Refractory Alkali‐Free Cristobalite Glass‐Ceramics: Activated Reaction Sinter‐Crystallization Synthesis and Properties
Refractory Alkali‐Free Cristobalite Glass‐Ceramics: Activated Reaction Sinter‐Crystallization Synthesis and Properties
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耐火无碱方石英玻璃陶瓷：活化反应烧结结晶合成与性能
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发表时间：
2012
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通讯作者：
J. Schmelzer
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作者：
R. Pascova;G. Avdeev;I. Gutzow;I. Penkov;F. Ludwig;J. Schmelzer
提出了一种合成化学稳定的β-方石英类微晶玻璃的新方法。它基于在相对较低的温度（1400-1450°C）和较短的热处理时间下压实粉末混合物的活化反应烧结-结晶过程。为了促进均匀的掺杂剂分布，从而形成高含量的β x-方石英样相，具有非常低的热膨胀系数，批料组分以化学、机械或热预活化的形式引入。通过这种方式，避免了在玻璃陶瓷的“经典”合成中通常采用的高温玻璃预熔融。使用不同的，相互补充的分析技术，它表明，最佳的耐火性能实现与玻璃陶瓷含有αx-和β x-方石英固溶体的晶格参数值接近。在这种情况下，这两种方石英类固溶体之间的转变通过一级位移转变进行，通过表现出抑制的一级相变和二级λ型相变的特征的过程进行。由此合成的玻璃陶瓷材料的耐火性能和使用各种成形技术的可能性为其应用开辟了许多领域。
A new approach for the synthesis of chemically stabilized β-cristobalite-like glass-ceramic materials is developed. It is based on an activated reaction sinter-crystallization process of compacted powder mixtures at relatively low temperatures (1400–1450°C) and short heat treatment times. To facilitate homogeneous dopant distribution and thus the formation of a high content of βx-cristobalite-like phases, possessing a very low thermal expansion coefficient, the batch components are introduced in a chemically, mechanically, or thermally preactivated form. In this way, the high-temperature glass premelting usually employed in the “classical” synthesis of glass-ceramics is avoided. Using different, mutually complementary techniques of analysis it is revealed that optimal refractory properties are achieved with glass-ceramics containing αx- and βx-cristobalite solid solutions with close values of the lattice parameters. In this case, the transformation between these two cristobalite-like solid solutions proceeds instead by a first-order displacive transition, by a process exhibiting features characteristic for both a suppressed first-order phase change and a second-order λ-type phase transitions. The refractory properties of the glass-ceramic materials thus synthesized and the possibility to use various forming techniques open many fields for their application.