RU2453568C1 - Method to protect surfaces from abrasive wear - Google Patents

Abstract

FIELD: construction.

SUBSTANCE: method to protect surfaces of metal and ceramic parts from abrasive wear includes application of anti-abrasive paint onto the surface, soaking and thermal treatment, at the same time, the anti-abrasive paint is the paint of the following composition, wt %: boron carbide with grain size of the main fraction 28-40 mcm - 25.0-30.0%; bentonite - 10.0-15.0%; mineral bond - 60.0-65.0%; with the following composition of the mineral bond: aqueous solution of NaOH with specific weight of 1120 kg/m³ - 40.0%; dry concentrate of potash glass with a silicate module of 4.0 - 35.0%; bentonite - 10.0%; liquid sodium glass with specific weight of 1420 kg/m³ - 15.0%; thermal treatment is carried out in two stages: parts are heated to the temperature of 750-850°C with the speed of heating of 450°/hr, soaked for 30 minutes, afterwards cooled down to the temperature of 18-20°C with the speed of 450°/hr.

EFFECT: higher microhardness of anti-abrasive paint, heat resistance and fire resistance.

1 dwg, 1 tbl

Description

The invention relates to the field of protection of metal and ceramic surfaces of parts of mechanisms and installations from intense abrasive wear.

There is a method of producing protective coatings using hardfacing of iron-based carbide tapes (GOST 22366-93) on a protected surface.

The disadvantages of this method are:

- the inability to use to protect the surfaces of parts made of non-ferrous metals (copper, aluminum, etc.), and for surfaces of ceramic products;

- the tape can be welded onto products and parts having a straight surface;

- a sharp decrease in hardness after heat treatment of parts in tempering mode (almost 2 times).

A known method of protecting the surfaces of parts using epoxy coatings (see Product 7234 LOCTITE).

The disadvantages of this method are:

- toxicity of the components that make up the paints;

- limited survivability of ready-to-use compositions (~ 25-30 minutes);

- insufficient surface microhardness of cured paint;

- low operating temperature (fire resistance), limited to a maximum of 250 ° C.

The closest adopted as a prototype is a method of protecting the surfaces of parts from abrasive wear, including applying anti-abrasive paint to the surface, curing and heat treatment (see Irathane Futura polyurethane anti-abrasive coating).

As abrasive paint use paints based on polyurethane binders, the disadvantage of which is:

- surface microhardness not exceeding 20.0 HRc (less than 250 HB);

- the impossibility of using such paints at temperatures above 200 ° C.

A method is proposed for protecting the surfaces of parts from abrasive wear, including applying anti-abrasive paint to the surface, exposure and heat treatment, characterized in that anti-abrasive paint of the following composition is used, in wt.%:

Boron Carbide with Main Grain Size

fractions 28-40 microns - 25.0-35.0%; Bentonite - 10.0-15.0%; Mineral ligament - 60.0-65.0%;

The composition of the following content, wt.%, Is used as a mineral bond.

Specific Gravity NaOH Water Solution - 1120 kg / m ³ - 40.0%; Dry Potassium Glass Concentrate silicate module 4.0-35.0%; Bentonite - 10.0%; Sodium water glass with specific gravity - 1420 kg / m ³ - 15.0%;

Heat treatment is carried out in two stages: the parts are heated to a temperature of 750-850 ° C at a heating rate of 450 ° / h, held for 30 minutes, and then cooled to a temperature of 18-20 ° C at a speed of 450 ° / h.

The technical effect of the invention is a significant increase in microhardness, heat resistance, fire resistance of anti-abrasive paint while increasing technological properties.

The proposed method allows to obtain microhardness on a metal surface up to 70.0 HRc, on a ceramic surface up to 50.0 HRc, which significantly exceeds that of the prototype and analogues (see table).

An important effect achieved using the proposed method is the preservation of properties when exposed to high temperatures, i.e. fire resistance and heat resistance. The graph shows that after heating to 630 ° C and cooling with the furnace, coating samples No. 5 and 6 (epoxy and polyurethane) completely collapsed, coating No. 4 (hard-alloy tape surfacing) “lost” about 20% hardness, and on samples No. No. 1, 2 and 3, the microhardness value remained almost unchanged.

Microhardness measurements were carried out with the TEMP-4 impact principle hardness tester.

The solvent of the paint according to the proposed method is an aqueous solution of NaOH with a specific gravity of 1120 kg / m ³ and therefore, in a ready-to-use state, it does not have a life time limit and can be stored in a hermetically sealed container for more than 1.5 years at a temperature of at least 0 ° C .

In accordance with the proposed method, the anti-abrasive coating is applied according to the following technology:

- the surface is cleaned of extraneous mechanical deposits (dust, dirt, scale, etc., if necessary, degreased;

- the first coat of paint is applied and dried (dried) at a temperature of at least 0 ° C for two hours;

- a second coat of paint is applied and aged for four to six hours at a positive temperature;

- the part is placed in a thermal furnace and heated to a temperature of 750-850 ° C, at which (depending on mass) it is aged from 20 minutes to 2-3 hours;

- the furnace is turned off and cooled together with the painted part or at a given speed up to 30-35 ° С.

After cooling, the finished part is ready for use.

According to the proposed method, the rotor blades (blades) of the smoke exhausters DOD-31.5 were processed. After heat treatment, the coating had a surface hardness of ~ 70.0 HRc.

The coating applied to the blades of the crown of the draft machine continues to maintain hardness of 65-70 HRc and after processing in tempering mode (heating to 630 ° C ± 20 ° C and cooling with the furnace) retained hardness unchanged (tape surfacing reduces hardness during this treatment with 55.0 to 40.0 HRc.

The operation of the DOD-31.5 smoke exhausters with blades processed by the claimed method had a service life twice as high as the regular ones.

Thus, it is seen that the inventive method allows to achieve hardness indices that exceed this parameter available on other coatings, as a result of which the service life of the protected parts increases many times.

High refractoriness and heat resistance while maintaining the quality, not available on other coatings, necessary in the manufacturing process of machines and plants (tempering, annealing, normalization, etc.), solve problems arising at manufacturers.

The proposed method is high-tech, because painting can be carried out in any known manner, does not require expensive equipment, the paint is not prone to subsidence, is not limited in survivability, meets all safety and environmental requirements.

Claims (1)

A method of protecting the surfaces of metal and ceramic parts from abrasive wear, including applying anti-abrasive paint to the surface, exposure and heat treatment, characterized in that the following composition is used as anti-abrasive paint, wt.%:
boron carbide with primary grain size
fractions 28-40 microns 25.0-30.0 bentonite 10.0-15.0 mineral ligament 60.0-65.0
with the composition of the mineral ligament:
specific NaOH aqueous solution weighing 1120 kg / m ³ 40,0 dry potassium glass concentrate with silicate module 4.0 35.0 bentonite 10.0 liquid glass sodium with specific weighing 1420 kg / m ³ 15.0
heat treatment is carried out in two stages: the parts are heated to a temperature of 750-850 ° C with a heating rate of 450 ° / h, kept for 30 minutes, and then cooled to a temperature of 18-20 ° C at a speed of 450 ° / h.

Images