RU1799398C - Method of metallic coating application - Google Patents

Abstract

SUMMARY OF THE INVENTION: a method for applying metal coatings, mainly to pipes and articles with an internal channel, includes chemical cleaning, preheating in a protective atmosphere, processing in a flux melt in a separate bath, immersion in a molten metal coating and high-speed cooling, in the flux melt and in the molten metal, the coatings are carried out in a protective medium, which is used as an inert gas, in particular technical nitrogen, in the flux melt, the products are heated to a working temperature the temperature of the molten metal coating or above it. When applying an aluminum zinc coating containing 55% aluminum, 43.5% zinc and 1.5% silicon, preheating is carried out to 350-470 ° C, and the flux is heated to 640-650 ° C at a temperature melting flux 500-520 ° C. 2 s.p. fl, 1 tab.

Description

The invention relates to the technique of hot (liquid phase) methods for applying metal coatings, mainly, to steel pipes, cylinders, radiators and other products with internal channels in metallurgy, mechanical engineering and in the construction industry.

The aim of the invention is to improve the quality of the coating, expand technological capabilities, increase the reliability of the bath with molten metal coating.

The goal is achieved in the method of applying metal coatings, advantage on pipes and products with an internal channel, including chemical cleaning, preheating in a protective atmosphere, processing in a flux melt in a separate bath, immersion in a metal melt and rapid cooling, in which, according to the proposed method, the processing in the flux melt and in the metal-coating melt is carried out in a protective environment, and, as a result, XI

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An inert gas is used in the protective medium, and in the flux melt, the articles are heated to or above the working temperature of the coated metal melt. In addition, technical nitrogen is used as a shielding gas, and when applying an aluminum-zinc coating containing 55% aluminum, 43.5% zinc and 1.5% silicon, preheating is carried out to 350–470 ° C and heating melt flux up. 1O

, - ;: v ;;; :: - t:, ;;;, .... ;;. - - -. Г - JPoed | Ts1Ga / e ..pr p6b can be illustrated by the following example of a specific implementation, V

Coating according to the proposed, 15. the method and prototype were produced on steel tubes 021.3x2.5 mm long ЩУммиз steel mark 8K | 1: .V TV--:

The samples were processed barely. in the following way: degreased in an alkaline 20 solution with TMS; washed; etched in 15-20% HCl; washed. It was processed in a; ... 35% solution of the composition, May.%: ... ЦС1; g: .-: 25 - / -.

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t45 ..- -. : ZnCI .L. -:, .. ,,: -. 23, ::: L;:.; L: Dried ave: pr150-1800C .::

Samples prepared in this way were processed according to the following options: heating in 30 atmosphere of technical nitrogen to a temperature of UR 300-4200С; holding in the flux-melt for 20-200 s at a melt temperature of 52 ° C; galvanizing 15s at 4700C; cool 35

immersion in water ..

A 100% flux melt of the above composition was used (melting point 350-376QC);

Application of an aluminum-zinc coating of the galvalyum type according to the proposed method: Heating in an atmosphere of technical nitrogen to 350-470 ° C. Holding in 100% flux-melt-molten composition, May. %:

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Kf3

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AIF3 V3 for 15-190 s at 650 ° C.

The melt melting point is 500-520 ° C. . .

Melt dip metal coating composition, May. %:

Zn43.5

Si1.5 at 600 ° C for 10 s. Cooling in a stream of air.

Galvanizing according to the prototype.

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Immersion of samples in a zinc melt at 470 ° C through a 15 mm layer of 100% flux-melt of the specified composition. Cooling by immersion in water.

The quality of processing was evaluated as follows: by visual inspection (absence of uncovered spots, points); by the thickness of the intermetallic layer determined by the metallographic method.

The loss of non-ferrous metal in gartzInc was estimated by the iron content in the lower part of the zinc melt (by chemical analysis). The iron content in the lower part of the flux melt was determined by chemical analysis. : ;;: The results of comparisons of the proposed method and prototype are presented in the table. ,; :: -; U:.:.; v ;; :; U ;;. V ;; v / th /:;:; -:; v :; : ..- -: v. .- For galvanizing and applying aluminum-zinc coatings according to the proposed method, the holding time for the melt of the coating metal is even 3-5 seconds, which is practically impossible to carry out when coating the pipes. In jd the time, according to the prototype, the VRB (th; tsikovkini, necessary for the form: world of coverage) is

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When applying aluminum-zinc and zinc-aluminum coatings, the prototype method (wet) is impractical due to significant gas evolution - chloride

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It follows from the foregoing that the proposed technical solution, in comparison with the prototype, expands technological capabilities (applies aluminum-zinc coatings); improves the quality (plasticity) of the coating by reducing the thickness of the diffusion layer from 20-22, microns (according to the prototype) to 6-7 microns and 10-12 microns (when heated to a temperature below the melting point of the flux melt) to 6-7 μm, In the latter case, a decrease in the thickness of the intermediate layer is achieved due to the formation of fewer corrosion products of the workpiece when it is briefly in the flux melt, introduced into the molten metal of the coating and partially remaining in the coating in the form of zinc-iron phases, partially passing into hartzink alloy. In addition, it increases processing productivity by reducing the time required to form a coating to the minimum possible practically (3-15 s) instead of 70 s, as well as the time taken to warm up the product in the flux melt from 200 s to 20 s; reduces the consumption of non-ferrous metals and salts (a decrease in the mass of hartzinc in the molten metal and the dros in the molten flux), which

indicates a decrease in the iron content in the lower part of the metal melt from 11.4 parts to 9 (when heated below the melting point of the flux) and 6.5 colors (the proposed composition) and in the melt of the flux from 22 parts for long to 3 parts with short-term heating. A reduction in flow rate is also achieved with a decrease in entrainment with volatile compounds formed upon constant contact of the flux melt with the molten metal (prototype); reduces harmful emissions (by reducing gas emissions in a closed system with a protective atmosphere of technical nitrogen).

In addition, heating in the atmosphere of technical nitrogen with short-term heating in the flux-melt, also in contact with the protective gaseous medium, allows to reduce the corrosive effect of the flux not only on the steel being processed, but also on the material of the equipment and the lining of the bath, respectively reducing loss of flux in Dros. In this case, short-term heating of the pipes in the flux-melt is advisable for electrode heating of the flux-melt, and preliminary heating of the pipes by the induction method.

The proposed method can be widely used in the production of pipes with corrosion-resistant coatings, first of all, in the production of water-gas-conductive pipes 0 23-114 mm with aluminum-zinc coatings, in galvanizing or elimination of cylinders (with

the purpose of the long-term storage of highly pure gases and liquids; not reacting with these metals) and water heaters (to protect against corrosion).

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Claims (2)

1. The method of applying metal coatings mainly to pipes and products with an internal channel, including chemical cleaning, preliminary heating in a protective atmosphere, and treatment in a molten flux, which is separate. bath, immersion in a melt of metal coating and high-speed cooling, which requires that, in order to increase 5 qualities of the coating, expanding technological capabilities and increasing the reliability of the bath with the spreading of the metal-coating, the processing in the flux melt and the metal-coating melt is carried out in a protective medium, and an inert gas is used as a protective medium, and in the flux melt the products warm up to a higher temperature of the molten metal coating or above it; 5 2. The method according to claim 1, with the exception that inert gas is used as inert gas: Ut technical nitrogen. 3, The method according to paragraphs. 1 and 2, starting with the fact that when applying an alumina-zinc coating containing 55% aluminum, 43.5% zinc and 1.5% silicon, the preliminary heating is carried out to 350-4700С and the density of the flux in the melt is up to 640-650 ° C at a melting point of the flux of 500-520 ° C. 5 - - .... .;