硅溶胶凝胶工艺成型钛酸铝-莫来石复相陶瓷的研究

STUDIES ON FABRICATION OF ALUMINUM TITAN ART MULLET COMPOSITE BY SILICA SOL GEL CASTING

利用硅溶胶凝胶化反应实现了钛酸铝-莫来石复相陶瓷的原位凝固成型,研究了钛酸铝在硅溶胶中的分散行为和氯化铵浓度对浆料固化时间的影响规律,从显微结构入手对比分析了不同成型工艺对钛酸铝复相陶瓷强度的影响。结果表明:硅溶胶通过静电排斥和位阻效应显著提高了钛酸铝浆料的分散性。随着氯化铵浓度的提高,浆料的固化时间缩短。硅溶胶凝胶成型试样的烧成强度明显高于干压和凝胶注模成型的试样,其主要原因是由于硅溶胶凝胶成型的试样颗粒分散好、烧结程度高以及在烧成过程中原位形成的细小莫来石对钛酸铝晶粒生长的抑制作用。

The green body of aluminium titanate-mullite ceramic was fabricated by in situ solidification through the silica sol gelating. The dispersion behavior of AT powder in silica sol was studied and the dependence of idle time of AT slurry on the concentration of NH4Cl was also discussed. Influence of different shaping methods on the strengths of AT specimens was compared by analyzing their microstructures. The results show that the dispersion of AT slurry was remarkably improved due to both the electrostatic repulsion and the steric effect of silica sol and increase in concentration of NH4Cl can shorten idle time of AT slurry. The bending strength of sintered specimens shaped by silica sol gelcasting is significantly higher than those shaped by drying press and slip casting mainly because of the favorable dispersion, less aggregation of particles, high sintering quality and suppression of AT crystal growth caused by small mullite particles synthesized in situ during firing process.