Fabrication of Structural Leucite Glass-Ceramics from Potassium-Based Geopolymer Precursors
作者:Ning Xie、Jonathan. L. Bell、Waltraud M. Kriven
DOI:10.1111/j.1551-2916.2010.03794.x
日期:——
Leucite glass–ceramics were fabricated by cold isostatically pressing K2O·Al2O3·4SiO2·11H2O geopolymer powders into pellets followed by firing at 950°–1200°C, every 50°C in air. Leucite formation was observed in specimens heat treated to ≥1000°C. The relative density, Vickers hardness, fracture toughness, and biaxial flexural strength of sintered samples ranged approximately 96%–98%, 767–865 kg/mm2, 0.94–2.36 MPa·m1/2, and 90–140 MPa, respectively. The toughness and biaxial flexure strength increased with the firing temperature, while the density and hardness were relatively constant. Scanning electron microscopic and transmission electron microscopic analysis revealed that the sintered geopolymer formed leucite crystals and a compositionally variable glassy phase. Samples heated to 1200°C attained the highest biaxial flexure strength and toughness. This higher strength is believed to arise from an optimum in density, leucite content, and crystal size distribution.
通过冷等静压成型K2O·Al2O3·4SiO2·11H2O地聚物粉末成颗粒,随后在空气中以950°–1200°C(每50°C为一个温度阶)的温度下烧结,成功制备了白榴石玻璃-陶瓷材料。实验发现,当样品的热处理温度达到≥1000°C时,开始形成白榴石晶体。烧结样品的相对密度、维氏硬度、断裂韧性和双轴弯曲强度分别约为96%–98%、767–865 kg/mm2、0.94–2.36 MPa·m1/2和90–140 MPa。随着烧结温度的升高,样品的韧性和双轴弯曲强度逐渐增加,而密度和硬度则保持相对稳定。扫描电子显微镜和透射电子显微镜分析表明,烧结后地聚物样品形成了白榴石晶体和化学成分可变的玻璃相。在1200°C下烧结的样品获得了最高的双轴弯曲强度和韧性。这一更高的强度被认为源于密度、白榴石含量以及晶体尺寸分布的综合优化。