SU737498A1 - Composition for tungstensilicylation of steel articles - Google Patents

Description

The invention relates to chemical heat treatment and can be applied as a saturating medium for diffusive bolt-mercylation of steel products.

The melt composition for volframosilcation is known, containing the following components, wt%: Sodium tungstate 85

Silicocalcium 15 1 j.

However, such a composition requires the use of expensive equipment, is difficult to operate, and makes it difficult to heat treatment after the chemical heat treatment process.

A known composition for filfrasilization, containing the following components, wt%:

Tungsten Oxide35-38

Silikokaltsy22-25

Ammonium Chloride2

Alumina Rest J2j.

The disadvantage of this composition is the relatively low speed of

The development of tungsten diffusion layers, the need to carry out the saturation process of powders in hermetic heat-resistant containers using fusible closures. In addition, a large amount of the saturating mixture is consumed, and the thermal treatment after the chemico-thermal treatment process is difficult.

The aim of the invention is to increase the activity of the saturating medium and provide the possibilities of carrying out the process in a conventional furnace environment.

The goal is achieved by

15 that the composition contains tungsten carbide as a tungsten-containing substance, silicon carbide as a silicon-containing substance, sodium fluoride as an activator and additionally but 20 contains iron scale in the following ratio of components, wt.%: Tungsten carbide 10-60

Silicon carbide 10-60 Sodium fluoride 3-10 Iron oxide scale 25-45 The presence of iron oxides in scale prevents the oxidation of both the saturable surface and the active components of the composition, which allows the process to be conducted in a conventional furnace medium during prolonged high-temperature exposure (1-20 hours at 800 -IOO C). The interaction of iron oxides, which are part of the scale, with the active components of the composition accelerates the formation of the active atoms of tungsten and silicon, and consequently, increases the saturation rate, in this case, the scale has the effect of a catalyst. The diffusion layer consists of a solid solution of tungsten and silicon in оС. - iron. Example. Conducted diffusion tungsten silicate in daubings on specimens of steel U8. The coating is prepared 7 84 by mixing the powder components (size of the fraction 0.1-0.2 mm) with hydrolyzed ethyl acetate. Apply a coating of 4-5 mm thick on samples of steel U8 coated. After drying for 10-20 min. At room temperature in air, the samples are placed in an electric furnace heated to the temperature of the process of chemical heat treatment (9OO-11OO C) and maintained for 4-6 hours. The quenching is carried out from the diffusion saturation temperature. During quenching, TepsteT coating is intact and separated from the surface of the samples. The results of the diffusion saturation of the ultrasonic steel with the proposed composition at a process temperature of 900 and a holding time of 4 hours are presented in the Table. At saturation with a known content, wt.%: 35 oxide + 25 silicocalcium + 2 ammonium chloride + 38 alumina (the process is carried out in crucibles with a fusible bolt), the depth, layer is 350 µm.

Claims (2)

The components for the preparation of the coating are used in the form of powdered tungsten carbide and silicon carbide, sodium fluoride of grade H 4463-66, iron oxide (waste from forging and thermal production). The results of measuring the thickness of the diffuse layers after carrying out the processes of chemical-and-ogerm treatment show that the saturability of the proposed composition is 1.5-2 times higher than the saturability of the known composition; . The use of the proposed composition for tungstenization of steel products provides, in comparison with known compositions, the possibility of carrying out the process in a conventional furnace environment without using special protective ocHacTKF to increase the saturability of the composition, improve processability and reduce the cost of the mixture, combining diffusion control of large-sized products with their heating for quenching. Claims Composition for eopramysilicating steel products containing tungsten silicon-containing substances and activator, characterized by the fact that, in order to increase the activity of the saturating medium and ensure the possibility of carrying out the process in the furnace environment, it additionally contains iron, as an activator sodium fluoride, as tungsten content 5 7374986 tungsten carbide, in ka “-sources (gasification, quality of silicon-containing substances are impurity during the examination of silicon carbide in the following ratio of components, wt.%: 1. L khovich L. S. Multicomponent Tungsten carbide 10-60j diffusion coatings. Minsk, 1974, Silicon carbide 1O-60c. 223. Sodium fluoride W. Yu. 2. USSR author's certificate Iron scale 25-45№ 448250. кл. C 23 C 9/02, 1972.