RU2509176C1 - Solution for chemical deposition of composite coating - Google Patents

Abstract

FIELD: chemistry.

SUBSTANCE: solution for chemical deposition of a composite coating contains components in the following ratio, g/l: nickel chloride 15-25, sodium hypophosphite 15-25, sodium acetate 8-15, nanodiamond powder with particle size of 0.004-0.450 mcm 1-20, silver nitrate 0.5-2, 5% aqueous polyvinyl alcohol solution 0.5-2, fluoroplastic suspension F-4D 2-30 and distilled water - up to 1 l.

EFFECT: improved tribological properties and microhardness of the coating.

1 tbl, 1 ex

Description

The invention relates to the field of applying composite coatings by chemical deposition in order to increase the wear resistance of steel products and can find application in mechanical engineering, chemical industry.

The known composition of the electrolyte to obtain a galvanic coating, containing, g / l: nickel chloride 200-350, cobalt sulfate 8-12, boric acid 25-40, chloramine B 1.5-4.5, ultrafine diamond suspension 0.1-2 , 3. The technical result is an increase in the microhardness of coatings (RF patent No. 2362843, publ. June 19, 2008).

The disadvantage is the unevenness in the thickness of the coating on the steels and the relatively low tribological properties.

The closest in technical essence known composition of the solution (RF patent No. 2357002, publ. July 25, 2007) for chemical deposition of coatings on products consisting of the following components, g / l: nickel sulfate 16-27, sodium hypophosphite 21-24, ammonium chloride 28-32, ammonia 47-52, sodium citrate 40-50, nanodiamonds 3-15 (particle size from 0.004 to 0.450 microns).

The disadvantages of this composition are the relatively low tribological properties of the resulting coating, a relatively low microhardness.

The authors were faced with the task of increasing the tribological properties and microhardness of the coating at elevated temperatures.

This problem is solved in that a solution containing nickel salt, sodium salt of an organic acid (sodium acetic acid), sodium hypophosphite, nanodiamond powder, silver nitrate, 5% aqueous solution of polyvinyl alcohol, a suspension of F-4D fluoroplastic are added and the components are taken in the following ratio, g / l:

Nickel chloride - 15-25;

Sodium hypophosphite - 15-25;

Sodium acetic acid - 8-15;

Powder of nanodiamonds (particle size 0.004 to 0.450 μm) - 1-20;

Silver nitrate - 0.5-2;

5th aqueous solution of polyvinyl alcohol - 0.5-2;

Suspension of ftoroplast F-4D - 2-30;

Distilled water - up to 1 liter.

Diamond nanoparticles are an ultrafine powder of synthesized detonation nanodiamonds with a particle size of 0.004 to 0.450 μm. The introduction of nanodiamonds significantly increases the wear resistance of the coating and microhardness.

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.

Polyvinyl alcohol is a synthetic, water-soluble, thermoplastic polymer with the chemical formula [-CH ₂ CH (OH) CH ₂ CH (OH) -] _n. A 5% aqueous solution of polyvinyl alcohol is used to stabilize the solution, as well as to maintain particles of nanodiamonds in suspension in suspension throughout the entire process of coating deposition.

The fluoroplastic suspension F-4D is a suspension of particles produced according to TU 6-05-1246-81. The introduction of a suspension of fluoroplastic F-4D helps to reduce the coefficient of friction.

The uniform distribution of the particles of nanodiamond powder in the coating was achieved by thoroughly mixing all the components of the solution.

The composition and amount of all components included in the solution for chemical deposition of the composite coating was selected experimentally in accordance with chemical nanoconstruction methods.

An example of a coating by chemical deposition.

A solution for the chemical deposition of the coating is prepared as follows: in distilled water heated to 55-60 ° C, with thorough stirring (until the components are completely dissolved), the calculated amount of nickel chloride, sodium acetate, nanodiamonds powder, silver nitrate, 5% an aqueous solution of polyvinyl alcohol prepared in advance, and a suspension of ftoroplast F-4D. The resulting solution is subjected to ultrasonic treatment and then it is heated to 80-85 ° C and the calculated amount of sodium hypophosphite is added to it. Before loading the parts into the bath, the temperature of the solution for chemical deposition of the composite coating is adjusted to 90-92 ° C. The process of chemical deposition of the composite coating is carried out at a solution temperature of 90-92 ° C and a pH of 4.8-5.

Mixing is carried out using a magnetic stirrer with a speed of 10-40 rpm.

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

The surface preparation of steel samples before the deposition of the composite coating of steel samples was carried out as follows: degreasing with Vienna lime, etching in a 10-20% hydrochloric acid solution at a temperature of 25-30 ° C for 30-60 seconds and washing with running water.

Heat treatment of composite coatings was carried out at a temperature of 360 ° C for 1 hour.

Testing the tribological properties of the obtained composite coating and coating obtained from the solution of the prototype was carried out on a reciprocating friction machine, the speed of movement V = 0.04 m / s, P = 5 MPa at a temperature of + 23 ° C ± 2 ° and 100 ° C ± 2 °. Lubricating medium MP-601 oil. Samples from ШХ15 steel were used as a counterbody.

The quantitative composition and physico-mechanical properties of the tested compositions are shown in the table.

The composition of the solution (g / l) and physico-mechanical properties Claimed solution Prototype one 2 3 four 5 6 Nickel chloride fifteen twenty twenty 25 21 fifteen Sodium hypophosphite fifteen twenty fifteen 25 25 fifteen Sodium Acetate 8 8 10 fifteen fifteen 10 Nanodiamonds one 7 10 fifteen fifteen twenty 3-15 Silver nitrate 0.5 2 one 1,5 1,5 Polyvinyl alcohol 0.5 2 1,5 2 2 1,5 Fluorinated polymer suspension 2 10 fifteen thirty twenty 25 solution pH 4.8-5 4.8-5 4.8-5 4.8-5 4.8-5 4.8-5 8.0-9.0 The temperature of the solution, ° C 90-92 90-92 90-92 90-92 90-92 90-92 90-92 Friction coefficient at + 23 ° С ± 2 ° 0.1 0.12 0.11 0,090 0.1 0.09 0.14 Wear, mg / hour at + 23 ° С ± 2 ° 0.1 0.2 0.1 0.15 0.1 0.15 0.4 Coefficient of friction at + 100 ° С ± 2 ° 0.09 0.11 0.1 0.08 0.09 0.08 0.13 Wear, mg / hour at + 100 ° C ± 2 ° 0.14 0.2 0.17 0.14 0.08 0.15 0.36 Microhardness, kgf / mm ² 720 860 980 1020 1050 1120 460-792

As can be seen from the results presented in the table, the composite coating obtained by chemical deposition from the solution we developed has a lower friction coefficient, increased wear resistance and high microhardness, which, therefore, increases the life of the products when working at elevated temperatures.

Products with a coating obtained by the method of chemical deposition from a solution developed by us were 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 by its invention: novelty, inventive step, industrial applicability, and can be protected by a patent of the Russian Federation.

Claims (1)

A solution for the chemical deposition of a composite coating containing nickel salt, sodium salt of organic acid, sodium hypophosphite and nanodiamond powder, characterized in that it additionally contains silver nitrate, a 5% aqueous solution of polyvinyl alcohol, a suspension of F-4D fluoroplastic, with the components taken in the following ratio, g / l:
nickel chloride 15-25 sodium hypophosphite 15-25 sodium acetate 8-15 nanodiamond powder with a particle size of from 0.004 to 0.450 microns 1-20 silver nitrate 0.5-2 5% aqueous solution of polyvinyl alcohol 0.5-2 fluoroplastic suspension F-4D 2-30 distilled water up to 1 liter