Abstract: An electric induction furnace for heating and melting electrically conductive materials is provided with a lining wear detection system that can detect replaceable furnace lining wear when the furnace is properly operated and maintained. In some embodiments of the invention the lining wear detection system utilizes an electrically conductive wire assemblage embedded in a wire assemblage refractory disposed between the replaceable lining and the furnace's induction coil.

Abstract: A reactor for preparing granular polysilicon by deposition of polycrystalline silicon on silicon seed particles has a reaction vessel, an inner reactor tube for a fluidized bed comprising granular polysilicon and a reactor bottom within the reactor vessel, a heating device for heating the fluidized bed in the inner reactor tube, at least one bottom gas nozzle for introduction of fluidizing gas and at least one reaction gas nozzle for introduction of reaction gas, a feed device to introduce silicon seed particles, an offtake line for granular polysilicon, and a device for discharging reactor offgas from the reactor vessel, and has a cylindrical component which has openings on its cylindrical surface, with at least 5% and not more than 95% of the cylindrical surface being open located between the inner reactor tube and the heating device.

Abstract: A channel inductor of a channel induction furnace, the channel inductor comprising (a) a channel liner and (b) a back-up liner that supports the channel liner such that the integrity of the channel liner is not compromised during heat-up, dry-out, or operation of the channel induction furnace.

Abstract: An apparatus for SIC single crystal has an induction heating control unit such that frequency f (Hz) of alternating current to the induction heating unit satisfies Formula (1); D1 (mm) is permeation depth of electromagnetic waves into a crucible side wall by the heating unit, D2 (mm) is permeation depth of electromagnetic waves into a SIC solution, T (mm) is thickness of the crucible side wall of the crucible, and R (mm) is crucible inner radius: (D1?T)×D2/R>1.5??(1) where, D1 is defined by Formula (2) and D2 by Formula (3): D1=503292×(1/(f×?c×?c))1/2??(2) D2=503292×(1/(f×?s×?s))1/2??(3); ?c is electric conductivity (S/m) of the sidewall, ?s is electric conductivity (S/m) of the SiC solution; ?c is relative permeability of the sidewall, and ?s is relative permeability of the SIC solution.

Abstract: Silicon nitride coated crucibles for holding melted semiconductor material and for use in preparing multicrystalline silicon ingots by a directional solidification process; methods for coating crucibles; methods for preparing silicon ingots and wafers; compositions for coating crucibles and silicon ingots and wafers with a low oxygen content.

Abstract: An electric induction furnace for heating and melting electrically conductive materials is provided with a lining wear detection system that can detect replaceable furnace lining wear when the furnace is properly operated and maintained.

Abstract: A molten metal handling device comprising an outer shell defined by a bottom and two side walls, an insulating layer partially filling the outer shell and a thermally conductive castable refractory body for carrying molten metal, the refractory body being within the insulating layer. The device further includes at least one heating element positioned in the insulating layer, adjacent to the refractory body. The refractory body is preferably fabricated from a castable alumina or castable silicon carbide material.

Abstract: An induction furnace comprising a upper furnace vessel; an induction coil positioned below the upper furnace vessel; and a melt-containing vessel positioned inside the induction coil and communicably connected to the upper furnace vessel, wherein the positioning of the melt-containing vessel inside the induction coil defines a gap between an outside surface of the melt-containing vessel and an inside surface of the induction coil. A system for direct-chill casting comprising at least one an induction furnace; at least one in-line filter operable to remove impurities in molten metal; at least one gas source coupled to a feed port associated with the gas; and at least one device for solidifying metal by casting. A method of cooling an induction furnace comprising introducing a gas into a gap between an induction coil and a melt-containing vessel positioned inside the induction coil; and circulating the gas through the gap.

Abstract: The present invention provides a metal sector and a cold crucible induction melter having the same. The cold crucible induction melter includes a wall formed of a plurality of metal sectors insulated by an insulator. Each metal sector includes an outer curved portion which forms an outer surface of the wall and is convex outward relative to the wall, an inner planar portion which forms an inner surface of the wall, and a side planar portion which connects the outer curved portion to the inner planar portion.

Abstract: An electric induction furnace for heating and melting electrically conductive materials is provided with a lining wear detection system that can detect replaceable furnace lining wear when the furnace is properly operated and maintained.

Abstract: An induction heated furnace assembly for producing a directionally solidified casting includes a susceptor that tailors strength of the magnetic field within the chamber to provide a desired grain structure in a completed cast part. The susceptor proportionally blocks portions of the magnetic field to provide different levels of magnetic stirring within the molten material at different locations within the furnace assembly stirring induced by the magnetic field is controlled and varied throughout the furnace assembly to create the desired grain structures in the completed cast article.

Abstract: Process for combustion and vitrification of waste in which at least one oxygen plasma jet is associated with a continuous melting device by high frequency direct induction. The crucible is composed of a continuous external shell and a sole plate, both cooled by a liquid circulating in internal channels. The inductor is placed below the sole plate. There is a gravity drain valve at the bottom or on the side.

Abstract: The present invention is apparatus for, and method of, heating, melting and purifying a material by electric induction heating in a susceptor furnace. Non-electrically conductive solid charge may initially be placed in the furnace. Output frequency from a power source supplying current to one or more induction coils surrounding the furnace is selected to maximize magnetic coupling with the susceptor material in the susceptor furnace to induce eddy current heating in the material. Heat transfers by conduction from the susceptor material to the non-electrically conductive charge placed in the susceptor furnace to melt the charge. Output frequency is reduced as the charge melts and becomes electrically conductive to enhance magnetic coupling with the melt in the furnace. Degassing of impurities from the melt can be achieved by bubbling a gas through the melt while the surface level of the melt is maintained at vacuum.

Abstract: Thus, as shown by an exact electrodynamic computation of EMBF and the estimations described above of the velocity of turbulent flows arising due to their effect, application of amplitude- and frequency-modulated helically traveling (rotating and axially traveling) electromagnetic fields in metallurgical and chemical technologies and foundry can considerably increase the hydraulic efficiency of MHD facilities, intensify the processes of heat and mass transfer in technological plants, significantly increase their productivity, considerably decrease energy consumption for the production of metals, alloys, cast articles, and chemical products, and improve their quality.

Abstract: Process for combustion and vitrification of waste in which at least one oxygen plasma jet is associated with a continuous melting device by high frequency direct induction. The crucible is composed of a continuous external shell and a sole plate, both cooled by a liquid circulating in internal channels. The inductor is placed below the sole plate. There is a gravity drain valve at the bottom or on the side.

Abstract: The present invention relates to a silicon refining installation, having a cold sectorized induction crucible, having its internal wall lined with a refractory material.

Abstract: A fixture (30) adapted to permit the heated exchange of a liner (14) from an operating vertical furnace (10). The fixture is adapted to secure to the base of the liner (14) to both unlock and lower the heated liner, such as a silicon carbide liner, at an controlled rate. The fixture is also adapted to elevate a new liner into the operating vertical furnace at a controlled rate to control the rate of heating of the liner as it is inserted into the operating vertical furnace. The fixture includes an inner ring (34), a low-friction Teflon® ring (36), and an outer ring (38) permitting the rotation of the inner ring within the outer ring. Advantageously, the low friction ring comprises a flanged portion and a vertical portion allowing rotation of the inner ring within the outer ring even when elevated at extreme temperatures exceeding 500° C.

Abstract: Vertical segments of a side wall of a crucible for an induction furnace are assembled at an adjustable, invariable position by screws screwed into tapped holes of a flange common to all segments. A precise assembly is thus obtained producing no deformation and no internal stresses. The segments are coated with a ceramic coating for their protection and to prevent formation of electric arcs. Junction edges of faces are rounded to achieve the same effect. Water cooling boxes of the lower furnace hearth are similarly constructed. The apparatus can, as an example, be applied to vitrification techniques.

Abstract: Disclosed is a thermal insulation to be inserted between two structures, surfaces, walls or the walls of components which are to be insulated. The thermal insulation consists of an plurality of hollow spheres made up by loose hollow spheres or by hollow spheres which are interconnected by sintered contacts. The ratio of the outer diameter of the hollow spheres to their wall thickness is 5 300. The hollow spheres are made of silicides, silicide composites, metals and intermetals and the alloys thereof, ceramics or glass. When the walls of the hollow spheres have a closed porous structure, the inner pressure in the hollow spheres is between 0 to 0.1 that of the surrounding air pressure at room temperature.

Abstract: An article and method for its manufacture are described. The article is preferably a ladle used in the manufacture of metals and receives molten metal for further chemical processing in the ladle or for transportation. The ladle is transparent to a wide range of electromagnetic radiation wavelengths which allows the metal to be heated or stirred by induction without heating the ladle itself. The ladle is made of glass fibers and an inorganic cement, and this provides strength along with high temperature resistance. The article is manufactured by winding glass fiber around a mandrel, the glass fiber having an inorganic cement adhered to it. In one technique, the cement is provided on the fiber as an aqueous slurry, and the product is allowed to air cure after winding. In a second technique, the cement is adhered to the fiber by electrostatic attraction.

Abstract: A solid charge of metal or alloy is placing in a crucible melting chamber defined by a monolithic refractory tubular sleeve disposed on a water cooled metallic base, an energizing induction coil disposed about the sleeve to inductively heat the solid charge to a molten state in the melting chamber including forming a skull of solidified metal or alloy on inner surfaces of the sleeve and base to confine the molten charge, and removing the molten charge from the melting chamber, leaving the skull in place on the inner surfaces of the sleeve and base. The crucible can be reused in melting another solid charge of metal or alloy after the molten charge is removed.

Abstract: A method and an apparatus for inductively heating a refractory shaped member provided with an internal space, particularly for a metallurgical vessel, enable as rapid, uniform heating of the shaped member as possible. An inner inductor is introduced into the internal space, the shaped member is heated from the interior by such inductor, and the inductor then is removed from the internal space.

Abstract: An induction furnace apparatus and method for reducing the magnetic field produced by the operation of the furnace. The induction furnace including a refractory vessel, an induction coil, and an outer shell having a layer of metallic and magnetically permeable material. The metallic and magnetically permeable material comprising a plurality of elements having a shape and size that is chosen to maximize the packing density of elements throughout the layer. The outer shell further including a top, base, and sidewall arranged about the refractory vessel such that the metallic and magnetically permeable material is formed between the refractory vessel and the outer shell. The invention provides a method for casting metallic and magnetically permeable material with or without a non-conductive matrix. The castings can be formed into inserts or incorporated into the top, base, and side wall of the outer shell.

Abstract: A high temperature furnace formed from a stack of ceramic fiber--toroidal discs each fabricated to have an upper and lower groove for accommodating a heating coil so as to permit thermal elongation without buckling. The stacked array form a hollow cylindrical inner chamber which receives heat in the form of radiation through a window formed by removing a portion of the material between the groove and inner chamber.

Abstract: A cooling water conduit extending through a segment of a crucible is curved inward in the portion around a molten metal tapping hole.

Abstract: An improved induction melting coil apparatus encapsulated with homogeneous inserts for controlling the direction of inductor flux density is disclosed. The inserts are relatively thick and rigid members which provide a low reluctance path within which the magnetic field travels while inhibiting inductive coupling of the magnetic field with surrounding auxiliary components. The inserts can be easily formed or machined into any desired shape for effectively encapsulating virtually any type of coreless induction melting coil.

Abstract: This invention relates to a refractory lining for use in a coreless induction furnace having a refractory crucible, wherein the refractory lining lines the inner surface of the refractory crucible and has a porosity of between 0.2% and 1%.

Abstract: An improved induction melting coil apparatus encapsulated with homogeneous inserts for controlling the direction of inductor flux density is disclosed. The inserts are relatively thick and rigid members which provide a low reluctance path within which the magnetic field travels while inhibiting inductive coupling of the magnetic field with surrounding auxiliary components. The inserts can be easily formed or machined into any desired shape for effectively encapsulating virtually any type of coreless induction melting coil.

Abstract: A crucible assembly for use in induction melting furnaces utilizes an inner crucible formed of partially stabilized zirconia and an outer support member formed of a sintered alumina. The crucibles are in the shape of a cylinder with a closed bottom wall and in the cylindrical wall area, the inner crucible and the outer support member are separated by a layer of porous ceramic fibers of alumina and silica and the entire assembly has been centered as a unit so that the outer support member with a porous layer allows for the thermal expansion and contraction of the inner crucible while limiting any stresses applied to the inner crucible and providing additional strength and support for the inner crucible.

Abstract: An induction furnace for heating a portion of an optical preform in order to draw an optical fiber therefrom. The furnace includes a tubular susceptor which is disposed centrally within a housing. The electromagnetic field from a high frequency coil surrounding the susceptor is coupled to the susceptor to heat and reflow a portion of the preform. A cellular refractory tubular insulator is located between the coil and the susceptor.

Abstract: A heat shielding cladding for walls, ceilings, or similar surfaces, especially of industrial furnaces, including butted together parallelepipedal modules that are secured to the wall and comprise a plurality of held together and compacted fiber mat webs that are prestressed in a direction parallel to the wall. Adjacent modules are held together in a permanently flexible bond on non-prestressed sides thereof by at least one filamentary, temperature-resistant binder that is guided, without kinking, from a surface of the heat shielding cladding that is remote from the wall to the wall.

Abstract: A shallow vessel (50,52) for being horizontally disposed when containing a molten metal or metal alloy (66) for meniscus coating one side of a clean metal strip (34A) when the strip is moved vertically past one side of the vessel. The vessel includes a shell (68) such as austenitic stainless steel, a refractory lining (70), a molten metal departure lip (72) mounted on the upper surface of the side of the vessel, a spirally shaped induction coil (64) for maintaining the molten metal above its melting point and a flux concentrator (74). The induction coil is positioned below the refractory lining and the flux concentrator is positioned below the induction coil. The induction coil and the flux concentrator underlie the area occupied by the molten metal.

Abstract: A prewarning device for an induction melting furnace serves for warning of breakouts of molten metal on ceramic furnace linings of melting furnaces. The device has electrodes that may be arranged on the furnace lining in question which are divided into two groups of different polarity and are spaced apart from each other. The electrode groups can be connected to an evaluation unit in order to determine the electrical temperature-dependent resistance of the furnace lining. In order to permit a simple application of the electrodes on the outside of the furnace lining and assure a high reliability of indication of the entire system, at least a high reliability of indication of the entire system, at least one of the electrodes is arranged as an electrode network on a first side on a ceramic foil. Either the first side of the ceramic foil or the opposite side is arranged on the furnace lining.

Abstract: In a segmented water-cooled induction melting crucible mainly used for melting special metals such as reactive metals or alloys, two adjacent segments are coupled as a segment having two legs, one leg having an inlet water passage and the other leg having an outlet water passage, so that these water passages form a one-way water flow path when they are connected. When the two legs are connected at their top portion to form a shorted portion, the lower end of the legs are insulated from each other and from a base forming a bottom of the crucible. Alternatively the two legs can be entirely separated by elongating the slit and the water passage formed in each leg can be connected throgh an insulative, connecting member.

Abstract: A furnace refractory extraction system and method includes a selectively removable bottom portion which is attached to a refractory extraction device associated with a container for drawing the refractory lining of a coreless induction furnace into the container. A plug portion in the furnace bottom is selectively removable to provide access to a bottom wall of the refractory lining. An opening is made in the bottom wall of the lining through which an extractor shaft is inserted and then attached to the removable bottom portion of the furnace bottom. The other end of the shaft is attached to a piston and cylinder assembly associated with the container at the open end of the furnace. When the piston and cylinder assembly is powered, the lining is drawn into the container.

Abstract: An induction furnace includes a crucible having a plurality of cooled metallic segments (6A, 6B) electrically insulated from each other and an electromagnetic induction coil (5) arranged around the crucible, wherein the electromagnetic induction coil is energized with low frequency electric current. Each of the metallic segments forming the crucible wall is made of a relatively thin sheet, and a cooling pipe is provided on each segment. The cooling pipes (22) are welded or brazed to an outer surface of each corresponding segment. A refrigerant flows through each pipe in order to evacuate heat from the corresponding segment. The furnace further includes a magnetic core (8) disposed above and near the top surface of the charge placed in the crucible. This magnetic core provides local narrowing of the magnetic field lines, causing centripetal motion of the melted part of charge located at or near the top surface of the charge.

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: A method is disclosed for the semi-continuous melting of ceramic material by means of inductive melting in high-frequency and medium-frequency induction melting furnaces whose melting coil surrounds a sintering crust crucible and contains a run-out channel. In the method, melt is periodically run out and material to be melted is supplied to the crucible so as to replace the material removed preferably so as to maintain a constant level. An intensively cooled channel is used as a run-out device. For the melt broaching, the melt nose is grasped from below by way of an automatically controllable broaching lance of a broaching device and raised. The broaching lance is then advanced between the bottom of the channel and the solidified melt until the sintering crust is pierced. The method permits a reliable and economic management of the process and the maintenance of the quality of the melted products.

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: A furnace lining is formed by a plurality of lining bricks. The bricks have surfaces defining an internal surface of the lining that is to face the interior of the furnace and to receive therefrom radiant heat. At least one depression is formed in the lining and opens onto the surface through an opening. The depression has internal wall surfaces that are geometrically configured to cause radiant heat from the furnace interior that impinges on a first internal wall surface to be reflected thereby and to impinge therefrom onto a second internal wall surface. Thus, the heat will be absorbed by the bricks of the lining, and such heat will be emitted thereby from the inner surface thereof.

Abstract: A high frequency core and coil electric metal melting furnace is shown. This furnace has a lined channel in its inductor for carrying the molten metal. The invention provides an improved inductor for a core and coil furnace that is not subject to leakage of the molten metal from the channel into the rammed refractory support bed for the channel which leakage otherwise shortens the lift of the furnace. Also a method of lining the channel in the inductor for carrying the molten metal which forms the core is disclosed.

Abstract: A lining for use in an aluminum reverberatory furnace or the like for heating molten aluminum in a cavity which cavity is formed by a roof, sidewalls and a bottom which are to be lined with refractory materials. The lining comprises a band of hot face refractory material around the interior periphery of the cavity sidewalls for contacting molten aluminum in the furnace at the normal operating levels of the upper surface of the molten aluminum. A layer of backup refractory material is interposed between the furnace shell and the band of hot face refractory material.

Abstract: A refractory product is shown in the form of a dense sintered alumina-chromia, zirconia-alumina-silica, zirconia-alumina body, or zirconia-chromia-alumina having less than about 8% of homogeneously distributed closed porosity formed by sintering an intimate interdispersion of fine particles of alumina-chromia, zirconia-alumina-silica, zirconia-alumina, or zirconia-chromia-alumina.

Abstract: An induction furnace has an inner discardable lining formed from one or more preformed shapes of refractory, heat-insulating material. The discardable lining is easily replaceable using a minimum of time and effort. The lining provides more efficient furnace operation, as less electrical energy is consumed and less time is required to melt down the solid metallic charge. In addition the molten metal is cleaner i.e. it contains fewer deleterious inclusions compared with a conventional refractory, inner lining.

Abstract: A reactor tube 20 for a high-temperature fluid wall reactor has a generally cylindrical shape and is made of a refractory material which permits the tube to be heated to incandescence. The reactor tube in turn radiates energy inwardly to a reaction zone to sustain the desired high-temperature reaction. At least a length of the tube 20 is perforated to permit an inert gas to pass through the tube to form a protective fluid wall for preventing the radially-inward reactant products from contacting the inner surface 84 of the tube. Perforations 78 are located, shaped and dimensioned such that inert gas jets 86 are formed each having a substantially radially-directed momentum sufficient to repel the reactants. The injection of inert gas is controlled so that gas jets overlap to form the protective fluid wall, but the gas jets do not disturb flow within the radially-inward reaction zone. Sections of the reactor tube may remain unperforated, but are protected by the downstream flow of the injected inert gas.

Abstract: A ladle or tundish has a side wall comprising a refractory lining adapted to be contacted by molten metal, and a concrete wall surrounding the lining and reinforced by metal wires, the side wall being free from a metal shell. Therefore the side wall is relatively permeable to the field of an induction heating coil on the outside of the side wall.

Abstract: Process for the production of ceramic materials by high frequency induction melting.The powder containing the various components of the material to be prepared is introduced in a continuous manner into an aperiodic high frequency electric furnace, whose single flat coil serves both as the induction system and the cold crucible, the molten material also being continuously removed from the furnace in a chute passing through the coil.

Abstract: A high temperature induction furnace (10) for drawing lightguide fiber (52) from a silica preform (44) has an axially located tubular zirconium dioxide susceptor (34) therein. Prior to use, at least a portion of the inside surface of the susceptor (34) is coated with a vapor deposited silica "soot" (54). The silica soot (54) is then consolidated at an elevated temperature. Surprisingly, such a technique substantially eliminates migration of zirconium dioxide particles from the susceptor (34) to the preform (44) and/or the fiber (52) without deleteriously affecting the susceptor (34) and/or the operation of the furnace (10).

Abstract: A furnace comprises a crucible surrounded by an induction heating coil and having a filling mouth and a pouring spout. The crucible is cylindrical in shape having an oval external cross-sectional profile with a major diameter and a minor diameter, and an internal profile of substantially constant diameter. In the portions of the crucible wall of greater thickness are formed a filling duct and a pouring duct which connect the filling mouth and the pouring spout respectively to the bottom of the crucible.

Abstract: An induction furnace for melting and casting highly pure metals and alloys such as uranium and uranium alloys in such a manner as to minimize contamination of the melt by carbon derived from the materials and the environment within the furnace. The subject furnace is constructed of carbon free materials and is housed within a conventional vacuum chamber. The furnace comprises a ceramic oxide crucible for holding the charge of metal or alloy. The heating of the crucible is achieved by a plasma-sprayed tungsten susceptor surrounding the crucible which, in turn, is heated by an RF induction coil separated from the susceptor by a cylinder of inorganic insulation. The furnace of the present invention is capable of being rapidly cycled from ambient temperatures to about 1650.degree. C. for effectively melting uranium and uranium alloys without the attendant carbon contamination problems previously encountered when using carbon-bearing furnace materials.