RU2409700C1 - Procedure of nitriding in plasma of glow discharge - Google Patents

Abstract

FIELD: machine building. ^ SUBSTANCE: according to invention steel items are nitrided in glow discharge by means of vacuum heating in plasma of nitride of increased density; further, items are quenched. Also, plasma of nitride of increased density is generated in a circular region of rotation of electrons caught with magnetic field, power lines of which are parallel to treated surface. Notably, electron cloud is maximally localised at the part-cathode. ^ EFFECT: intensified process of nitriding, increased contact service life and wear resistance of strengthened layer. ^ 1 ex, 2 dwg

Description

The invention relates to plasma chemical-thermal treatment of the surface of parts and can be used in mechanical engineering to increase the reliability and durability of a wide range of machine parts and tools, and also allows to intensify the nitriding process.

A known method of applying a wear-resistant coating on the surface of steel products, in particular on machine parts, including ion-plasma nitriding in a reactive gas-nitrogen medium, cleaning the surface of the part and applying titanium nitride from the plasma phase (RU 2013463 C1, 05/30/94). The method allows you to create a transition region between the coating and the material of the product itself.

The disadvantages of the analogue are the complexity of equipment and technology, as well as the need to design special equipment for moving products. Moving products further complicates and increases the duration of the entire work.

A known method of producing nitrided ferroalloys containing components having a high affinity for nitrogen, in which the molten starting materials are kept in an atmosphere of nitrogen or other nitrogen-containing gases. The nitrogen contained in the gas phase dissolves in the metal melt, and when the melt solidifies, it is released in the form of a dispersed nitride phase distributed in a metal matrix (see Gasik M.I. et al. Theory and production technology of ferroalloys. - M .: Metallurgy, 1988. - S. 382-384).

The disadvantage of this method is the need for a long (several hours) exposure of the ferroalloy in a liquid state in an atmosphere of nitrogen-containing gas, which requires a large energy expenditure to maintain the temperature of the melt, as well as a low (1 ... 2%) nitrogen content in the alloy, due to the low solubility of nitrogen in the alloys at high temperature nitriding components.

The closest in technical essence and the achieved effect to the claimed one is the method (RF Patent No. 2276201, class C23C 8/36 05/10/2008) nitriding products in a glow discharge with the effect of a hollow cathode, including nitriding in a glow discharge, for which vacuum heating is carried out products in a high-density nitrogen plasma formed between the part and the screen due to the creation of the hollow cathode effect.

The disadvantage of the prototype is the spraying and introduction into the nitrided layer of the material of the hollow cathode mesh, which reduces the hardness of the resulting coating.

The task to which the invention is directed is the intensification of the nitriding process, increasing contact durability and wear resistance of the hardened layer.

The problem is solved by using a method of processing steel products, including nitriding in a glow discharge and hardening, for the implementation of which vacuum heating of products in a high-density nitrogen plasma is carried out, and unlike the prototype, a high-density nitrogen plasma is formed in the annular region of rotation of electrons captured by a magnetic field , the lines of force of which are parallel to the surface being processed, while the electron cloud is maximally localized at the cathode part.

The invention is illustrated by drawings.

Figure 1, 2 shows a diagram of the implementation of the method of vacuum ion-plasma nitriding of steel products. The circuit contains a power source 1, a cathode-part 2, a magnet 3, an anode 4, a vacuum chamber housing 5, an electronic cloud 6, magnetic field lines 7, workpieces 8.

An example of a specific implementation of the method.

In the vacuum chamber, workpieces are installed along an annular path, for example, tips of cutters from tool steel P6M5. Then, a working pressure equal to 100 Pa is created in the chamber, which is necessary for ignition of a glow discharge. A mixture of gases (N ₂ 50% -80%, Ar 25% -10%, C ₂ H ₂ 25% -10%) is fed into the chamber and the parts are heated to a temperature of 500 ÷ 540 ° C, while nitriding occurs for 3- 5 hours, after which the part is additionally heated to 900-1000 ° C, held for 15-20 minutes and sharply cooled in a helium stream at a speed exceeding the critical quenching rate.

The Curie temperature for the magnet material is about 300-350 ° C. Since the magnet is located inside the working chamber, and the nitriding temperature is 500 ÷ 540 ° C, the magnet must be cooled. For this, water circulates in the magnet cavity indicated in the drawing.

All processes take place in one chamber and in one atmosphere, which allows to minimize the auxiliary time spent on preparatory operations, which are associated with the use of different equipment and equipment.

It should be noted the following advantages of the claimed method: high processability, environmental friendliness of the process due to the absence of harmful industrial emissions into the atmosphere, simplicity of the processing scheme, which does not require the design of special devices and the relatively low cost of equipment.

Claims (1)

A method of processing steel products, including nitriding in a glow discharge, for the implementation of which vacuum heating of products in a high-density nitrogen plasma and hardening is carried out, characterized in that the high-density nitrogen plasma is formed in an annular region of rotation of electrons captured by a magnetic field, the lines of force of which are parallel to the processed surface, while the electron cloud is maximally localized at the cathode part.

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