高性能碱土铝硅玻璃纤维高温熔体结构与流变性能的研究

The aluminum-silicon glass fibers have excellent mechanical properties and are widely used in the preparation of high-strength high-modulus composite materials to meet the light and high-strength requirements in the fields of national defense, military, and new energy etc., which is of great significance. However, the glass transition process from high temperature to low has not been studied systematically in terms of the rheological properties of the melt. The short in theoretical knowledge has resulted in high production costs and difficulties in obtaining high-strength and high-modulus glass fibers. This project regulates the ratio between alkaline-earth metal oxides, alumina and silica, as well as temperatures during preparation procedures, combining the fitting model to study the relationship between high-temperature melt viscosity and temperature, changes in the fragility and workability; then the application of research methods such as nuclear magnetic resonance to structure research. Explore the underlying reasons of "mixed alkaline earth metal effects" and "aluminous anomalies" as well as their effects on rheological properties. Molecular dynamics simulation will also be used to illustrate the effects of composition and temperature on bond lengths, bond angles, and coordination environment. Finally, the relationship model between component-high temperature melt structure-rheological performance changes will be found. The research results of the project can provide valuable information for exploring the composition of aluminum-silicon glass fibers, with effects from temperature, the "mixed alkaline earth metal effect", "aluminum anomaly" and other structural changes. Their rheological properties such as melt fragility and workability will also be applied to fiber production.

碱土铝硅玻璃纤维具有优异的力学性能而被广泛应用于高强高模复合材料制备以满足国防军工、新能源等领域的轻质高强要求，具有重要的意义。但对于该体系熔体的流变性能，尤其从高温降到低温过程中玻璃转变情况没有系统研究，缺乏理论基础，导致生产成本过高，难以得到高强高模的玻璃纤维。本项目调控碱土金属氧化物、氧化铝及氧化硅比例及制备温度，结合拟合模型研究高温熔体粘度与温度的关系，研究熔体的脆性、料性等变化情况；使用核磁共振等研究手段探究“混合碱土金属效应”、“铝反常现象”的根本原因，及其对于流变性能的影响；使用分子动力学模拟直观模拟组分和温度等对于键长、键角、配位情况的作用，建立并完善组分-高温熔体结构-流变性能变化间的关系模型。项目研究成果能为探究碱土铝硅玻璃纤维体系的组分、温度对“混合碱土金属效应”、“铝反常现象”等结构变化提供宝贵资料，完善其对熔体脆性、料性等流变性能的系统研究，指导纤维生产。

本项目对碱土铝硅酸盐玻璃的高温熔体结构、流变性能以及成型工艺和纤维力学性能进行了研究。碱土铝硅酸盐玻璃纤维具有优异的力学性能而被广泛应用于高强高模复合材料制备以满足国防军工、新能源等领域的轻质高强要求。但是该体系熔体的流变性能，尤其从高温降到低温过程中玻璃转变情况没有系统研究，缺乏理论基础，导致生产成本过高，难以得到高强高模的玻璃纤维。本项目首先进行了Al2O3/SiO2、MgO/CaO、Na2O/SiO2对玻璃结构、流变性能和玻璃纤维拉伸强度的影响，研究表明随着MgO取代CaO，碱土金属氧化物对桥氧的破坏作用先增加后减小。当MgO和CaO含量相等时对桥氧破坏作用最大。铝氧网络和硅氧网络共同构成的玻璃网络，若处于碱过度的条件下，玻璃的聚合度逐渐增加，且拉伸强度逐渐提高。另外，项目研究表明稀土氧化物阳离子具有较大的离子的半径并且其离子场强较大，所以稀土阳离子在玻璃中不能以形成体的形式参与玻璃网络成键，而是以修饰体的形式存在于玻璃网络间隙中，并通过提供游离氧和本身具有较强的电场强度和极化率影响玻璃的结构和性能。而且，项目通过分子动力学模拟对玻璃的高温和低温以及玻璃纤维拉伸过程中玻璃网络的变化进行可视化以及定量表征。利用分子动力学模拟计算了玻璃结构单元对组成、高温流变性能、拉伸过程影响规律，揭示了碱土铝硅酸盐玻璃拉伸过程中以及玻璃熔体高温降至低温的结构演变。本项目为高强高模玻璃纤维的研发提供了有利的理论基础和模拟方法。