SHAPED SILICON NITRIDE BEAD AGGREGATES

摘要

Silicon nitride-containing spheroidal beads 3-4 mm in diameter were made by an alginate route from Si,N_4 powder in such a way that their surface contained calcium alginate. Wet beads were rendered tacky upon treatment with an ethylenediaminetetraacetic acid diammonium salt chelating solution. These tacky beads were transferred to containers of desired shape, microwave--dried, calcined, and sintered in nitrogen. The result was shaped Si_3N_4 bead aggre- gates with enough cohesive strength to permit their use as insulation board in high-temperature furnaces.