RU2560486C1 - Composition for removing atmospheric corrosion products from surface of corrosion-resistant steel - Google Patents

Abstract

FIELD: chemistry.

SUBSTANCE: composition contains orthophosphoric acid, oxalic acid, surfactants in the form of synthanol and an acidic industrial detergent, a disinfecting additive which is a mixture of a disinfectant based on a quaternary ammonium compound, urotropin and hydrochloric acid, as well as silicon oxide and water. Components of the composition are in the following ratio, g/kg: orthophosphoric acid 250-350, oxalic acid 5-10, synthanol 1-6, acidic industrial detergent 5-10, disinfecting additive 10-15, silicon oxide 50-80, water - the balance.

EFFECT: invention provides efficient removal of corrosion products from the surface of large units and components, as well as from a surface of any size and inclination angle, including from an overhead surface, shorter treatment time and disinfection of a treated surface without irritating the surface, while improving fungal resistance thereof, as well as adhesion to paint coats.

3 cl, 5 tbl, 12 ex

Description

The present invention relates to the field of chemical surface treatment of corrosion-resistant steels, including martensitic class, in order to clean the surface of atmospheric corrosion products, disinfecting treatment and increase the corrosion resistance of steels of various products. The invention can be used in the repair of equipment in the aerospace industry, in the chemical, gas, construction, transport, shipbuilding, automotive, tractor and other industries, as well as in the restoration of objects and cultural monuments, during repair work on road objects, transport and urban infrastructure.

When assessing the surface condition of assemblies and parts after prolonged use in atmospheric conditions, the products of microorganism vital activity are present in the corrosion products, which intensify the corrosion processes. This leads to a decrease in the reliability of the design and premature failure of the products.

Measures to combat microorganisms in corrosion products are multistage, include mechanical opening and cleaning of the affected surface, followed by chemical exposure to special disinfection agents with deep penetration into the pores of the affected material, but disinfectant preparations have a negative effect on the metal, leading to the formation of additional corrosion damage and the raster of the treated surface.

Adding surfactant mixtures to the paste composition is carried out to ensure uniformity of composition and better wettability of the surface with the paste.

The use of chemical methods of surface treatment of parts improves the decorative appearance of products and increases their service life. When repairing large-sized products, it is impossible to carry out their processing by immersion or pouring. The most affordable and economical is the use of pasty chemical formulations (pastes or gels). To prevent the further development of corrosion and the restoration of presentation in the repair process, not only corrosion products are removed, but also paint and varnish coatings (LPC) are used at the final phase of the repair to enhance protection, and therefore the issues of LCP adhesion are extremely relevant.

Based on the analysis of domestic and foreign inventions and patents in the field of chemical processing of metals, in particular, corrosion-resistant steels, three groups of compositions for the removal of oxide films, deposits and atmospheric corrosion products are distinguished:

- liquid compositions (solutions);

- viscous liquids or gel formulations;

- pasta.

Almost all of the proposed compositions include: activators (mineral, organic acids), complexing agents and a binder (dextrins, starch, polysaccharides, gelatin, natural or biosynthetic rubber, wood dust, clays, silicon dioxide and others) and surfactants (surfactants) )

Most of the proposed compositions for removing corrosion products are liquids.

A known composition for removing corrosion products containing sulfuric acid, hydrochloric acid, potassium monopersulfate, fatty alcohols of polyoxyethylene ether and water (CN 103132089 A, 06/05/2013).

The disadvantage of this composition is the presence in it of strong inorganic, including volatile, acids. This requires increased safety measures during cooking and when working with the composition.

A known composition for removing corrosion products, containing, wt.%:

phosphoric acid - 10-65, aliphatic alcohol (for example, isopropyl) - 15-50, nonionic surfactant - 10-0.01-5.0, emulsifier - 0.05-5.0, zinc oxide and / or titanium - 5 , 0-30, zinc nitrate - 0.5-4.0, alkali metal fluoride - 0.2-2.0 or ammonium, triethanolamine - 0.5-8.0, water - the rest (RU 2027794 C1, 27.01. 1995).

The disadvantage of this composition is the presence of a large amount of toxic isopropyl alcohol, which makes it difficult to use in production conditions and is dangerous for humans.

A common drawback of all liquid compositions is the environmental friendliness of working with them, as well as the impossibility of cleaning large products with corrosion products with surfaces having different tilt angles. To clean parts from corrosion products, they must be immersed in bathtubs, which makes this process inconvenient, in particular, makes it impossible to process large-sized products in assembled form during their operation.

These problems are partially solved by the use of gel formulations.

Known gel-like composition for removing rust from the surface of metals, containing an acid solution of formic, acetic and citric acids and a thickener, which is used as a polysaccharide. To obtain a polysaccharide using natural or biosynthetic rubber, as well as their mixture (EP 0233110 A1, 08.19.1987).

The disadvantage of this composition is that it uses weak organic acids, for which the reaction rate with the metal is too low, as a result of which the processing process requires a significant amount of time.

Known gel-like composition for removing rust and corrosion products from metals, containing an anticorrosive component (phosphoric acid or a mixture of hydrochloric acid with urotropin), liquid glass, colloidal stabilizer (CMC), dye indicator (methyl blue) and water. In some cases, a small amount of a weak organic acid (oxalic acid, citric acid, etc.) is added (WO 9946425 A1, 09.16.1999).

The disadvantage of this composition is the complexity and duration of its preparation (at least 3 days).

Of greatest interest are compositions for removing corrosion products in the form of pastes. Processing them allows you to exclude operations cleaning from corrosion products by immersion and spill.

Known means for cleaning products from corrosion products, including phosphoric acid, starch and water, subjected to heat treatment with the following components, wt.%: Phosphoric acid - 30.0-32.2, starch - 8.0-10.0, water - the rest (RU 2365682 C2, 08/27/2009).

The disadvantage of this paste is the need for heat treatment at relatively high temperatures (60-70 ° C) to convert this composition into a jelly-like mass.

The closest analogue is paste of the following composition, g / kg: phosphoric acid - 200-300, oxalic acid - 5-10, PAV-1-6, silicon oxide - 40-75, water - the rest (RU 2105085 C1, 02.20.1998 )

The disadvantages of the paste of the specified composition include the lack of the possibility of disinfecting treatment of the part during repair from the vital products of microorganisms in corrosion products, moreover, due to the expansion of the geography of the operating areas, including tropical and marine conditions, this processing during repair is necessary. Another drawback of the closest analogue is the cessation of release of the KI-1 inhibitor (TU 6-01-873-74) based on catapine. Because of this, it is impossible to use paste to remove corrosion products from the surface of steel parts with reduced corrosion resistance with a chromium content of less than 15%.

The objective of the proposed invention is to develop an environmentally friendly composition that effectively removes atmospheric corrosion products from the surface of corrosion-resistant steels of a wide range, including martensitic class, while disinfecting the surface.

The technical result of the claimed invention is the provision of effective removal of corrosion products from the surface of large-sized units and parts, from surfaces of any size and inclination angle, including from the ceiling, with reduced processing time, with disinfection of the treated surface without its dissolution, while increasing its mushroom resistance, and adhesion to coatings.

To achieve a technical result, a composition is proposed for removing atmospheric corrosion products from the surface of corrosion-resistant steels, including phosphoric acid, oxalic acid, surfactants, silicon oxide and water, characterized in that it additionally contains a disinfectant, which is a mixture of disinfectants based on quaternary ammonium compounds, urotropine and hydrochloric acid, and surfactants are syntanol and acid technical its agent, wherein the composition has the following ratio of the components, g / kg:

orthophosphoric acid 250-350 oxalic acid 5-10 syntanol 1-6 acid technical detergent 5-10 disinfectant 10-15 silica 50-80 water rest

Preferably, the disinfectant component ratio

additives were as follows, parts by weight:

based disinfectant quaternary ammonium compound one urotropin one hydrochloric acid 3

For corrosion-resistant steels with a chromium content <13%, including the martensitic class, it is better that the composition additionally contains a corrosion inhibitor based on plant amines in an amount of 10-20 g / kg.

The introduction of a mixture of surfactants in the form of syntanol and an acidic technical detergent improves the wettability of the surface of the parts and provides a uniform surface treatment and higher adhesion of coatings during their subsequent application.

Introduction to this composition of a disinfectant with the amount of a disinfectant based on a quaternary ammonium compound (for example, Vapusan 2000P, Desavid-BAS, Foriserf, etc.) 0.2-0.3 wt.% (2-3 g / kg of composition ) provides disinfection of the surface from molds and other microorganisms, however, with its introduction of more than 3 g / kg of the composition, paste thickening is observed, which is economically disadvantageous and requires frequent change of paste on the treated surface.

A quaternary ammonium compound disinfectant must be administered together with urotropine and hydrochloric acid. These additives reduce the activity of the disinfectant and prevent the surface of the base metal from being tarnished.

The optimal ratio of the components in the disinfectant, taking into account its content in the composition of 10-15 g / kg, is the following, wt.h:

based disinfectant quaternary ammonium compound one urotropin one hydrochloric acid 3

When processing steels with reduced corrosion resistance having <13% chromium in their composition, with pastes of the proposed composition, an increase in the corrosion effect is observed — surface grinding with an increase in the corrosion rate. To reduce the corrosion activity of the composition, a corrosion inhibitor based on plant amines (for example, Malkor-A, IKB-4, etc.) is additionally introduced into it.

The introduction of a plant-based amine-based corrosion inhibitor into the paste prevents surface grinding and does not affect the completeness of the removal of corrosion products over a period of approximately 3 hours from the surface of corrosion-resistant steels with a chromium content of <13%, including martensitic class. However, with insufficient concentration of the indicated inhibitor (up to 10 g / kg), to some extent, surface damage to the steel is observed. The introduction of an inhibitor into the composition at a concentration of 10 g / kg to 20 g / kg reduces the corrosion rate to negligible values. Etching of the base metal after 3 hours of exposure to pastes with the selected concentration of inhibitor was not detected.

It was experimentally established that in order to achieve the desired level of viscosity of the paste, ensuring the absence of swelling of the paste from vertical and inclined surfaces, at least 50 g / kg of thickener, silicon oxide, should be introduced into the composition. With the introduction of a smaller amount, swelling of the paste layer from vertical surfaces is observed. On the other compositions, swelling was not observed.

The proposed composition allows you to qualitatively remove atmospheric corrosion products from corrosion-resistant steels of all grades, including martensitic class with a low chromium content (Cr <13%), while the processed products can have different dimensions and surfaces with different angle of inclination.

The composition is environmentally friendly. The technology for cleaning corrosion products is simple and does not require special equipment, facilities and highly skilled workers.

Examples of implementation

10 formulations were prepared to remove atmospheric corrosion products from the surface of stainless steels. First, aqueous bases were prepared, including phosphoric acid, oxalic acid, syntanol, an acidic technical detergent, disinfectant and additive. The resulting aqueous bases were thickened with finely divided silica, bringing them to the desired consistency.

The prepared compositions were applied to the following steels: austenitic steel 12X18H10T, martensitic aging steel 08X15H5D2T.

Then, a corrosion inhibitor based on plant amines Malkor-A was added to compositions 1, 2, and 3, after which they processed martensitic steel 13Kh11N2V2MF-Sh (EI 961-Sh).

Table 1 shows the results of processing samples of two grades of steel: 12Kh18N10T austenitic steel and 08Kh15N5D2T martensitic aging steel, on which corrosion products are formed in a moderately warm climate of the coastal zone and salt fog chamber (KST-35). The data presented indicate that the processing of samples with a paste of the proposed composition (examples 1-3 and 6-8) within the specified limits leads to the complete removal of corrosion products over a period of 3 hours, while the paste does not adversely affect the base metal.

Also, the data in table 1 show that the paste does not drain from a vertical surface. The degree of thickening, which characterizes the consistency of the paste, was checked at a temperature of (23 ± 5) ° С by swelling the paste from a vertical surface, for which a 0.5 mm thick stencil was applied to the glass plate with a slot in the form of a square of 10 × 10 mm in size. A paste was applied on the surface of the slot with a layer of not more than 0.5 mm. After removing the stencil, the glass plate was kept in a vertical position in air for 0.5 hours. The magnitude of the displacement (swelling) of the layer was measured using the scale of the object micrometer located in the inner cavity of the MBS-2 microscope eyepiece body with an increase of 16. Runoff (displacement of the paste layer) should not exceed 1 mm from the initial position.

At the same time, the initial samples of steel without corrosion products were treated with paste of the proposed composition to determine the degree of corrosion effect on the surface. It was found that the paste of the selected composition does not lead to a change in mass within the weight measurements (when controlled using analytical scales with an accuracy of 0.0002 g) for the same period of time (3 hours).

Table 1 in examples 5 and 10 presents the results of exposure to paste compositions with an increased concentration of phosphoric and oxalic acids. Processing with such compositions for 3 hours leads to the complete removal of corrosion products, but metallographic studies have found that this paste composition affects the base metal in the form of a light raster surface. In this case, the corrosion rate on steel 08Kh15N5D2T was 0.04 g / (m ² · h), on steel 12Kh18N10T-0.02 g / (m ² · h).

Examples 4 and 9 show the results of exposure to a paste with a concentration of phosphoric and oxalic acids in an amount below the selected limits. The impact on the samples of steel grades 12X18H10T and 08X15H5D2T pastes with low concentrations of components for 3 hours does not provide complete removal of corrosion products.

The results of processing steel grade 13X11H2V2MF-Sh (EI 961-Sh) with a corrosion inhibitor Malkor-A to remove atmospheric corrosion products are presented in table 2.

The processing of samples from steel 13Kh11N2V2MF-Sh with corrosion products with pastes containing components according to the examples of Table 1 with the addition of the Malkor-A inhibitor, regardless of concentration, leads to the complete removal of corrosion products within 3 hours. However, with an insufficient concentration of the inhibitor (from 5 to 10 g / kg), a raster of the steel surface is observed.

The introduction of the corrosion inhibitor Malkor-A into the composition (examples of Table 1) at a concentration of 10 g / kg to 20 g / kg reduced the corrosion rate. Etching of the base metal after 3 hours of exposure to pastes with the selected concentration of inhibitor was not detected.

Evaluation of the mushroom resistance of the proposed composition was carried out according to GOST 9.052-88. The studied compositions contained from 0.1 to 1.0 wt.% Disinfectant Vapusan 2000P, which is equal to a concentration of 1 g / kg to 10 g / kg of the composition. The test results for fungus resistance are shown in table 3.

Tests in a salt spray chamber KST-35 (operating mode: temperature 35 ° C, periodic spraying of a 5% neutral NaCl solution in accordance with GOST 9.308-85) showed that the samples treated with the proposed composition have higher corrosion resistance than raw, unpaste paste.

Table 4 shows the effect of processing the proposed composition of the paste on the corrosion resistance of steel 08X15H5D2T (exposure in KST-35).

Thus, the processing of the proposed composition, as well as the processing of the composition of the prototype, improves the quality of the passive film on corrosion-resistant steels, including martensitic class, compared with samples without processing paste.

The adhesion of the paintwork is determined on samples made of steel 08Kh15N5D2T. The system AK209 + AK079 + AC1115 was used as the paintwork. At the same time, samples that underwent standard surface treatment were tested: etching followed by passivation according to industry instructions PI 1.2A-499-98. ” Adhesion was determined according to GOST 15140-78. The test results are presented in table 5.

The data obtained confirm that the processing of the proposed composition allows to obtain high adhesion of the paint coating on steel, as well as the processing of the composition of the prototype.

The presented results indicate that the proposed composition allows qualitatively removing atmospheric corrosion products and disinfecting the surface of any angle of inclination of corrosion-resistant steels of all grades, including martensitic ones with a low chromium content (<13%), in products of any size after operation. The composition is environmentally friendly. The treatment with the composition provides high adhesion of the paintwork.

Table 1 Compositions for removing atmospheric corrosion products and the results of their processing of stainless steels Example No. steel grade Components of the proposed composition, g / kg Processing result H ₃ PO ₄ C ₂ H ₄ O ₂ Surfactant Oxide
silicon Disinfectant
Vapusan 2000P Water Base metal condition Completeness
removal
of products
corrosion Runoff with
vertical
surface Syntanol
brand DS-10 Those.
washing
means
TMSDP one 12X18H10T 250 7 3 5 fifty 2 oct. No pickling detected Full No 2 300 5 5 8 80 5 - // - Similarly Full No 3 350 10 2 10 70 3 - // - Similarly Full No four 180 3 one four 60 four - // - No pickling Not complete No 5 380 12 2 6 40 2 - // - Light etching Full there is 6 08X15H5D2T 250 7 3 5 fifty 2 - // - No pickling Full No 7 300 5 5 8 70 5 - // - No pickling Full No 8 350 10 four 10 60 3 - // - No pickling Full No 9 180 one one four 60 four - // - No pickling Not complete No 10 380 3 2 6 70 2 - // - Light etching Full there is eleven 12X18H10T 250 8 5 - 75 - up to 1 kg No pickling detected Full No 12 08X15H5D2T
prototype 250 8 5 - 75 - up to 1 kg No pickling detected Full No

table 2 The results of processing steel grade 13X11H2V2MF-Sh (EI 961-Sh) of the proposed composition with a corrosion inhibitor Malkor-A to remove atmospheric corrosion products The content of the main components The content of the corrosion inhibitor Malkor-A, g / kg Processing time, hours Completeness of removal of corrosion products The state of the base metal after processing For examples 1, 2, 3 of table 1 0 3 complete etching 5 3 complete light etching 7 3 complete light etching 10 3 complete practically unchanged fifteen 3 complete without change twenty 3 complete without change

Table 3 The effect of the concentration of disinfectant Vapusan 2000P in the composition of the paste on the resistance to mold Composition and concentration of components (except Vapusan 2000P) The content of Vapusan 2000P, g / kg Mushroom resistance according to GOST 9.052-88 Appearance of paste after testing According to example 6 table. one - 1-2 The development of fungi in all samples In examples 1 or 2 or 3 of the table. one one one The development of fungi on individual samples 2 0 Lack of development of fungi on all tested samples, paste state unchanged. 5 0 Lack of development of mushrooms in all tested samples; in the composition of the paste, precipitation of individual crystals is observed (thickening of the paste) 10 0 Lack of mushroom development, strong thickening and thickening of the paste

Table 4 The effect of processing the proposed composition of the paste on the corrosion resistance of steel 08X15N5D2T (exposure in KST-35) Processing No. Composition Processing The surface state of the samples through: 5 days 15 days one According to examples 6, 7, 8 of the table. one Without changes Without changes 2 No compound treatment Single points of corrosion products Single pits and spots of corrosion products 3 According to example 12 (prototype) table. one Without changes Without changes

Table 5 The results of adhesion testing of steel grade 08X15H5D2T with LKP in accordance with GOST 15140-78 Surface preparation Coating Adhesion to Steel Source After moisturizing in a day one four 10 Processing composition according to examples 6, 7, 8 of the table. one one one one one Pickling + passivation one one one 2 Processing composition according to example 12 (prototype) table. one one one one one

Claims (3)

1. The composition for removing atmospheric corrosion products from the surface of stainless steels, including phosphoric acid, oxalic acid, surfactants, silicon oxide and water, characterized in that it further comprises a disinfectant additive, which is a mixture of a disinfectant based on a Quaternary ammonium compound , urotropine and hydrochloric acid, and as a surfactant contains syntanol and an acidic technical detergent, in the following ratio Components, g / kg:
orthophosphoric acid 250-350 oxalic acid 5-10 syntanol 1-6 acid technical detergent 5-10 disinfectant 10-15 silica 50-80 water rest 2. The composition according to p. 1, characterized in that it has the following ratio of components of a disinfectant, wt.h:
based disinfectant quaternary ammonium compound one urotropin one hydrochloric acid 3 3. The composition according to p. 1, characterized in that it further comprises a corrosion inhibitor based on plant amines in an amount of 10-20 g / kg.