Heat-Pulse Effects on Glass

Glass components of technological devices that are subject to heat pulses of short duration may suffer damage. At the same time, pulsed heating of glass is a feature of some new processing techniques. An experimental investigation of some of the relevant effects produced in three common glasses of widely different properties is described. Heat pulses were generated in a gas discharge tube under conditions of controlled ambient temperature in the range 20 to 600 degrees C. The intensity of the pulses could be varied up to a level at which considerable evaporation of the glasses occurred. Cracking, weakening, strengthening, and phase separation effects are described and discussed in relation to the stress conditions, and to physical and chemical changes at the surface. Their significance with regard to practical applications is considered.