SU1721121A1 - Chromizing steel products by coating process - Google Patents

Abstract

The invention relates to the field of metallurgy and can be used in engineering, instrument making, tool manufacturing to improve the performance characteristics of products. The goal is to intensify the process, increase corrosion and cavitation resistance. The method involves applying a saturating coating containing 50-60% by weight of chromium powder and 40-50% by weight of a 1-2% organic solution of a mixture of polyvi-Nilchloride and dimethylformamide at a ratio of 1: (9-10), drying, applying protective coating containing 39-43 wt.% alumina, 7-16 wt.% cryolite and 45-50 wt.% saturated solution of boric anhydride in an organic solvent in a ratio of 1: (3-4), drying and saturation. The method allows to intensify the saturation process 1.3-1.9 times, corrosion resistance 1.5-2.0 times, cavitation resistance 1.5-2 times. 1 tab. (L with

Description

The invention relates to the field of metallurgy and can be used in mechanical engineering, instrument making, tool manufacturing to improve the performance characteristics of products .---.

A known composition for the chromium plating of products in the coating, containing the following components, wt.%:

Chrome 10-40

SI5-15.

A-Powder12-20

Connection

Zaponlak solution in an organic solvent was used as a binder.

The disadvantages of this composition are low saturability, low cavitation and corrosion resistance of the resulting coating.

The closest in technical essence and the achieved result to the proposed is a method of chromium plating of steel products in the coating, which consists of the following components, wt.%:

Chromium oxide30-45

Aluminum powder 10-20

Aluminum oxide 14-24

Ammonium Chloride 3-6

Acetone blend with polyvinyl butyral modified phenol-formaldehyde resin glue, 5-25

Moreover, the mixture of acetone with an adhesive based on phenol-formaldehyde resins modified with polyvinyl butyral contains components in the following ratio, vol.%:

-h

Yu

KZ

Adhesive based on phenol-formaldehyde resins modified with polyvinyl butyral 10-40 Acetone 60-90

The coatings obtained in this way are distinguished by high hardness and wear resistance.

The disadvantages of this method are not sufficiently high processability of the process and the activity of saturating coating. In addition, porous layers are formed with low cavitation and corrosion resistance.

The aim of the invention is to intensify the chromium plating process in the coating and to obtain diffusion layers with enhanced cavitation and corrosion resistance.

The goal is achieved by the fact that the method of chromium plating of steel products in plastering involves applying to the surface parts of an active paste containing 50–60 wt.% Chromium powder and 40–50 wt.% Binder, consisting of 1–2% organic solution. a mixture of polyvinyl chloride and dimethylformamide in a ratio of 1: (9–10), drying, applying a protective paste containing 39–43 May. % alumina, 7-16 wt.% cryolite and 45 - 50 wt.% a saturated solution of boric anhydride in an organic solvent in a ratio of 1: (3 - 4), drying and saturation.

Cavitational resistance of coatings increases 1.7 times, corrosion resistance - 1.4 times in the environment of 0.1 n. H2SO4 solution, and in 3% NaCl solution - 1.8 times, coating thickness - 1.5 times, compared with the prototype.

Chrome plating in daubs using a chlorine-containing bond saves saturating materials, does not cause the appearance of rust, which is observed during chromium plating; in plaster containing ammonium chloride does not cause sintering of saturating plaster with the surface of products, which, in turn, does not require cleaning products and intensifies the process of saturation. All this leads to an increase in the processability of the chrome plating process in daubs. The chemistry of the process is the following: polyvinyl chloride (-CH2-CHC-) n when heated to a chromium plating temperature of 1000 ° C dissociates with the release of chlorine, hydrogen and carbon atoms

(-CH2-CHC1-) hp Ј-SG + H SG4. Chlorine, interacting with chromium, forms chromium chlorides 2СГ + Cr-CrCl2.

Chromium chlorides interact with the iron of the processed products by the reaction of CrCte + Fe-Cr + FeCla. In this case, active atoms are formed.

chromium, which diffuse into the steel matrix of the hardened product. The role of hydrogen is that it prevents oxidation of the products being processed, and carbon, together with chromium, in diffusion

0 steel matrix, contributes to the intensification of the formation of a carbide layer consisting of the phases Cr2cSb and.

More intensive arrival of chromium atoms to the saturable surface of steel

5 carbon contributes to the formation of more dense carbide layers, as this suppresses the opposite diffusion of iron.

Protective coating is used to protect against scattering of the coating after decomposition of the binder and helps preserve the chlorine-containing atmosphere in the saturating coating.

The bond in the saturating coating at the same time plays the role of an activator, since it contains chlorine and carbon, and is also a binder with a high binding capacity.

As a result of diffusion processes occurring during chromium plating, carbide coatings are formed in the coatings of the proposed composition; they are practically non-porous, with a small crystallite size — grains of 1–2 µm. Fine grain coatings obtained

5 determines the high strength characteristics, which leads to a high cavitational resistance of the coatings obtained. In addition, compressive stresses are formed in the coatings, which increases their resistance to wear under conditions of cavitation in corrosion. There is no open porosity in these coatings, i.e. there is no contact of the matrix material with the surrounding atmosphere. All this in a complex allows to increase

5 cavitation and corrosion resistance of the coating, i.e. to achieve the goal. Chrome plating of products in the coating by the proposed method consists in applying a saturating coating. Thereafter

0 follows a drying operation; then a protective coating is applied, drying and high-temperature exposure for diffusion processes are carried out. A chrome plating coating is being prepared, on

5 chlorine-containing binder, which is a solution of polyvinyl chloride in organic solvents (for example, dimethylformamide, followed by dilution with acetone), and the protective coating is prepared from a mixture of powders AlaOs and cryolite (A1zP 3NaF) mixed with a saturated solution of boric anhydride in an organic solvent of boric anhydride in an organic solvent (for example, technical alcohol or acetone). At the same time for saturating coating the ratio of components is as follows, wt.%:

Chromium Powder50-60

Linkage.The rest

The link is prepared as follows. Polyvinyl chloride (-CH2-CHC1-) xn and dimethylformamide () in a ratio of 1: (9-10) are taken and diluted with an organic solvent, for example acetone, to 1-2% of concentration. The saturating coating prepared in this way is applied to the articles by dipping into a paste or paste and applied to the products with a brush. After that, they are dried in air at room temperature for 4-5 hours. Then a protective coating is applied.

The protective coating is prepared as follows.

Mix powders (39–43 wt.%) With cryolite AlFs- 3NaF (7–16 wt.%).

Prepare a saturation solution of boric anhydride (HCO) in an organic solvent (e.g., acetone or technical alcohol) c. ratio 1: (3 - 4), respectively.

A mixture of powder (39–43 wt.%) And cryolite (7–16 wt.%) Is mixed with a saturated solution of boric anhydride in an organic solvent (45–50 May.%).

After the operation of applying a protective coating with a brush or by dipping, the products are dried in air at room temperature for 3-4 hours. Then the product with the coating is packed in a container and covered with neutral filling, which is ground chamotte or quartz sand, sealed with fusible shutter (silicate lumps) and placed in an oven for chrome plating. The temperature in the furnace is 1000 ° C, the duration of saturation, 4 hours. Then the crucibles are removed from the furnace and, after cooling to room temperature, they are unpacked. At the same time, saturating coating is easily separated from hardened products.

The microhardness and thickness of the diffusion layers are determined on a PMT-3 instrument using a standard procedure.

The cavitation resistance is determined by the magnetostriction method on the UZDN-2T device, the medium is tap water, the wear is estimated by the weight loss on the scales VLR-200 g for 10 hours,

Corrosion resistance is assessed by the gravimetric method, the corrosive environment is 0.1 n. a solution of 2525cm and a 3% solution of NaCl in water.

The table shows the characteristics of the coatings obtained.

FORUMAWLAH AND ISLANDS

A method of chromium plating of steel products in plastering, including the application of a saturated plaster containing chromium powder and a binder, drying and saturation, characterized in that, in order to intensify the process, increase the corrosion and cavitation resistance, a protective plaster is applied before saturation containing alumina, cryolite and a saturated solution of boric anhydride in an organic solvent in a ratio of 1: (3-4), followed by drying, with the following ratio of ingredients, in m.%:

- Aluminum oxide 39 - 43

Cryolite7-16

Saturated solution

 boric anhydride in an organic solvent in

the ratio of 1: (3-4) 45-50,

and as a binder, a saturating coating contains a 1-2% organic solution of a mixture of polyvinyl chloride and dimethylformamide at a ratio of 1: (9-10), with the following ratio of ingredients, wt.%:

Chromium Powder50 - 60

1-2% organic

solution of a mixture of polyvinyl chloride and dimethylformamide with their ratio. 1: {9-10) 40 - 50.

Characteristics of coatings based on hcom carbides obtained by bronirovania in daubings at 1000 ° C and aging of carbon steel became x

link 2t (prototype

Chromium POWDER 50, binder (0, organic solution of polyvinyl chloride in dimethylformamide (1: 9)) 50 Chromium powder 50, binder (IJ-th organic solution of polyvinyl chloride in dimethylformamide (1: 3)) 50

Chromium powder 50, binder (1, organic solution of polyvinyl chloride in dimethylformamide (1:10)) 50

Chromium powder 50, binder (2% organic diluent of poly (vinyl chloride) e dimethylformamide (1:10)) 50

Chromium powder 50, binder (2.54% ovarian solution of polyvinyl chloride and dimethylformamide (1:11)) 50

Chromium powder 50, binding Ot-organic solution of lolivinyl chloride and dimethylformamide (1:10)) 50

Chromium powder 30, binder (1, organic solution of polyvinyl chloride and dimethylformamide (1.0: 8.5))

Chromium powder 0, binder (1.5% organic solution of polyvinyl chloride and dimethylformamide (1: 9)} 60

Chromium powder 55, binder (1, organic solution of polyvinyl chloride and dimethylformamide (1: 3.5)) 5

Chromium powder 60, binder (1.5% solution of polyvinyl chloride and cimethylformamide 0:10)) YO Chromium powder 65 binder (1, solution of polyvinyl chloride dimethylformamide (1: 9)) 35

Chromium powder 45, binder (1, dimethylformamide polyvinyl chloride solution. (1: 9)) 55

Claims (1)

Claim A method of chromizing steel products in coatings, including applying a saturating coating containing chromium powder and a binder, drying and saturation, characterized in that, in order to intensify the process, increase corrosion and cavitation resistance, a protective coating containing aluminum oxide, cryolite is applied before saturation and a saturated solution of boric anhydride in an organic solvent in a ratio of 1: (3-4), followed by drying, in the following ratio of ingredients, wt.%: - Alumina 39 - 43 Cryolite 7-16 A saturated solution of boric anhydride in an organic solvent in the ratio of 1; (3-4) 45-50, and as a binder, the saturating coating contains a 1-2% organic solution of a mixture of polyvinyl chloride and dimethylformamide at a ratio of 1: (9-10), in the following ratio of ingredients, wt.%: Chromium Powder 50 - 60 1-2% organic solution of a mixture of polyvinyl chloride and dimethylformamide in their ratio. 1: (9-10) 40-50. Ί Characterization of coatings based on house carbides obtained by chromium plating in coatings at 1000 ° С and exposure 4 and on carbon steels Coating components, .masD - Saturable material The thickness of the diffusion layer, microns Microhardness, NPa Cavitation resistance. kgfpf 10 ’’ Weight indicator of corrosion, kg / (m ⁵ * h) saturating ' protective aggressive environment 1n H ₂ S0 ₄ solution 3% solution NaCl Chromium oxide ^ 0, - Steel 20 thirty 1300-1400 6.5 1,0060 0.0028 aluminum powder 15 " A5 steel 10 16500 6.4 1,0090 0.0028 alumina 20, ...__ .. .. ·>. - ......., L 1. Steel Ub 12 16700 6.2 1,0100 0.0028 bunch 21 (prototype) Chromium Powder 50, A1 ₂ 0 ₃ 38 Steel 20 40 1400 5.2 0.8020 0.0018 ligament (0.5% cryolite 6 Steel 45 10 16500 5,0 0.8060 0.0018 organic plant solution B ₂ 0 ₃ in Steel U8 eleven 16700 5,0 0.8080 0.0018 thief polyvinyl organic _; reed to dimethyl solvent Mamida (1: 9)) 50 (1: 2) 56 Chromium Powder 50, A1 ₂ O _and 39, Steel 20 52 1420 M 0.7310 0.0016 ligament (1% or cryolite 16, Steel 45 19 '16500 3.8 0.7350 0.0016 ganic solution B ₂ 0 ₃ in Steel U8. 21 16750 3.4 0.7390 0.0016 thief polyvinyl organic • reed to dimethyl solvent mamide (1: 9)) 50 (1: 3) 45 Chromium Powder 50, A1 ₂ O ₃ 4 i, Steel 20 55 1450 4.0 0.7300 0.0015 ligament (1.9% cryolite 11, Steel 45 20 16500 3,5 0.7330 0.0015 organic plant solution B ₂ 0 ₃ in UZ steel 22 16750 3.2 0/380 0.0015 thief polyvinyl organic reed in dimetslfor- ' solvent iamide (1:10)) 50 (1: 3,5) 48 Chromium Powder 50, A1 ₄ 0 _e 43, Steel 20 53 1540 4.0 0.7300 0.001? ligament (2% or cryolite 7, Steel 45 20 16500 3.6 0.7380 0.0015 Plant Growth ^z solution of 8 _g 0z in Steel U8 21 16750 3.3 0.7380 0.0015 thief polioinilkhlo- organic reed e dimethyl solvent mamide (1:10)) 50 (1: 4) S0 Chromium Powder 50, A1 ₂ 0 _e 44, Steel 30 46 1450 6.5 0.7500 0.0016 ligament (2.5% * ny or cryolite 17 " Steel 45 16 16500 m 0.7600 0.0016 ganic solution 8 ₂ 0) B Steel U8 17 16750 4.0 0.7600 oh οοt6 thief polyvinyl organic reed and dimethyl solvent Mamida (1:11)) 50 (1: 4,5) 39 Chromium Powder 50, Al ₂ O _ft 45, Steel 20 38 1420 4.7 0.8000 ο, οοίδ ligament (3% or cryolite 6, Steel 45 12 16500 4.3 0.8050 0.0016 ganic solution B ₂ 0 ₃ in Steel. U8 14 16700 4.1 0.8050 thief polyvinyl organic reed and dimethyl solvent Mamida (1:10)) 50 (1: 5) 51 Chromium powder 30, A1 _g o _e 39, Steel 20 32 1400 4.8 0.8000 0.0016 ligament (1.5% or cryolite 16, Steel 45 8 16500 4,5 0.8040 0.0016 ganic solution 8 ₂ 0z in Steel U8 10 16700 4.2 0.8040 0.0016 thief polyvinyl organic reed and dimethyl solvent mamida (1.0: 8.5)) 70 (1: 3) 45 Chromium powder 40, A1 ₂ 0 ₃ 43, Steel 20 32 1320-1440 4.8 0.7800 0,0016 ’ ligament (1.5% or cryolite 7, It became: 45 thirteen 16500 4.6 0.7800 0.0016 ganic solution 8 ₂ 0z c. UZ steel 14 16750 4.6 0.7800 0.0016 thief polyvinyl organic reed and dimethyl solvent Mamida (1: 9)) 60 (1: 4) 50 Chromium powder 55, A1 ₂ 0 ₅ 41, Steel 20 53 1320-1450 3.8 0.7260 o.pois ligament (1.5% or cryolite 11, Steel 45 20 16500 3.5 0.7300 0.0015 mortar solution B ₂ 0 ₃ in Steel U8 ²² 16750 3.2 0.7300 0.0015 Polyvinyl chloride and organic dimethylformamide solvent (1: 9.5 »45 (1: 3) 48 Chromium powder 60, - L1 ₂ O ₃ 41, Steel 20 41 1320-1450 3.8 0.7280 0.0015 ligament (1.5% or cryolite 11, Steel 45 16 16500 3,7 0.7400 0.0015 mortar solution B ₂ 0 ₃ 9. Steel U8 18 (6750 3.3 0.7400 0.0015 polyvinyl chloride and organic dimethylformamide solvent (1:10)) Powder 40 65 chromium, bunch (1.5% ⁿ th organic solution (1: 3) 48 A1 ₂ 0 ₅ 41, Cryolite 11, solution B ₂ 0 ₃ c Steel 20 Steel 45 Steel U8 thirty 12 thirteen 1300-1420 16500 16750 4.9 4.7 4.7 0.8100 0.8100 0.8100 0.0018 0.0018 0.0018 polyvinyl chloride and organic dimethylformamide solvent (1: 9)) 35 Chromium Powder 45, (1: 3) * 8 A1 ^ O s 41, Steel 20 Steel 45 Steel U8 34 thirteen fifteen 1320-1440 16500 16750 4.6 4.4 0.8000 0.8000 0.0016 0.0016 ligament (1.5% organic solution cryolite 11, solution B ₂ 0 ₃ c 4.4 0.8000 0.0016 polyvinyl chloride and organic dimethylformamide. solvent (1: 9)) 55 0: 3) 48 “y'y'y'y” a ”n” y ”e1” for “steel” l5y * Uv ”carbide layers were made for steel 20 - o ^ th thickness of the carbide layer and solid solution