SU975827A1 - Composition for boronizing steel products - Google Patents

Description

The invention relates to chemical-heat treatment and can be used as a saturating medium for the diffusion borophosphorization of steel products.

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There is a known method of boronation in plastering, according to which saturation is carried out in a mixture of boron-containing substances, a filler of an abrasive-metal mixture (grinding and sharpening waste from steels) and _an activator in the following ratio of components, wt%:

Boron carbide 45-60

Sodium fluoride 3-10

Abrasive-metal mixture 35-52 15

This composition allows saturation in an oxidizing environment without protective equipment (1].

However, the boride layers obtained by saturation have an increased brittleness. ₂₀ The closest in technical essence and the achieved effect is a composition for boronating steel products, containing, weight. %: boron carbide 40-60; sodium phosphate 2-5; fto2

sodium sodium 4-6; iron oxides 32- 51 12].

However, the known composition has insufficient wear resistance of the diffusion layers.

The aim of the invention is to improve the wear resistance and surface finish of the processed products.

This goal is achieved by the fact that the composition containing boron carbide, acidic sodium phosphate and sodium fluoride contains in addition an abrasive-metal mixture containing 30–40% of the steel component, 50–70% of the abrasive component, 8–12% of carbon with the following ratio of components, weight . %:

Carbide boron 40-60

Acidic sodium phosphate 2-5

Sodium fluoride 4-6

Abrasive-metal mixture 32-51

The mixture allows the process to

conventional furnace environment with long high-temperature exposure.

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Example. Carry out diffusion borophosphorization on steel samples 5HNM. The mixture is prepared by mixing the powdered components (fraction size O,, 2 mm). Samples measuring 10 X 10 X X 10 mm cover the mixture in such a way

so that the thickness of the mixture was at least 5 mm. Samples were placed in an electric furnace heated to 900 ° C and kept at this temperature for 4 hours. The diffusion saturation results are shown in Table ⁵ face.

The composition of the mixture, wt.% Area share hardenable surfaces that subject to sticking particles% Wear, mg / cm ² At ₄ C Man ₂ RO ₂ IAE Abrasive metal mixture bo 2 6 32 12-15 46 50 3 five 42 10-12 45 40 five four 51 8-10 44

Contrasting composition:

50% B ₄ C + 3% ΝβΗ ₂ Ρ0 ₂ + 5% IaR + 42% 35-45 56 iron oxides

According to chemical analysis data, the abrasive-metal mixture contains: a steel component of 30–40%, an abrasive component of 50–70%, and the presence of 8–12% carbon in the mixture. The presence of silicon and aluminum compounds in the abrasive component (the basis of most grinding and grinding wheels) leads to additional doping of the diffusion layers with these elements, which in turn increases their wear resistance by 25-30%. Tests for wear were carried out under conditions of dry sliding friction with the parameters: pressure 15 MPa, sliding speed 0.42 m / s.

The presence of carbon in the abrasive-metal mixture, which, as is well known, has non-stick properties, largely eliminates the adhesion of particles of the diffusion-active composition to the hardened surface after chemical-thermal treatment. At the same time, the area of the hardened surface, which is subject to sticking of particles for borophosphorination, decreases by a factor of 3–4.

Claims (1)

Claim ₃₀ Composition for boring steel products containing boron carbide, acidic sodium phosphate and sodium fluoride, characterized in that, in order to increase the wear resistance and surface cleanliness of the products being processed, it additionally contains an abrasive-metal mixture in the following ratio of components, weight. %: Boron carbide Sour phosphoric acid 40-60 ly sodium 2-5 Sodium fluoride 4-6 Abrasive metal kaya mixture 32—51