METHOD FOR THERMAL TREATMENT OF GLASS CERAMIC PRODUCTS Russian patent published in 2009 - IPC C04B33/32 

FIELD: technological processes.

SUBSTANCE: invention is related to production of items from glass ceramics of lithium-silica-alumina composition and may be used in ceramic and aviation industry, in particular for production of large-size, geometrically-complex ceramic items like nose dielectric cones of aircrafts. Method for thermal treatment of glass ceramic items includes drying of item at temperature of 120-250°C, with delay of 1-2 hour. After drying annealing is carried out at the temperature of nucleation of 630-670°C, with delay for 5 hr in low-temperature furnaces. Then additional annealing is carried out at temperature of 850-900°C, for 1-5 hours. Afterwards items are cooled down to temperatures within the limits from room temperature to 250°C. Then temperature is increased with the rate of 100-500°C/hr, and final annealing is carried out at upper crystallisation and sintering temperature of 1230-1250°C, with delay for 4-7 hr in high-temperature furnaces. Afterwards furnace is cooled down to temperature of 250-300°C.

EFFECT: reduced duration of thermal treatment of glass ceramic items in high-temperature annealing furnaces and less rejected items.

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