Strengthening of Glass and Pyroceram With Hydrophobic Coatings

Abstract : The objective of this study was to determine whether significant improvements in strength of soda-lime glass and Pyroceram 9606 could be obtained by applying thin hydrophobic coatings. Soda-lime glass slides were coated with a few different hydrophobic compounds (containing organosilicon groups) and then subjected to strength tests in flexure. The glass slides were acid etched to remove surface defects and to slightly mimic the outer fortified surface of Pyroceram. A hydrophobic coating of octadecyl dimethylchlorosilane on soda-lime glass slides led to doubling or more of the strength. The increase in strength is attributed to a reduced role of stress corrosion cracking that is promoted by moisture at the surface. Similar hydrophobic treatments were not effective on Pyroceram bars. Thick was coatings on dry Pyroceram surfaces were successful at improving the strength by about 40%, similar to the effects of dipping in silicone oil.