RU2491370C1 - Solution to produce composite coating - Google Patents

Abstract

FIELD: metallurgy.

SUBSTANCE: solution to produce a composite coating contains 20-25 g/l of nickel chloride, 8-15 g/l of sodium hypophosphite, 8-15 g/l of sodium acetate, 1.5-15 g/l of potassium polytitanate powder with particle size of 20-80 nm and particle diameter of 200-800 nm, 0.5 g/l of silver nitrate and 1 litre of distilled water.

EFFECT: increased speed of coating deposition and makes it possible to produce a composite coating on a metal, having low friction coefficient and high wear resistance.

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Description

The invention relates to composite nickel-phosphorus coatings obtained by chemical deposition on steel products in order to increase their wear resistance, and can be used in the engineering industry.

Known composite coating with the inclusion of particles of finely divided powder of silicon nitride (Copyright certificate No. 1808881 A, publ. 04/15/1993, BI No. 14). The coating is characterized by good hardness, low internal stresses, and good chemical resistance. However, the resulting coating has insufficient wear resistance and an increased coefficient of friction.

Known chemically deposited coating with the joint inclusion of particles of different chemical nature (RF Patent No. 2235803, Pub. 10.09.2004, BI No. 25), however, coatings obtained from this solution do not provide a long service life.

A composite coating containing diamond particles (RF Patent No. 2375494 C2, publ. 10.12.2009), allows to increase its microhardness and wear resistance, but does not provide a low coefficient of friction.

The closest in composition is a solution for chemical deposition of coatings on products consisting of the following components, g / l: nickel chloride 20, sodium acetate 8, sodium hypophosphite 10. The temperature of the solution is 80-85 ° C, pH = 4.6. (Latatuev V.I. et al. Metal coatings by the chemical method, - Barnaul, 1968. p. 91).

However, the disadvantage of this solution is that the deposition rate of the coating is low and the resulting coatings have low wear resistance, increased friction coefficients.

The authors were faced with the task of obtaining a composite coating on metals with low friction coefficients, high wear resistance, and a high deposition rate of the coating.

This problem is solved in that an additional solution of potassium polytitanate and silver nitrate are additionally introduced into the initial solution containing nickel chloride, sodium acetate, sodium hypophosphite, the components are taken in the following ratio, g / l:

Nickel chloride - 20-25;

Sodium hypophosphite - 8-15;

Sodium acetic acid - 8-15;

Potassium polytitanate powder - 1.5-15;

Silver nitrate - 0.5;

Distilled water - 1 liter.

Potassium polytitanate powder is a scaly layered nanocrystal having a thickness of 20-80 nm and a significant diameter of 200-800 nm. Potassium polytitanate powder is produced by Nanocomposite LLC according to TU 2146 - 021 - 96961827 - 2008. The introduction of potassium polytitanate contributes to increased wear resistance, reduced friction coefficient and increased deposition rate of the coating.

Silver nitrate is a colorless transparent crystals in the form of plates or odorless white crystal rods. Very soluble in water. The introduction of powder helps to reduce the coefficient of friction.

The uniform distribution of the particles of potassium polytitanate powder in the coating was achieved by thoroughly mixing all the components of the solution using a magnetic stirrer with a speed of 10-40 rpm.

The amount of all components included in the solution for chemical deposition of the coating was selected experimentally.

An example of a coating by chemical deposition.

A solution for chemical deposition of the coating is prepared as follows: take one liter of distilled water and heat it to 55-60 ° C. Then, with thorough stirring (until the components are completely dissolved), the calculated amount of nickel chloride, sodium acetate, potassium polytitanate, silver nitrate are successively introduced into water. Next, the solution is heated to 80-85 ° C and at the end of heating, the calculated amount of hypophosphite is added to it. Before loading parts into the bath, the temperature of the solution for chemical deposition is adjusted to 90-92 ° C. One of the necessary conditions for coating the product is to maintain in the working bath: the calculated temperature, the required acidity, pH - 4.8-5. The temperature of the solution is maintained using a laboratory autotransformer in the range of 90-92 ° C. Mixing is carried out using a magnetic stirrer with a speed of 10-40 rpm.

To confirm the effectiveness of the proposed solution, four solutions were prepared for chemical deposition of the coating (see table). The deposition of metal coating was carried out on samples of steel 40X.

The surface preparation before deposition of the coating of steel samples was carried out as follows: degrease with Viennese lime, etch in a solution of hydrochloric acid in the ratio of 100 g / l at a temperature of 25-30 ° C for 30-60 seconds and rinse with running water.

The tribological properties of the resulting coating were tested on a reciprocating friction machine, displacement velocity V = 0.132 m / s, P = 20.2 MPa at a temperature of + 23 ° C ± 2 ° C in air. The coating was applied to samples of steel, and both steel and samples with a solid lubricant coating developed at FSUE OKTB ORION (Copyright certificate No. 1644489 A1, September 30, 89) were used as a counterbody.

The quantitative composition of the tested compositions are shown in table 1.

Table 1 The composition of the solution (g / l) and physico-mechanical properties Claimed solution Prototype one 2 3 four Nickel chloride twenty twenty twenty 25 21 Sodium hypophosphite 8 8 10 fifteen 24 Sodium Acetate 8 8 10 fifteen 10 Potassium Polititanate 1,5 1,5 8 fifteen Silver nitrate 0.5 0.5 0.5 solution pH 4.8-5 4.8-5 4.8-5 4.8-5 4.6 Solution temperature ° C 90-92 90-92 90-92 90-92 90-92

Products coated chemically from the proposed solution were tested at the pilot production of FSUE OKTB "ORION".

The test results of the physico-mechanical properties of the applied coating are presented in table 2.

table 2 The composition of the solution (g / l) and physico-mechanical properties Claimed solution Prototype one 2 3 four The deposition rate, microns / h 22 22 28 26 fifteen Steel sample friction coefficient 0.20 0.22 0.18 0.18 0.26 Hard Lubrication Coefficient of Friction 0,075 0,085 0.06 0.06 0.11 Wear rate, μm / h in steel specimen 1.8 2.1 1.7 1.7 2,4 Wear rate, μm / h for solid lubricant coating 0.55 0.75 0.4 0.4 0.9

As can be seen from the results presented in table 2, the developed composition of the solution to obtain a composite coating allows to obtain a reduced coefficient of friction for steel samples and solid lubricant coatings, to provide increased wear resistance and increase the deposition rate of the coating, and therefore increase the life of the products. The developed solution for chemical deposition was tested at the pilot production of FSUE OKTB "ORION".

Based on the foregoing, and also taking into account the patent information search, we believe that the “Solution for Composite Coating” developed by us meets the requirements for recognition as an invention: novelty, inventive step, industrial applicability and can be protected by a patent of the Russian Federation.

Claims (1)

A solution for preparing a composite coating, including nickel chloride, sodium hypophosphite, sodium acetate and distilled water, characterized in that it additionally contains potassium polytitanate powder with a particle size of 20-80 nm and a particle diameter of 200-800 nm and silver nitrate, while the components solution taken in the following ratio, g / l:
nickel chloride 20-25 sodium hypophosphite 8-15 sodium acetate 8-15 potassium polytitanate powder 1,5-15 silver nitrate 0.5 distilled water 1 liter