| 摘要 |
1,130,070. Induction heating. COMMISSARIAT A L'ENERGIE ATOMIQUE. 29 March, 1967 [5 April, 1966], No. 14243/67. Heading H5H. [Also in Division B1] A radio frequency induction furnace for melting refractory materials, e.g. UO 2 , Al 2 O 3 , MgO, zirconia, introduced in powder form and subsequently resolidified has the water-cooled copper inductor coil 1 separated from the charge 3 by a protective sheath 2 transparent to the radio-frequency radiation of coil 1 and comprising water cooled copper casings 5 separated by quartz or alumina strips 6 or sprayed with alumina. The casings 5 are mounted on a water-cooled ceramic base 11, and bound with glass or alumina fabric (see chain dots) or provided with top and bottom manifolds. Initially, to start the fusion, coil 1 is in the bottom position with respect to sheath 2 and a thin layer of the powdered charge is placed on the base 11 and preheated. If the fusion is performed in air thin plates of the metal whose oxide constitutes charge 3 are placed on the layer and the metal oxidizes and heats to start fusion. If the fusion is performed in a protective atmosphere, e.g. reducing, O 2 , an impervious quartz casing 16 has tubes for establishing this atmosphere and a tungsten filament is placed on the layer. Preheating can alternatively be carried out by a plasma or auxiliary arc torch. The layer melts except for an annular zone (12, Fig. 2) adjacent the sheath, which remains in the powdered or sintered state. Sheath 2 is then fed progressively with charge 3 and coil 1 is moved progressively in direction 4, the melted zone behind coil 1 re-solidifying, zone adjacent coil 1 melting, and zone above coil 1 remaining in powdered form, the liquid-solid fronts moving with coil 1. Casings 5 may have a profiled crosssection and sheath 2 may have a square- or star-shaped cross-section to produce refractory rods of similar shape. |
