METHOD FOR MELTING AND VACUUM CLARIFICATION OF HIGH-TEMPERATURE GLASS Russian patent published in 2014 - IPC C03B5/225 

FIELD: chemistry.

SUBSTANCE: glass is melted in a platinum vessel in a vacuum furnace to volume of more than 4/5 of its height and held for 2-3 hours at a given melting temperature. The vacuum in the furnace is then increased in 8-9 steps in the range from 700 to (100-50) mbar and viscosity interval of (160-35) Pa·s while holding for 0.25-12 hours at each step. After clarification, temperature is optionally lowered until the glass mass achieves working viscosity and the glass mass is moulded into blocks.

EFFECT: obtaining glass of high quality on bubble content with less than 10 bubbles per kg of the glass mass with diameter of less than 0,1 mm when refractory glass is melted in platinum vessels with volume of 5-50 litres.

3 cl, 1 tbl