磷酸盐基矿聚物材料的制备与机理研究

Preparation and mechanism of phosphate based geopolymer

为分析酸激发矿物键合材料的形成机理,使用镁砂作为改性剂,利用磷酸铝溶液和偏高岭土反应,制备了一种磷酸盐矿物键合材料.通过正交实验测定试件的抗压强度,得到具有最优性能的材料配合比,对最优配合比的试样进行微观结构表征,分析磷酸盐矿物聚合材料的反应机理.结果表明,当硅和磷的物质的量比为1.2、磷和铝的物质的量比为3.0、镁砂的质量分数为18%时,磷酸盐矿物键合材料的抗压强度最高;偏高岭土与磷酸盐溶液反应生成磷酸盐矿物键合材料的反应机理的阶段为解聚、缩聚和凝胶网络化,聚合反应主要是发生在偏高岭土的铝氧层并非硅氧层;镁砂主要作用不是参与聚合反应,而是通过结合磷酸盐溶液生成水化磷酸镁(MgHPO 4·3H 2O)晶体,增强材料的致密性.

A phosphate based geopolymer was studied to understand the formation mechanism of acid activated mineral.The material was prepared by the reaction of aluminum phosphate solution and metakaolin,and magnesia was used as a modifier.The optimal material mix ratio was obtained by an orthogonal experiment,and the compressive strength test and microstructure analysis were carried out on the sample with the optimal mix ratio,then the reaction mechanism of phosphate based geopolymer was analyzed.The results show that when Si and P molar ratio is 1.2,P and Al molar ratio is 3.0,and the magnesia content is 18%,the compressive strength of the phosphate based geopolymer is the highest.The formation mechanism between metakaolin and phosphate solution is divided into three stages,depolymerization,polycondensation and forming gel network.The polymerization occurs mainly in the alumina layer rather than the silicon oxide layer in metakaolin.Magnesia does not participate in the polymerization,but it reacts with phosphate solution to form MgHPO4·3H2O crystal,which improves the microstructure of phosphate based geopolymer material.