RU2160324C1 - Composition for protection from corrosion of ferrous metal surfaces - Google Patents

Abstract

FIELD: chemistry, petrochemistry, protection of metals from corrosion; applicable in mechanical engineering, in mechanical engineering, instrumentation engineering and other industries. SUBSTANCE: composition contains, g/l: orthophosphoric acid 85-117; cyclohexylamine or monoethanolamine 0.5-0.6; zinc oxide 3-4; N-benzylidenecyclohexylamine 0.01-0.015; detergent 9.06-10.06; and water. Detergent contains, g/l: sodium metasilicate 2.0-2.5; trisodium phosphate or sodium tripolyphosphate 7.0- 7.5; sodium tetraborate 0.05-0.055; sodium hexametaphosphate 0.01- 0.11. EFFECT: simultaneous increase of washing, degreasing, corrosion- converting, passivating and corrosion protective properties, extended assortment of acting corrosion inhibitors. 2 cl, 2 tbl, 1 ex

Description

 The invention relates to the field of chemistry, petrochemistry, more specifically to the protection of ferrous metals from corrosion and can be used in machine, instrument making and other industries.

 Known compositions that clean metal surfaces from corrosion for subsequent application of paint coatings on them - modifiers based on phosphoric acid (I. L. Rosenfeld, F. I. Rubinstein, K. A. Zhigalova "Protection of metals from corrosion by paint and varnish coatings" M .: Chemistry, 1987, pp. 162-167, AM Elizovetsky et al. "Paintwork materials and their application", 1985, N 3, p. 22-25; Recommendations on the use of rust converters (modifiers) for the protection of metal surfaces with complex paintwork ", Cherkasy, NIITEH M, 1985, p. 48), as well as compositions based on wastes of hydrolysis-yeast production — lignin (“Ester groups in the products of lignin oxidation with nitric acid.” AE Egorov et al. VNIIhydrolysis N 24, 1971, p. 172-178; RF Patent N2063480, class C 236 1/06, published in 1996.) The inclusion of modifying additives — urotropine, metal hydroxide of group 1 of the Periodic Table of Elements in the indicated compositions reduces the removal time of corrosion damage and increases the efficiency of rust conversion.

 However, all of the above compositions cannot protect the surface of ferrous metals from further corrosion.

 A known composition that protects metals from corrosion by phosphating (ed. Certificate. USSR N 1562362, IPC class. With 23 G 1/06 published. BI N 17, 1990).

The composition consists of the following components, g / l:
Phosphoric acid (pl. 1.7) - 70 - 100
Chromium trioxide - 0.3 - 0.6
Zinc Oxide - 15 - 20
Sodium Nitrate - 2 - 3
Primary aliphatic alcohol of normal structure with the number of carbon atoms 2 - 4 - 60 - 150
Water - Else
The use of this composition can reduce the temperature of phosphating and at the same time increase the impact strength of the applied coatings, as well as their corrosion resistance.

Significant disadvantages of the composition are:
- complex manufacturing technology, as being two-component, it is required before its use to perform the operation of mixing primary aliphatic alcohols with an aqueous solution of the ingredients of the composition: phosphoric acid, chromium trioxide (VI), zinc oxide and sodium nitrate; to perform this operation, in addition, it is necessary to have a special site with equipment at the place of use that meets the requirements for working with acids;
- the composition contains toxic hexavalent chromium trioxide, which negatively affects the environment during manufacture and use, and also complicates the disposal of both waste and the composition itself;
- limited suitability of the ready-to-use composition - the time from preparation of the solution to its use is 0.5-0.7, and since after mixing it, a chemical reaction of interaction between the ingredients immediately begins spontaneously, leading to a gradual decrease in the efficiency of phosphating, and therefore to a decrease in the protective properties; because of this, the composition after 6-8 hours becomes completely unusable.

 Amine-based formulations, including cyclohexylamine, are widely known from the patent and technical literature. (V.P. Persianseva, L.L. Rosenfeld. Sat. "Investigations on metal corrosion", issue 5 "New methods and instruments for corrosion testing", ed. AN USSR, 1969, p. 41; P.L. Rosenfeld et al., Housing and communal services, N 34 N 9, 1961; Khanlarova A.G., Mamedov P.L. Azerbaijan, oil industry 41, 42, 43.1962; J. Bregman "Corrosion inhibitors" Edition of "Chemistry" A.K. Efimova, N.M. Shatunova, Wolf "Sulfuric oils and products of their processing" (T.Z. 1960, p. 181).

 Amine-based corrosion protection compounds are designed to increase the effectiveness of protection against atmospheric corrosion in acidic and aqueous environments, in petroleum products with different durations of protection, but they do not have the ability to remove corrosion products from metal surfaces.

The closest in composition and effectiveness among the known cyclohexyl amine-containing inhibitors to the proposed is a composition comprising, in g / l:
Phosphoric Acid - 85 - 105
Cyclohexylamine - 0.7 - 0.9
Detergent - 15 - 25
Water - Else
As a detergent preparation, the product ML-51, manufactured by the domestic industry according to TU-84-228-80, is used.

The drug contains,%:
Sodium Carbonate - 44
Trisodium phosphate - 34.5
or sodium tripolyphosphate
Sodium Metasilicate - 20
Wetting agent - 1.5
(RF patent N2066708, IPC С 23 С 22/07 publ. Bull. N 26,1996 -prototype)
The specified composition of the prototype is used to protect against sweat corrosion of the metal, to remove corrosion products from the metal surface, however, it is ineffective for converting atmospheric and biological corrosion products and further protection against these types of corrosion.

 The objective of the present invention is the creation of such a composition that would not have the disadvantages inherent in the known compositions, and had complex properties.

 The technical result of the invention is to increase both washing, degreasing, rust-converting, passivating and protective properties against corrosion (including biocorrosion) of ferrous metals, as well as expanding the range of active inhibitors.

According to the invention, to achieve the specified technical result, it is proposed to use a new composition with the following ingredients, g / l:
Phosphoric Acid - 85 - 117
Cyclohexylamine or Monoethanolamine - 0.5 - 0.6
Detergent - 9.06 - 10.06
Zinc Oxide - 3 - 4
N-benzylidenecyclohexylamine - 0.01 - 0.015
Water - Else
As a detergent, use a mixture consisting of, g / l:
Sodium metasilicate - 2.0 - 2.5
Trisodium phosphate
or sodium tripolyphosphate - 7.0 - 7.5
Sodium tetraborate - 0.05 - 0.055
Sodium hexametaphosphate - 0.01 - 0.011
Detergent, like the composition itself, is prepared by mixing these components and dissolving them in water under ordinary conditions.

 A detergent preparation with a different content of components used in the proposed composition for corrosion protection is presented in table 1.

 The preparation time of the solution is 25-30 minutes.

 The shelf life of the composition before use is unlimited.

 Significant distinguishing features of the proposed structure from the prototype is the presence in it of 0.01-0.015 g / l. N-benzylidenecyclohexylamine, 3-4 g / l of zinc oxide, 0.5-0.6 g / l of monoethanolamine and the new composition of the used detergent in an amount of 9.06-10.06 g / l.

 The proposed composition is a colorless liquid with a density of 1.2-1.3 g / cm, the concentration of hydrogen ions (PH) -1.5-1.7, the total acidity of the "point" is 225-235.

 The composition is applied by brush, spraying, immersion at ordinary temperatures on a surface of ferrous metals, covered with rust, scale and on welds, and then kept in air for at least 3 hours.

The corrosion resistance of the treated surfaces is evaluated on ferrous metal samples by accelerated cyclic tests after a certain exposure to them in a chamber with periodic moisture condensation at a relative humidity of 98 ± 2% and with a temperature drop of 20-22 ^o C per day (40 ^o C for 8 hours and 18-20 ^o C for 16 hours according to GOST 9.509-89 ESZKS. - 1 cycle).

 The test duration is 48 hours (2 cycles).

 The effectiveness of protection against atmospheric corrosion is assessed by the area of corrosion damage on the surface of metal samples; for this, using a stereoscopic microscope on the surface, determine the number of cells on the grid and calculate what percentage is one cell of the total surface taken as 100%.

For a metal sample measuring 50 x 25 x 2-3 mm, 1 cell corresponds to 0.01%, because such a surface has 10,000 cells. Then, according to the formula S = n • 0.01, the area of the affected surface is determined, where S is the area of the affected surface,%
n is the number of affected cells;
0.01 is the percentage of cell damage.

 The results are shown in table 2.

The effectiveness of the protection against biological corrosion was determined according to GOST 9.048-75 ESZKS: on steel samples (the same as during atmospheric corrosion tests) treated with the proposed composition and known from the prototype according to the patent of the Russian Federation N 2066708 and from analogues according to as USSR N 1562362 class. C 23 C 22 / 03.1987, Bull. N 7, 05/07/90. Samples are placed on a fluoroplastic frame and are infected with an aqueous suspension of fungal spores specified in clause 2.1 of the GOST by uniformly applying it with a spray gun. The infected samples are kept in a box at a temperature of 25-30 ^o C and a relative humidity of not more than 80% for 55-60 minutes, then they are placed in desiccators, on the bottom of which water is poured to create a relative humidity of 98 ± 1% and Control Petri dishes with wort-agar nutrient medium are placed in the same place; desiccators are hermetically sealed with lids; a temperature of 29 ± 2 ^o C is created in the box. The effectiveness of protection against biocorrosion is assessed by the growth of molds on the surface of the samples and the lesion area according to a six-point scale given in GOST 9.04875 ESZ KS in the table, both visually with the naked eye and under the microscope.

 The results are shown in the table.

 The conditions for determining the effectiveness of protection when using the proposed composition are described in the examples.

 When the content of components having an amount less than the lower indicators, the protection efficiency is significantly reduced, if more than the highest indicators, then its value increases slightly.

 The evidence of the non-obviousness of the obtained results of corrosion protection, including biological, is that N-benzylidenecyclohexylamine and the new composition of the detergent preparation enhance the corrosion protection of ferrous metal products.

 From the patent and technical literature, we do not know the use of these components in such a combination to protect metal surfaces.

 Industrial applicability of the proposed structure is illustrated by the following examples.

 Example.

Metal samples from St3 steel with a size of 50 x 25 x 2-5 mm with a weld, having corrosion over the entire surface with a thickness of 20-25 μm, are treated with a composition - 1, containing, g / l of water:
Phosphoric Acid - 85
Cyclohexylamine - 0.5
Zinc Oxide - 4
N-benzylidenecyclohexylamine - 0.01
Detergent preparation "A" - 9.06
The detergent preparation "A" contains, g / l:
Sodium Metasilicate - 2.0
Trisodium phosphate - 7.5
or sodium tripolyphosphate
Sodium tetraborate - 0.055
Sodium Hexametaphosphate - 0.01
The composition is applied to the surface of metal samples with a brush evenly over the entire surface, after which the samples are exposed to air until their surfaces become dry. If unreacted (not transformed) sections of rust are found on the samples, the composition is applied repeatedly until all rust on the surface of the samples is converted. Then the samples are placed in a chamber for cyclic testing for 48 hours. At the same time, these corroded metal samples with a weld seam are infected with an aqueous suspension of fungal spores according to GOST 9.048-75 EC ZKS by applying it with a spray gun.

The infected samples are kept in the box at a temperature of 25-30 ^o C and relative humidity not more than 80% for 1 hour, then they are placed in desiccators, the bottom of which is poured water to create a relative humidity of 98 ± 1%, and the desiccators are hermetically sealed closed with lids, in the box create a temperature of 29 ± 2 ^o C.

 The effectiveness of protection against biocorrosion is assessed by the growth of molds on the surface of the samples and the area of damage according to GOST 9.048-75 EC ZKS according to the table.

 The test results for corrosion resistance and biostability of metal samples treated with composition 1 are presented in table 2.

 Similarly, on metal samples, compositions with limit values of the constituent ingredients (compositions 2, 3, 4) are tested and, for comparison, composition 5 by analogy, ed. St. USSR N 1562362 and composition 6 of the prototype - RF patent N 2066708.

 The test results are presented in table 2.

Claims (1)

1. The composition for protection against corrosion of metal surfaces of ferrous metals, containing phosphoric acid, a detergent based on sodium trisodium phosphate or sodium tripolyphosphate and sodium metasilicate and water, characterized in that it additionally contains zinc oxide, N-benzylidenecyclohexylamine and cyclohexylamine or monoethanolamine, and the washing preparation additionally contains tetraborate and sodium hexametaphosphate, in the following ratio of components, g / l:
Phosphoric Acid - 85 - 117
Cyclohexylamine or Monoethanolamine - 0.5 - 0.6
Zinc Oxide - 3 - 4
N-benzylidenecyclohexylamine - 0.01 - 0.015
Detergent - 9.06 - 10.06
Water - Else
2. The composition according to claim 1, characterized in that the detergent preparation contains components in the following ratio, g / l:
Sodium metasilicate - 2.0 - 2.5
Trisodium phosphate or sodium tripolyphosphate - 7.0 - 7.5
Sodium tetraborate - 0.05 - 0.055
Sodium hexametaphosphate - 0.01 - 0.011r

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