SU1615230A1 - Solution for passivating zinc-coated steel - Google Patents

Abstract

The invention relates to the chemical treatment of the surface of metals, in particular to passivation compositions for galvanized steel, and can be used in various industries to increase the corrosion resistance. The purpose of the invention is to increase the chemical resistance of galvanized steel in combination with a paint coating. The proposed passivation solution contains, g / l: chromium ions (CR ⁺⁶ ) 1.5-6.3, phosphate ions (PO ₄ ) 0.7-3.3, nitrate ions (NO ₃ ) 0.3-1 , 6, fluorine ions (F ^- ) 0.05-0.3, molybdenum ions (MO ⁺⁶ ) 0.00001-0,0003

tartrazine 0,0002-0,002, water the rest. The introduction of tartrazine into the solution for passivating galvanized steel makes it possible to increase the chemical resistance of galvanized steel in combination with a paint coating. 1 tab.

Description

 The invention relates to the chemical treatment of the surface of metals in order to protect them from corrosion, in particular, to passivation of galvanized steel, and can be used in various industries.

The purpose of the invention is to increase the chemical resistance of galvanized steel in combination with a paint coating.

The proposed solution contains, g / l

1.5-6.3 0.7-3.3 0.3-1.6

ct

PC 4 NO,

m -t

Mo

Tap tr a zin

0.05-0.3

0,00001-0,0003

0,0002-0,002

The following substances and products can be used as sources of these ions and components in solution: chromium oxide (6), nitric acid and phosphoric acid, hydrofluoric acid or hydrofluoric acid, ammonium molybdenum oxide and tartrazine.

The introduction of tartrazine in the amount of 0.0002 - 0.002 g / l into the passiviruses leads to an increase in the resistance of galvanized steel in combination with the paint-and-lacquer coating.

) Tartrazine is an orange-red crystalline substance soluble in water; it is obtained by azo combining of diazotized sulfanilic acid with 1- (4-sulfophosphate O5 SL

to

Od

Nile) -3-car6oxypyrazolone-5 by the condensation of dioxinic acid with 4-sulf- / phenophenylhydrazine followed by cyclodehyDraction of the resulting bis-g razon. It is used as a yellow food dye, acid dye for wool, for dyeing cosmetics.

Structural formula of tartrazin 10

KoOz8- / L- - - 1

 t5

Passivation solutions are prepared by mixing the components or, for example, by diluting a concentrated aqueous solution with water, which has the following ratio of components, May. %

, 6-28,7

Pot3,1-14,8

NO: 1.3-7.3

P-0.2-1.1

Mo 0.0004-0.02 Tapl gap 0.001-0.006 Water Else The tests are carried out on samples of single-rolled thermal galvanized steel with a thickness of 0.8-0.9 mm and dimensions of 150x70 mm,

Sample processing includes passivation by dipping or spraying from a prepared passivating solution with a composition of 9–35 g / l at a solution temperature of 30–, pH 1.2–1.5 and a processing time of 3–60 min, then drying at t20 ± 20 c for 5 s and re-drying at PO + ZO C for 5 s.

The effect of the concentration of the components of the solution and the protective properties of the coating in Examples 1-34 are given in the table.

The experimental data presented show that coatings formed from solutions (Examples 1-3.5-7 10-12.15-17.20-22.25-27.30-32) with an ion content of 1.5-6 , 3 g / l, ions 0.7-3.3 g / l, ions N03

0

five

0

five

five

0

0

dz

about

0.3-1.6 g / l, F ions 0.05-0.3 g 7 L 7

ions, 00001-0,0003 g / l, tartrazine 0.0002-0.002 g / l have a high corrosion resistance of 40 - 45 minutes, good external appearance from the point of view, darkening or discoloration, high chemical resistance in combination with paint and varnish coatings .

With the introduction of Cg ions into the passivating solution less than 1.5 g / l, P0 ions less than 0.7 g / l, N0 ions less than 0.3 g / l F ions less than 0.005 g / l, Mo ions less than 0.00001 g / l, more than 6.3 g / l of ions, PO4 ions more than 3.3 g / l, NOj ions more than 1.6 g / l, F ions more than 0.3 g / l, Mo ions more than 0.0003 g / l Coatings with low corrosion resistance, low chemical resistance and poor appearance are formed.

Retaining tartrazine less than 0.0002 g / l and more than 0.002 g / l significantly worsens the chemical resistance of galvanized steel in combination with the paint-and-lacquer coating.

The corrosion resistance (resistance to the formation of white corrosion) of galvanized steel coatings is checked a day after the treatment with a passivative mortar,

To determine the corrosion resistance, a solution containing 50 g / l of sodium chloride and 10 ml / l of 30% hydrogen peroxide is used.

Corrosion resistance is determined in minutes, which show the time at which the first signs of white corrosion appear.

The determination of atmospheric corrosion resistance is carried out by an accelerated method.

Samples of galvanized steel treated with a passivating solution are placed in a glass beaker and filled with distilled water at 37.7 ° C. Regularly at fixed intervals of 1100 hours, the appearance of the surface is evaluated from the point of darkening or color change. The assessment is carried out on a scale from 1 to 8, with this 8 means the constancy of color, and 1 - complete darkening.

Dp assessment of chemical resistance of passive metal samples are sprayed with EP-0200 primer by spraying. Before use, the primer is diluted with solvent R-4 to

sixteen

working viscosity 20-22 s by viscometer VZ-246. MJI 1202 enamel is applied to the primer using pneumatic spraying. The working viscosity of the enamel ML 1202 is 30-35 s, according to VZ-246 at 20 + 0.5, the working viscosity is diluted with solvent.

Samples with a total layer thickness of 31–33 microns are taken for testing.

Samples are immersed at 2/3 of the height in 3% solution, HC1,.

In the process of testing: no regular monitoring of the state of the paint coatings, which are evaluated visually, is carried out.

Using the invention to passivate galvanized steel provides the following technical and economic advantages:

production of galvanized steel with high resistance to atmospheric and white corrosion;

obtaining galvanized steel with high chemical resistance in lumps

all with a paint and varnish covering;

an increase in the service life of paint coatings that are used in chemical environments.

Formula

the invention

A solution for smoothing galvanized steel containing hexavalent chromium, phosphate, nitrate, fluoride, molybdenum and water ions, characterized in that, in order to improve the chemical resistance of galvanized steel in combination with the paint coating, it will additionally contain tartrazine in the following ratio of components.

P () N0,

The

Tartrazine

Water

g / l 1.5-6.3 0.7-3.3 0.3-1.6 0.05-0.30

o; rooot oooz

0,0002-0,002 Else

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Claims (1)

Solution for passivation of galvanized steel, containing hexavalent chromium, phosphate, nitrate, fluoride, molybdenum and water ions, characterized in that, in order to increase the chemical resistance of galvanized steel in combination with paintwork, it additionally contains tartrazine in the following ratio of components, g / l