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首页> 外文期刊>Journal of Non-Crystalline Solids: A Journal Devoted to Oxide, Halide, Chalcogenide and Metallic Glasses, Amorphous Semiconductors, Non-Crystalline Films, Glass-Ceramics and Glassy Composites >Thermal expansion of glass-ceramics in the system BaO/Al2O3/B2O3
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Thermal expansion of glass-ceramics in the system BaO/Al2O3/B2O3

机译：BaO / Al2O3 / B2O3系统中玻璃陶瓷的热膨胀

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Glasses in the system BaO/Al2O3/B2O3 with and without the addition of platinum were melted. In one sample series, the BaO-concentration was varied while the ratio [Al2O3]/[B(2)O3] was kept constant. In another sample series, the [BaO]/[Al2O3]-ratio (= 0.9) was kept constant and the B2O3 concentration was varied. The samples were thermally treated at 720 degrees C for 24 h and subsequently at 780 degrees C for 4 h. In most thermally treated samples, the crystalline phase BaO center dot Al2O3 center dot B2O3 occurred. At some compositions, the platinum-doped samples showed larger concentrations of the crystalline phases. The most remarkable property of the obtained glass-ceramics is their zero or neaative thermal expansion coefficient. Here, notable differences were observed: samples with fine grained microstructures showed thermal expansion coefficients approximately zero up to temperatures of around 80 degrees C. By contrast, samples with coarser microstructures and large spheroidal crystals exhibit negative expansion coefficients up to temperatures of around 280-375 degrees C. The thermal expansions of these samples were close to those of the mean thermal expansion of the unit cell of the BaO center dot Al2O3 center dot B2O3 phase. The thermal expansion of the fine grained samples was approximately equal to that of the crystallographic a-axis of the BaO center dot Al2O3 center dot B2O3 phase. (c) 2005 Elsevier B.V. All rights reserved.
机译：BaO / Al2O3 / B2O3体系中添加和不添加铂的玻璃均被熔化。在一个样品系列中，BaO浓度发生变化，而[Al2O3] / [B（2）O3]的比值保持恒定。在另一个样品系列中，[BaO] / [Al2O3]-比率（= 0.9）保持恒定，并且B2O3浓度变化。将样品在720摄氏度下热处理24小时，然后在780摄氏度下热处理4小时。在大多数热处理过的样品中，会出现结晶相BaO中心点Al2O3中心点B2O3。在某些组成下，掺杂铂的样品显示出较大的晶相浓度。所获得的玻璃陶瓷的最显着特性是其零或初始热膨胀系数。在这里，观察到显着差异：具有细晶粒微结构的样品在80摄氏度左右的温度下显示的热膨胀系数约为零。相比之下，具有较粗微结构和大球状晶体的样品在高达280-375的温度下显示负膨胀系数这些样品的热膨胀接近BaO中心点Al 2 O 3中心点B 2 O 3相的晶胞的平均热膨胀。细颗粒样品的热膨胀大约等于BaO中心点Al 2 O 3中心点B 2 O 3相的晶体学a轴的热膨胀。 （c）2005 Elsevier B.V.保留所有权利。

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