SU834238A1 - Method and composition for tungsten-plating of steel articles - Google Patents

Description

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The invention relates to chemical treatment of metals and alloys, in particular to diffusion metallization with heating when electric current passes through electrolytes, and can be applied in mechanical engineering, instrument engineering and other areas of technology.

The known method of diffusion metallization with tungsten with saturation in a gaseous medium and induction heating in special installations, which will receive, using HDTV at a heating temperature on carbon steel, tungsten, a layer of 0.15-0.2 mm in depth with H 350-400 kgf / mm D.

The disadvantage of this method is the need to create complex installations for the preparation of the supply and dispensing of gaseous media, the creation of sealed muffles. The use of hydrogen or hydrogen chloride is dangerous. In addition, this method requires the application of special protective coatings during local processing.

A method of electrolytic tungstate is also known, and the composition which is molten tungsten salts, e.g., tungstate, sodium. The known method allows to obtain at-solid solutions of tungsten in Armco iron with a depth of 10-20 microns during a processing time of 2-6 hours at a heating temperature of 1000 ° C and a current density of 0.2-0.3 A / cm f2j.

The disadvantages of this method are the long duration of the process of filling and the need for additional heating of the electrolyte above the melting point, which leads to additional energy costs.

The purpose of the invention is to intensify the saturation process and reduce the heating temperature of the electrolyte. This goal is achieved by the fact that the process of tungstenization is carried out in an electrolyte consisting of an aqueous solution of tungsten-phosphoric acid and hydrochloric acid in a ratio, wt.%: Tungstophosphoric acid 2-10 Solor acid acid 5-15 Water Others at a voltage of 170-280 B, current density 0.4-0.9 A / cm using a nickel, modabden or lead cathode, an electrolyte temperature of 15-35 C and a sample surface temperature of 850-050PC. When the voltage on the electrodes is not less than 170 V and the current density is less than 0.4 A / cm, the part is not heated, and when the voltage is more than 280 V and the current density is more than 0.9 A / cm, the heating process is disrupted. The process of diffusion of tungsten at temperatures of less than 850 C practically does not proceed. The physical features of the part heating process prevent the part from heating above 1050 C in the electrolytes used for tungsten heating. The temperature of the electrolyte should be no more, since at high solution temperatures the temperature of the heating of the part drops sharply. Dp maintaining temperatures lower than 15 ° C, it is necessary to install special coolers, which is not particularly necessary. PRI me R. A constant voltage from a power source is applied to an electrolytic cell consisting of a lead cathode and an anode part. After a voltage is established on the electrodes, the anode is immersed in the electrolyte. Depending on the voltage on the electrodes, the surface temperature of the part varies from 850 to 1050 ° C, and the electrolyte temperature from 15 to 35 ° C. Processing time 2-10 min. The cooling of the part is carried out by disconnecting the electric current. Cylinders with a diameter of 10-12 mm made of armco iron are used as samples. The modes of the tungling process and the processing results are shown in the table.

Claims (2)

The tungsten concentration in the layer is determined by layer-by-layer chemical analysis, the depth of the layer is determined by the change in microhardness and by the results of chemical analyzes. The measurement results show that the concentration of tungsten in a layer 10-15 µm deep is 2-4%, in the first 100 µm it is 0.9-0.6%, in the second 110 µm it is 0.2-0.8%, and in the third 100 μm — O, 03–0.06%, during sample processing for 6 min at a sample temperature of 950 ° C and an electrolyte temperature of 25 ° C. Thus, the use of the proposed method of tungsten carbide makes it possible to intensify the Naxstance process by tungsten 7-10 times and to obtain layers of a depth of 0.2-0.3 mm within a few minutes. The process is carried out at very low electrolyte temperatures (15-. It does not exclude the use of high-temperature heating devices, which leads to a 10–20% reduction in electricity. The formula isobert 1. The method of tungsten-fi xing steel Products, including treatment In tungsten-containing electrolytes, I distinguish The aim is to intensify the process of saturation and decrease the heating temperature of the electrolyte, the treatment is carried out at a current density of 0.4-0.9 A / cm, voltage 170-280 V and a temperature of 850-1050 ° C, electrolyte 15 -35 pp. 2. Composition for carrying out the method according to claim 1, such as an electrolyte with a tungsten-containing component, characterized in that it additionally contains water and hydrochloric acid, and tungstophosphoric acid as the tungsten-containing component Sources of information adopted into account during the examination 1.Kidin I.N. and others Elek ical metal processing. M., Metallurgists, 1978, p.12-42, 2. Multiple diffusion coatings. Ed. LSL Hovic. Minsk, 1974, p.68.