石英玻璃光纤断裂的化学动力学模型

Chemical Kinetics Model for Silica based Optical Fiber Fracture

本文用化学动力学模型描述了石英玻璃光纤中裂纹扩张速率与外部应力和光纤表面反应物种的函数关系，并用以前的光纤断裂模型把裂纹顶端原子键断裂过程看作应力水化反应。对受应变二氧化硅环状结构的水化速率测定可导出硅氧烷水化与应力的相互关系。由硅氧烷水化引起的应力产生了２．０ｃｍ３／ｍｏｌ的活化体积，这与石英玻璃光纤断裂产生的应力一致。此结果支持了基于绝对反应速率理论的光纤断裂模型，并预测了裂纹扩张速率与外部应力强度的关系。

Based on chemical kinetics model, it is described that the rate of crack extension in silica based optical fiber as a function of the applied stress and the presence of reactive species. The approach builds upon previous fracture models that treat the atomic bond rupture process at the crack tip as stress enhanced hydrolysis reaction. The stress dependence of siloxane hydrolysis can be derived from measurement of the hydrolysis rates for strained silicate ring structrues. The stress dependence determined for siloxane hydrolysis yields an activation volume of 2.0cm 3/mol, which is in good agreement with the stress dependence determined for silica glass fracture. This result supports previous fracture models that are based on absolute reaction rate theory and predicts an exponential dependence of crack extension rate on applied stress intensity.