Stable cordierite glass-ceramics were prepared from natural kaolin, silica sand and magnesite as raw materials. Furthermore the effect of fluorine additions was tested by addingAlF₃ or MgF₂tothe glass composition. Stable cordierite was crystallized in all glass-ceramic samples during thermal treatment at temperatures in the range from 900to 1200 °C. In the microstructure cordierite, crystals of sizes 15to 50 nm in parent sample and 500 nm to 1 μm in the sample prepared using AlF₃ as raw material were observed, while in the sample prepared from MgF₂as raw materials, the crystal sizes were > 1 μm. The coefficients of thermal expansion of the present cordierite glass-ceramic (CTE) were found to be, 1.14 × 10⁻⁶ K⁻¹ (100–300 °C) for the parent glass and 4.93 × 10⁻⁶ K⁻¹(100–500 °C) for the glass-ceramic containing high AlF₃sample.Also, the microhardness values were between 5. 20 and 6.34 GPa for glass-ceramic samples. The densities of cordierite glass-ceramics increased from 2.07 g/cc in the parent sample to 2.54 g/cc and 2.58 g/cc in AlF₃ and MgF₂ containing samples, respectively. The resultant material can resist the temperature up to 1200 °C.

中文翻译：

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从天然原料中添加不同氟化物的纳米级堇青石玻璃陶瓷

以天然高岭土，硅砂和菱镁矿为原料制备稳定的堇青石微晶玻璃。此外，通过向玻璃组合物中添加AlF ₃或MgF _2来测试氟添加的效果。在900至1200°C的温度范围内进行热处理期间，所有玻璃陶瓷样品中的稳定堇青石都会结晶。在显微组织堇青石中，观察到母体样品中的晶体尺寸为15至50 nm，以AlF ₃为原料制备的样品中的晶体为500 nm至1μm ，而以MgF ₂为原料制备的样品中，晶体的尺寸> 1微米 发现本堇青石玻璃陶瓷（CTE）的热膨胀系数为1.14×10 ^-6母玻璃的 K ^-1（100-300°C）和含高AlF ₃的玻璃陶瓷的4.93×10 ^-6  K ^-1（100-500°C），显微硬度值在5。玻璃陶瓷样品为20和6.34 GPa。堇青石玻璃陶瓷的密度从母体样品中的2.07 g / cc增加到含AlF ₃和MgF ₂的样品中的2.54 g / cc和2.58 g / cc 。所得材料可耐受高达1200°C的温度。