A method for the production of expanded threads of inorganic temperaturbestaendigen substances from the melt

摘要

1,195,947. Crystal-pulling. TYCO LABOIRATORIES Inc. 24 May, -1968 '[29 May, 1967], No. 24955/68. Heading BIS. A dendritic filament is pulled continuously through the orifice (non-die) at the upper end of a capillary tube from melt contained therein and supplied from a crucible containing melt within which, the lower end -of the tube is immersed. The orifice may have a diameter of 0.05-0.5 mm. Pulling may be in a vacuum or an atmosphere of argon or helium and may be at a rate of 150 mm/min. The material may be aluminium, beryllium, chromium, or magnesium oxide, -alumina may be pulled in the direction of its c (0001) axis. The crucible may be of molybdenum or iridium. As .shown, a seed is inserted into and withdrawn from melt 72 in a capillary tube 64 having a cone-shaped upper end 54 with a narrow orifice, the melt being replenished from a crucible 46 having a cover 52 which fits around the cone-shaped end. Melt flows into the tube at its lower end fromthe main body of -melt through slits 70 in a plate 60 having a depending skirt 62. The temperature of the melt is measured by a thermocouple 58. Alternatively, the plate .may be; flush with the bottom of the crucible, the tube being provided with. an orifice above the plate (Fig. 3) or the tube being replaced by a rod having a longitud inal slot (Fig. 4 and 4A). Two or more capillary tubes may be situated in the crucible the thermocouple being ,situated in one tube and a filament being pulled from the other(s) (Fig. 5).