Surface Flattening Kinetics of Lead Silicate and Borosilicate Glasses by Sinusoidal Profile Decay Method

Abstract

In order to elucidate the mechanism of mass transport on glass surface, the amplitude decay was measured of multiple parallel surface scratches on lead silicate and borosilicate glasses in dry N₂ at 547.5°-610.7°C and 694.6°-714.8°C, respectively. The surface profile, which was close to square wave initialy, developed into a sinusoid by pre-annealing, and further annealing resulted in exponential decay of the amplitude of the sinusoidal wave with time. The decay rate constant was inversely proportional to the wave length of the profile. This finding led to the conclusion that the mass transport process occurred via the viscous flow mechanism. The viscosity calculated from the decay rate constant was larger than that obtained by the conventional fibre elongation method, indicating that the viscosity in the surface region was larger than in the bulk.