以化學共沉法製備SiC鬚晶強化ZTA微粉之研究

Preparation of Fine SiCw/ZTA Powders by Chemical Coprecipitation Methods

陳智成(C. C. Chen) ； 顏富士(F. S. Yen)

《鑛冶：中國鑛冶工程學會會刊》 37卷1期 (1993/03) Pp. 127-140

摘要

鬚晶強化陶瓷的製備存在許多問題，包括：鬚晶不易均勻分散於陶瓷基底，鬚晶易產生方向性排列及燒結緻密化困難等。故常以添加分散劑、燒結促進劑及採用熱壓燒結法來改善製程，唯其不利於機械性質，且難以商業化生產。本研究以化學共沉法製備SiC_w/ZTA微粉，可使SiC鬚晶均勻分散於ZTA微粉中，且粉末粒徑細，表面積高，唯其燒結密度受鬚晶的影嚮，隨鬚晶添加量的增加而急速降低。SiC鬚晶之前處理會影響到微粉之性質，經HF酸處理後之SiC鬚晶可去除其表面之不純物，雖然在同一pH值下，其介面動電位之分散效果較差，唯在pH=10的條件下皆可達到分散之效果。本研究並探討在膠體煆燒過程中，SiC鬚晶對AI_2O_3相變化之影嚮。

並列摘要

Many problems are encountered in the preparation of whisker-reinforced ceramics: uneven dispersion of the whisker which shows preferred-orientation over the ceramic matrix, and difficulty in densification, etc. As a result dispersants and sintering aids are often used, and the hot pressing method is employed as well. Both methods cause deterioration in its mechanical properties and retard its commercialization potential. This study attempts to prepare SiC_w/ZTA ceramics through powders obtained by chemical coprecipitation methods, by which SiC whiskers can be dispersed evenly in the powders. Powders thus prepared is of ultrafine size with high specific surface area. However sintering density is highly affected by the addition of whisker. As the amount added incerases, the sintering density decreases quickly. Pretreatments for SiC whiskers with HF acid would afftect the nature of the powders obtained. HF seems to remove the impurity on the surface of SiC whiskers compared with the oringinal at the same aqueous pH, although the treated SiC whisker can also be well dispersed at pH-10. In this study also discuss the phase transformation phenomena of AI_2O_3 duing calcination of Xerogels due to the presence of SiC whiskers is also disussed.