The method of obtaining products of chrome carbide

 

(57) Abstract:

Usage: the invention relates to the production of carbide materials. The inventive method consists in that the synthesis of chromium carbide is carried out directly in the harvest of the future details. Implementation of the proposed method in comparison with the prototype ensures carbide not just in powder form, but also in the form of products of a certain form. Furthermore, the method allows to obtain products of different composition (type of carbide, carbide-carbon) and different porosity (within certain limits). 3 C.p. f-crystals, 1 table.

The invention relates to the production of carbide materials.

The main methods of obtaining refractory carbides are the synthesis of the elements or the recovery of oxides of carbon, for example,

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However, the high temperature synthesis 1500 1550oC, as a rule, do not contribute to the formation of carbides dispersed in the form.

The chromium carbide in powder form and at a lower temperature synthesis can be obtained by using the carbon component is formed by the decomposition of natural gas or other hydrocarbons. As a prototype of the selected method, consisting in on what abotu carried out at 800 to 1200oC in the reactor with a fluidized bed of metal oxide, through which serves hydrocarbon. The oxide of the metal begins to actively naglergasse. When this oxide particles begin to evenly covered with pyrolytic carbon (PU). The speed of accumulation of hydrocarbon oxide depends on the temperature and gas flow. The degree of carbonization depends on the duration of the process. Incorporated PU has a fine structure, high reactivity, spectral purity.

The disadvantages of the prototype method is that this method is only preparation of the oxides of rare metals to carbidization; synthesized in the future from this material carbide can only be obtained in powder form.

The task of the invention to provide chromium carbide in the form of finished products.

This goal is achieved due to the fact that the carbide synthesis takes place directly in the harvest of the future details.

The invention consists in the following.

From a powder of chromium oxide (III) a temporary binder to form the workpiece, as close in shape to the desired items. The obtained porous preform, the porosity of which can WA is the mass change of the workpiece 20 34% from the initial one. While in the pores of the workpiece on the surface of the particulate source of chromium oxide proceeds in a heterogeneous chemical reaction of formation of the carbon layer. The formed layer is a strongly connected with the base (the surface of the particles) graphite-like carbon.

Obtained at this stage, the semi-finished product is a reactive system with uniform distribution of components, which, in addition, is provided in direct contact with a highly developed surface section, which facilitates the further course of the reaction of their chemical interaction.

The semi-finished product has the same shape and size as the workpiece. He has more strength and can be subjected to machining (e.g. drilling) for the formation of surfaces that cannot be obtained by shaping the workpiece. Synthesis of carbide is carried out at 1150 1250oC by high-temperature processing of semi-finished product in a vacuum or inert gas environment.

The porosity of the preform is set depending on the requirements posed details:

composition (type carbide);

the porosity of the part.

To mould the workpiece with an initial on the Sabbath.

To mould the workpiece with an initial porosity of more than 65% does not make sense, because even in the formation of carbide porosity details will be more than 75% and the item will have very low strength.

The increase in the mass of the workpiece by more than 34% is not always advisable, because after a reaction time of carbidopazapomnit in the pores of the items will remain the excess carbon that is often undesirable. The increase in the mass of the workpiece is less than 20% does not provide the possibility of obtaining from it the final details.

The mutual combination of the initial porosity of the workpiece and the amount of typing in her carbon allows to obtain details with different porosities.

Example 1. From a powder of chromium oxide (III) is formed into a billet parts, for example, ROM. The item is placed in the reactor, served there natural gas and maintained at a temperature of its decomposition. Then the reactor is cooled. The resulting intermediate product is placed in a vacuum furnace, heated to 1200oC and incubated for 20 minutes After the furnace is cooled and the part is removed. The thus obtained disk of porous chromium carbide.

Examples 2 and 3. Carried out analogously to example 1 (see table).

Thus, implementation of the proposed JV is a certain form. Furthermore, the method allows to obtain products of different composition (type of carbide, carbide-carbon) and different porosity (within certain limits).

Literature

1. Kosolapov So Ya Carbides. M. Metallurgy, 1968. 299 S.

2. "The method of preparation oxides of rare metals to carbidization" (Listov A. I. Galitsky N.In. Live N.A. /Description of the invention to the author's testimony. Bulletin No. 15, published 26.04.1968.

1. The method of obtaining products of chrome carbide, synthesized from oxide chromium (III) and pyrolytic carbon, including heat treatment of chromium oxide in an environment of gaseous hydrocarbons or their mixtures at a temperature above the temperature of decomposition, wherein the pre from a powder of chromium oxide is formed into a billet products, after which it thermoablative to increase the weight by 20 34% from the initial and synthesis of carbide is carried out directly in the volume of the workpiece by heat treatment.

2. The method according to p. 1, characterized in that the carbide synthesis is carried out at 1150 1250oC.

3. The method according to PP.1 and 2, characterized in that the carbide synthesis is carried out in a vacuum.

4. The method according to PP.1 to 3, characterized in that sintech carbide carry out

 

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