SU1094395A1 - Powder-like compound for complex saturation of carbon steel articles - Google Patents

Abstract

POWDER COMPOSITION FOR COMPLEX SATURATION OF CARBON STEEL PRODUCTS, containing chromium, alumina, halogen-containing activator and molybdenum compounds. characterized in that, in order to increase the corrosion resistance of the processed products in aggressive media, it contains boron or carbon molybdenum as molybdenum compounds in the following ratio, wt.%: Halogen containing 0.75 - 1.5 activator Borisy or carbon molybdenum 2- 4 Chrome 75 - 82 Aluminum Oxide Else S

Description

four;

with

The invention relates to the field of chemical heat treatment, in particular, to the complex differential absorption of ferrous metals, and can be used in metallurgical, chemical, industrial, as well as in mechanical engineering for the protection of corrosion of parts and tools. A powder composition is known for complex diffusion saturation containing the components listed below with the following ratio,%: 14 - 17 Aluminum oxide 1.0 - 1.7 Aluminum chloride Rest Chromium The disadvantage of this composition is the relatively low ductility and low protective ability of the resulting layer. in chloride solutions at elevated temperatures. The closest in technical essence and achievable results is a powder composition of complex diffusion saturation of carbon steel products containing chromium, alumina, halogen-containing activator and molybdenum compound, in the following ratio of components, wt.%: Chromium Ammonium Bor. Molybdenum Alumina mini-oxide This composition allows to increase the plasticity of the diffusion layer, however, the erg protective ability in chlorine solutions at elevated temperatures remains unsatisfactory. In addition, this composition is relatively expensive because it involves the use of such expensive components as boron and molybdenum The purpose of this invention is to increase the corrosion resistance of processed products in corrosive environments. (For example, in solutions of hLorides and suspensions of strong liquors with a solid phase of chlorides). The goal is achieved by the fact that the known powdered composition for complex saturation of carbon steel products containing chromium, alumina, the halogen-containing activator and molybdenum compounds, according to the invention, it contains molybdenum boron molybdenum or carbon molybdenum as molybdenum compounds in the following ratio, wt.%: Halogen-containing ak0, 75 - 1.5 tivator Boron or carbon 2-4 molybdenum 75 - 82 Chromium 14.5 - 30 Alumina The components of the composition in the form of powders in appropriate quantities are thoroughly mixed; The resulting mixture was poured into a hermetically sealed box, where the treated products were placed. The box was heated in an oven to saturation temperature, kept for the required time (until the reinforced layer was obtained of the required thickness), cooled with the oven to 300 ° C, and then in air. An example of a specific implementation. Prepare a mixture consisting of powders of the following components, wt%: Boron molybdenum Ammonium chloride Alumina oxide The mixture was thoroughly mixed, put into a hermetically sealed box with the samples to be protected. The box was heated in a furnace to 1000 ° C, held for 5.5 hours, then cooled with a furnace to 300 ° C, and then in air. The thickness of the hardened layer on the samples was O, 1 mm. Other examples to justify the limits of the claimed composition are presented in Table 1. The results of the comparative tests with the prototype are shown in Table 2.. The properties of the resulting coatings were evaluated by corrosion rate at 60–80 ° C in a solution containing 250 g / l of chlorides and 85 g / l of chlorates, as well as in a suspension of strong liquors with a solid chloride phase: 810 g / l of KOH and KC1 (solid) ; Such a suspension takes place in the production of caustic soda. The test duration was 1200 hours.

In addition, the continuity of the layer was determined by the method of exposure to a Walker reagent (by the number of developed colored points per 1 cm of the surface), and the microhardness of the layer was also measured.

As can be seen from Tables 1 and 2, the proposed composition allows to obtain a diffusion layer with a high passiviruitis capacity, as evidenced by the very low corrosion rate of the samples. 0.008 - 0.009 g / m h when tested in a solution containing chlorides against 0.025 g / m h when protecting samples with a known composition. Rate of Correction of the limits of the proposed composition

The sieves of the samples protected by the proposed composition in a solution of strong alkali are 0.003 to 0.004 g / m h versus 0.022 g / m h while protecting the samples with a known composition. At the same time, the microhardness and the smoothness of the layer obtained by protecting the samples with the proposed composition are not inferior to the samples protected by known compounds (see), h

Thus, the technical and economic advantages of the proposed composition consist in increasing the passivating ability of the diffusion

layer, and, consequently, in increasing the corrosion resistance of the coating in. electrolyte solutions containing chlorides in strong liquors. In addition, the composition is more economical due to the use of cheaper components.

Table 1

1.25 13.75 0.024 missing Disturbance of plasticity of the layer when the diamond pyramid is pressed in

Comparative characteristics of the properties of coatings obtained in the processing of carbon steel proposed and known compositions

The corrosion rate g / m h in a solution containing, g / l:

a) chlorides - 250

chlorates - 85 t 60-80 ° С

b) strong liquor KOH-810

KC1 - solid phase

table 2

0,008 0,008 0,009 (uniform corrosion)

0,004 0,003 0,004 (uniform corrosion)

t SOC

Microhardness kg / mm in HV

The continuity of the layer (points by 1 cm)

1100

1080

1080

no-no-no

Claims (2)

POWDER COMPOSITION FOR INTEGRATED SATURATION OF PRODUCTS FROM CARBON STEEL, containing chromium, alumina, a halogen-containing activator and molybdenum compounds, characterized in that, in order to increase the corrosion resistance of the processed products in aggressive environments, it contains molybdenum or molybdenum compounds the following ratio of components, wt.%: Halogenated activator Boron or carbon molybdenum Chromium Alumina 0.75 - 1.5 2-4 75 - 82 Else 1094395.