RU2405860C2 - Method for obtaining powder coatings on basis of metal matrix - Google Patents

Abstract

FIELD: metallurgy.

SUBSTANCE: method involves application of copper base to the surface, which is heated to 70-90°C, layer of jelly flux, its heating to 100-120°C. Then to the base there applied is layer of copper powder pre-dried to humidity of 3-4% and heated to 110-130°C, and burnt to the base by means of roller electrodes by using alternating current pulses. Duration of pulses is 0.7-0.8 of sinusoid period, and pause between them is 0.2-0.3 of sinusoid period. At that, prior to drying and heating, copper powder is subject to mechanical activation during 50-70 min.

EFFECT: improving mechanical properties of coatings.

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Description

The invention relates to the field of powder metallurgy, in particular to methods for producing coatings of metal powder materials by baking.

A known method of producing coatings of metal powder, including applying a metal powder to the surface of the substrate and its baking using two roller electrodes through which electric current is passed and at the same time apply pressure [A.S. USSR No. 1743697, IPC B22F 7/04, 1992].

The disadvantages of the method are the low physical and mechanical characteristics of the coating.

Closest to the invention in terms of technological essence and the achieved result is a method for producing powder coatings, comprising applying to the surface of a metal base heated to 70-90 ° C, a gel-like flux layer, heating it to 100-120 ° C, and then applying a layer of dried to humidity 3-4% of the metal powder and baking it using roller electrodes, using pulses of alternating electric current, the duration of which is 0.7-0.8 sine wave period, and the duration of the pause between pulses with nent 0.2-0.3 sinusoid period, before application to the layer of jelly flux metal powder is heated to a temperature of 110-130 ° C [Russian Patent 2326184, IPC S23S 24/08, B22F 7/04, 2008 (prototype)].

The disadvantages of this method are the low mechanical characteristics of the coating.

The objective of the invention is to improve the mechanical characteristics of the coating.

The problem is solved in that according to the method for producing powder coatings based on a metal matrix, which includes preliminary deposition of a jelly-like flux layer on the surface of a metal base heated to 70-90 ° C, its heating to 100-120 ° C, and subsequent application of a layer of dried to a moisture content of 3-4% and a metal powder heated to a temperature of 110-130 ° C and baking it using roller electrodes, using alternating electric current pulses, the duration of which is 0.7-0.8 sine wave periods, and for The duration of the pause between pulses is 0.2-0.3 sine wave periods, before drying and heating, the metal powder is subjected to mechanical activation for 50-70 minutes.

The solution to this problem is provided by increasing the strength in the zones of contact interaction between the particles of the powder coating, as well as between the coating and the metal base. This is facilitated by a decrease in the area of oxide films on the surface of metal powder particles and, as a result, an increase in the number of metal contacts between them due to a decrease in temperature gradients in the material under the indicated temperature conditions for processing the components.

Obtained by the proposed method, the coating in comparison with the coating obtained in a known manner, has improved mechanical properties.

The invention is illustrated by the following examples.

Example 1 (prototype). A coating of metallic powder material is obtained by electrocontact baking. As a metal base, a copper tape of the DPRNM-0.35 × 15 NDM 3 grade GOST 1173-77 is used, and as a coating material is a copper powder PMS-1 GOST 4960-75 with a particle size of 50-100 microns. The coating is carried out on the installation made on the basis of the resistance welding machine MSH-3207. In the feed device, the copper tape is heated to a temperature of 80 ° C. A layer of jelly-like flux PKB-26 M with a thickness of 60-70 μm is applied to the surface of the copper tape and heated to a temperature of 110 ° C. Using a dispenser, 3% pre-dried to a moisture content of 3% and heated to a temperature of 110-130 ° C in a heated dispenser is applied and a layer of metal powder is formed in thickness. Then a copper tape with a deposited and formed powder layer is placed between two roller electrodes with a diameter of 200 mm and a width of 16 mm, compressed by means of pneumatic cylinders, and rolled with transmission of alternating electric current with a frequency of 50 Hz in the form of pulses described by an incomplete sinusoid, the duration of which is less than the period of the sinusoid and is 0.75 of its period, and the duration of the pause is 0.25 of the sinusoid period, and the simultaneous application of pressure. As a result, the powder layer is baked to the tape. The required pulse duration in relative values is set on the control unit of the resistance welding machine MSH-3207. The main indicators of the process are shown in table 1.

Table 1 Process indicators Indicators Electrode pressing force, N Baking speed
m / s Current, kA The thickness of the powder layer, microns The thickness of the resulting coating, microns Quantitative Characteristics 9500 0,03 17-19 190-200 90-100

Example 2. Example 2 differs from example 1 in that before drying and heating, the metal powder is subjected to mechanical activation for 60 minutes in a drum-type activation device.

To illustrate the invention, Table 2 shows the methods and parameters of technological processes, and in Tables 3 and 4, the comparative properties of coatings obtained from metal powder materials.

The bond strength of the coating with the metal base is determined according to GOST 10885-75, the tensile strength of the coating is determined according to GOST 1497-73.

As follows from the above data, coatings obtained by the proposed method, compared with coatings obtained in a known manner, are characterized by improved mechanical characteristics and increased service life.

table 2 Powder Coating Name The method of producing coatings and process parameters parameters According to the prototype Beyond Declare Beyond Technological
process one 2 3 four 5 6 7 8 1. The heating temperature of the metal base, ° C 80 80 80 80 80 80 80 80 80 2. The temperature of the heating layer of a jelly-like flux, ° C 110 110 110 110 110 110 110 110 110 3. The temperature of the heating of the metal powder, ° C 120 120 120 120 120 120 120 120 120 4. The time of mechanical activation of the metal powder, min - 5 10 twenty fifty 60 70 90 120

Table 3 Comparative properties of coatings obtained from PMS-1 copper powder GOST 4960-75 Numbers Received Coating Characteristics coatings The strength of the connection of the coating with a metal base, Tensile Strength MPa MPa Prototype 325-329 118-122 one 327-330 118-122 2 331-333 123-126 3 334-337 127-129 four 338-340 130-132 5 341-345 132-133 6 339-342 130-132 7 330-335 112-118 8 300-310 100-102 Note. When determining the characteristics, 5 samples of coatings of each type were tested and statistical processing of the test results was carried out.

Table 4 Comparative properties of coatings obtained from bronze powder Numbers Received Coating Characteristics coatings The strength of the connection of the coating with a metal base, Tensile Strength MPa MPa Prototype 330-338 129-133 one 338-340 130-134 2 341-342 136-139 3 344-348 140-144 four 349-353 145-148 5 354-360 149-154 6 354-356 148-152 7 351-354 144-148 8 336-339 130-133 Note. When determining the characteristics, 5 samples of coatings of each type were tested and statistical processing of the test results was carried out.

Claims (1)

A method of obtaining a coating of metal powder, comprising applying to the surface of a copper base heated to 70-90 ° C, a gel-like flux layer, heating it to 100-120 ° C, then applying a layer of copper powder pre-dried to a moisture content of 3-4% and heated to a temperature of 110-130 ° C, and baking it to the base using roller electrodes using alternating electric current pulses, the duration of which is 0.7-0.8 sine wave periods, and the pause between them is 0.2-0.3 sinusoidal period, characterized in that d drying and heating of the copper powder is subjected to mechanical activation for 50-70 minutes.