配方原料中SiO_2含量的改變對低溫合成堇青石之影響

Low Temperature Effects on Cordierite Synthesis Induced by SiO_2 Content Variation of the Starting Formula

林逸歆(Yi-Hsin Lin) ； 顏富士(Fu-Su Yen) ； 向性一(Hsing-I Hsiang)

《臺灣鑛業》 69卷2期 (2017/06) Pp. 21-32

摘要

本研究觀察改變堇青石計量配方中的SiO_2 含量，對於低溫生成堇青石的過程以及α-cordierite 生成量的影響。研究中以滑石、高嶺土以及人工氧化鋁粉末為配方原料，將原料中部分高嶺土以SiO_2（石英粉）及Al_2O_3（氧化鋁粉）取代。同時改變SiO_2 含量，設計出缺SiO_2 配方及富SiO_2 配方。研究結果主要透過PSD、DTA、XRD、TEM 等儀器分析。得到結果發現：富SiO_2 配方的SiO_2 會先和Al_2O_3 在低溫合成富鋁紅柱石。加上原有高嶺土轉化過來之富鋁紅柱石，再與滑石生成之頑火輝石於較低溫大量合成β-cordierite，也使大量α-cordierite 在較高溫出現。相較之下，缺SiO_2 配方的β-cordierite 雖也於低溫生成，但其主要反應途徑為Spinel。由Spinel 生成之α-Cordierite 配合β-cordierite 的相變反應，顯然可於低溫得到較多α-Cordierite。

關鍵字

堇青石 ； 氧化矽 ； 富鋁紅柱石 ； 氧化鋁

並列摘要

The alternation in thermal reaction routes induced by varying SiO_2 contents of the formulas used in synthesizing cordierite powders were investigated. Talc, kaolin and corundum were used as the basic raw materials, in which a part of kaolinite powder was replaced by powders of quartz(SiO_2) and alumina (Al_2O_3) on the base of stoichiometry. Samples with SiO_2-lean, SiO_2 were reduced, and SiO_2-rich, SiO_2 was increased, were formulated. Examinations were then performed by PSD, DTA, and XRD techniques. It is found that, for the SiO_2-rich samples, the SiO_2 would react with Al_2O_3 to form mullite at lower temperatures, resulting in a continuous presence of β-cordierite from low to moderate high temperatures. As a result, the α-cordierite that mostly converted from β-cordierite then inevitably appears at higher temperatures. On the contrary, for the SiO_2-lean samples, the SiO_2 deficiency would promote the reaction of Al_2O_3 in the formula with the prevailing enstatite to form spinel, resulting in the formation of α-cordierite starting at a lower temperature. As a result, the α-cordierite can be existence instead of β-cordierite at lower temperatures for SiO_2-lean samples.

並列關鍵字

Cordierite ； SiO_2 ； Mullite ； Al_2O_3