Repair of glass by sol-gel coating and heating with microwave or conventional techniques

Methods of glass repair were explored. Sol-gel coating and heat treatment by either conventional resistance heating or microwave hybrid heating (MHH) were combined to provide a promising repair method. Repair resulted from filling intentionally induced cracks with sol-gel material via dip coating and then developing strong bonding between the densified gel and the crack sides. Heating the coated samples to the annealing point of the glass resulted in higher fracture strength. Glasses with large crack sizes appeared to need more than one coating while a single coating layer was sufficient with small cracks. Over the range of temperatures studied, microwave hybrid heating produced the same results as conventional heating for all material parameters under consideration. Microwave heating of the glass without the assistance of a microwave susceptor (stand-alone microwave heating or two-step heating using conventional then microwave heating) resulted in large data scattering.