Glass and Water: Fast Surface Relaxation
Glasses exhibit relaxation, i.e. time-dependent change of structure, properties and residual stresses normally at a temperature near glass transition temperature or higher temperatures. At a temperature 50°C below the glass transition, no relaxation is expected, in a practical time scale. It was discovered that the surface of glasses can exhibit much faster relaxation in the presence of a trace amount of water or water vapor in atmosphere. For example, a silica glass with the glass transition temperature 1100°C can exhibit surface relaxation at 500°C or lower temperatures. Using this newly discovered phenomenon, it was possible to make mechanically stronger glass fibers and explain various long-standing mysteries, such as unexpected strength degradation of ion-exchange strengthened glasses, glass toughening by application of sub-critical tensile stress, and the origin of the fatigue limit.
Professor Tomozawa received a Ph.D. degree in metallurgy and materials science from the University of Pennsylvania in 1968, after working for the Nippon Electric Company for four years. He joined the faculty at Rensselaer in 1969. He has published extensively in the area of glass science and edited several books on the subject. He served as the Chair of the Glass and Optical Materials Division of the American Ceramic Society and is a fellow of the American Ceramic Society.