SU30181A1 - A method of manufacturing electrical resistance furnaces - Google Patents

Description

The construction and construction of electrical resistance furnaces for high temperatures (above 2000) operating for some / long time encounters considerable difficulties.

The main role here is played by the choice of material for both the conductor heated by the current and the thermal insulating lining surrounding it. As a first, in such cases, a sufficiently refractory conductor is taken, in particular, carbonaceous materials (coal, graphite, carbides, tungsten, molybdenum, tantalum and other materials) can be used for temperatures of 2000 ° C and higher, but for the most part chemically active and reacting, especially at high temperatures, with most known substances. As a refractory lining, the above-mentioned carbonaceous materials can be used again, as well as a whole range of metal oxides characterized by their refractoriness. In many cases, in order to be robust, constructive, and economical, as well as in those cases where the presence of coal inside the furnace is undesirable, the most convenient is to use as heated current.

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conductor of one of the above-mentioned tugsk fusible metals, and as lining one of these oxides; The conductor heated by current is so-called furnace winding — usually located either on the outer surface of a hollow body of lining material, l is either laid inside it, or finally on the inner surface formed by the lining of the working space of the furnace. In the latter case, the winding is in contact with its own hot part of the material of the lining and, since the refractory metals mentioned above, such as: tungsten, molybdenum, etc., readily react with oxides at sufficiently high temperatures, quickly deteriorate. To eliminate the possibility of chemical reaction or fusion of the substance. liners with a heated current conductor, it is necessary that the furnace coil does not directly touch the lining with its hottest parts. To avoid the same bias. deflection% or sagging of the heated current no. of the body, especially in the hot state, no. associated with this danger of contact with the surface of the lining are usually used to mount the furnace windings using holders or hooks of a sufficiently refractory material embedded in the lining, located) radially and made of the same material as the furnace winding, or their ends embedded in a futof, can be made of a material that cannot act on the lining material, such as platinum. When used for winding materials such as tungsten, molybdenum, etc., the furnace must operate in a reducing or inert atmosphere, or finally / in a vacuum. Since the characteristic feature of the described furnace is the separation of the lining from the winding and their independent position, the manufacture of such a furnace can be very difficult.

The present invention is a method of manufacturing this type of furnace, which consists in applying a certain layer of a low-melting plastic substance to the metal conductor used for heating and then removing the lining, after which the substance is removed by heating.

The drawing shows a schematic of a furnace manufactured in this manner.

A method of manufacturing electrical resistance kits, preferably high temperatures, is as follows. On the metal conductor 4, which is used for heating, and the holders 3 bonded to it, impose a layer of plastic fusible substance corresponding to the internal void space of the furnace, paraffin wax, on which

lining / is applied, after which the plastic substance is removed by heating. Furnaces of this type can be successfully used both for various kinds of continuous processes, such as roasting tungsten and molybdenum jars, sintering layers on refractory cores, for example, tungsten platinization, and for other types of heat treatment. In each case, the material being processed does not come into contact with either the heating conductor or the furnace lining, and heat transfer is carried out only through radiation and thermal conductivity of the furnace gas atmosphere.

The subject of the patent.

A method of manufacturing electrical resistance furnaces, mainly for high temperatures, in which furnaces the resistance heated by current is fixed at some distance from the furnace walls by means of radially arranged holders made in the part in contact with the lining, of a substance that does not fusion and does not react with the lining material, characterized in that the metal conductor serving for heating and the holders fastened to it are superimposed by the corresponding internal hollow space and a layer of a fusible plastic material, such as wax, which is then applied to the liner, whereupon the plastic material is removed by heating. E to the patent of the State All-Union Electrotechnical Union .ВЭО № 30181