Partial growth of crack in laser scribing of glass

Abstract

Laser cutting ceramics using an unstable fracture technique Nd:YAG laser drilling of 8.3 mm thick partially stabilized tetragonal zirconia-control of recast layer microcracking using localized heating techniques The scribing of glass by a CO 2 laser is much more effective compared to the conventional mechanical technology in use because the strength of the cut glass is improved since microcracks and particles along the cut edge are lessened. However, the crack depth of laser scribing is limited because the inner compressive stress region under the cooling area prevents median crack growth. This fact was shown by the experimental and thermal stress analyses with a finite element method ͑FEM͒ in the authors' previous study. In this study, the glass was masked partially on the scribing line so as not to generate an inner compressive stress region, and the authors found that the median crack depth of laser scribing was deeper in the experiment. Thermal stress analysis of this phenomenon was conducted by using three-dimensional FEM. As a result, the stress distribution and the phenomenon of which the median crack grew deeper corresponded qualitatively well. It has been supported that the model of laser scribing mechanism proposed in the authors' previous study is valid.