Damping of water infiltrated nanoporous glass

Damping studies of Coming Vycor porous glass, code 7930, infiltrated with w ater showed a mechanism in which water Hows from compressed to tensile regi ons of the specimen which is undergoing a three point bending vibration. Th is glass had 28% volume porosity, 2.3 nm average pore radius and 207 m(2)/g internal surface area. The effect of water content in partially saturated specimens revealed that about 40% of water was free to How and the other 60 % or about three molecular layers was adsorbed on the internal glass surfac es and was not free to flow. However, the adsorbed water appeared to increa se the damping background at room temperature. The behavior of the loss tan gent of the specimen partially saturated with water implied that some ports are full and others are empty except for the adsorbed layer. In addition, the effects of temperature, specimen thickness and average pore size were f ound consistent with the proposed mechanism. (C) 2000 Elsevier Science S.A. All rights reserved.