SU55959A1 - Method for producing boron, silicon and titanium carbides - Google Patents

Description

Boron, silicon, and titanium compounds with carbon (carbides) and their alloys, for example, with boron, have a high hardness that makes it possible to replace diamond dust and diamond circles with them in a number of operations. In a number of cases, it is necessary to obtain carbides containing the minimum amount of impurities; at the same time they must have increased hardness.

The production of high-purity carbides in electric resistance and arc furnaces is made difficult by the need to use graphite electrodes — an expensive and scarce product. In addition, the uneven thermal field results in a material that is heterogeneous in composition and crystallization. Sealing these ovens is difficult.

To obtain pure preparations of boron carbide, silicon, and titanium, the author of the present invention proposes the formation reaction of carbides in a high-frequency induction (heartless) electric furnace. In this case, the charge is placed in a graphite crucible, hermetically sealed with a graphite cap, or in several coal or graphite cartridges installed in a crucible of non-conducting material.

The electric efficiency of the furnace depends on the ratio of the specific resistances of the inductor and the charge, and since the inductor can be considered constant (copper), it turns out that with an increase in the specific resistance of the charge, the electric efficiency increases.

The oven can be easily sealed to reduce losses.

The insulating layer around the crucible can be charcoal, corundum or magnesite.

The resulting product due to the direction of heat flow from the inside to the inside will be more uniform in composition and crystallization.

In particular, useless heat losses for heating unreacted charges, specs, etc., are eliminated, which should increase the efficiency of the furnace and reduce the specific energy consumption.

The use of a high-frequency electromagnetic field fundamentally changes the physico-chemical pattern of carbide production processes, since if in an arc furnace and resistance furnace the source of heat and heat transfer to the mixture are extraneous bodies (electrodes in an electric arc furnace, core-core in a resistance furnace) then, and the method proposed by us, the heat source will be particles of a reducing agent (carbon) distributed throughout the entire charge consisting of carbon and oxide of the corresponding metal.

Obtaining the desired temperature can be regulated by changing the size of carbon and its grade (petroleum, coke, soot, graphite, etc.). Particles of carbonaceous material, being heated by currents induced in them to a higher temperature than the surrounding non-conducting material (quartz sand , boric acid, boric anhydride, etc.) will heat the latter, i.e. they will be the current source themselves (secondary circuit), which will speed up the process, as in arc furnaces or resistances before carbon grains (on which surface goes reaction) reacts, they must be heated, and this is surrounded by the surrounding layer of oxide grains with poor thermal conductivity.

The subject matter of the invention.

A method for producing boron, silicon and titanium carbides by roasting a mixture of oxygen compounds of these elements with carbon in an electric furnace, characterized in that the formation of carbides is carried out in high-frequency furnaces, for example, of the type of induction furnace.