莫来石/硅酸盐低膨胀率粘接材料固化机理与结构性能

以硅酸钠水溶液、莫来石粉体为原料制备了低膨胀率的莫来石/硅酸盐粘接材料,并通过FT-IR、XRD、NMR等方法对不同温度下热处理的样品进行了表征。结果表明,材料的固化反应发生在室温与400℃之间,为硅酸钠水溶液中的链式或环式聚硅酸、莫来石粉体上的铝羟基间缩合脱水反应,构建了以硅、氧、铝为主的三维体型网状结构;所制备的具有低膨胀系数的莫来石/硅酸盐粘接材料在100～400℃的温度范围,线膨胀系数为(1.2～3.7)×10-6K-1,600℃时线膨胀系数最大为1.45×10-5K-1,套接压缩剪切强度达25MPa。

Structure,properties and curing mechanism of the silicate/mullite composite with low coefficient of thermal expansion

The silicate/mullite composite material with low coefficient of thermal expansion (CTE) for in high temperature bonding has been prepared using a sodium silicate solution and mullite powder. Samples heat treated at different temperatures were investigated by FT-IR, XRD, NMR and other methods. The results showed that curing of the material occurred between room temperature and 400℃ and involved a condensation reaction between hydroxyl groups of linear or cyclic polysilicic acid in the sodium silicate solution and those on the mullite particle surface, leading to a network structure. The CTE increased slowly from 1.2×10^-6 K^-1 to 3.7×10^-6K^-1 as the temperature was increased from 100℃ to 400℃, and the maximum CTE was 1.3×10^-5K^-1at 600℃. The compression shear strength of the material reached to 25 MPa at 600℃. 