铝硅酸盐纤维增强SiO2复合材料的制备与性能研究

Research on Fabrication and Properties of Aluminosilicate Fiber-reinforced SiO2 Composites

摘要:

对SiO₂凝胶的无机化与烧结特性进行了研究,结果表明：SiO₂凝胶为无定形结构；经500 ℃煅烧后,凝胶中Si-OH完全无机化,随着煅烧温度的继续升高,产物的结晶性逐渐增强,经1400 ℃煅烧后析出方石英；随着烧结温度的升高,SiO₂陶瓷的相对密度、弹性模量和硬度均逐渐升高。采用溶胶-凝胶工艺制备了三维铝硅酸盐纤维增强SiO₂复合材料,并对热处理温度进行了优化。研究表明：热处理温度为900 ℃时制备的复合材料的力学性能最优,其密度为1.97 g/cm₃,弯曲强度、剪切强度和断裂韧性分别为119.7 ± 7.5(MPa)、10.8 ± 0.7(MPa)和4.0 ± 0.4(MPa.m_1/2)。随着热处理温度的升高,复合材料断面拔出纤维长度逐渐缩短直至消失。

Abstract:

The mineralization and sintering behaviors of SiO₂ gels were investigated. After calcined at 500 °C, the decomposition of Si-OH in the amorphous gels accomplished. As the temperature continued rising, crystallinity of the products strengthened grdually. After calcined at 1400 °C, cristobalite was separated out from amorphous SiO₂. As sintering temperature increased, relative density, elastic modulus and hardness of SiO₂ ceramics were all increased gradually. Three-dimensional aluminosilicate fiber-reinforced silica matrix composites were fabricated by sol-gel process. Effects of sintering temperature on the density, microstructure and mechanical properties of the composites were investigated. The composites prepared at 900 °C displayed the highest mechanical properties. The average flexural strength, interlaminar shear strength and fracture toughness of those composites, with the density of 1.97 g/cm₃, were 119.7 ± 7.5 (MPa)、10.8 ± 0.7 (MPa) and 4.0 ± 0.4 (MPa.m_1/2), respectively. Moreover, as sintering temperature increased, the pullout fiber shortened gradually and eventually disappear at the composite fracture surface.