METHOD FOR APPLYING GLASS COATING ONTO INNER SURFACE OF STEEL TUBE Russian patent published in 1998 - IPC

FIELD: production of glass coatings. SUBSTANCE: glass granules are charged into steel tube which is heated in furnace with its simultaneous rotating and displacing. The latter is subjected to cooling in such a manner that temperature in entrance zone of furnace would be higher than melting temperature of glass, and that temperature in exit zone of furnace would be lower than temperature of glass solidification. Rotational speed and movement speed of tube in furnace are maintained constant as function of glass composition and tube diameter. Glass granules may have the following composition, wt.-%: silica, 53, alumina, ; calcium fluoride 5, potassium oxide, 8; sodium oxide, 12; titania, 2; cobalt oxide, 0.5; nickel oxide, 0.5; strontium oxide, 5; barium oxide 10; chrome oxide, 0.5; impurities, 0.5. Temperature in entrance zone of furnace is equal to 850-870 C, while that in its exit zone is 450-500 C. Rotational speed of tube is adjusted to be within range 0.2-1.5 rpm, and it movement speed is 1.0-2.0 m/min. Residence time of tube in furnace is not exceed 15 min. In addition, tube or molten glass mass are caused to vibrate. EFFECT: higher quality of pore-free monolithic glass coating. 4 cl, 1 tbl