Healing of lithographically introduced cracks in glass and glass-containing ceramics

The morphological evolution of lithographically defined cracklike flaws in glass and glass-containing ceramics was studied at elevated temperatures. The systems studied have glass contents from 100 to approximately 0.5 vol%, providing insight to the contribution of viscous flow of the glass to crack healing over a range of glass contents spanning many industrial ceramics. Healing behavior is found to be controlled by viscous flow of glass in all cases except the lowest glass content, for which significant mass transport is only accomplished by diffusional mechanisms. This implies a change of mechanism below some critical glass content.