Electrodes for monitoring erosion and / or corrosion

Abstract

The present invention relates to a method for monitoring erosion and / or corrosion comprising: a) a base layer; b) a sensor layer comprising a water-absorbent conductive composition comprising a water-soluble and / or water-swellable and / or water-absorbent resin; and c) a top layer, the sensor layer comprising an electrode between the base layer and the top layer. The electrode can be used to monitor erosion and / or corrosion.

Description

[Technical field]

[0001] The present invention relates to an electrode comprising: a) a base layer; b) a sensor layer comprising a water-absorbent conductive composition comprising a water-soluble and / or water-swellable and / or water-absorbent resin; and c) a top layer, said layer of water-absorbent conductive composition being between said base layer and said top layer. The electrode according to the present invention can be used for monitoring erosion and / or corrosion. [Background technology]

[0002] Ceramic-filled epoxy coatings are a well-established protective coating for protecting pump casings and propellers from corrosion and erosion. Typical ceramic-filled epoxy coatings are typically applied to the surface in two layers, up to 500-1000 μm each, depending on the application and location. These coatings are used to protect the substrate from the environment, but over time and / or the surrounding environment, the coating begins to lose its performance and defects in the coating result in degradation of the substrate. In other words, erosion of the coating is followed by corrosion of the substrate. In some cases, erosion of the coating is visible and easy to detect, but this is not always the case. Furthermore, detection depends on the location where the coating material is used, and sometimes that location is not detectable by eye. For example, in a chemical process environment, it is not possible to continuously monitor by eye alone how coatings on containers, pipes, propellers, etc. erode over time. Similarly, it is difficult to keep monitoring the corrosion of the substrate under various coating layers. Summary of the Invention [Problem to be solved by the invention]

[0003] With the boom of digitalization and IoT, the use of sensors is increasing across industries. Currently, there are many sensors available on the market. Acoustic and vibration sensors are well established for machine learning and structural health monitoring applications. However, they are external and not sensitive enough to detect erosion of coatings. There are embeddable sensors based on printed electronics that can measure stress, strain, pressure, humidity, temperature, etc. and correlate with degradation of coatings, etc. However, they have several limitations such as adhesion and compatibility with coating systems, long-term stability in environmental operation including various pH solutions, chemicals, abrasion, and sometimes high temperatures. Furthermore, many of these current sensors based on printed electronics or semiconductor-based MEMs are embedded or externally attached to the asset and have many limitations such as adhesion, battery life, and handling reliability. There are passive RFID sensors on the market that bring the advantages of wireless and low cost. However, these are mainly used for asset tagging, etc. and have very limited industrial use for structural health monitoring applications as the transmission of RF signals is blocked by metal and they do not work on metal substrates.

[0004] Thus, there is a need for an electrode that is an integral part of the protective coating. [Brief description of the drawings]

[0005] [Figure 1] FIG. 1 shows an electrode according to the invention on a substrate. [Diagram 2] FIG. 2 shows a test strip (electrode) for sensor applications. [Diagram 3] FIG. 3 shows the electrical resistance measurement of an electrode according to the invention.

[0006] Summary of the Invention The present invention relates to an electrode comprising: a) a base layer; b) a sensor layer comprising a water-absorbent conductive composition comprising a water-soluble and / or water-swellable and / or water-absorbent resin; and c) a top layer, said sensor layer being between said base layer and said top layer.

[0007] The present invention relates to a method for making an electrode according to the present invention, comprising the steps of: (i) providing a base layer on a substrate by coating, laminating, spraying, printing or brushing; (ii) which on a sensor layer comprising water absorbing, electrically conductive composition is applied via coating, laminating, spraying, printing or brushing; and (iii) applying a top layer over the layer of water absorbing, electrically conductive composition by coating, laminating, spraying, printing or brushing.

[0008] The invention encompasses the use of an electrode according to the invention for monitoring erosion and / or corrosion. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0009] Detailed Description of the Invention In the following passages the invention will be described in more detail. Each aspect so described may be combined with any other aspect, unless expressly indicated to the contrary. In particular, any feature indicated as being preferred or advantageous may be combined with any other feature indicated as being preferred or advantageous.

[0010] In the context of the present invention, the terms used are to be construed in accordance with the following definitions, unless the context dictates otherwise.

[0011] As used herein, the singular forms "a," "an," and "the" include both singular and plural referents unless the context clearly dictates otherwise.

[0012] As used herein, the terms "comprising," "comprises," and "comprised of" are synonymous with "including," "includes," or "containing," and are inclusive or open-ended and do not exclude additional, non-limiting members, elements, or method steps.

[0013] As used herein, the term "consisting of" excludes unspecified elements, components, members, or method steps.

[0014] The recitations of numerical endpoints include all values ​​and fractions subsumed within the respective ranges as well as the recited endpoints.

[0015] All percentages, parts, ratios, etc. referred to herein are by weight unless otherwise indicated.

[0016] When an amount, concentration, or other value or parameter is expressed in the form of a range, a preferred range, or an upper preferred value and a lower preferred value, it is to be understood that any range obtained by combining any upper or preferred value with any lower limit or preferred value is specifically disclosed, regardless of whether the resulting range is expressly stated in the context.

[0017] All references cited herein are incorporated by reference in their entirety.

[0018] Unless otherwise defined, all terms used in disclosing the present invention, including technical and scientific terms, have the meanings commonly understood by one of ordinary skill in the art to which this invention belongs. As a further guide, definitions of terms are included to better understand the teachings of the present invention.

[0019] The present invention relates to an electrode comprising: a) a base layer; b) a sensor layer comprising a water-absorbing conductive composition comprising a water-soluble and / or water-swellable and / or water-absorbent resin; and c) a top layer, said sensor layer being between said base layer and said top layer. Figure 1 shows an electrode according to the present invention.

[0020] Applicants have discovered that the water-absorbent conductive coating composition can be used as a sensor for monitoring the erosion of a coating and / or the corrosion of a substrate. The water-absorbent conductive coating composition can be incorporated as a sensor layer between two layers (a base layer and a top layer) of a protective coating. The sensor layer has a stable resistance because it is protected under the top layer, but as the top layer erodes and the sensor layer is exposed to water, the resistance increases several fold, triggering a signal of partial damage of the coating, which is transmitted via an edge device to an end user for action. The edge device receives the raw signal from the sensor, converts it to a digital format and transmits it via a wireless connection to cloud-based software for analysis and ultimately to a customer dashboard.

[0021] The present invention uses a smart conductive layer as a sensor layer between two coating layers (base layer and top layer) of a ceramic-filled epoxy-based protective coating. The sensor layer, which includes a water-absorbent conductive composition including water-soluble and / or water-swellable and / or water-absorbent resin, is protected from any fluids such as water, slurry, etc. by the chemically and abrasion-resistant top layer. Because it is protected by the top layer, the resistance under operating conditions is stable and does not change. Over time, the top layer will erode due to cavitation, and the sensor layer made of the water-absorbent conductive composition including water-soluble and / or water-swellable and / or water-absorbent resin will be exposed to water. When the sensor layer, which includes a water-absorbent conductive composition including water-soluble and / or water-swellable and / or water-absorbent resin, absorbs water, the resistance will increase several times. If the resistance suddenly increases, an alarm will be triggered based on the set threshold limit, and a signal about the partial coating damage can be sent to the end user through the IoT device. Because the signal is generated in the middle layer, operators know the remaining life of the base layer and can therefore plan downtime during the slower production cycle, thereby preventing losses due to equipment failure and damage.

[0022] The electrode according to the present invention includes a base layer. The requirement of the base layer is to provide a coating that is chemically and abrasion resistant. The base layer suitable for use in the present invention can be any commercially available coating composition.

[0023] Preferably, the base layer is selected from the group consisting of epoxy-based compositions, polyurethane-based compositions, acrylate-based compositions, vinyl ester-based compositions, polyester-based compositions, phenoxysiloxane-based compositions, epoxysiloxane compositions, and mixtures thereof.

[0024] Particularly suitable base layers for use in the present invention may be based on ceramic-filled epoxy-based compositions that are widely used as protective coatings. For example, commercially available two-component, room temperature curing, corrosion-resistant, abrasion-resistant, and chemical-resistant epoxy coating systems can be used in the present invention. This type of coating system is commonly used to protect equipment such as pumps, pipes, and heat exchangers from harsh environments.

[0025] Commercially available base layers suitable for use in the present invention include, but are not limited to, Loctite PC 7333 manufactured by Henkel AG & Co. KGaA.

[0026] Preferably, the base layer has a thickness of 100 to 500 μm, preferably 150 to 400 μm.

[0027] The base layer is preferably applied in two coating layers to prevent pinholes or air bubbles that could provide leak paths for fluid to enter and damage the coating. For example, the base layer is added in two layers, each 250 μm thick, or 150 μm thick.

[0028] The electrode according to the present invention includes a top layer. The requirement of the top layer is to provide a chemically and abrasion resistant coating. The top layer suitable for use in the present invention may be any commercially available coating composition.

[0029] Preferably, the top layer is selected from the group consisting of epoxy-based compositions, polyurethane-based compositions, acrylate-based compositions, vinyl ester-based compositions, polyester-based compositions, phenoxysiloxane-based compositions, and mixtures thereof.

[0030] Top layers particularly suitable for use in the present invention may be based on ceramic-filled epoxy-based compositions that are widely used as protective coatings.

[0031] Commercially available top layers suitable for use in the present invention include, but are not limited to, Loctite PC 7333, Loctite PC 7255, Loctite PC 7337 and Loctite PC 7226 available from Henkel AG & Co. KGaA.

[0032] Preferably, the top layer has a thickness of 100 to 600 μm, preferably 125 to 500 μm.

[0033] If the top layer is less than 100 μm thick, it may not provide adequate coverage as required. The more severe the operating conditions, the thicker the top layer should be to provide adequate and reliable coverage against harsh operating conditions and environments, as well as against chemical etching.

[0034] The top layer is preferably applied in two coating layers to prevent pinholes or air bubbles that could provide leak paths for fluid to enter and damage the coating. For example, the top layer is added in two layers, each 300 μm thick, or 2 layers, each 250 μm thick.

[0035] In one embodiment, the base layer is the same material as the top layer.

[0036] In one embodiment, the base layer is a different material than the top layer.

[0037] In one embodiment, a thin primer coating layer may be applied to the surface of the substrate prior to application of the base layer. Any commercially available primer coating composition suitable for the substrate used may be used in the present invention. The optional primer layer may have a thickness of 25 to 100 μm.

[0038] The electrode according to the present invention comprises a sensor layer comprising a water-absorbing conductive composition, preferably selected from the group consisting of vinyl resin-based compositions, 2k epoxy-based compositions, polyester-based compositions, polyurethane and acrylate copolymer-based compositions, polyurethane and polyester copolymer-based compositions, vinyl copolymer-based compositions and mixtures thereof.

[0039] In a preferred embodiment, the water-absorbing conductive composition is based on a resin selected from the group consisting of copolymers of vinyl chloride and vinyl acetate, polyvinyl alcohol resins, polyvinyl butyrate resins, and mixtures thereof.

[0040] These resins are preferred because they are non-oxidizing, permanently flexible, yet tough and durable, and are characterized by being color, odor, and taste free.

[0041] Thus, the composition comprises a resin selected from the group consisting of vinyl resins, epoxy resins, polyester resins, polyurethane and acrylate copolymers, polyurethane and polyester copolymers, vinyl copolymer resins, and mixtures thereof, preferably a vinyl resin or an epoxy resin.

[0042] The resin may be present in the water-absorbing conductive composition according to the present invention in an amount of 5 to 25% by weight, preferably 7.5 to 20% by weight, more preferably 9 to 15% by weight of the total weight of the composition.

[0043] The water-absorbing conductive composition according to the present invention comprises a water-soluble and / or water-swellable and / or water-absorbent resin. The water-soluble and / or water-swellable and / or water-absorbent resin can be any resin that is water-soluble, swells in the presence of water, or absorbs water. Preferably, the water-soluble and / or water-swellable and / or water-absorbent resin is selected from the group consisting of sodium polyacrylate, polyvinylpyrrolidone (PVP), cellulose ethers, methylcellulose, hydroxylpropylcellulose, gum arabic, starch (dextrin), casein (phosphoprotein) and mixtures thereof, more preferably, the group consisting of sodium polyacrylate, polyvinylpyrrolidone (PVP), methylcellulose and mixtures thereof.

[0044] Sodium polyacrylate, polyvinylpyrrolidone (PVP) and methylcellulose are preferred due to their excellent water solubility / absorbency.

[0045] Commercially available water soluble and / or water swellable and / or water absorbent resins suitable for use in the present invention include, but are not limited to, sodium polyacrylate from Prime Specialities, India, polyvinylpyrrolidone (PVP) from Ashland Specialty Industries, and methylcellulose from DOW Chemical Company.

[0046] The water-soluble and / or water-swellable and / or water-absorbent resin may be present in the water-absorbent conductive composition according to the present invention in an amount of 5 to 30% by weight, preferably 7.5 to 25% by weight, more preferably 8 to 22% by weight of the total weight of the composition.

[0047] Applicant has found that these amounts are preferred because amounts greater than 30% may cause stability issues during application. Amounts less than 5% may not provide the desired water detection effect. Furthermore, it has been found that a range of 5-30% of water-soluble and / or water-swellable and / or water-absorbent resin is optimal to provide a better response as a sensor.

[0048] The water-absorbing conductive composition according to the present invention contains a conductive filler. In theory, any conductive filler may be used. Preferably, the conductive filler is selected from the group consisting of carbon, carbon black, carbon nanotubes, graphite, graphene, silver, nickel, copper, gold, platinum, aluminum, iron, zinc, cobalt, lead, tin alloy, silver-coated copper, silver-coated graphite, silver-coated polymer, silver-coated aluminum, silver-coated glass, silver-coated carbon, silver-coated boron nitride, silver-coated aluminum oxide, silver-coated aluminum hydroxide and mixtures thereof, more preferably, the conductive filler is selected from the group consisting of carbon black, carbon nanotubes, graphite and mixtures thereof.

[0049] In one embodiment, the conductive filler is carbon black.

[0050] In one embodiment, the conductive filler is carbon nanotubes.

[0051] In one embodiment, the conductive filler is graphite.

[0052] In yet another embodiment, the conductive filler is a mixture of carbon black and graphite.

[0053] In yet another embodiment, the conductive filler is a mixture of carbon black, graphite, and carbon nanotubes.

[0054] Commercially available conductive fillers suitable for use in the present invention include, but are not limited to, Timrex SGF 15 from Imerys Graphite & Carbon, Vulcan PF from Cabot Corporation, and Vulcan XC 72 from Cabot Corporation.

[0055] The conductive filler may be present in the water-absorbing conductive composition according to the present invention in an amount of 10 to 35% by weight, preferably 12 to 33% by weight, more preferably 15 to 30% by weight of the total weight of the composition.

[0056] If the conductive filler is carbon black, carbon nanotubes, or graphite, the amount may also depend on the oil absorption. The oil absorption varies for carbon black, carbon nanotubes, and graphite and depends on the particle size and specific surface area of ​​the conductive filler. For example, carbon nanotubes have a small nanoscale particle size and therefore a high oil absorption. As a general guideline, the higher the oil absorption, the lower the particle size. Oil absorption is measured according to ASTM-D281.

[0057] Applicants have found that these amounts are preferred because amounts greater than 25% can cause rheological problems during application, while amounts less than 5% may not provide the desired adhesion to the substrate / undercoat / overcoat layer.

[0058] The water-absorbing conductive composition according to the present invention comprises a solvent. Solvents suitable for use in the present invention have a boiling point below 235° C. Preferably, the solvent is selected from the group consisting of n-butanol, butyl carbitol, 1-methoxy-2-propanol acetate, isopropyl alcohol, butyl cellosolve and mixtures thereof, more preferably, n-butanol, butyl carbitol, 1-methoxy-2-propanol acetate and mixtures thereof.

[0059] The preferred solvents, n-butanol, butyl carbitol, and 1-methoxy-2-propanol acetate, are polar solvents, which are desirable because they act during processing of the composition, and furthermore, these solvents also act as coalescing agents in the composition.

[0060] Commercially available solvents suitable for use in the present invention include, but are not limited to, n-butanol from Sigma Aldrich.

[0061] The solvent may be present in the water-absorbing conductive composition according to the present invention in an amount of 10 to 70% by weight, preferably 20 to 65% by weight, more preferably 30 to 60% by weight of the total weight of the composition.

[0062] This range of the amount of the solvent is preferable since it provides good coatability (composition) on the substrate.

[0063] The sensor layer comprising the water-absorbing conductive composition according to the present invention may have a thickness of 10 to 300 μm, preferably 50 to 200 μm, and / or an electrical resistance of 5 Ω to 800 kΩ, preferably 20 Ω to 500 kΩ, wherein said electrical resistance is measured according to ASTM D2739-97.

[0064] The thickness range is preferred because thicknesses below 10 μm may not be uniformly applied due to expected ink rheology and available application methods. Thicknesses above 300 μm may cause cracks. Furthermore, the total coating thickness may increase, which may cause part tolerance issues. Tolerance issues mean that the total thickness of the electrode, i.e., the combined thickness of the base layer, the sensor layer, and the top layer, becomes too thick, which may reduce the inner diameter of the pump, for example, thereby adversely affecting the pump's tolerance diameter.

[0065] A resistance range of 5 Ω is preferred as resistances below this may not be reliably achievable with carbon-based inks and resistances above 800 kΩ may lead to reduced sensor sensitivity.

[0066] The sensor layer completely or partially covers the base layer. The degree of coverage varies depending on the application. A non-limiting example of complete coverage would be a small pump housing.

[0067] On the other hand, the top layer completely covers the sensor layer.

[0068] The present invention relates to a method for making an electrode according to the present invention, comprising the steps of: (i) providing a base layer on a substrate by coating, laminating, spraying, printing or brushing; (ii) applying a sensor layer comprising a water-absorbing conductive composition by coating, laminating, spraying, printing or brushing; and (iii) applying a top layer over the layer of water-absorbing conductive composition by coating, laminating, spraying, printing or brushing.

[0069] In a preferred embodiment, in step (ii), the sensor layer comprising the water-absorbing conductive composition completely or partially covers the surface of the base layer, and in step (iii), the top layer completely covers the surface of the water-absorbing conductive composition layer.

[0070] In the method according to the invention, after applying the sensor layer comprising the water-absorbing conductive composition, said sensor layer is cured for 10 minutes to 10 hours, preferably 30 minutes to 8 hours.

[0071] In the method according to the invention, after application of the sensor layer comprising the water-absorbing conductive composition, said sensor layer is cured at a temperature of 20-150°C, more preferably at 25-100°C.

[0072] In the method according to the invention, after application of the base layer (step (i)) and after application of the top layer (step (iii)), said base layer and / or top layer are cured for a period of from 10 minutes to 10 hours, preferably from 30 minutes to 8 hours, wherein said curing times can be the same or different for the base layer and the top layer.

[0073] In the method according to the invention, after application of the base layer (step (i)) and after application of the top layer (step (iii)), the base layer and / or the top layer are cured at a temperature between 20 and 150°C, more preferably between 25 and 100°C, wherein said curing temperature may be the same or different for the base and top layer.

[0074] The present invention relates to the use of an electrode according to the invention for monitoring erosion and / or corrosion.

[0075] In one embodiment, an electrode according to the present invention is used to detect erosion and / or corrosion from the surface of a substrate.

[0076] In one embodiment, the electrodes according to the present invention are used to detect erosion and / or corrosion from a top layer.

[0077] In one embodiment, the electrodes according to the present invention are used to detect erosion and / or corrosion from a base layer.

[0078] For example, the electrodes may be used on pump housings, propellers, or storage tank shells for erosion and / or corrosion monitoring. EXAMPLES

[0079] The following chemicals are used in the examples: Timrex SGF 15 made by Imerys Graphite & Carbon Vulcan PF and Vulcan XC 72 from Cabot Corporation Arcosolv PM Acetate from Lyondell Chemical Company Butyl Carbitol manufactured by Dow Chemical Company UCAR Wagh manufactured by Dow Chemical Company Polyvinylpyrrolidone (PVP) from Ashland Specialities Ingredients Methylcellulose from DOW Chemical Company n-Butanol from Sigma Aldrich Sodium Polyacrylate from Prime Specialities, India

[0080] Compositions containing water-absorbing polymers based on PVP or Methocel VLV in a thermoplastic binder are shown below in Table 1. Compositions containing 10% and 20% PVP and Methocel VLV were prepared in a high speed mixer at 2000 rpm for 30 minutes.

[0081] [Table 1]

[0082] Preparation of test electrodes and application of electrodes Composite specimens with dimensions 125 x 12.7 x 3 mm were used for the electrode performance study. Copper leads of 50 μm thickness were attached to both ends of the composite specimens using cyanoacrylate adhesive. These copper leads were used for soldering wires to measure the resistance of the coated specimens. The specimens were prepared by applying three layers of coating. On a base layer of Loctite PC 7333 (from Henkel AG & Co. KGaA) with a thickness of 200 μm, a layer of water-absorbent conductive composition containing water-soluble and / or water-swellable and / or water-absorbent resin with a thickness of 100 μm, and a top layer of Loctite PC 7333 (from Henkel AG & Co. KGaA) with a thickness of 200 μm were applied. An image of the specimen is shown in Figure 2. Figure 2 shows 2a) bare sample, 2b) base layer + layer of water-absorbing conductive composition (sensor layer), 2c) 100% layer of water-absorbing conductive composition (sensor layer) covered with a top layer, 2d) 90% layer of water-absorbing conductive composition (sensor layer) covered with a top layer (10% open). The base layer was cured at 100°C for 1 hour, the sensor layer was cured at 100°C for 1 hour, and the top layer was cured at 100°C for 1 hour.

[0083] The electrodes were evaluated by using a water drop test. The water drop test was performed by applying 2-3 drops of water to the center of the coated specimen and the electrical resistance was recorded before and after applying the water drops. The electrical resistance of the specimen was measured using a Keysight DAQ970 A - Data Acquisition System (the system is shown in Figure 3).

[0084] The change in electrical resistance after applying a water drop onto the center of the electrode was recorded from 0 to 10 minutes. The test specimens completely covered with the top layer Loctite PC 7333 showed no change in the electrical resistance of the electrode even after applying a water drop onto the test specimen (Figure 2c). However, the layer of water-absorbent conductive composition (sensor) containing water-soluble and / or water-swellable and / or water-absorbent resin was not completely covered by the top layer (Figure 2b). 90% of the layer of water-absorbent conductive composition (sensor) containing water-soluble and / or water-swellable and / or water-absorbent resin was covered by the top layer Loctite PC 7333 (Figure 2d), showing a change in electrical resistance when a water drop was applied onto the top layer. The water drop test results of the open electrode test specimens are shown in Table 2. Example 1 showed a high electrical resistance change of 27054% in 10 minutes, whereas Example 4 showed an electrical resistance change of 25.86%. When a droplet of water is added onto the conductive coating, the water-absorbing polymer absorbs the water, breaking the conductive path and changing the electrical resistance of the electrode.

[0085] [Table 2]

[0086] Comparative Example Table 3 below illustrates compositions that do not include water-soluble resins and / or water-swellable resins and / or water-absorbent resins. The compositions were prepared in a high speed mixer at 2000 rpm for 30 minutes.

[0087] [Table 3]

[0088] A substrate was coated with the composition according to Example 6 and used to perform a water drop test. The results of the water drop test for Comparative Example 6 are shown in Table 4 below. Comparative Example 6 showed no change in electrical resistance even after 5 minutes.

[0089] [Table 4]

Claims

1. a) A base layer; b) A sensor layer comprising a water-absorbing and electrically conductive composition containing a water-soluble and / or water-swellable and / or water-absorbent resin; and c) A top layer comprising an electrode, wherein the sensor layer is between the base layer and the top layer.

2. The water-absorbing and electrically conductive composition is selected from the group consisting of vinyl resin-based compositions, 2k epoxy-based compositions, polyester-based compositions, copolymer-based compositions of polyurethane and acrylate, copolymer-based compositions of polyurethane and polyester, vinyl copolymer-based compositions, and mixtures thereof, preferably a vinyl resin-based composition or a 2k epoxy-based composition. The electrode according to claim 1.

3. The water-absorbing and electrically conductive composition contains a water-soluble and / or water-swellable and / or water-absorbent resin selected from the group consisting of sodium polyacrylate, polyvinylpyrrolidone (PVP), cellulose ether, methylcellulose, hydroxypropylcellulose, gum arabic, starch (dextrin), casein (phosphoprotein), and mixtures thereof, more preferably selected from the group consisting of sodium polyacrylate, polyvinylpyrrolidone (PVP), methylcellulose, and mixtures thereof. The electrode according to claim 1.

4. The sensor layer i) has a thickness of 1 to 300 μm, preferably 10 to 200 μm; and / or ii) has an electrical resistance of 5 Ω to 800 kΩ, preferably 20 Ω to 500 kΩ, wherein the electrical resistance is measured according to ASTM D2739-97. The electrode according to claim 1.

5. The base layer is selected from the group consisting of epoxy-based compositions, polyurethane-based compositions, acrylate-based compositions, vinyl ester-based compositions, polyester-based compositions, phenoxysiloxane-based compositions, epoxy siloxane compositions, and mixtures thereof, and has a thickness of 100 to 500 μm, preferably 150 to 400 μm. The electrode according to claim 1.

6. The top layer is selected from the group consisting of epoxy-based compositions, polyurethane-based compositions, acrylate-based compositions, vinyl ester-based compositions, polyester-based compositions, phenoxysiloxane-based compositions, and mixtures thereof, and has a thickness of 100 to 600 μm, preferably 125 to 500 μm. The electrode according to claim 1.

7. The electrode according to claim 1, wherein the base layer is made of the same material as the top layer or the base layer is made of a material different from the top layer.

8. (i) providing a base layer on a substrate by coating, laminating, spraying, printing or brushing; (ii) applying a sensor layer comprising a water-absorbing conductive composition by coating, laminating, spraying, printing or brushing; and (iii) applying a top layer on the layer of the water-absorbing conductive composition by coating, laminating, spraying, printing or brushing The method for manufacturing the electrode according to claim 1, comprising:

9. The method according to claim 8, wherein in step (ii), the sensor layer comprising the water-absorbing conductive composition completely or partially covers the surface of the base layer, and in step (iii), the top layer completely covers the surface of the water-absorbing conductive composition layer.

10. The method according to claim 8, wherein after applying the sensor layer comprising the water-absorbing conductive composition, the sensor layer is cured for 10 minutes to 10 hours, preferably 30 minutes to 8 hours.

11. The method according to claim 8, wherein after applying the sensor layer comprising the water-absorbing conductive composition, the layer is cured at 20 to 150 ° C, more preferably 25 to 100 ° C.

12. A method of curing the base layer and / or the top layer for 10 minutes to 10 hours, preferably 30 minutes to 8 hours, after application of the base layer (step (i)) and after application of the top layer (step (iii)), wherein the curing time may be the same or different for the base layer and the top layer. The method according to claim 8.

13. A method of curing the base layer and / or the top layer at 20 to 150 ° C, more preferably 25 to 100 ° C, after application of the base layer (step (i)) and after application of the top layer (step (iii)), wherein the curing temperature may be the same or different for the base layer and the top layer. The method according to claim 8.

14. Use of the electrode according to claim 1 for monitoring erosion and / or corrosion.

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