松坂 壮太

Abstract Wheel scribing on glass generates a vertical crack with a periodic stripe pattern beneath the wheel (hereafter referred to as the first crack). After the passage of the scribing wheel, sometimes seconds later, the first crack is repropagated with a smooth surface (the second crack). The second crack propagates to 90% or more of the glass thickness under suitable scribing conditions, facilitating the breaking process. The mechanism of secondary crack propagation has not been sufficiently explained in previous studies. Therefore, this study used analytical and experimental methods to examine stress distribution and crack propagation behavior during wheel scribing. Finite element analysis suggests that the increase in the stress intensity factor contributing to the propagation of the second crack was due to not only the crack opening force but also the bottom deformation of the glass specimen. An analytical model accounting for the bottom deformation can simulate the characteristic behavior, such as rapid deepening when the scribing load exceeds a specific threshold value, of the second crack. This study indicates that the elastoplastic deformation caused by wheel contact induces the deformation of the entire specimen, and the state of the bottom constraints is important for controlling the second crack.

ガラスへの機能付与の一例として，固体イオン交換法を利用したガラス内銀析出物の形成があり，工業応用に向けて銀析出物形状の制御手法が検討されている．本研究では，レーザでの局所加熱を用いた銀析出物形状の制御を試行した．その結果，レーザ加熱部で選択的に銀析出が進行し，析出方向や太さはレーザ走査方向・スポット径により制御可能だとわかった．さらに，環境温度を下げたときレーザ加熱部以外の不要な析出が抑制できた．