Abstract: A graphite crucible for electromagnetic induction-based silicon melting and an apparatus for silicon melting/refining using the same, which performs a melting operation by a combination of indirect melting and direct melting. The crucible is formed of a graphite material and includes a cylindrical body having an open upper part through which a silicon raw material is charged into the crucible, and an outer wall surround by an induction coil, wherein a plurality of first slits are vertically formed through the outer wall and an inner wall of the crucible, and a plurality of second slits are vertically formed from an edge of the disc-shaped bottom of the crucible toward a center of the bottom.

Abstract: A cold crucible induction furnace has a slotted-wall with a slotted inner annular protrusion that is disposed around the base of the crucible's melting chamber. The protrusions may be separated from the base by a gap that can be filled with an electrical insulating material. Slots may also be provided in the protrusions and/or the outer perimeter of the base.

Abstract: A continuous- or intermittent-melt induction furnace useful for heating and/or melting semi-conductor or other materials includes an induction coil, a susceptor switchable between open and closed electric circuit modes, and a crucible. The susceptor is inductively or resistively heated in the closed circuit mode and transfers heat to material in the melting cavity to make it susceptible to inductive heating. The susceptor is then switched to the open circuit mode and the susceptible material is directly inductively heated to melt remaining solid material. A cone-shaped flow guide in the melting cavity improves molten material flow to improve the ability to draw small-particle material into the melt and increase crucible life due to improved heat uniformity. A trap passage communicating with the melting cavity and an exit opening in the crucible allows the flow of material through the exit opening to be controlled by pressure differentials on either side of the trap passage.

Abstract: A continuous- or intermittent-melt induction furnace useful for heating and/or melting semi-conductor or other materials includes an induction coil, a susceptor switchable between open and closed electric circuit modes, and a crucible. The susceptor is inductively or resistively heated in the closed circuit mode and transfers heat to material in the melting cavity to make it susceptible to inductive heating. The susceptor is then switched to the open circuit mode and the susceptible material is directly inductively heated to melt remaining solid material. A cone-shaped flow guide in the melting cavity improves molten material flow to improve the ability to draw small-particle material into the melt and increase crucible life due to improved heat uniformity. A trap passage communicating with the melting cavity and an exit opening in the crucible allows the flow of material through the exit opening to be controlled by pressure differentials on either side of the trap passage.

Abstract: An induction furnace capable of operation at temperatures of over 3100° C. has a cooling assembly (60), which is selectively mounted to an upper end of the furnace wall (76). The cooling assembly includes a dome (62), which is actively cooled by cooling water coils (68). During the cool-down portion of a furnace run, cooling initially proceeds naturally, by conduction of heat away from the hot zone through a furnace insulation layer (58). Once the temperature within the furnace hot zone (20) reaches about 1500° C., a lifting mechanism (80), mounted to the dome, raises a cap (16) of the furnace slightly, allowing hot gases from the hot zone to mix with cooler gas in the dome. This speeds up cooling of the hot zone, reducing cool-down times significantly, without the need for encumbering the furnace itself with valves or other complex cooling mechanisms which have to be replaced periodically.

Abstract: A vacuum chamber for induction heating and/or melting of a metal permits a significant portion of the magnetic field produced in the vacuum induction heating and/or melting process to make contact with the wall of the chamber without causing the chamber wall to overheat from induction heating.

Abstract: An induction furnace that has a plurality of high temperature electrically conductive ceramic electrodes having no connecting electrical lead (leadless electrode). The leadless electrodes are exterior to and proximate a working furnace space. At least one metallic electrical conductor surrounds but is not connected to the ceramic electrodes and a power supply is connected to the at least one electrical conductor so that activation of the power supply creates an alternating current through the electrical conductor of sufficient energy to create an electromagnetic flux of sufficient flux density to heat the at least one ceramic electrode to a temperature in excess of about 1700° C. to heat the space.

Abstract: An induction furnace capable of operation at temperatures of over 3100° C. has a cooling assembly (60), which is selectively mounted to an upper end of the furnace wall (76). The cooling assembly includes a dome and a lifting mechanism (80), mounted to the dome, which raises a cap (16) of the furnace slightly, allowing hot gases from the hot zone to mix with cooler gas in the dome.

Abstract: The invention relates to a device for manufacturing a preform, wherein a carrier tube is collapsed to a preform, which device comprises a heating element forming a cylindrical envelope, which envelope defines an annular inlet opening and an annular outlet opening at opposite ends of the envelope, a carrier tube being present within the cylindrical envelope, between said openings, the heating element being movable in axial direction with respect to the carrier tube, and means for supplying a non-oxidizing gas to the space between the carrier tube and the envelope.

Abstract: Apparatus suitable for vitrifying nuclear waste comprises a tunable microwave cavity connected by a first wave guide to a source of microwave energy; cooling coils for cooling the exterior of the cavity; a hopper for loading particulate fusible material to the interior of the cavity; within the cavity a crucible made of melted and re-solidified fusible particulate material; an exit-chamber connected by a second waveguide to a second microwave source; and a pipe for supplying argon gas to the exit chamber so that a plasma torch can be generated. The separating of the crucible form the cavity walls by unmelted material gives significant advantages in case of cleaning and reduced energy consumption.

Abstract: The invention relates to a device for manufacturing a preform, wherein a carrier tube is collapsed to a preform, which device comprises a heating element forming a cylindrical envelope, which envelope defines an annular inlet opening and an annular outlet opening at opposite ends of the envelope, a carrier tube being present within the cylindrical envelope, between said openings, the heating element being movable in axial direction with respect to the carrier tube, and means for supplying a non-oxidizing gas to the space between the carrier tube and the envelope.

Abstract: Device for injecting non-oxidizing gas into a furnace with a graphite concentrator (12) as the heating element used to heat a primary preform in the enclosure of the furnace (14) and moving relative to the furnace in its axial direction, and comprising at the inlet orifice (24) and at the outlet orifice (26) of the enclosure a respective annular injector (40, 42) for injecting two conical curtains of non-oxidizing gas, the gas for each of the curtains being directed towards the apex of the cone and in the direction away from the enclosure (14) so as to prevent any entry into the enclosure of air that could cause combustion of the graphite.

Abstract: The fiber-drawing furnace includes a graphite tube positioned vertically, heated by induction, and subjected internally to an inert atmosphere, said tube internally defining a fiber-drawing chamber. In the furnace said graphite tube is a double-walled tube having an inner wall and an outer wall, its inner wall is porous and separates the fiber-drawing chamber from a peripheral chamber defined between the walls and subjected to a flow of inert gas which diffuses through said porous wall into said fiber-drawing chamber. Application to drawing down an optical-fiber preform.

Abstract: Disclosed is a levitation melting crucible which can facilitate penetration of magnetism into the crucible and which can prevent a molten metal from being contaminated by an insulating material. The levatation melting crucible comprises a cylindrical main body having a closed bottom, a plurality of slits defined vertically in the circumferential wall of the main body to open inward and outward at predetermined intervals in the circumferential direction and an insulating material filled in each of the slits; wherein each slit is designed to have an inner opening width smaller than its outer opening width, with respect to the radius of the main body, for example, 1.5 A>B.

Abstract: A furnace configuration is disclosed in which the furnace is inductively heated by external insulated coils and a susceptor is placed within the charge of reactants away from the outer surfaces of the charge. Consequently, heat is transferred to the charge and the process approaches completion before the insulation is subjected to high temperatures.

Abstract: Induction heating vessels and methods are disclosed. One embodiment of an induction heating vessel is a bottom pouring vessel with a crucible for containing a molten metal to be heated and having an outlet in the bottom. A metallic shell with integral current limiters surrounds the crucible. A stopper is provided for selectably controlling the flow of molten metal through the outlet. A method of preheating an induction heating vessel comprises placing a susceptor inside the vessel prior to charging the vessel with material to be heated and inductively heating the susceptor by an induction coil.

Abstract: The inductive heating of a reactor vessel by an external electromagnetic heating source is made more uniform by placing a susceptor between the heating source and the reactor vessel. In preferred embodiments, the reactor vessel is a fluidized bed vessel made of graphite and suitable for the preparation or treatment of polysilicon particles, and the susceptor is also made of graphite.

Abstract: An induction melting vessel comprising a refractory crucible having an opened top end and closed bottom end, with a substantially continuous side wall. A substantially continuous metallic shell surrounds and generally conforms to the side wall and extends for at least a majority of the height of the side wall from the bottom end to the top end. The shell has a bottom end corresponding to the bottom end of the crucible and a top end corresponding to the top end of the crucible. A portion the shell adjacent the top end thereof and a portion of the shell adjacent the bottom end thereof have discrete physically integral but electrically isolated regions therein for limiting the flow of electric current in the shell. In one embodiment of the invention, the regions are defined by a plurality of slits through the shell and extending from the top and bottom ends thereof toward the respective opposite ends. The slits have a length not exceeding have the distance to the respective opposite end.

Abstract: An apparatus for melting metallic stock as a crucible in which the metallic stock is received and melted, the stock in the crucible having an axis along which the force of gravity varies, and an inductive heating system which generates an inductive heating field having an inductive power density which varies along the axis. The inductive heating field interacts with the metallic stock in the crucible so that the radiation energy generated by the inductive heating field counteracts the hydrostatic pressure of the melt in the crucible.

Abstract: A method for impregnating a shaped ceramic material with an impregnation liquid, comprising the steps of placing the shaped ceramic material in the impregnation liquid, and applying an impregnation pressure to the impregnation liquid through a pressure transfer liquid so that the shaped ceramic material is impregnated with the impregnation liquid.

Abstract: The present invention relates to a cold crucible adapted to be discharged through the bottom. The crucible consists of a conductive wall consisting of a plurality of longitudinal hollow segments which are electrically insulated at least partially from one another and which are by virtue of the longitudinal hollows adapted to be traversed internally by a cooling fluid and which crucible is adapted to be placed inside an inductor and in which the wall is provided in its bottom part with an aperture inside which there is a removable occluding member, formed of segments which member is cooled like the wall of the crucible. The crucible is used in the processing of materials of high purity which can be recovered in the liquid state in a convenient complete and rapid manner.

Abstract: A refractory heat-insulating graphite sheet material characterized in that the material comprises a graphite sheet.

Abstract: Apparatus for melting and continuously casting metals, comprising a vertical, conductive cold crucible (1) with at least part of the height of its wall in the form of longitudinal sectors (2) which are electrically insulated from one another and have a cooling fluid running through them; an inductor (6) with coils helically surrounding the crucible (1) over part of its height and supplied with alternating current both for heating and confining the metal; a system for drawing down the ingot; and possibly a chamber with a controlled external atmosphere, separating at least the contents of the crucible (1) from the external atmosphere, characterized in that the crucible (1) has an upper zone (4) divided into sectors, with parallel vertical generating lines, and a lower zone (5) divided into sectors and joined to the upper zone (4), the generating lines of the lower zone spreading apart in a downward direction from the join (45) between the two zones (4 and (5), and that the lowest coil (60) of the inductor (6) i

Abstract: An induction furnace for melting refractory materials into a molten state by induction from a high frequency alternating current source. The furnace comprises a material holding crucible formed by a substantially cylindrical side wall having a single cylindrical turn. The side wall terminates in end portions which are spaced apart from each other to define a slot therebetween which extends generally longitudinally of the cylindrical wall. The side wall portions are connected to the source of alternating current so that the side wall turn comprises both the crucible and an inductor. An electrically conductive, elongated cooled member is mounted in the slot in spaced relation between each of the end portions. The elongated member is electrically insulated from the end portions to increase the breakdown voltage between the end portions.

Abstract: According to the invention, an apparatus for producing a monocrystal comprises at least one thermally conductive crucible for receiving the material, a thermally conductive holder having a part able to receive each crucible and extended by a projection, a heater for heating the thermally conductive holder and each crucible containing the material, a drive for the relative displacement of the thermally conductive holder and each crucible containing the material with respect to the said heater and a crystalizer able to bring about the crystallization of one end of the material melted in the heater, once said end has been extracted therefrom, and wherein the projection is positioned so as to check the temperature gradient undergone by the material during the relative displacement.

Abstract: Cold cage for a crucible with melting by high frequency electromagnetic induction comprising in per se known manner a series of hollow segments traversed by the cooling water and surrounded by a high or medium frequency induction coil and in which the products to be melted are confined, wherein at least part of the walls of each cage segment is constituted by at least two layers of adjacent materials, whereof the one which resists corrosion is in contact with the products to be melted and whereof the other is a good electricity conductor and wherein the relative thicknesses of these layers as well as the supply frequency of the induction coil are chosen in such a way that the eddy currents induced in the cage mainly develop in a good electricity conducting layer.

Abstract: Concepts for producing thermal conditions, in strip material, conducive to directional recrystallization are disclosed. An inductively heated susceptor contains a slot and the susceptor shape develops a thermal condition where the edges of the strip are cooler than the center of the slot. The furnace includes a fluid cooled cold zone as well as the hot zone and can produce a steep longitudinal thermal gradient in the strip.

Abstract: An automated sample analyzer for induction furnace analysis includes an induction furnace having an induction coil housing with an induction coil therein. The coil housing has a lower opening through which a crucible with a sample can be moved to allow the sample to be analyzed by burning. An elevator is provided for raising and lowering a crucible to and from the induction coil through the lower opening and includes a cover for covering the lower opening. A rotatable and radially movable tray has crucible openings for holding a series of crucibles. The tray openings also radially receive the elevator allowing the tray to move out of the way of the cover as it moves with the elevator while the elevator holds a crucible. A drive is provided for moving the tray rotationally and radially in a series of steps such that the crucible receptacle openings are sequentially moved to and from the elevator for automated loading and unloading of the crucibles on the elevator.

Abstract: An inductive heating device for uniformly heating a workpiece at rest has a plurality of heating coil units disposed so as to surround the workpiece. The heating coil units are connected in parallel to a power source, and a transformer is used to vary the voltage across the terminals of the outermost units to increase the current flowing through these outermost units. The device, therefore, has a very short insufficient heating temperature zone attributable to an end magnetic flux effect.

Abstract: An inductive heating device for heating a workpiece made of carbon has a heating coil disposed so as to surround the carbon workpiece. A first and second heat insulating layer is interposed between the workpiece and the heating coil, with the first layer being made of a carbon powder and the second layer being made of a carbon and silica powder mixture. A high frequency electrical source is used to drive the heating coil, which causes an eddy current to be induced in the workpiece, thus heating the workpiece. The first and second heat insulating layers prevent the surface of the workpiece from oxidizing and minimize heat loss from the workpiece during the heating thereof.

Abstract: A composite crucible for melting by an induction process samples to be analyzed is placed in the interior of an induction heating coil supplied with electric current ofhigh frequency. The composite crucible is constituted by two containers, one inserted into the other with a small play between the containers. The outer container is of platinum or a platinum alloy, and the inner container is of refractory material of good heat conductive characteristics, preferably vitreous carbon, and is destined to receive the sample to be melted.

Abstract: A direct induction furnace or device for melting a charge held in a cold sheath or shroud with electromagnetic confinement of the conducting portions of the charge. The cold shroud comprises a cylindrical sidewall, which is composed of a plurality of juxtaposed segments in the shape of a hairpin inductor, each formed by two parallel tubular conductors, which are insulated from each other along their entire interface with the exception of a transverse section which electrically and hydraulically connects one end of one of the sections to the adjacent end of the other section.

Abstract: Apparatus for casting directionally solidified articles is disclosed. Concepts for obtaining a desired temperature profile in an induction furnace are discussed.An induction furnace 10 has increased heating capacity at the withdrawal end 32 of the susceptor 28. A hot zone baffle 42 is disposed at the withdrawal end to inhibit the radiation of heat energy from the hot zone 12. A plurality of grooves 34 are formed about the interior of the susceptor at the withdrawal end to inhibit the conduction of heat energy out of the susceptor. A preferred thermal profile in the operating furnace with a peak temperature in close proximity to the withdrawal end results.