Procedure for vacuum ion-plasma nitriding items out of steel

FIELD: metallurgy.

SUBSTANCE: procedure consists in vacuum heating items in plasma of nitrogen of higher density. Plasma of nitrogen of higher density is generated in toroid region of electron motion formed with crossed electric and magnetic fields. Under effect of magnetic field created with two cylinder magnets one of which is hollow, electrons move along cycloid closed trajectories.

EFFECT: intensified item nitriding, increased contact durability and wear resistance of strengthened layer.

1 dwg, 1 ex

 

The invention relates to the field of chemical-heat treatment, namely vacuum ion-plasma nitriding, and can be used in various engineering industries to improve the reliability and durability of a wide range of machine parts and tools, and also allows to intensify the process of nitriding.

The known method (Patent RF № 2058421, CL SS 8/36. 20.04.96) nitriding parts of the structural alloy steels, including high-temperature ion nitriding, quenching from the temperature of complete dissolution of nitride phases, vacation, finish machining and low-temperature ion nitriding at a depth of not less depth diasteranes layer.

The disadvantages are the counterpart of the complexity of the equipment and technology, and the need to design special equipment.

The known method (Patent RF № 2127330, CL SS 8/26. 10.03.99) heat treatment for the formation of high-strength austenitic surface layer in stainless steels, including nitriding in containing nitrogen gas atmosphere at 1000-1200°C and subsequent cooling at a rate that permits to avoid selecting nitride.

The disadvantages are the counterpart of the complexity of the equipment and technology, and the need to design special equipment.

Most Liskin to the technical essence and the achieved effect to the claimed is a method (Patent RF № 2276201, CL SS 8/36. 10.05.2008) nitration products in a glow discharge with hollow cathode effect, including nitriding in a glow discharge, for which conducting vacuum heat the product in the nitrogen plasma high density formed between the part and the screen through the creation of hollow cathode effect.

The disadvantages of the prototype are spraying and implementation azotiruemogo layer of mesh material of the hollow cathode, which reduces the hardness of the resulting coating.

The task to be solved by the invention is the intensification of the nitriding process, increasing contact the longevity and durability of the hardened layer.

The problem is solved by using the method of nitriding steel workpieces in a glow discharge, comprising the vacuum heating products in the plasma of nitrogen increased density, according to the invention the nitrogen plasma high density create in the toroidal motion of electrons formed by the crossed electric and magnetic fields, and under the action of magnetic fields generated by the two cylindrical magnets, one of which is hollow, the electrons move in a cycloidal closed trajectories.

The availability of a closed magnetic field at the surface of the substrate allows to localize the plasma discharge directly from podlog is I. Emitted from the cathode under the action of ion bombardment of the electrons trapped in the magnetic field generated by the two cylindrical magnets, one of which is hollow, it is reportedly difficult cycloidal motion along closed trajectories at the surface of the target. The electrons are trapped generated on the one hand the magnetic field, return the electrons to the cathode, and on the other hand the target surface, which repels the electrons. Electrons cycleroute in this trap until then, until a few ionizing collisions with atoms of the working gas, in which the electron loses obtained from the electric field energy. Most of the energy of the electron before it reaches the anode, is used for ionization and excitation, which, in turn, causes an increase in the intensity of the ion bombardment of the surface of the substrate, and a significant increase in the rate of nitriding.

The invention is illustrated by a drawing.

The drawing shows a diagram of the method of vacuum ion-plasma nitriding of steel products. The circuit contains a power source 1, a magnetic system 2, the cathode-part 3, the feeder of the working gas 4, an anode 5, the electron cloud 6, your batch with the machined parts 7.

A specific example of implementation of the method.

In the vacuum chamber octanal who live workpiece along a circular trajectory, for example drill from tool steel R18. Then the camera create a working pressure of 100 PA required for ignition of the glow discharge. The camera serves a mixture of gases (N250%-80%Ar 25%-10%, With2H225%-10%). Using the energy of the electrons moving along a circular trajectory, there is a heating of the parts to a temperature of 500-540°C, while nitriding occurs within 4-6 hours.

The magnets, creating a rotating field of the electrons are in the working chamber under the table-cathode. Since the nitriding process takes place at 500-540°C and the Curie temperature for the material of the magnets is of the order of 300-350°C, there is provided a cooling system of magnets. The water in the cooling system circulates between internal and external (hollow) magnet.

All processes take place in one camera and one atmosphere, which makes it possible to reduce the auxiliary time spent on preparatory operations that involve the use of different equipment and tooling.

It should be noted the following advantages of the claimed method: high technology process, environmental cleanliness of the process due to the absence of harmful industrial emissions, ease of handling scheme that does not require the design of special devices, and relatively low cost are equipped with the I.

Method of nitriding steel workpieces in a glow discharge, comprising the vacuum heating products in the plasma of nitrogen increased density, characterized in that the nitrogen plasma high density create in the toroidal motion of electrons formed by the crossed electric and magnetic fields, and under the action of magnetic fields generated by the two cylindrical magnets, one of which is hollow, the electrons move in a cycloidal closed trajectories.



 

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