Reactions at Glass‐Ceramic to Metal Interfaces

Advanced pyrotechnic components can be fabricated from Ni-based superalloys with hermetic seals to high expansion lithium-silicate glass ceramics (LSGC). Prior studies have characterized the interfacial reactions in these systems necessary for good chemical bonding. Similar reactions occur when LSGCs are bonded to 300-series stainless steel except that these seals debond on cooling to room temperature. Cr-depletion (from {approximately}18 wt % to {approximately}5 wt %) from the steel interface cases an fcc-to-bcc phase transition that expands the interfacial grains and decreases their thermal expansion coefficient, putting the LSGC into tension, causing the seal to fail. 9 refs., 5 figs., 1 tab.