Surface Modified Silicon Nitride Powder with Highly Dispersed Sintering Aid via Aqueous Processing

摘要

Highly dispersive loading of Y~(3+) ions, as a sintering aid, on Si~N4 powder via aqueous processing has been presented. The chemical stability of Si_3N_4 powder in pressured and saturated water vapor was improved by a chemical surface modification with dicarboxylic sebacic acid, while maintaining hydrophilic surface. The treatment of the sebacic acid-modified powder with yttrium acetate tetrahydrate resulted in strong immobilization of Y~(3+) ions at a highly dispersive level on the Si_3N_4 powder surface through ion-exchange with the free carboxyl groups of the sebacic acid molecules attached to the Si_3N_4 surface. The highly dispersive sintering aid promoted hot-press densification of Si_3N_4 even with a small loading amount, in comparison with materials added with Y_2O_3 powder as a sintering aid.