【摘要】 原位凝固胶态成型工艺 ,譬如凝胶注模成型 ,是目前能制备形状复杂 ,均匀性好和可靠性高的陶瓷材料的理想成型工艺。含硅的陶瓷粉料 ,包括硅 ,碳化硅和氮化硅粉料 ,适于在碱性水溶液中分散。然而 ,硅粉及含在碳化硅和氮化硅粉料中的游离硅易于发生水解 ,放出氢气 ,在胶态成型的坯体中产生显气孔 ,特别在碱性溶液中如此。氮化硅本身在水溶液中具有化学不稳定性 ,易于在碱性条件下水解或与其他化学物质反应放出气体 ,同样可能在坯体中产生气泡。确定凝胶注模成型坯体中产生显气孔的真正原因 ,采用恰当的解决方案 ,可制备无显气孔的坯体更多还原

【Abstract】 In situ consolidation colloidal forming processes, such as gelcasting, are promising techniques for complex shapes of materials with high density, high uniformity and, thus, high reliability of performance Sicontaining powders, eg Si, SiC and Si 3N 4, are suitable for being well dispersed in alkaline solutions However, silicon powder and free silicon contained in silicon carbide and silicon nitride powders have a tendency to hydrolyze, especially in a basic aqueous solution for gelcasting, causing a large amount of macropores in green bodies as a consequence of hydrogen gas evolution Moreover, silicon nitride itself is chemically unstable in aqueous solutions and easy to react with other reagents when processed by aqueous gelcasting, which also affects the microstructure of green bodies After identifying the causes of macropores formation in the gelcast green bodies, some solutions are proposed to overcome these problems更多还原