SU834235A1 - Method of chemical and thermal treatment of metal articles in electrolytes - Google Patents

Description

one

The invention relates to the chemical-thermal and heat treatment of metals and alloys, in particular, to the chemical-thermal treatment when heated in an electrolyte, and may find application in mechanical engineering, instrument engineering and other areas of technology.

The known method of chemical thermal treatment (cementation) with heating in the electrolyte during the anodic and ca1: one processes. This method is characterized by a high rate of diffusion processes, the time of chemical heat treatment is several minutes. L.

However, the depth of the diffusion layer can reach several millimeters.

Also known is a method of chemical heat treatment (cementation and carbonitrization) with immersion of the part in the electrolyte. When immersed parts in the electrolyte corresponding composition

It is possible to carry out high-speed chemical heat treatment. For example, using a solution containing 15% ammonium chloride and 10% acetone, it is possible to carbonize the steel. During the processing time of 5 min at 900 ° C, followed by cooling in the electrolyte, the thickness of the continuous white layer at the base of the electrode is 80 µm G2} "

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The disadvantage of the method of chemical heat treatment with immersion of the part in the electrolyte is the presence of a temperature gradient along the height of the part both at the anode and at the cathode.

5 processes due to thermal conductivity along the sample and heat transfer through the vapor-gas shell. The presence of a temperature gradient along the height of the sample causes a different depth of the diffusion layer during chemical heat treatment. The depth of these layers decreases with increasing distance from the base of the electrode. The purpose of the invention is uniform diffusion layers over the entire surface of the part during the chemical-heat treatment with heating in electrolyte. The goal is achieved by supplying a submerged jet of electrolyte to the top of the part at the electrolyte surface at a speed of 0.5-1.5 m / s. If in the process of heating a submerged jet of electrolyte is supplied to the aerchic part of the electrode near the surface of the electrolyte, it is possible to increase the temperature of this part of the electrode and thereby adjust the temperature gradient over the height of the sample. This is achieved due to the fact that the structure of the vapor – gas shell changes, eliminating heat transfer along the sample. The greater the temperature of the base of the electrode, which is controlled by the voltage across the electrodes, the greater must be the speed of the submerged jet of electrolyte supplied to the upper part of the electrode at the surface of the electrolyte. Thus, when the temperature of the electrode base is 500 ° C, the speed of the submerged jet should be 0.5 m / s. In this case, a uniform temperature is achieved over the entire height of the sample. At a speed of more than 0.5 m / s, the temperature of the upper part of the electrode becomes higher than at the base, i.e. the reverse gradient of the terature is obtained. At the temperature of the electrode base, the speed of the submerged jet should be 1.5 m / s. At this speed, a uniform temperature is reached over the height of the sample, and at a speed of more than 1.5 m / s, the temperature in the upper part is higher than at the base. Example 1 An anode of steel C 10 with a diameter of 8 mm is immersed in a solution of 15% ammonium chloride per hl 54 bin 40 mm. Thermocouples for measuring the heating temperature are placed in the electrode at a distance of 2 and 37 mm from the base. With normal heating, a temperature gradient of 10 degrees / mm is observed at a base temperature of 850 ° C. When a submerged jet of electrolyte is applied at a speed of 0, J5 m / s, the temperature gradient is zero. Example 2. An anode of St 10 steel with a diameter of 6 mm is immersed in a solution containing 15% ammonium chloride and 20% used for nitriding. Depth is 18. mm. A flooded electrolyte jet is fed to the upper part of the electrode at a speed of 0.65 m / s. The heating temperature at the base and at the top of the sample is 4 minutes. Microstructural analysis shows that the continuous nitride zone over the entire height of the electrode is uniform and equal to 30 µm. Example 3. An anode of St 10 steel with a diameter of 6 mm is immersed in an aqueous solution consisting of 15% ammonium chloride and 10% acetone used for carburization. Depth 18 mm. A submerged jet of electrolyte is fed to the upper part of the electrode at a speed of 0.8 m / s. The heating temperature of the sample at the bottom and at the top is 900s, the processing time is 5 minutes. Cooling is carried out in an electrolyte. A microstructural analysis shows that the solid white layer resulting from quenching is uniform over the entire height and equal to 80 microns. The results of machining of parts from low carbon steel with a diameter of 6-7 mm with an immersion depth in the electrolyte of 16-18 mm are shown in the table.

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80

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Also

Cementation

Also

Nn401

Nitrogen 15 NOV40H 20

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0.8

80

80

1.5 software

ON 30 0.65 30

15 0.5

Claims (2)

SUMMARY OF THE INVENTION A method for chemical-thermal treatment of metal products in electrolytes, including heating to a processing temperature and exposure, characterized in that, in order to obtain uniform diffusion layers, a flooded electrolyte stream is fed to the upper part of the product at the electrolyte surface at a speed of 0.5 - 1.5 m / s. Sources of information, ₅₀ decayed at 3xcnepTH3ej 1. Minkevich A. N. Chemical-thermal treatment of metals and alloys. '· M., 1965, p. 73. 2. Electronic processing of materials, 1977, No. 2, p. 15-18. Circulation 1048 Subscription Uzhhorod, st. Project, 4