| Thermal behavior of several types of sealing glasses containing PbO, ZnO and B₂O₃, and a borosilicate glass were characterized by differential thermal analysis. Using an isothermal technique, the activation energy for crystallization of a 2PbO·ZnO ·B₂O₃crystalline phase was determined to be 33.6 kilocalorie/mole, and the crystal morphology was plate-like as predicted in the analysis. Using a borosilicate glass and Fe-Ni-Co alloy as a model, reactions between glass-metal systems were evaluated. Microscopic studies of the glass-metal interface indicate the dissolution process of the oxide as well as the precipitation of a second crystalline phase at and near the interface. Two types of Kovar alloys (one standard and the other containing 0.24wt% Cu) were oxidized in air. The oxidation rate of the Kovar alloy containing Cu was slightly lower than that of the standard Kovar at temperatures lover than 850℃. At higher temperature, the effect was negligible. The oxide structure found fur both alloys was a Ni- and Co-containing spinel. |
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