高純度富鋁紅柱石粉末之合成

Preparation of High-Purity Mullite Powders

顏富士(Fu-su Yen)

《鑛冶：中國鑛冶工程學會會刊》 33卷1期 (1989/03) Pp. 119-127

https://doi.org/10.30069/MM.198903_33(1).0010

摘要

富鋁紅柱石（mullite, 3Al_2O_3．2SiO_2～2Al_2O_3．SiO_2）由地殼上最主要的三元素氧．矽及鋁構成。傳統上為最重要的中、高溫材料。未來以其易獲得之優勢，在高科技材料上之應用，前景極看好。以Al_2O_3-SiO_2膠系統合成富鋁紅柱石時，富鋁紅柱石相的生成過程與膠系統性質之關係密切。所謂單相（monophase）與雙相（diphasic）膠混合系，係建立在有否Al-Si-尖晶石（Al-Si-Spinel）之形成。此一尖晶石相的生成似與某些SiO_2-Al_2O_3之混合型態有關，並可能建立在顯微規模上的差異。此種差異使尖晶石相可在低溫生成再轉化高富鋁紅柱石（單相混合），或使富鋁紅柱石之生成不經由尖晶石相之轉換，於低溫或延至高溫由膠系統中直接生成（雙相混合）。

並列摘要

Mullite (3Al_2O_3．2SiO_2～2Al_2O_3．SiO_2), a traditional refractory material will be of high-technologocal importance due to its superior properties and the abundance of the aluminium and the silicon elements in the earth crust. Property of the Al_2O_3-SiO_2 xerogel systems plays the most important role in the preparation of the synthetic high purity mullite powders. Two paths of mullite formation have been found: The single-phase path, in which the mullite has been obtained via transformation of Al-Si spinel, and the diphasic path, in which the phase is formed directly from the reaction of Al_2O_3 and SiO_2. Possible reasons for the difference between the two paths can be the contact surface energy, or the strain energy between the networks of Al_2O_3 and SiO_3. Those with high strain energy can result in formation of the spinel which then transfroms to mullite at higher temperatures. While xerogel which is a mixture of independent particles of Al_2O_3 and SiO_2 will react to form mullite directly. The finer the particle size is, the lower temperature the mullite will be formed.