作者：Takashi Sato;Yoshinari Sawabe;Yutaka Ohya;
作者單位：Akita University
刊名：Journal of the Technical Association of Refractories
ISSN：0285-0028
出版年：2006-01-05
卷：26
期：3
起頁：242
止頁：0
分類號：TQ175
語種：英文
關鍵詞：
內容簡介It has been reported that when mullite system ceramics containing glassy phase were heat-treated at a temperature less than eutectic point (1585 deg C), the mechanical properties were improved due to crystallization of the glassy phase into cristobalite1'. This crystallization phenomenon progresses with time into the interior from the surface. In the case where the specimen is perfectly protected from the introduction of impurities, it is possible to transform the whole specimen into crystalline material. However, in the case of heat-treating in an open system, it was observed that the crystalline surface returned to the amorphous state. To investigate this phenomenon in detail, qualitative analysis of the specimen surface was carried out by secondary ion mass spectrometry (SIMS). This analysis disclosed that more sodium component was present on the surface layer than in the interior part. It was conjectured, judging from the result of this analysis, that the return of crystallized cristobalite into the amorphous state was greatly influenced by the presence of Na_2O.
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