20 likes | 151 Views
Adsorbed Water Can Make Glass Weaker or Stronger Seong H. Kim, Pennyslvania State Univ University Park, DMR 1207328. Pyrex ball counter-surface.
E N D
Adsorbed Water Can Make Glass Weaker or StrongerSeong H. Kim, Pennyslvania State Univ University Park, DMR 1207328 Pyrex ball counter-surface Although multicomponent silicate glasses are used in a variety of advanced technical applications, little is known about their surface chemistry in humid ambience. Researchers at Penn State studies the effects of water adsorbed on glass on surface reactions and properties of multicomponent glass materials. The spectra shown here indicate the presence of three distinct water species or structures on soda lime glass. Their populations vary with the relative humidity (RH) of the ambience. When a soda lime glass is scratched with a pyrex ball, its wear behavior changes from soda lime wear at low RH to pyrex wear at high RH. This wear behavior change upon increase of humidity can be correlated with the growth of the water peak at 3200cm-1 at the soda lime glass, which is putatively attributed to the hydronium (H3O+) ion. When Na+ ions are exchanged with larger ions (such as K+ in the Gorilla glass used for iPhone), then a compressive stress is generated in the silicate network and the glass becomes tougher. The similar effect is expected when the H3O+ ions (larger than Na+) are formed in the soda lime glass surface at high humidity. Water at soda lime glass surface RH 90% RH 20% Soda lime glass substrate Wear of ball and substrate surfaces
Adsorbed Water Can Make Glass Weaker or StrongerSeong H. Kim, Pennyslvania State Univ University Park, DMR 1207328 Sammie Ely III, an undergraduate student from Tuskegee University, Alabama, worked on poling of soda lime glass to increase the surface concentration of sodium and its effects on the sodium leaching / ion exchange and wear behavior of the glass surface. Na-Yeon Hong from Korea University, Korea, and Hongtu He from Southwest Jiaotong University, China, came to Penn State and studied surface reactions of soda lime glass in humid air as well as aqueous solutions. They brought international culture to the lab and interacted with many graduate and undergraduate lab members. Sammie Ely measuring friction of glass in controlled humidity Hongtu He and Na-yeon Hong working for microscopic imaging