RU2383491C1 - Method of producing microdiamonds - Google Patents

Abstract

FIELD: chemistry.

SUBSTANCE: invention relates to a method of producing microdiamonds used for making cutting tools and volume doping material and can be used in machine building, aerospace and instrument making industries. The method involves formation of plasma of a carbon-containing gas using an arc plasmatron 1, synthesis of microdiamonds 10 in a reaction chamber 5 which are deposited in a bath 7 with cooling liquid 6. The microdiamonds are synthesised when the plasma jet 8 interacts with the surroundng cone-shaped stream 9 of cooling process material which is introduced into the jet with pressure inside the reaction chamber 5 equal to the height H of the hydraulic lock, defined by the immersion depth of the reaction chamber into the cooling liquid 6.

EFFECT: obtaining 0,2 mm microdiamonds with developed sharp-grain structure.

2 cl, 3 ex, 3 dwg

Description

The invention relates to methods for producing micro diamonds used for the production of cutting tools and bulk alloying of material, and can be used in instrumental, engineering, aerospace and instrument-making industries.

A known method of synthesizing a diamond film on a substrate (Japanese application No. 1201097, IPC S03B 29/04) located in the reaction chamber using methane plasma

(CH ₄ ) directed to the substrate from a nozzle formed by coaxially arranged central and ring electrodes. The central electrode is made in the form of a tungsten rod pointed downward and located vertically in the chamber; its upper part is cooled by a stream of water in a jacket covering the electrode. The ring electrode is made of copper. Gas is introduced into the space between the electrodes: a mixture of methane, hydrogen and argon; voltage is applied to the electrodes to obtain a glow discharge. The resulting plasma flow is directed from the nozzle down to the substrate. In this case, a diamond film is synthesized on the substrate. The disadvantages of this method include the low film growth rate and its insignificant thickness (up to 1 μm).

The closest in technical essence to the present invention is a method for producing diamonds (RF patent No. 2045474, IPC СВВ 31/06), including the formation of a plasma of carbon-containing gas and the synthesis of diamond in the reaction chamber. Plasma is formed in an arc plasmatron connected to the reaction chamber, and the resulting diamonds are collected in a bath with coolant located at the outlet of the reaction chamber.

This method is intended to obtain diamond-like particles up to 0.5 mm in size of a spherical, oval or pear-shaped.

The disadvantages of this method include the fact that such particles do not have a pronounced cutting edge and their use as a filler of an abrasive tool is impossible.

The objective of the invention is to obtain diamonds with a pointed structure.

The problem is achieved in that in a method for producing micro-diamonds, including the formation of a carbon-containing gas plasma by an electric arc plasmatron, the synthesis of micro-diamonds in a reaction chamber deposited in a bath with a cooling liquid, according to the invention, micro-diamonds are synthesized by the interaction of a plasma jet with a conical flow of cooling process material enveloping it at excess pressure in the cavity of the reaction chamber, equal to the height of the water seal, determined by the immersion depth of the reaction to measures in the coolant. As the technological material used: gases, for example carbon dioxide; liquids, for example water; aerosols, for example a mixture of acetone with argon.

Figure 1 schematically shows the installation for implementing the proposed method.

Figure 2 presents the x-ray of the synthesized microdiamonds.

In figure 3. a photograph of microdiamonds obtained by the claimed method is presented.

The installation contains a plasma torch 1 with a nozzle 2 for introducing a plasma-forming gas (POG), a nozzle 3 for introducing a carbon-containing gas (CH gases) and a nozzle 4 for introducing a process material (TM). The plasma torch is hermetically mounted on the end of the reaction chamber 5, the lower edge of which is immersed in the coolant 6 located in the bath 7, to a depth H with the formation of a water seal.

The method is as follows.

In the cathode region of the plasma torch 1, a plasma-forming gas is supplied through the pipe 2, an arc is ignited between the cathode and the anode of the plasma torch, forming a plasma jet 8, into which carbon-containing gas is introduced through the pipe 3, passing through the high-temperature region of the plasma jet and flowing into the cavity of the reaction chamber 5. Through the pipe 4, technological material is supplied, which in the plasma torch cavity is converted into a conical flow. In a plasma, carbon-containing gas dissociates into its constituents — carbon and hydrogen. In the interaction of a plasma jet with a stream of technological material that has a cooling effect on the products of dissociation of carbon-containing gas, an active process of carbon condensation occurs, affecting the size and facetness of micro diamonds. The process of condensation of carbon occurs in the cavity of the reaction chamber in the environment of exhaust gases and technological material, continuously inverted into the plasma jet at a pressure determined by the height of the hydraulic trap N. Condensed carbon in the form of micro diamonds 10, having passed through the hydraulic trap, is deposited on the bottom of the bath 7, and a mixture of argon and hydrogen in safe concentration, passing through a water trap, is released into the atmosphere.

Example 1

As the source of the plasma jet, the Saunin electric arc plasmatron (RF patent No. 2276840) was used, the design of which provides for the transportation of the technological material, which ensures the formation of a conical stream. The plasma torch of Saunin 1 is hermetically mounted on the end of the reaction chamber 5, the lower edge of which is immersed to a depth of H = 20 mm in the coolant 6 (water) located in the bath 7, while the overpressure in the cavity of the reaction chamber is 0.002 kg / cm ² . Plasma-forming gas — argon, is supplied through the nozzle 2 to the plasmatron, an arc is ignited between the cathode and the anode, forming a plasma jet 8, into which carbon-containing gas — propane — is introduced through the nozzle 3, passing through the high-temperature region of the plasma jet and flowing out into the cavity of the reaction chamber 5. In the plasma carbon-containing gas dissociates into its constituents — carbon and hydrogen. When the plasma jet 8 interacts with the conical stream 9 of the technological material — carbon dioxide introduced through the nozzle 4 at a distance of L = 10 mm from the nozzle exit of the plasma torch, the dissociation products are cooled, as a result of which carbon condenses in the form of micro diamonds 10, which, after passing through the water seal, are deposited at the bottom of the bath 7. The process proceeds with the following process parameters: I = 600 A; U = 60 B; consumption of plasma-forming argon gas - 7 l / min; propane consumption - 7.2 l / min; consumption of technological material - carbon dioxide - 6.3 l / min. Precipitated particles, the size of which is approximately 0.2 mm, have a sharp-edged structure (figure 3).

Example 2

The micro-diamond production scheme and technological parameters are the same as in example 1. As the technological material, water was used introduced through the pipe 4 at a distance L = 10 mm from the nozzle exit of the plasma torch. Water consumption - 0.06 l / min. The precipitated particles also have a sharp-edged structure, their size is approximately 0.2 mm (figure 3).

Example 3

The micro-diamond production scheme and technological paramers are the same as in Example 1. An aerosol is used as the technological material — a mixture of acetone and argon introduced through pipe 4 at a distance of L = 10 mm from the nozzle exit of the plasma torch. Aerosol consumption: acetone - 0.06 l / min, argon - 1.6 l / min. The precipitated particles also have a sharp-edged structure, their size is approximately 0.2 mm (figure 3).

On the x-ray (figure 2) obtained by the proposed method of particles there is a reflex corresponding to the spectrum of diamond in the range of angles 2θ 42.57 and 43.95 °.

Thus, the task of obtaining microdiamonds with a sharp-edged structure is achieved. The obtained micro diamonds can be used as a filler of an abrasive tool and bulk alloying of a material.

Claims (2)

1. A method of producing micro-diamonds, including the formation of a carbon-containing gas plasma by an electric arc plasmatron, the synthesis of micro-diamonds in a reaction chamber deposited in a bath with a cooling liquid, characterized in that micro-diamonds are synthesized by the interaction of a plasma jet with a conical stream of cooling technological material introduced into the plasma jet at a pressure in the cavity of the reaction chamber equal to the height of the water seal, determined by the immersion depth of the reaction chamber in the coolant st. 2. The method according to claim 1, characterized in that carbon dioxide is used as the process material.

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