relative density of all the sintered bulk ceramics were higher than 97%. Furthermore, fracture toughness had a trend of becoming higher, which reached a value of 10.2 MPam~(0.5). Correspondingly, bending strenth became a bit lower.