Investigation of Processes in Glass-Ceramic Solders of Sapphire-Niobium Seals in Gas-Discharge Lamps

The processes occurring in glass-ceramic solders of sapphire-niobium seals, used as current lead-ins in gas-discharge lamps with a discharge in alkali-metal vapor, were studied. The structural changes occurring in the glass-ceramic solder, based on the system of oxides CaO-Al2O3 and CaO-MgO-Al2O3, upon heating to 1600 degrees C with niobium diffusing into the melt, are analyzed on the basis of x-ray phase analysis of the composition and a study of the microhardness.