Fabrication of dense Si₃N₄ ceramics via coating amorphous Si₃N₄ nano-powders by sodium reduction in liquid ammonia

抄録

Commercial Si₃N₄ powders coated with 0–30% amorphous Si₃N₄ nano-powders were fabricated successfully. Amorphous Si₃N₄ nano-powders coating were prepared through the reduction of silicon tetrachloride (SiCl₄) by sodium in liquid ammonia at −45°C. Dense Si₃N₄ ceramics with 97.2% relative density of theoretic value were obtained from Si₃N₄ micro-powders coated with 30% nano-powders sintered by spark plasma sintering at 1500°C without sintering additives.