STRUCTURED-FIELD PRODUCING ELECTROMAGNET, BERYLLIUM CRYSTAL ANNEALING AND OPERATION Russian patent published in 2000 - IPC

FIELD: thermal treatment of crystals; jewelry industry. SUBSTANCE: electromagnet has wound toroidal coil whose radii ratio R₁:R₂ = 1:2 and series-connected sectors placed on coil over torus surface generating line in which extreme and mean ratio of their width to width of unwound areas S1:S2 = 3: 5. Crystal annealing device has electromagnet, heat-insulating body of furnace, working chamber accommodating specimens and electrodes, and power supply. Nonmagnetic heater is, essentially, bifilar winding. Beryllium crystals are cleaned of impurities, rinsed with distilled water, and dried out in drying cabinet at 105-120 C for 24-72 h. Then they are toned in molten benzoic acid at 130-140 C. After that, specimens are placed in furnace working chamber and heated at a rate of 5-15 deg/h and temperature of 450-500 H followed by their exposure to this temperature for 24-72 h. Specimens are cooled down in furnace at a rate of 5-15 deg/h to room temperature. During their heating in furnace specimens are also exposed to DC magnetic field of 400-450 A/m intensity and electrostatic field of 3000 V/m intensity. Upon cooling down, specimens are held in water for 172-120 h and then compared with standard. So, natural properties of crystals occurring in raw material are recovered. EFFECT: improved yield of good and spent crystals. 3 cl, 9 dwg, 1 tbl