漂珠尺寸对35%漂珠/铝硅酸盐聚合物复合材料组织结构与性能的影响

Influence of Size of Fly Ash Cenosphere on the Microstructure and Property of 35% FAC/Geopolymer Matrix Composite

研究漂珠的尺寸对复合材料的密度、热导率、力学性能以及显微组织和结构的影响。当漂珠尺寸增大到306μm时,抗弯强度从28.5MPa降低至6.4MPa,密度由1.37g·cm–3逐渐减小到0.99g·cm–3,热导率由0.361W·(m·K)–1降低到0.178W·(m·K)–1。SEM观察表明,漂珠在铝硅酸聚合物基体中较均匀地分布。TEM观察发现,在基体和漂珠之间存在一层厚度约为200nm的非晶相的界面层,能谱分析确定界面层成分为KAl9.9Si19Fe2.2O69.9(at%)。非晶相的界面层的生成对降低复合材料的热导率也起到一定作用。结果表明,当在铝硅酸盐聚合物中添加35%(体积分数),直径为306μm的漂珠时可制备出既能满足强度要求又具有较低密度、热导率以及低热收缩的复合材料。

Fly ash cenosphere/geopolymers matrix composite were prepared by adding fly ash cenosphere (FAC) with various sizes. The effect of the size of FAC on the microstructure, mechanical properties, thermal conductivity, density and thermal shrinkage of the composite was studied. When the diameter of FAC is increased to 306 μm, the flexural strength, density and thermal conductivity of the composites are decreased from 28.5 MPa, 1.37 g·cm-3 and 0.361 W·(m·K)-1 to 6.4 MPa, 0.99 g·cm-3 and 0.178 W·(m·K)-1, respectively. The results of SEM indicate that FAC distributes evenly in geopolymers matrix. An amorphous phase layer with thickness of 250 nm between FAC and matrix is observed by TEM, and its chemical composition is Al9.9Si19O69.9KFe2.2 (at%). This amorphous phase layer has an effect on the decreasing of thermal conductivity. The results show that the composite which not only has low density, low thermal conductivity, and low thermoshrinking but also can meet the requirement of the mechanical properties is prepared by adding 35% FAC with diameter of 306 μm.