Paste for testing the corrosion resistance of materials, method for its production, and method for corrosively damaging a corrodable component

Abstract

The invention relates to a paste for testing the corrosion resistance of materials, the paste containing or consisting of at least one salt having a water solubility of at least 10 g per litre at 23°C, at least one swelling agent, at least one component which causes the paste to adhere to the component or test specimen, and water.

Description

[0001] Paste for testing the corrosion resistance of materials, processes for their production, and processes for corrosive damage to a corrodible component. The salt spray test (also salt spray test) is a standardized test for evaluating the corrosion protection effect of organic coatings, metallic coatings, or chemical or physical surface treatments [https: / / de. wikipedia. org / wiki / Salzspühtest (accessed on May 6, 2020)].

[0002] Accelerated methods for corrosion testing of materials, based on the use of salt spray, have been standardized since the early 1930s. Despite the many significant advances in the mechanistic understanding of atmospheric corrosion phenomena since those days, most changes to accelerated test standards have been implemented to reduce the duration of the tests and thus their cost by increasing their severity. Although accelerated laboratory test methods have played an important role in evaluating material performance, they have generally not been adopted due to their ability to simulate and enhance natural weathering. In particular, wet-dry cycles simulate the natural wetting and drying processes found in practice and, under many conditions, can promote the formation of naturally occurring corrosion product films, which often play a role in the kinetics of metal corrosion.Furthermore, the use of a relatively diluted mixed salt spray can result in corrosion morphologies and behaviors that are more representative of natural conditions compared to the more commonly used 5% NaCl-based solutions (e.g., ASTM B 117, Method for Salt-Spray Fog Testing).

[0003] The principle of the salt spray test is simple: In a chamber, a sprayed salt solution (usually a sodium chloride solution) creates a corrosion-promoting atmosphere, which initiates corrosion attack on exposed test specimens. Under these conditions, the corrosion process accelerates, and any existing coatings lose their corrosion protection during the test. The tested parts corrode faster than under normal application conditions, e.g., in cars, structural components, buildings, etc. The duration of the test depends on the application requirements. Since the concentration of the aqueous salt solution, temperature, pressure, and pH must be maintained constant, the results can be reproduced.

[0004] However, salt spray testing has been criticized for several reasons because it does not recreate real corrosion conditions. Some of the reasons for not replicating real corrosion conditions are listed below: "Salt spraying causes rapid degradation of the surface. However, this is hardly comparable to the deterioration of material properties under real conditions. Salt-induced degradation follows different mechanisms than degradation under real outdoor conditions. Therefore, the test produces relatively imprecise results." [Appleman, B. 'Cyclic Accelerated Testing: The Prospects for Improved Coating Performance Evaluation', J Protective Coatings & Linings, pp. 71-79, Nov 1989]

[0005] The surface of the samples is constantly moist and doesn't dry out in between. This alone doesn't reflect real-world conditions. Metals such as zinc cannot form a passive protective layer in the test as they do under real-world conditions.

[0006] The chloride content in the spray mist is very high (typically 5% NaCl), which greatly accelerates corrosion. However, different metals and metal components are susceptible to different accelerating factors.

[0007] The environmental conditions created in the test are not realistic and are harsher than those encountered in normal outdoor use.

[0008] The salt spray test completely ignores the damaging influence of UV light on coated surfaces, although this is usually the most important cause of deterioration of coated surfaces.

[0009] When comparing different metallic coatings, the salt spray test produces results that differ significantly from weathering under real-life conditions. International standards such as DIN EN ISO 14713-1:2010-05 "Zinc coatings - Guidelines and recommendations for the protection of iron and steel structures against corrosion" therefore state that short-term tests such as the salt spray test may not be used for material comparisons and that results from short-term tests cannot be used to derive statements about the duration of corrosion protection. For example, DIN EN ISO 14713-1 states: "A realistic result cannot be achieved by applying salt spray tests to steel with a zinc coating because these spray tests falsely accelerate the failure mechanism."[DIN EN ISO 14713-1 - Zinc coatings - Guidelines and recommendations for the protection of iron and steel structures against corrosion - Part 1: General design principles and corrosion resistance (ISO 14713-1:2009); German version EN ISO 14713-1:2009, page 25],.

[0010] The goal of environmental simulation tests is to characterize material behavior under complex mechanical-corrosive stress. In addition to sinusoidal mechanical loading, the material samples are also subjected to simultaneous corrosive stress from a corrosive medium. As a result, fatigue life curves under constant load amplitudes, so-called Wöhler curves, are determined. These curves represent a relationship between the local stress or external load and the tolerable fatigue life. These test results on fatigue crack corrosion behavior can be compared with reference tests in air, without exposure to a corrosive medium, to derive conclusions about the influence of corrosion stress.

[0011] Typically, these media influence tests are conducted using liquid media. The corrosive medium can be applied to the material samples by sprinkling, immersion, or spraying.

[0012] In addition to Wöhler tests, tests are often conducted on components under variable amplitudes. These use signals from real-life application situations—so-called operating loads.

[0013] From operational load simulation tests (OLV) with different load scales, fatigue life curves, also known as Gassner curves, are obtained. These are compared with the Wöhler curves at constant amplitude. In OLV tests on components exposed to severe environmental influences or made of materials susceptible to corrosion, for example, environmental influences are simulated by sprinkling with salt spray, dirt cider, or even at elevated temperatures.

[0014] Another major disadvantage of salt spray is that corrosion cannot be targeted at a specific location on the test specimen; instead, the entire component must usually be sprayed with salt spray. A further consequence of this is often that the corrosive aerosol humidifies and contaminates the entire test chamber and its surroundings, causing corrosive damage even where it is not desired. The salt spray test is therefore a costly and time-consuming test.

[0015] An overview of patents for various versions of salt spray as a corrosion simulation can be found below:

[0016] DE 10 2010 023 655 A1 describes a method for assessing corrosion damage through non-destructive testing of a workpiece using pulsed thermography. This method utilizes different temporal temperature behavior in damaged and undamaged areas of the workpiece to detect corrosion damage.

[0017] DE 10 2010 026 662 A1 describes a method for testing the corrosion behavior of a component consisting of at least two joined individual elements made of different materials. It comprises the following process steps:

[0018] - in a first process step, the component is subjected to thermal and / or mechanical stress;

[0019] - in a second process step, the component is then immersed in an aqueous electrolyte for a specified time;

[0020] - in a third process step, the component is subjected to a current load so that a current flows through at least one of the joints between the at least two individual elements;

[0021] - Process steps 2 and 3 are repeated several times. DE 10 2012 022 946 A1 discloses a method for determining the corrosion progression on a component, in particular on a vehicle component.

[0022] In this case, chemical and physical parameters relevant for a corrosion reaction as well as dimensions and a material composition of the component are specified, by means of which a model of the component is created, whereby a corrosion process on the component is simulated based on the model of the component and the specified values.

[0023] In addition, DE 102008010973 A1 describes a method for assessing the corrosion resistance of materials, in which, in a first step, a test specimen made of a material to be tested is exposed to a corrosive environment, in a second step the corroded material is removed from the test specimen and, in a third step, the depressions created in the test specimen by the removal of the corroded material are recorded.

[0024] US 2 019 090 A relates to the testing of stainless steel for its corrosion resistance and, in particular, relates to a test for determining the presence or absence of corrosion-promoting imperfections, scale and / or free iron on the surface of stainless steel.

[0025] US 1 753 301 A discloses a method and a corrosion agent for detecting the presence and location of tiny pinholes in thin sheets, such as metal plating, paint, and similar adherent coatings or foils. The method involves applying the thin sheet to a base of a different material and takes advantage of the fact that certain substances are characterized by a chemical reaction on the base that differs from their chemical reaction on the sheet under test. The method is most useful in testing thin metal sheet or metal plating that adheres to its base, such as electroplating, but can also be used to test non-adherent sheets; the base in this case serves merely to create the desired reaction difference.In commercial terms, the process and method are most useful in testing nickel plating on iron or copper bases, and the specific means and methods described herein as illustrative of the invention are limited to their application for this purpose.

[0026] According to US 2013 / 0164852 A1 and US 8,927,289 B2, an atmospheric corrosion test method and an apparatus used for the test are disclosed. The method comprises a salt spray step for applying salinity containing chloride ions to the surfaces of test specimens placed in a thermo-humidity chamber, followed by a dry-wet cycling step including a dry sub-step for drying the surface of the test specimens in the thermo-humidistat chamber at a low relative humidity, and a subsequent wet sub-step at a higher relative humidity than the dry sub-step, which are cycled through. The salinity is provided by spraying the salt water in the salt spray step. An exhaustion step for removing the salt mist sprayed into the thermo-humidistat chamber is further inserted between the salt deposition step and the dry sub-step.The amount of salt deposited on the surfaces of the test specimens is controlled by adjusting the amount of salt water sprayed on.

[0027] DE 103 31 474 A1 relates to a method and the associated device for simulating corrosion stress, preferably on components that are exposed to aggressive environmental stress in the engine compartment of a motor vehicle.

[0028] The invention described therein is based on the object of creating a method and an associated device for simulating the corrosion load on components arranged in the engine compartment of a motor vehicle and exposed to aggressive environmental stress, wherein realistic operating conditions are to be taken into account in order to draw conclusions about the aging of the components. According to the invention, the ambient temperature in the test chamber is adjusted in such a way that it corresponds to the temperature profile of the component to be tested during engine operation, and the spray nozzles are controlled by the programmable controller in such a way that the component is sprayed with spray fluid at predetermined time intervals. The test chamber is arranged in a climatic chamber in which the temperature profile of the component is adapted to realistic conditions.

[0029] According to documents CN 1435384 A and CN 1206175 C, lanolin, polyacrylic acid, and sodium polyacrylate are described as components of oil- and water-soluble corrosion inhibitors used to treat circulating cooling water or for use in boilers. Furthermore, the addition of such substances is also intended to prevent limescale deposits. The advantages of these additives are their high effectiveness, low dosage, and the fact that the materials do not contain phosphorus or other components harmful to the environment.

[0030] CN 10 1 063 060 A describes the production of an effective oil-soluble rust protection agent for ferrous and non-ferrous metals. It is shown that, among many other substances, the products may contain wool wax alcohol, lanolin, and polyacrylic acid resin.

[0031] CN 105 315 743 B describes a water-based, nanoporous anti-corrosive coating based on thixotropic gels that act as templates. Organic thixotropic gels contain, for example, lanolin or polyacrylic acid salts.

[0032] Likewise, CN 104531 095 A describes a corrosion protection composition that also provides protection against freezing.

[0033] A rust inhibitor is known from PL 162 189 Bl, which may contain, among other components, waxes, polyacrylic acid and the inorganic salts sodium nitrite and tin chloride.

[0034] US 2010 162941 A relates to freezing indicators comprising dispersions of solid, semi-solid, or liquid particles in a liquid medium, components of such freezing indicators, and methods for producing the components and the freezing indicators. In particular, but not exclusively, the invention relates to freezing indicators that can provide a reliable indication of whether a host product has been exposed in the past to a temperature approximately or below the freezing point of water or another liquid. The invention comprises a freezing-sensitive host product to which the freezing indicator is associated to monitor possible freezing exposure.

[0035] US 2013 046 275 A discloses a hydrophilic, biocompatible, delayed-release material. The material comprises amounts of Pluronic F-127, PEG-400, HPMC, and water effective to produce a composition with a sufficiently low viscosity at room temperature to allow injection into an internal body cavity via a tube inserted into a urinary catheter. At body temperature, the material exhibits a much higher viscosity and adheres stably to the internal surface of a body cavity. As the material dissolves, a therapeutic agent incorporated therein is slowly released into the body cavity, while the material itself is excreted from the body.

[0036] The object of the present invention was therefore to counteract some of the described disadvantages, i.e., to develop a composition and a method that causes accelerated corrosion on a component or test specimen without the use of salt spray, in which the component or test specimen is not completely exposed to the corrosive conditions and in which the test chamber or test bench is not contaminated with a corrosive medium. Furthermore, the accelerated corrosion method according to the invention should lead to the same result as a salt spray test conducted according to a standard and can be used instead of it.

[0037] This object is achieved with regard to a paste for testing the corrosion resistance of materials having the features of patent claim 1, a method for producing the paste according to the invention having the features of patent claim 11 and a method for corrosively damaging a corrodible component having the features of patent claim 14. The respective dependent claims represent advantageous developments. The invention thus relates, in a first aspect, to a paste for testing the corrosion resistance of materials, containing or consisting of

[0038] (A) at least one water-soluble salt,

[0039] (B) at least one swelling agent,

[0040] (C) at least one component that causes the paste to adhere to the component or test specimen and

[0041] (D) Water.

[0042] The problem of avoiding the described disadvantages of the salt spray test was solved according to the invention by generating corrosion at defined points on test specimens and components by selectively applying a corrosive paste.

[0043] According to the invention, water solubility is understood to mean a solubility of at least 10 g / l water of the salt at 23°C, preferably at least 100 g / l.

[0044] According to the invention, a swelling agent is understood to be a substance that can adsorb or absorb water without dissolving in it.

[0045] The component that causes the paste to adhere to the test specimen has an adhesion-enhancing effect when the paste is applied to a test piece. This component is preferably hydrophobic and contains, for example, long-chain saturated hydrocarbon groups that can interact with the corrodible test specimen.

[0046] For components, tools, etc., a corrosive effect can be specifically achieved by applying the salt paste described above to precisely defined areas. During the corrosion test, it is not necessary to continuously expose the entire test specimen to a liquid salt solution. This results in significant savings in media. Furthermore, after the tests, complex cleaning processes of the test rig and the removal of corrosion damage that occurs on and around the test rig are eliminated. This ensures that during fatigue strength tests, the corrosive medium also attacks the areas where the corrosion stress is to be investigated.

[0047] The moisture contained in the paste formulation maintains the paste-like appearance for many hours, allowing the paste to be easily removed after the test, allowing the damage to be analyzed more precisely.

[0048] A major advantage over tests using a liquid saline medium is the targeted application to a specific location on the component under investigation. This eliminates the need for large-scale and rather unspecific wetting with the liquid medium, significantly preventing adverse effects on adjacent components or the test environment.

[0049] In addition, the salt spray test requires many liters of salt solution per test. Depending on the size of the component being tested, more or less paste is needed, although the required amount is considerably lower.

[0050] Quite surprisingly, it was found that it combines the properties of a hydrophobic material such as lanolin, which ensures optimal adhesion of the paste to the surface of metals, and those characteristics of a hydrophilic corrosive component (polymer swollen with a low-molecular salt solution).

[0051] According to a preferred embodiment, the at least one water-soluble salt (A) is selected from the group consisting of inorganic and organic salts and mixtures and combinations thereof.

[0052] Advantageously, the at least one water-soluble salt (A) has a cation which is selected from the group consisting of inorganic monovalent metal cations, such as sodium, lithium or potassium, inorganic divalent metal cations, such as magnesium, calcium, iron(II), nickel or zinc, copper, manganese(II) or cobalt, inorganic free-valent metal cations, such as iron(III), manganese(III) or aluminum, and organic cations, such as ammonium, pyridinium, piperidinium or methylimidazolium, and their methyl, ethyl, propyl, butyl, pentyl, hexyl, heptyl, octyl, nonyl and decyl derivatives.

[0053] The water-soluble salt (A) preferably has an anion selected from the group consisting of inorganic anions such as chloride, bromide, hydrogen sulfate, hydroxide and / or hydrogen carbonate.

[0054] Suitable water-soluble salts include, for example, salts of monovalent cations, such as sodium chloride, lithium chloride, or potassium chloride. Also suitable are inorganic salts of divalent metal cations, such as magnesium chloride, calcium chloride, iron chloride, nickel chloride, or cobalt chloride. Soluble salts of higher-valent metal ions, such as iron(III) chloride or aluminum chloride, can also be used. Soluble salts of organic cations, such as ammonium chloride, pyridinium chloride, piperidinium chloride, or methylimidazolium chloride, including methyl, ethyl, propyl, butyl, pentyl, hexyl, heptyl, octyl, nonyl, and decyl derivatives of the cations.

[0055] Preferably, the at least one swelling agent (B) is selected from the group consisting of superabsorbents, in particular poly(meth)acrylates, such as sodium polyacrylate, starch, pectin, polyethylene oxide, polyethylene oxide-polypropylene oxide block copolymers, polyvinyl alcohol, polyvinylpyrolidone, polyvinylpyridine, gelatin, chitosan, hyaluronic acid and mixtures and combinations thereof.

[0056] A further preferred embodiment provides that component (C) is selected from the group consisting of lanolin, lanolin alcohols, and animal, vegetable, or (semi-)synthetic waxes, as well as mixtures and combinations thereof, in particular a combination of lanolin and lanolin alcohols. According to the invention, lanolin is used synonymously with the term wool wax. A particular advantage of incorporating lanolin is that the paste adheres optimally to the surface of all types of metals, even when the component is exposed to high-frequency vibrations. Since hydrophobic lanolin normally has anticorrosive properties, the added crosslinked sodium polyacrylate acts as a transport medium for the low-molecular-weight aqueous salt solution, allowing the hydrophilic medium to reach the surface of the paste and thus optimally exert its corrosive effect at the wool wax / metal interface.

[0057] In addition, the incorporation of component (C) prevents premature drying of the paste according to the invention.

[0058] If a mixture or a combination of lanolin and lanolin alcohols is used, it is particularly preferred if the mass ratio of the total lanolin and the total lanolin alcohols in the combination of lanolin and lanolin alcohols is 99:1 to 20:80, preferably 98:2 to 50:50, particularly preferably 97:3 to 80:20.

[0059] The paste according to the invention is preferably characterized by a viscosity of 10 2 up to 10 7 Pa s, preferably from 10 4 up to 10 6 Pa s particularly preferred from 5 10 4 up to 5 10 5 Pa.s, determined according to DIN EN ISO 2431:2020.

[0060] In a particularly preferred embodiment, it is provided that, in each case based on the total amount of the paste, the content

[0061] (A) of the at least one water-soluble salt from 0.5 to 15% by weight, preferably from 2 to 13% by weight, particularly preferably from 3 to 5% by weight,

[0062] (B) of the at least one swelling agent from 3 to 15 wt.%, preferably from 5 to 12 wt.%, particularly preferably from 7 to 10 wt.%,

[0063] (C) the at least one component which causes the paste to adhere to the component or test specimen is from 25 to 45% by weight, preferably from 30 to 40% by weight, particularly preferably from 25 to 30% by weight and / or (D) the water is from 35 to 65% by weight, preferably from 40 to 60% by weight, particularly preferably from 50 to 60% by weight.

[0064] It is further preferred if the paste consists of relatively few components, namely, for example, sodium chloride, cross-linked sodium polyacrylate, lanolin, lanolin alcohols and water.

[0065] In addition, the present invention relates to a process for producing a paste according to the invention, in which

[0066] (A) an aqueous solution of the at least one water-soluble salt with

[0067] (B) at least one swelling agent,

[0068] (C) at least one component which causes the paste to adhere to the component or test specimen and is mixed.

[0069] In this process, it is advantageous if the at least one component (C) which causes the paste to adhere to the component or test specimen is meltable and is melted before mixing, and the aqueous solution of the at least one water-soluble salt is heated to a temperature within a range of ± 20 °C, preferably ± 10 °C, particularly preferably ± 5 °C of the temperature used when melting the at least one component (C) before mixing with the molten component (C).

[0070] Furthermore, the present invention relates to a method for corrosively damaging a corrodible component, in which a paste according to the invention is applied to the component at least in some areas.

[0071] The invention also relates to the use of a paste according to the invention for corrosively damaging a corrodible component. The present invention is described in more detail below, without limiting the invention to the preferred embodiments shown.

[0072] For the corrosion test, the paste is applied to the component or test specimen. The paste can be applied to the surface with a spatula or brush. The applied layer can be used in various thicknesses, ranging from 1 to 6 mm.

[0073] Depending on the duration of the corrosion test and the ambient humidity or temperature, it may be necessary to prevent the paste from drying out. This can be achieved by covering the paste with a damp cloth or cling film. The damp cloth can be a cloth or cellulose paper, although these must be replaced or re-moistened regularly, approximately every 8 to 12 hours.

[0074] Preparation of the salt paste:

[0075] The lanolin and wool wax alcohol were melted at 70 °C. The salt solutions were also heated to the aforementioned temperature. The superabsorbent Favor PSXM (Evonik Nutrition & Care GmbH, Bäkerpfad 25, 47805 Krefeld) was added as fine grains to the oil phase while stirring. The aqueous medium was then added again while stirring. The resulting gel was cooled in a water bath and homogenized by mixing with a spoon spatula. The wool wax, lanolin alcohol, and the superabsorbent were always able to bind the entire aqueous phase.

[0076] The compositions were summarized in the following table:

[0077] Example of experimental validation:

[0078] Description of the experiment:

[0079] The systematic investigations into the influence of corrosive damage of salt pastes with different compositions were carried out on notched (settled) round specimens under bending load (plane bending).

[0080] The notched bending specimens were made of 25CrMo4. Since this material is used in the rail transport sector, it is designated EA4T (in the quenched and tempered "V" condition) according to DIN EN 13261:2011-01. This is an actively corrosive material.

[0081] The fatigue strength tests were conducted under force control at ambient temperature with a sinusoidal alternating load (R = -1). An electrical testing machine with a nominal load of 200 kN was used for the tests.

[0082] Results:

[0083] Fig. 1 shows the fatigue strength results of the tested specimens. In the first step, fatigue strength tests were conducted in air to determine a reference for the material's strength behavior. Using regression calculations based on minimum squares of the individual test results, the Wöhler curve (shown in blue) for a survival probability of PÜ = 50% was subsequently determined.

[0084] In the next step, fatigue crack corrosion tests were conducted under irrigation with a 5% NaCl solution to evaluate the influence of this corrosive medium on the strength behavior. Based on the individual test results, the Wöhler curves with the survival probabilities of PÜ = 10%, 50%, and 90% were derived using regression calculations. These test results, shown in gray, form the reference for the paste to be developed. The goal of the paste development was to optimize the composition so that the samples coated with the paste achieve a service life in the fatigue strength test that lies within the scatter band spanned by PÜ = 10% and PÜ = 90% of the salt corrosion tests, or as close as possible to the average survival probability of PÜ = 50%.Ultimately, the random tests conducted with the different paste formulations showed that the MW3 paste provides the most accurate description, Figure 1.

Claims

Patent claims Paste for testing the corrosion resistance of materials containing or consisting of (A) at least one salt with a water solubility of at least 10g per liter at 23°C, (B) at least one swelling agent, (C) at least one component that causes the paste to adhere to the component or test specimen and (D) Water. Paste according to claim 1, characterized in that the at least one water-soluble salt (A) is selected from the group consisting of inorganic and organic salts, as well as mixtures and combinations thereof. Paste according to one of the preceding claims, characterized in that the at least one water-soluble salt (A) has a cation selected from the group consisting of inorganic monovalent metal cations, such as sodium, lithium, or potassium; inorganic divalent metal cations, such as magnesium, calcium, iron(II), nickel, zinc, copper, manganese(II), or cobalt; inorganic trivalent metal cations, such as iron(III), manganese(III), or aluminum; and organic cations, such as ammonium, pyridinium, piperidinium, or methylimidazolium, as well as their methyl, ethyl, propyl, butyl, pentyl, hexyl, heptyl, octyl, nonyl, and decyl derivatives.

4. Paste according to one of the preceding claims, characterized in that the water-soluble salt (A) has an anion selected from the group consisting of inorganic anions, such as chloride, bromide, hydrogen sulfate, hydroxide and / or hydrogen carbonate.

5. Paste according to one of the preceding claims, characterized in that the at least one swelling agent (B) is selected from the group of hydrophilic but water-insoluble polymers which can absorb at least 10% by weight of their own weight in water and aqueous salt solutions, consisting for example of poly(meth)acrylates, sodium polyacrylate, starch, pectin, polyethylene oxide, polyethylene oxide-polypropylene oxide block copolymers, polyvinyl alcohol, polyvinylpyrrolidone, polyvinylpyridine, gelatin, chitosan, hyaluronic acid and mixtures and combinations and copolymers thereof.

6. Paste according to one of the preceding claims, characterized in that component (C) is selected from the group consisting of lanolin, lanolin alcohols and animal, vegetable cider or (semi-)synthetic waxes as well as mixtures and combinations thereof.

7. Paste according to one of the preceding claims, characterized by a viscosity of 10 2 up to 10 7 Pa s, preferably from 10 4 up to 10 6 Pa s particularly preferred from 5 10 4 up to 5 10 5 Pa.s, determined according to DIN EN ISO 2431:2020.

8. Paste according to one of the preceding claims, characterized in that, in each case based on the totality of the paste, the content (A) of the at least one water-soluble salt from 0.5 to 15% by weight, preferably from 2 to 13% by weight, particularly preferably from 3 to 5% by weight, (B) of the at least one swelling agent from 3 to 15 wt.%, preferably from 5 to 12 wt.%, particularly preferably from 7 to 10 wt.%, (C) the at least one component which causes adhesion of the paste to the component or test specimen from 25 to 45 wt.%, preferably from 30 to 40 wt.%, particularly preferably from 25 to 30 wt.% and / or (D) the water is from 35 to 65 wt.%, preferably from 40 to 60 wt.%, particularly preferably from 50 to 60 wt.%. Paste according to one of the preceding claims, consisting of sodium chloride, cross-linked sodium polyacrylate, wool wax and water. Process for producing a paste according to one of the preceding claims, in which (A) an aqueous solution of the at least one water-soluble salt with (B) at least one swelling agent, (C) at least one component that causes the paste to adhere to the component or test specimen and is mixed. Method according to the preceding claim, characterized in that the at least one component (C) that causes the paste to adhere to the component or test specimen is meltable and is melted before mixing, and the aqueous solution of the at least one water-soluble salt is heated to a temperature within a range of ± 20 °C, preferably ± 10 °C, particularly preferably ± 5 °C of the temperature used to melt the at least one component (C) before mixing with the molten component (C). Method for corrosively damaging a corrodible component, in which a paste according to one of claims 1 to 9 is applied to the component at least in part.

13. Use of the paste according to one of claims 1 to 9 for corrosive damage to a corrodible component.

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