粉煤灰泡沫玻璃孔隙结构优化及导热机制研究

The organic insulating material(EPS,XPS) widely used in construction nowadays has great potential safety hazard. Fly ash foam glass is a kind of inorganic insulating material that has vesiculartexture. Pore structure of materials have an important bearing on their heat conduction and performance in physical mechanics. Rescently, investigations are mainly macrovisual study, which means pore structure of the materials is seldom concerned with, and there are lags in research of mechanism. Based on experiments, this study, by applying additive modification to fly ash foam glass, tries to characterize its inner pores and construct the physical model of its pore structure; this paper also attempted to employ mechanism of production and evolution law of pore structure in various influencing factors, then it will describe the relationship between pore structure and various influencing factors, which is based on forming process of pore structures and pore characteristics in different technique; simultaneously, the relation between pore structure of fly ash foam glass and its material ratio, additive, tempreture and material performance will be studied by computer simulation, manufacturing technique and analysis of its microstructure; The principle of heat transfer of fly ash foam glass was simulated as the fundation of improving its property and optimizing the preparation procedure and so as to offer the sample and advice to the applyment and popularization of fly ash foam glass plate and at the same time break new way for usage of Fly ash and glass as industrial solid waste.

目前建筑广泛使用的有机保温材料（EPS,XPS）具有重大的安全隐患。粉煤灰泡沫玻璃是防火性能为A级的无机保温材料，具有多孔状结构，孔隙结构与材料的导热、物理性能密切相关。目前研究主要以宏观研究为主，很少涉及到材料孔隙结构，相应机理研究滞后。本课题通过对该材料进行外加剂改性，在实验基础上，对材料内部各种不同孔隙进行表征，建立该材料的孔隙结构物理模型；建立不同影响因素条件下孔隙结构的产生机理及演化规律，通过孔隙结构的形成过程及不同工艺条件下的孔隙特点，给出孔隙结构与影响材料性能因素之间的关系；通过计算机模拟、制备工艺试验及材料显微结构之间的对比分析，研究材料孔隙结构与原料配比、外加剂、温度及材料性能之间的关系，根据孔隙结构利用数值计算模拟材料的传热机制，为材料性能提高及制备工艺优化提供基础，同时对粉煤灰泡沫玻璃板材在墙体的使用推广提供一定的借鉴及参考，也为工业废渣粉煤灰的利用开辟新的途径。

目前建筑中广泛使用的有机保温材料（EPS，XPS）具有重大的安全隐患。泡沫玻璃属于A级难燃多孔轻质保温材料，其气孔的大小和分布直接影响到材料隔热保温性能，而外加剂种类及用量、原材料配比、发泡温度和时间均会对孔隙结构产生直接影响。本项目以粉煤灰和玻璃粉为主要原料，添加适量碳酸钠、磷酸三钠、硼砂等外加剂制备泡沫玻璃，对制品的力学性能、表观密度、孔径、导热系数等物理性能指标进行了测定并对其孔隙结构进行表征。研究了外加剂种类及掺量对粉煤灰泡沫玻璃物理性能的影响，确定了外加剂的最优掺量；采用正交试验方法，研究泡沫玻璃制备的最佳工艺；运用有限元软件分析了泡沫玻璃孔隙率、孔径、厚度对其导热性能的影响，并对导热机理进行了分析，研究成果可有效指导泡沫玻璃的生产，提升产品品质。.项目通过单因素试验、正交试验和ANSYS数值模拟分析对粉煤灰泡沫玻璃强度、表观密度、导热系数等性能参数进行了系统的研究，得到的主要结论如下：.（1）当试样孔径在1-3mm范围均匀分布时，试样保温性能相对较好；当磷酸三钠掺量为4%时，表观密度达到较小值0.224 g/cm3，孔隙率达到80%，孔径大小及位置分布较均匀，其制得的泡沫玻璃试样综合性能较为理想。.（2）当碳酸钠掺量为5%时，制备的泡沫玻璃性能较好，其导热系数为0.0735W/( m•K)，抗压强度为1.58MPa，抗折强度为0.75MPa，表观密度为0.276g/cm3，孔隙率为87.7%。.（3）当碳酸钠的粒径一定时，随着气泡内压强的增大，气泡直径减小；当泡内气体的压强一定时，气孔直径随着碳酸钠粒径的增加而增大。.（4）通过正交试验分析得出制备粉煤灰泡沫玻璃试样的最优方案为：粉煤灰掺量25%、碳酸钠掺量4%、发泡温度为850℃和发泡时间为20min。.（5）当发泡时间为30min、碳酸钠掺量为4%及烧制温度为850℃时，泡沫玻璃试样的平均孔径达到最大0.81mm；泡沫玻璃试样孔径分布于0.1-2mm的孔数量达到80%，泡沫玻璃内孔数量近似呈正态分布。.（6）当孔径为定值时，导热系数随着孔隙率的增大而减小；当孔隙率为定值时，孔径对试样导热系数的影响并不明显；材料内部气孔分布越均匀、排列越整齐，材料热阻越大，其保温性能越好。