Title: PHYSICAL CHEMISTRY OF GLASS-METAL INTERFACES

Interface fracture resistance measurements have been conducted on metal/ceramic interfaces with and without reaction products. Both ductile and brittle interface fracture have been documented. Some effects of residual stress have also been investigated. The influence of thermal expansion misfit on the mechanical behavior of metal/ceramic bonded systems has been shown to be strongly governed by the sign of the misfit strain, its magnitude, the yield strength of the metal and to be subject to substantial geometric effects. In some cases, the misfit causes interface failure, while in other, cracking occurs in the ceramic. Generally, misfit has detrimental effects on bondmore » strength, but in special cases, the bond strength can actually be improved. Reaction products exhibit a wide variety of fracture behaviors. In some cases, the reaction products are brittle and subject to residual stress, leading to low fracture energy interfaces governed by the fracture resistance of the reaction product. In other cases ductile reaction products occur, resulting in good bond properties and fracture energies that increase as the reaction product layer thickness increases. Stress corrosion has been found to occur at oxide/metal interfaces, leading to substantial reductions in the fracture resistance. The phenomenon is governed by water vapor and is similar to, but more pronounced than, that found in oxides.« less

In 1986, approximately 2000 samples of waste glasses and proposed package components were buried in the salt formation at the Waste Isolation Pilot Plant (WIPP) in Carlsbad, New Mexico. These samples are part of a five year study, called the Materials Interface Interactions Tests (MIIT), being managed by Savannah River Laboratory (SRL) and Sandia National Laboratory (SNL). MIIT involves the active participation of eight countries, including Belgium, Canada, France, Germany, Japan, Sweden, the United Kingdom, and the United States. The main objective of the present study is to investigate the interactions of SRL Y (165/TDS) waste blass with proposed metalmore » canister or overpack materials, and more specifically, to determine what effect these metals have on leaching of the SRL waste glass system. Metal systems studied include 304L stainless steel, TiCode-12, lead, and A216 carbon steel. Analyses were performed using scanning electron microscopy (SEM) along with complementary energy dispersive x-rays (EDX). These results are then correlated to an earlier MIIT study which assessed the behavior of the same SRL waste glass system in WIPP but without metal present. 9 refs., 28 figs., 3 tabs.« less

During the formation of a glass-ceramic to metal seal with nickel-based superalloy Inconel 718, hydrogen bubble formation was observed in the glass-ceramic. This bubble formation was caused by the reaction of dissolved metals with adsorbed water, all of which are in the glass-ceramic. The dissolved metals are present in the glass from dissociation of the Inconel 718, and the water is present in the glass prior to seal formation. To inhibit bubble formation, the glass-ceramic was spiked with 1 wt % CuO. This spiking allowed competing reactions to occur, thus causing the formation of copper and/or Cu/sub 2/O in themore » glass-to-metal interface and reducing bubble formation. Spiking with 1 wt % Cr/sub 2/O/sub 3/ also inhibited bubble formation. Thermodynamic data suggest that hydrogen formation is responsible for bubbles in a wide variety of seal systems, including glass-to-metal seals in which the metal is or contains iron, manganese, chromium, niobium, titanium, or aluminum.« less