Deshkar Ambar, Gulbiten Ozgur, Youngman Randall E, Mauro John C, Goel Ashutosh
Department of Materials Science and Engineering, Rutgers, The State University of New Jersey, Piscataway, NJ 08854-8065, USA.
Science and Technology Division, Corning Incorporated, Corning, NY 14831, USA.
Phys Chem Chem Phys. 2020 Apr 29;22(16):8679-8698. doi: 10.1039/d0cp00172d.
The uncontrolled growth of nepheline (NaAlSiO4) crystals during the manufacturing of sodium aluminosilicate glasses via the fusion draw or float techniques and during the vitrification of some of the sodium- and alumina-rich nuclear waste glasses is a well-known problem. The addition of B2O3 to suppress the crystallization in these glasses is well documented in the literature. Another advantage of B2O3 is that it lowers the viscosity of the glass melt and, if incorporated in its trigonal coordination state, will improve the intrinsic damage resistance of the final glass product. Hence, B2O3 has been an integral component of glass compositions for advanced industrial applications and for nuclear waste vitrification. However, one major disadvantage of adding B2O3 to alkali aluminosilicate based glasses is its adverse impact on their chemical durability due to the rapid hydrolysis of B[3,4]-O-B[3,4] bonds in comparison to (Si, Al)-O-(Si, Al) bonds. Therefore, designing a boron-containing alkali aluminosilicate based functional glass with minimal tendency towards crystallization and high chemical durability requires an in-depth fundamental understanding of the mechanism through which B2O3 tends to suppress crystallization in these glasses. There is no current consensus on the fundamental mechanism through which B2O3 tends to suppress nepheline crystallization in these glasses. Based on the mechanisms described and the questions raised in the preceding literature, the present study focuses on addressing the ongoing debate through a detailed structural and thermo-kinetic investigation of glasses designed in the Na2O-Al2O3-B2O3-SiO2 based quaternary system over a broad composition space. Using a combination of Raman and (1D and 2D) nuclear magnetic resonance spectroscopies along with equilibrium and non-equilibrium viscosity, and liquidus temperature measurements, it has been shown that the substitution of Si-O-Al by Si-O-B linkages in the glass structure results in a significant increase in the glass forming ability as well as an increase in the liquidus viscosity (slower diffusivity), thereby suppressing the nepheline crystallization.
在通过熔融拉伸或浮法技术制造硅铝酸钠玻璃的过程中，以及在一些富含钠和氧化铝的核废料玻璃的玻璃化过程中，霞石（NaAlSiO4）晶体的无控制生长是一个众所周知的问题。文献中充分记载了添加B2O3以抑制这些玻璃中的结晶现象。B2O3的另一个优点是它会降低玻璃熔体的粘度，并且如果以其三角配位状态掺入，将提高最终玻璃产品的固有抗损伤性。因此，B2O3一直是用于先进工业应用和核废料玻璃化的玻璃组合物的一个不可或缺的组分。然而，向碱金属铝硅酸盐基玻璃中添加B2O3的一个主要缺点是，与（Si，Al）-O-（Si，Al）键相比，B[3,4]-O-B[3,4]键的快速水解对其化学耐久性产生不利影响。因此，设计一种具有最小结晶倾向和高化学耐久性的含硼碱金属铝硅酸盐基功能玻璃需要深入从根本上了解B2O3倾向于抑制这些玻璃中结晶的机制。目前对于B2O3倾向于抑制这些玻璃中霞石结晶的基本机制尚无共识。基于先前文献中描述的机制和提出的问题，本研究着重于通过对在Na2O-Al2O3-B2O3-SiO2基四元体系中设计的玻璃在广泛组成空间内进行详细的结构和热动力学研究来解决当前的争议。通过结合拉曼光谱和（一维及二维）核磁共振光谱以及平衡和非平衡粘度以及液相线温度测量，结果表明，玻璃结构中Si-O-Al被Si-O-B键取代会导致玻璃形成能力显著提高以及液相线粘度增加（扩散率降低），从而抑制霞石结晶。
