SU1738868A1 - Method of electric arc metal spraying - Google Patents

Abstract

Use: for protection against corrosion of parts for various purposes due to the formation of metal-polymer coatings. SUMMARY OF THE INVENTION: A polymer and an endothermically decomposable substance are introduced into a stream of electrode material melted in an electric arc formed by compressed air, the polymer being introduced in an amount of 28-38% of the volume of molten electrode material at a distance of 30-50 mm from their intersection point. and the endothermically decomposing substance is in the amount of 2.5-4.0% by weight of the polymer at a distance of 65-85 mm from the point of introduction of the polymer. At the same time, this substance has a melting point of 10–20% below the melting point of the polymer and a particle size of 20–40 µm. 7 tab. with s

Description

The invention relates to the coating of gas-thermal methods, in particular to electric arc coating of metal-polymer coatings, and can be used in various fields of engineering.

The aim of the invention is to reduce the permeability of coatings.

Example 1. A method for carrying out an EM-14 electrometallizer. Aluminum wire of brand АД-1 ф 1.6 mm (GOST 7871-75) was used as electrodes. The sample surface was prepared for sandblasting. The electric arc was reproduced with an electric current of 320 A and a voltage of 26 8. The air pressure at the entrance to the metallizer was 0.52 MPa. Electric arc melted wire electrodes. Strut

compressed air formed a cone of molten metal spray. Powdered high-density polyethylene was introduced into the spray cone at a distance of 40 mm from the point of intersection of the electrodes. (GOST 16337-77E) and at a distance of 65 mm from the insertion point of polyethylene, sodium bicarbonate (GOST 2156-76) was fed in the amount of 3.5% of the volume of powdered polyethylene. The particle size of sodium bicarbonate is 20-40 µm. The melting point of the powdered polymer is polyethylene 120 ° C, and the decomposition temperature of sodium bicarbonate is 100 ° C.

Samples of steel 3 installed at a distance of 180 mm from the point of intersection of the electrodes were sprayed onto the surface. A total of 8 samples were sprayed with coatings having a thickness of from 200 to

Oj

with

00 O 00

1200 microns The adhesion strength of the coating to the substrate was determined by the pin method, and the permeability of the coating was determined by the capillary method. Torn from the substrate. The lower surface was painted with chalk, and the upper surface of the coating was moistened with kerosene.

The results are shown in Table. one.

Example 2. Has the known method been carried out with an electrometallizer EM-12M. A powder wire with a sheath made of aluminum and filled with a mixture of powdered high-pressure polyethylene and chromium carbonyl 8.5% was used. Electrometallizer regulated on the departure of the electrodes no more than 12 mm. The sample surface was prepared for sandblasting. The electric arc was reproduced with an electric current of 320 A and a voltage of 26V. Air pressure at the entrance to the metallizer 0.52 MPa. Samples of steel 3 mounted at a distance of 120 mm from the point of intersection of the electrodes were sprayed onto the surface. A total of 8 samples were coated with coatings having a thickness of 200 to 1200 µm. The adhesion strength of the coating to the substrate was determined by the pin method, and the permeability of the coating was determined by the capillary method. Torn off the coating from the substrate. The lower surface was painted with chalk, and the upper surface of the coating was moistened with kerosene.

The results are shown in Table. one.

To determine the optimal amount of substance supplied to the spray cone by endothermicly decomposing with evolution of gases, the proposed method was repeatedly carried out using an EM-14 electrometallizer analogously to Example 1. Moreover, high-pressure polyethylene was used as a polymer powder (GOST 16337-77E), and endothermically decomposing with evolution of gases, sodium bicarbonate (GOST 2156-76) in the amount of 1.0-4.5% by weight of the powdered polymer. The permeability of the coating was determined similarly to the determination of permeability in samples of polymer coatings 1.

The results are shown in Table. 2

Example 3. Determining the effect of the amount of polymer injected into the spray cone on the properties of the coating.

The method was carried out analogously to example 1. 9 experiments were carried out. 9 samples were coated with coatings having a thickness of 300 µm. The amount of polymer injected into the spray cone varied within 26-40% by volume of the molten metal electrodes. The permeability of the coating and its adhesion to the substrate were determined as in Example 1.

The polymer content in the applied coatings was determined by a linear method. From the samples sprayed in experiments 1-9, prepared thin sections. Using a MEM-9 metallographic microscope,

summed up the lengths of the straight line segments passing through the polymer component at a certain length of the section line. The average value of the polymer component in the coating was determined by eight intersecting lines. To distinguish the boundaries of the polymer, pores and metal on the surface of the thin section, a red dye was introduced into the polymer before spraying.

The volume content of the polymer component in the coating is determined by the formula

J

Vn.c.

I 1

100%,

where vn.c. - volume content of the polymer component in the coating;

X I | - sum of lengths of polymer segments

component on a common secant line; L-length of the common secant line. The results obtained for the determination of permeability, adhesion strength

the coatings and the polymer content in the applied coatings are given in Table. 3

PRI me R 4. Determination of the point of entry of powdered polymer in the spray cone.

The method was carried out analogously to the example. It was conducted 9 experiments. 9 samples were coated with coatings having a thickness of 300 µm. The distance from the point of intersection of the electrodes to the point of introduction of the polymer

changed from 20 to 60 mm. The permeability of the coating was determined analogously to example 1. The polymer content in the coating was determined analogously to the determination of the polymer content in the coating in example 3.

The results obtained for determining the permeability and the content of the polymer in the applied coatings are given in Table. four.

Example 5. Defining an entry point

sodium bicarbonate in a spray cone.

The method was carried out analogously to the example. It was conducted 9 experiments. 9 samples were coated with coatings having a thickness of 300 µm. The distance from the polymer injection point to the sodium bicarbonate injection point varied from 55 to 95 mm. The permeability of the coating was determined similarly to the determination of the permeability of the coating in example 1.

The results are shown in Table. five.

Example 6. Determination of the optimal particle size of a substance that is endothermally decomposable with evolution of gases.

The method was carried out analogously to example 1. 4 experiments were conducted. Four samples were coated with coatings having a thickness of 300 µm. During the experiments, the granulometric composition of sodium bicarbonate was changed.

The permeability of the coating was determined similarly to the determination of the permeability of the coating in example 1.

The results are shown in Table. 6

Example 7: Determination of the effect of the decomposition temperature of a substance with evolution of gases on the permeability of the coating.

The method was carried out analogously to example 1. 4 experiments were conducted. Four samples were coated with coatings having a thickness of 300 µm. In the course of the experiments, various substances that were endothermically decomposing with evolution of gases, characterized by a decomposition temperature, were injected. The permeability of the coating was determined similarly to the determination of the permeability of the coating in example 1.

The results are shown in Table. 7

Claims (1)

DETAILED DESCRIPTION OF THE INVENTION The method of arc metallization includes melting electrodes in an electric arc, spraying melting products with compressed air when polymer is introduced into the gas flow and an endothermically decomposable substance is characterized in that, in order to reduce the permeability of coatings, the polymer is introduced in an amount of 28-38% volume of molten material at a distance of 30-50 mm from the point of intersection of the axis of the electrodes, and the endothermically decomposing substance with a melting point 10-20% below the melting point of the polymer and a particle size of 20-40 µm is introduced in an amount of 2.5-4.0% by weight of the polymer at a distance of 65-85 mm from the point of its injection into the jet. Table 1 table 2 Table 3 Table 4 Continued table. BUT Table 5 Table 6 Table 7