SU931801A1 - Composition for electrolytic sulphidizing - Google Patents

Description

() COMPOSITION FOR ELECTROLYTIC SULFIDING

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Isolation refers to chemical heat treatment of metals and can be used in mechanical engineering for the diffusion hardening of the cutting tool.

A known sulphidation composition containing a sulfurous hydrosulphide solution IV.

; For sulphidation, prepare a solution containing, g / l: sodium bicarbonate 2,3; sodium sulphide 0.7; technical hydrochloric acid 1. After heating in this solution for 1, 5 h and holding at this temperature for 0.5 h, the sulfur content in the outer layer of samples of steel kS increased by 2. times compared with the original condition.

With an increase in the content of sodium sulfide in an aqueous solution, the amount of sulfur in the surface layer increases.

So, in a solution containing, g / l; sodium sulphide 1.5; sodium bicarbonate 2,3; technical hydrochloric acid 1, an increase in sulfur in the surface layer 10 times.

The closest to the proposed technical essence and the achieved result is the composition for electrolytic sulfiding, containing an aqueous solution of sulfur-containing salts 2.

For sulphidation, the parts are immersed in an electrolyte containing an aqueous solution of sulfur-containing salts. The processing was carried out according to the V 100120 V mode, i 1.5-2.0 A / cm for 3 minutes. After processing on cast iron sleeves and piston pins from steel 12KhMZA, an increase in sulfur content in the surface layer is 5 times.

It has been established that the use of sulfide salts does not ensure the stability of the electrolyte composition due to the hydrolysis reaction, 0 2Na + 20fr +. The release of free hydrogen sulfide from the solution reduces the sulfur concentration in the solution and the treatment efficiency. Sulfate or sulphite salts, for example, Na (jSOj, also do not provide the required saturation rate, evidently due to the high decomposition energy of the S0 ions. The use of thiosulfate salts, for example Na-O. sulfur only at the time of electrolytic decomposition, ensures the stability of the saturability of the electrolyte. The purpose of the invention is to intensify the saturation process. To achieve this goal, the composition for electrolytic sulphidation containing water Op sulfur containing salt additionally comprises ammonium chloride as well as sulfur containing salts of sodium thiosulfate in the following ratio, vesD: Thiosulfate Sodium 10-15 1i «-16 Ammonium Chloride Water Balance

The use of ammonium chloride in a quantity provides the necessary electrical conductivity and, due to the high yield of gas-forming products during electrolysis, allows the formation of a gas-plasma shell on the surface of the workpiece at low voltages. The power of the developing spark discharge at these voltages is insufficient to heat the workpiece, so at the same time the instantaneous heating of the microzone provides surface activation and accelerated diffusion of the Moro element.

Example 1. A workable part is 5 talts - a cathode, a bath is an anode. A thermally formed and sharpened drill bit Ф18 mm is fixed in a clamp at the same time as

working surfaces of the teeth to a depth of mm at V 150 V; 1 80A; i 2.8 A / cm for 75 seconds, a diffusion layer is formed with 0.08 mm.

An example. An 82mm round roundabout is set horizontally with the immersion depth and rotational speed of Example 3 ensured. The treatment is carried out in an electrolyte containing:

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Claims (2)

When V 1-60 in; I 120 A; i 2.8 A / cm in C 90 sec., a dFyucis layer is formed up to 0 mm. 14 with the provision of electrical contact with the negative poles of the current source and immersed to a depth h 10 mm in a flow-through electrolyte corresponding to the composition, weight D: sodium thiosulfate 10; ammonium chloride water else. When applying voltage V 120 V, I 12A; i 2.4 A / cm — a diffusion layer is formed for 60 sec. (O, About, mm. Example 2. The heat treated countersink f 18, 25 is fixed as in Example 1 and immersed to a depth of 30 mm in an electrolyte corresponding to the composition, wt.% : Sodium thiosulfate Ammonium chloride Remaining Water When a voltage of V 130 V, 36A, i 2.5 A / cm is applied, a diffusion is formed in 70 sec. C / O, About mm Example 3. A disk mill of 55 mm is placed on the horizontal axis of rotation with the provision of contact and rotation with a speed of V 4 rpm, Pogruzhev electrolyte corresponding to tava, ve ,%: Sodium thiosulfate Chloride 16 Else, ammonium Voltage reduction below 120 V for an instrument whose processing is expedient leads to disruption of the plasma envelope, and increasing voltage above 1bO V leads to heating of the processed tool to tempering temperatures, which can reduce the hardness obtained by previous heat treatment The application of the proposed composition allows to obtain a deeper diffusion layer compared to the prototype (up to 60-80 microns instead of 30 microns) and in a shorter time (60-90 seconds) instead of 3 minutes. . In the study, a diffusion layer with a depth of 10–20 μm was obtained as a sulfur-containing component of a 10–15% solution of Na, 2S04 for 90 seconds. Thus, the proposed electrolytic sulphidation composition allows to intensify the saturation process. 16 The invention Composition for electrolytic sulfiding, containing an aqueous solution of a sulfur-containing salt. It is distinguished by the fact that, in order to intensify the saturation process, it additionally contains ammonium chloride and sodium thiosulfate as a sulfur-containing salt in the following ratio of components, wt.%: Sodium thiosulfate 10-15 Ammonium Chloride It-IS Water Else Sources of information taken into account during the examination 1. Solovieva N.А. Seron-saturation (g surface of parts from ferrous metals in hydrogen sulfide-hydrosulfide Metallography and terra-solutions. Metal processing of metals, M., Mashgiz, 1960, № 1, pp. Ly- S. 2. Bakharev A.P. and others. The advantage of heating metals in the electrolyte. Automotive and tractor industry, Moscow, 1956, No. 2, p. 31-33.