PURPOSE: Starting materials for glass are roasted in vacuum, then melted and glassified in air atmosphere or a neutral atmosphere, then gradually solidified in vacuum to give a glass completely free from bubbles with excellent high-frequency electromagnetic properties.
CONSTITUTION: A platinum crucible 8 containing starting materials 7 for glass is set on the center of the core tube 3 in the electric furnace and a shield plate 9 is set, then tightly sealed, then the tube 3 is evacuated through switch cock 5 with a vacuum pump 6 until the vacuum reaches 104W105mmHg. The electric power is applied to the furnace to raise the temperature in accordance with a program shown in the figures to control the pressure and the temperature of in the tube 3 with manometer 2 and thermocouple 1. Thus, the vacuum is kept until the temperature rises up to 450W1,000°C where glass starts melting and roasting is continued until the glas product becomes sintered. Then, switch cock 5 is turned to make the tube inside into an atmosphere of neutral or air, further the temperature is raised up to melt the sintered product, then gradually cooled down until splashing of glass can be avoided. The system is evacuated again and gradually cooled down to solidify the melted glass.
UENO TERUO
OTSUBO MITSUO
| JPS53111314A | 1978-09-28 |