International Journal of Hydrogen Energy, Vol.38, No.35, 15542-15552, 2013
Synergic effect of V2O5 and P2O5 on the sealing properties of barium-strontium alumino-silicate glass/glass-ceramics
The effect of combined addition of P2O5 and V2O5 on structural and sealing properties of glasses with nominal composition (mol.%) 27SiO(2)-23SrO-32BaO-4Al(2)O(3)-10B(2)O(3)-(4-x) P2O5 x V2O5 is reported in the present study. Si-29,P-31,V-51,(27)A1 and B-11 MAS-NMR have been used to characterize the local environment in the glasses and glass ceramics. The main network-forming elements (Si, Al, B) are not significantly affected, however, P and V show different local environment when they are associated in the composition. Characteristic temperatures (T-g, T-soft, T-shrink) decrease when V2O5 is added to the glass composition, which enable to decrease the sealing temperature. However, the combined addition of P2O5 and V2O5 is favorable to avoid extensive crystallization during sealing operation. TEC of the glass and glass ceramics samples is found compatible with those of metallic alloys and do not change after heat treatment. EPMA images show that the seals have good thermal and chemical stabilities when treated up to 1500 h at 800 degrees C. Sandwich seals tested under pressure are resistant to thermal cycling. Copyright (C) 2013, Hydrogen Energy Publications, LLC. Published by Elsevier Ltd. All rights reserved.