Damping of water infiltrated nanoporous glass

Damping studies of Corning Vycor porous glass, code 7930, infiltrated with water showed a mechanism in which water flows from compressed to tensile regions of the specimen which is undergoing a three point bending vibration. This glass had 28% volume porosity, 2.3 nm average pore radius and 207 m2/g internal surface area. The effect of water content in partially saturated specimens revealed that about 40% of water was free to flow and the other 60% or about three molecular layers was adsorbed on the internal glass surfaces and was not free to flow. However, the adsorbed water appeared to increase the damping background at room temperature. The behavior of the loss tangent of the specimen partially saturated with water implied that some pores are full and others are empty except for the adsorbed layer. In addition, the effects of temperature, specimen thickness and average pore size were found consistent with the proposed mechanism.