MgO-Al_2O_3-SiO_2系ガラスの表面結晶化現象

概要

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The surface crystallization of glass with a composition MgO (16.7) , Al_2O_3(22.3), SiO_2(61) (wt% ) was investigated, using XRD, DTA and SEM. Aggregated particles of β-quartz precipitated from fire-polished surface of the glass. The aggregation of non-crystalline spherical particles of about 500-1000 Å was observed in the region cotiguous to the surface layer containing β-quartz. However, the number of spherical particles decreased with depth from the crystallized surface by the logarithmic function, with substantially the same particle size regardless of the depth. The precipitation of β-quartz, petallite and α-cordierite was observed for the sample with mechanically polished surface. The surface crystallization; in this case developed into the glass with the dendrite structure. In the glass having a fire polished surface, the amounts of β-quartz and petallite passed through maxima during isothermal treatment at 950℃, whereas the amount of a-cordierite increased monotonously with time. This suggests that a-cordierite was formed not only by the direct precipitation from the glass, but also by the transformation of β-quartz and petallite.
社団法人日本セラミックス協会の論文
1988-03-01