Behaviors of Fracture Toughness of Thin Transparent Glass for LiquidCrystal Display by EB Irradiation

摘要

An influence of electron beam (EB) irradiation on the crack generation and propagation of transparent glasses arestudied by using a standard indentation fracture method. The thin (less than 0.5mm) transparent glass is used forsubstrate of more than 100 inches crystal liquid display. However, it is difficult to product ultra thin and large-sizesubstrate without fracture. Therefore, these glasses have been expected to enhance the fracture toughness ofsubstrate for the displays. As results, EB irradiation, which is one of short-time treatments of dry process at low temperature, increases thecrack nucleation energy of these glasses, although the EB irradiation does not change the crack propagation energyof these glasses. The EB irradiation generates dangling bonds in these glasses. Partial relaxation of the residualstrain occurs around these dangling bonds in the silica network structure. If the inter-atomic distance of thestronger metal-oxygen pairs becomes optimum on the potential curve of these glasses, the relaxation increases thebonding energy of the network structure. Evidently, the enhancement of crack nucleation energy is mainly due toan increase in the bonding energy for the stronger metal-oxygen atomic pairs in the atomic network structure, aswell as the relaxation of the network structure.