Thermophysical modeling of bump formation during CO2 laser texturing of silicate glasses

The thermophysical nature of CO2 laser texturing of glass is explored via numerical simulations. Recent data suggest that laser texture bumps are the product of a local elevation in fictive temperature in the heat affected zone. The numerical model is used to investigate the change in microstructure as manifested in a density change. Using viscosity data, the model employs a dynamic calculation of the glass transition temperature as a function of time scale. The calculation shows that the glass transition temperature increases by 150-300 K over the conventional value in the laser texture process. The maximum thermal penetration depth of the glass transition temperature is numerically determined and the density change calculated. On chemically strengthened glasses, laser texture leads to a density reduction of approximately 2%-3% in the heat affected zone. On unstrengthened glass the density reduction is similar to 1.3% (C) 1999 American Institute of Physics. [S0021-8979(99)08001-9].