Atmosphere corrosion sensor

Abstract

The invention relates to an atmosphere corrosion sensor. The invention discloses an atmospheric corrosion sensor (1) for detecting corrosion of electrical equipment caused by corrosive gases, the atmospheric corrosion sensor comprising at least one atmospheric corrosion sensing structure (2) placed on at least one insulated corrosion sensor substrate (3), wherein the atmospheric corrosion sensor (1) comprises at least one gas permeable layer (4) placed on the corrosion sensing structure (2), and wherein the gas permeable layer (4) allows molecules of a corrosive gas present in the atmosphere to be transferred to a surface of the sensing structure (2) opposite the insulated corrosion sensor substrate (3), thereby corroding it.

Description

Technical Field

[0001] The object of the present invention is an atmosphere corrosion sensor for detecting corrosion of electrical equipment caused by corrosive gases. The sensor can be used for various types of electrical equipment susceptible to atmospheric corrosion. In particular, the sensor is suitable for electrical equipment used in the most aggressive corrosive atmospheres in the power distribution industry, chemical plants, aircraft, automobile manufacturing, transportation infrastructure, offshore structures and construction industries. Background Art

[0002] Atmospheric corrosion is an electrochemical process of degradation of materials exposed to a corrosive atmosphere. The sensitivity of a material to atmospheric corrosion depends on many factors, the most important of which are: the type and structure of the material, the presence of water, the composition of the atmosphere, humidity, and the ambient temperature. Particularly susceptible to atmospheric corrosion are metals and their alloys, such as copper, aluminum, iron, zinc, nickel, silver, steel, brass, and many other metals. The most aggressive corrosive atmospheres are found in the power distribution industry, chemical production plants, aircraft, automobile manufacturing, transportation infrastructure, offshore structures, and the construction industry. These atmospheres are usually rich in many corrosive substances, such as chlorides, phosphates, nitrates, sulfates, carbonates, sulfur oxides, nitrogen oxides, carbon dioxide, hydrogen sulfide, which together with moisture and oxygen can cause severe metal corrosion.

[0003] Different electronic and electrical equipment are used in each of these environments, and because they are composed of various metals and alloys, they are particularly susceptible to damage due to atmospheric corrosion. The growing complexity and reliability requirements of electronic equipment make atmospheric corrosion an important issue. Therefore, atmospheric corrosion monitoring can help predict the service life of electronic and electrical equipment in a specific environment and help plan service and maintenance measures to prevent serious failures and equipment downtime.

[0004] Many corrosion sensors use metal films to detect atmospheric corrosion. The corrosive substances in the atmosphere react with the metal surface, causing corrosion to develop deep into the film, so the metal is consumed and the resistance increases until the continuity is broken. The time required to destroy the metal film depends on its thickness and a number of environmental conditions, such as the concentration of corrosive substances in the atmosphere, humidity and temperature. The thicker the film, the longer it takes to break the electrical continuity.

[0005] In the prior art, corrosion sensors are known. For example, document US8723534B2 discloses a corrosion sensor comprising a plurality of metal strips having different thicknesses. A first metal strip having the smallest thickness is first used to provide sensitive corrosion detection. After the exposed portion of the first metal strip is consumed, a second metal strip having a second smallest thickness can be used to provide continuous sensitive corrosion detection using the remaining uncorroded portion of the second metal strip. When the exposed portion of the thinner metal strip becomes unusable due to complete corrosion, multiple metal strips can be sequentially used, and the uncorroded exposed portion of the thicker metal strip becomes thin enough to provide sensitive corrosion detection.

[0006] Patent US8390306B2 discloses an atmospheric corrosion sensor. Its corrosion sensor is based on a metal film resistor. The corrosion sensor consists of a set of multilayer metal films with gradually increasing widths. The metal film is located on a non-conductive material. The corrosion sensor operates to measure the resistance of each metal film. The resistance of the metal film depends on its spatial dimensions. Therefore, atmospheric corrosion affects the spatial dimensions of the metal film and changes its resistance. When the width of the metal film changes from metal to non-conductive oxide due to corrosion, the resistance changes due to the reduction of the conduction path. When the corrosive gas in the atmospheric environment where the sensor operates erodes the metal of the metal film and converts it into a non-conductive oxide, the width decreases, thereby increasing the resistance of the metal film. The operation of the corrosion sensor is optimized to work at a relatively low corrosion rate, where corrosion products are formed at a rate of about 30 nanometers per month or less. The corrosion sensor is designed for indoor use. Therefore, when a certain degree of corrosion is detected via the sensor response, the internal atmosphere can be adjusted accordingly. In this solution, a reference sensor element can also be used, which is substantially not susceptible to corrosion caused by the atmosphere.

[0007] Patent application US20230134944A1 discloses a corrosive environment monitoring device, which includes a laminate, which includes an insulating plate, a base metal film and a sensing metal film, the base metal film is formed on the insulating plate and resists corrosion by corrosive substances, and the sensing metal film is formed on the base metal film and is susceptible to corrosion by corrosive substances. The corrosive environment monitoring also includes a housing containing the laminate, the housing includes an opening portion in the direction of the side surface, and a gas passage for corrosive substances is formed inside, wherein the sensing metal film is formed in a partial area on the base metal film.

[0008] To assess the corrosion rate of electronic equipment, a variety of methods are used, but four appear to be the most popular.

[0009] One of the approaches is based on the optical evaluation of the corrodible surface affected by the corrosion process. It can be based on optoelectronic components such as photodiodes and phototransistors. However, these simple solutions are very sensitive to dirt, dust and light conditions (i.e. daylight vs. artificial lighting), while more advanced solutions based on picture recognition (camera and picture processing unit) are not widely used because the size and cost of such solutions can be very high, which limits their use to protecting only the most important and valuable assets.

[0010] Another approach is based on electrochemical corrosion measurement, where very small potential, anodic and cathodic current values ​​are monitored. This approach requires the use of specific electrodes and extremely precise monitoring circuitry, which increases the cost and size of the solution.

[0011] Yet another approach is based on the continuous monitoring of some physical parameters of corrosion sensors made of corrodible materials to assess the course of the corrosion process - for example, monitoring the change in the resistance of a metal strip. In the continuous method, a single metal film of a predetermined thickness is used and its resistance is measured, so that the corrosion process can be monitored continuously in time. Sometimes, another layer of corrosion-resistant metal film is also used to compensate for temperature changes and other environmental factors that are not directly related to corrosion. This method requires high-quality measurement equipment to detect small changes in parameter values ​​and be sensitive to environmental conditions such as temperature and humidity. In addition, in order to detect trends within the device (when using a stand-alone solution that is not connected to a higher-level system), it may be necessary to store measurement data over a period of time and compare them. All these requirements will increase the cost of measurement equipment that can meet the required functions with reasonable sensitivity. As a result, the total cost of the solution and its size may still be too high to allow it to be placed in many products as an additional functional block.

[0012] The fourth method, called discrete method, is based on the detection of the moment when the corrosion process breaks the continuity of the corrosion sensor. The cost and size of the detection circuit are extremely low, but the disadvantage of using this solution is that the information about the corrosion process is limited - it can only indicate the threshold point at which the continuity break is reached, but it is impossible to provide information about the corrosion process over time.

[0013] To enhance the capabilities of the fourth solution, multiple sensing elements based on connection loss detection can be used. However, it is crucial to ensure that the multiple sensing elements are damaged by the corrosion process at different times, so that information about the connection loss in subsequent sensing elements can be obtained and based on this sequence, the corrosion process of the protected equipment can be evaluated. The disadvantage of the discrete approach is that metal films of different thicknesses must be used, which increases the manufacturing cost and limits the choice of available technologies.

[0014] Predicting corrosion processes on different materials often requires knowledge of the composition of the corrosive atmosphere. In reality, corrosion processes are not caused by one single corrosive gas, but by a mixture of gases that react in different ways with various materials. Existing corrosion sensors only provide collective information about the ongoing corrosion process of a specific material.

[0015] An object of the present invention is to provide a low-cost corrosion sensor that provides comprehensive information about atmospheric corrosion due to corrosive gases in the operating environment of electrical equipment. Summary of the invention

[0016] This object is achieved by a device according to claim 1 .

[0017] An atmospheric corrosion sensor for detecting corrosion of electrical equipment caused by corrosive gases, the atmospheric corrosion sensor comprising at least one atmospheric corrosion sensing structure placed on at least one insulating corrosion sensor substrate. The atmospheric corrosion sensor comprises at least one gas permeable layer placed on the corrosion sensing structure, wherein the gas permeable layer allows molecules of corrosive gas present in the atmosphere to be transferred to the surface of the sensing structure opposite to the insulating corrosion sensor substrate, thereby corroding it.

[0018] Advantageous embodiments of the device are subject matter of the dependent claims or can be found in the following description and examples.

[0019] Preferably, the gas permeable layer is a gas selective layer that allows a single corrosive gas or a predetermined group of corrosive gases to transfer to the atmosphere corrosion sensing structure. Thus, the atmospheric corrosion rate can be monitored relative to the selected corrosive gas. The gas selective layer can be made, for example, in the form of a gas selective membrane layer.

[0020] The atmospheric corrosion sensor preferably comprises at least two gas selective layers located on top of each other, wherein the combination of these gas selective layers allows a single corrosive gas or a predetermined group of corrosive gases to be transferred to the atmospheric corrosion sensing structure.

[0021] In another preferred embodiment, the atmosphere corrosion sensor comprises at least two atmosphere corrosion sensing structures, wherein these atmosphere corrosion sensing structures are covered by different gas selective layers or different combinations of gas selective layers, wherein each gas selective layer or each combination of gas selective layers allows a different corrosive gas or a different predetermined group of corrosive gases to be transferred to the atmosphere corrosion sensing structure. The use of a plurality of such atmosphere corrosion sensing structures with different gas selective layers or different combinations of gas selective layers allows not only monitoring of the corrosion process, but also determination of the presence and concentration of selected corrosive gases in the atmosphere.

[0022] It is preferred to use multiple such atmosphere corrosion sensing structures of the same spatial dimensions with different gas selective layers in the sensor. This enables easy comparison of the results of multiple sensor structures sensitive to different corrosive gases. For example, the corrosion rate of gas x is CRx, and the corrosion rate of gas y is CRy. If CRx>CRy, it means that the atmosphere is richer in corrosive gas x, which leads to strong corrosion of the corrosion sensing structure. This allows to assess that the concentration of corrosive gas x in the atmosphere is higher than that of corrosive gas y.

[0023] In another preferred embodiment of the present invention, the atmosphere corrosion sensor comprises at least two atmosphere corrosion sensing structures of the same spatial size, wherein the sensing structures are covered by gas permeable layers of the same type but with different thicknesses. The use of non-corrodible gas permeable layers of different thicknesses allows the corrosion rate of the corrosion sensing structures to be controlled.

[0024] Preferably, the atmospheric corrosion sensor includes at least one reference structure covered with an impermeable protective layer. The reference structure is made of the same material as the atmospheric corrosion sensing structure and has the same spatial dimensions. The reference structure can be used together with the corrosion sensing structure to compensate for the effects of temperature and other environmental factors on the measurement.

[0025] The atmospheric corrosion sensor preferably includes a groove layer between the corrosion sensing structure and the gas permeable layer. If the gas selective layer cannot be applied directly to the corrosion sensing structure, the groove layer can be used. The groove layer can be made of a material with very high permeability but low selectivity, such as poly [(1-trimethylsilyl) -1-propyne] (PTMSP) and polydimethylsiloxane (PDMS), for example.

[0026] Preferably, the corrosion sensing structure of the atmospheric corrosion sensor is made of a corrodible metal or metal alloy, in particular copper, aluminum, iron, zinc, nickel, silver, steel, brass.

[0027] Preferably, the corrosion sensing structure of the atmosphere corrosion sensor is made of a metal or metal alloy film.

[0028] The present invention also aims at a group of the atmosphere corrosion sensors and electrical equipment for corrosion detection, wherein the electrical equipment comprises at least one atmosphere corrosion sensor or at least one group of atmosphere corrosion sensors among the atmosphere corrosion sensors.

[0029] Advantages of the present invention

[0030] Atmospheric corrosion sensors according to the present invention provide more comprehensive information about atmospheric corrosion in the operating environment of equipment. They allow more accurate estimation of its life and more effective planning of maintenance actions.

[0031] Predictive maintenance is enabled by monitoring the severity of the corrosive environment in which the corrosion sensor operates; this information can also be used to estimate the corrosion rate of assets operating in the same environment as the corrosion sensor, allowing prediction of when the end of their operating life due to corrosion processes will be reached, maintenance actions can be planned in advance, and the cost of unplanned service actions due to unexpected failures can be reduced.

[0032] This information can also be used to select corrosion protection measures and to more adequately design warranty provisions.

[0033] In addition, since multiple corrosion sensing structures of the same thickness and / or spatial dimensions are used and gas permeable layers of different thicknesses and / or different gas selective layers are utilized to control the corrosion rate, a single corrosive gas or a predetermined group of corrosive gases can be transferred to the atmosphere corrosion sensing structure, thereby allowing a low-cost corrosion sensor to be provided. BRIEF DESCRIPTION OF THE DRAWINGS

[0034] The object of the present invention is illustrated in the embodiments of the accompanying drawings, in which:

[0035] Figure 1 An atmospheric corrosion sensor according to a first embodiment of the present invention is schematically presented;

[0036] Figure 2 An atmospheric corrosion sensor according to a first embodiment of the invention is presented, which is incorporated in a circuit allowing verification of the electrical continuity of a corrosion sensing structure;

[0037] Figure 3 An atmospheric corrosion sensor according to a second embodiment of the present invention is schematically presented, the atmospheric corrosion sensor comprising a gas selective layer that transmits only molecules of a single corrosive gas to the corrosion sensor structure;

[0038] Figure 4 An atmospheric corrosion sensor according to a third embodiment of the present invention is schematically presented, the atmospheric corrosion sensor comprising a combination of two layers - a first layer transmitting only gas molecules A and gas molecules B, and a second layer transmitting only gas molecules A and gas molecules D;

[0039] Figure 5 An atmospheric corrosion sensor according to a fourth embodiment of the present invention is schematically presented, the atmospheric corrosion sensor comprising a series of corrosion sensing structures having the same spatial dimensions covered by different gas selective layers, each corrosion sensing structure being designed to transmit molecules of a single corrosive gas;

[0040] Figure 6An atmospheric corrosion sensor according to a fifth embodiment of the present invention is schematically presented, the atmospheric corrosion sensor comprising a corrosion sensing structure and a reference structure implemented on a universal printed circuit board;

[0041] Figure 7 An atmospheric corrosion sensor according to a sixth embodiment of the present invention is schematically presented, the atmospheric corrosion sensor comprising a series of corrosion sensing structures having the same spatial dimensions covered by gas permeable layers of different thicknesses;

[0042] Figure 8 The effect of atmospheric corrosion on the electrical resistance of a corrosion sensing structure covered with a gas permeable layer of varying thickness presented at discrete points in time is presented;

[0043] Fig. 9 An oscillator feedback network including an atmospheric corrosion sensor according to the present invention is presented;

[0044] Fig.10 An example of an RC oscillator based on a Schmitt inverter comprising an atmospheric corrosion sensor according to the present invention is presented;

[0045] Fig.11 Presents an example output frequency change due to corrosion of a corrosion sensing structure of an atmospheric corrosion sensor according to the present invention, the atmospheric corrosion sensor being incorporated into a Schmitt inverter-based RC oscillator;

[0046] Fig.12 An example of a Colpitts oscillator based on a logic inverter including an atmospheric corrosion sensor according to the present invention is presented;

[0047] Fig.13 Presents example output frequency changes due to corrosion of a corrosion sensing structure of an atmospheric corrosion sensor according to the present invention, the atmospheric corrosion sensor being incorporated in a logic inverter-based Colpitts oscillator;

[0048] Fig.14 An example of an LM555-based oscillator whose output frequency is a function of the resistance of the corrosion sensing structure of the atmospheric corrosion sensor according to the present invention connected in parallel with R1 is presented;

[0049] Fig.15 An example of an LM555-based oscillator whose output frequency is a function of the resistance of the corrosion sensing structure of the atmospheric corrosion sensor according to the present invention in parallel with R2 is presented;

[0050] Fig.16 An example of a circuit of a current source controlled by the resistance of a corrosion sensing structure of an atmospheric corrosion sensor according to the present invention is presented;

[0051] Fig.17 Another example of a circuit of a current source controlled by the resistance of the corrosion sensing structure of the atmospheric corrosion sensor according to the present invention is presented;

[0052] Fig.18 A schematic diagram of a measuring system having a distributed atmosphere corrosion sensor and a universal measuring unit according to the present invention is presented;

[0053] Fig.19 A schematic diagram of a measuring system having a distributed atmospheric corrosion sensor according to the invention and a universal measuring unit capable of demodulating signals from different sources is presented;

[0054] Fig. 20 An example of a circuit of a current sink whose output current is a function of the resistance of the corrosion sensing structure of the atmospheric corrosion sensor according to the present invention is presented;

[0055] Fig.21 An example of a circuit of a current source whose output current is a function of the resistance of the corrosion sensing structure of the atmospheric corrosion sensor according to the present invention is presented;

[0056] Fig. 22 An example of a narrow bandpass filter whose center frequency is controlled by an atmospheric corrosion sensor according to the present invention is presented;

[0057] Fig.23 A measuring circuit based on a filter of a corrosion sensor according to the invention is presented;

[0058] Fig.24 An example of a narrow bandpass filter with very high quality factor and center frequency controlled by a corrosive atmosphere corrosion sensor according to the present invention is presented;

[0059] Fig.25 A schematic diagram of a measuring system having a distributed narrow bandpass filter and a universal measuring unit controlled by an atmospheric corrosion sensor according to the present invention is presented;

[0060] Fig.26 A narrow bandpass filter is presented whose center frequency is a function of the resistance of the corrosion sensing structure of the atmospheric corrosion sensor according to the present invention;

[0061] Fig. 27 A narrow bandpass filter is presented, which has a very high quality factor and center frequency as a function of the resistance of the corrosion sensing structure of the atmospheric corrosion sensor according to the present invention; DETAILED DESCRIPTION

[0062] Example 1

[0063] Figure 1An atmospheric corrosion sensor 1 for detecting corrosion of electrical equipment caused by corrosive gases is presented, which comprises an atmospheric corrosion sensing structure 2 placed on an insulating corrosion sensor substrate 3. The atmospheric corrosion sensor 1 comprises a non-corrodible gas permeable layer 4 placed on the corrosion sensing structure 2, wherein the gas permeable layer 4 allows molecules of corrosive gases present in the atmosphere to be transferred to the surface of the sensing structure 2 opposite to the insulating corrosion sensor substrate 3, thereby corroding it.

[0064] The corrosion sensing structure 2 is in the form of a metal film made of a corrodible metal or metal alloy, in particular copper, aluminum, iron, zinc, nickel, silver, steel and brass. However, other structures of the corrosion sensing structure 2 are possible, such as a metal plate.

[0065] The gas permeable layer 4 may be, for example, an inorganic, polymeric, mixed matrix or transport-facilitating layer.

[0066] The atmospheric corrosion sensor 1 also includes a groove layer 5 located between the corrosion sensing structure 2 and the gas permeable layer 4. The groove layer 5 can be made of a material with extremely high permeability but low selectivity, such as poly [(1-trimethylsilyl) -1-propyne] (PTMSP) and polydimethylsiloxane (PDMS), for example. However, the groove layer is completely optional and is not necessary for the operation of the sensor 1.

[0067] Molecules of the corrosive gas present in the atmosphere pass through the non-corrodible gas permeable layer 4 and reach the surface of the corrosion sensing structure 2. The corrosive gas reacts with the surface of the corrosion sensing structure 2, causing corrosion to progress in depth, so that the material is consumed and the resistance of the film increases until the continuity is destroyed.

[0068] The corrosion process of the uncovered corrosion sensing structure 2 is faster than the transport of the corrosive molecules through the gas permeable layer 4. Therefore, the corrosion rate of the corrosion sensing structure 2 depends on the thickness of the gas permeable layer 4. The thicker the gas permeable layer 4, the slower the transport of the corrosive molecules, and thus the lower the concentration of molecules at the surface of the corrosion sensing structure 2. Therefore, an atmospheric corrosion sensor having different corrosion rates without using metal films of different thicknesses can be provided, thereby reducing manufacturing costs.

[0069] The electrical continuity of the corrosion sensing structure 2 can be determined by measuring the resistance (eg Figure 2 a) or by using a simple voltage divider circuit that can be connected to the input of a logic device ( Figure 2 b). A full resistance measurement is more expensive, but it can provide more information about the corrosion process because it allows continuous measurement of the electrical properties of the sensing membrane. On the other hand, a simple voltage divider circuit only provides binary information about the state of the sensing membrane (V out =VHIGH , where V HIGH indicates a logic high state (uncorroded film), and V out =V LOW , where V LOW Represents a membrane with low destruction of the logic state), but this is a very low-cost solution.

[0070] Example 2

[0071] Figure 3 An atmospheric corrosion sensor 1 for detecting corrosion of electrical equipment caused by corrosive gases is presented, which comprises an atmospheric corrosion sensing structure 2 placed on an insulating corrosion sensor substrate 3. The atmospheric corrosion sensor 1 comprises a gas permeable layer 4 placed on the corrosion sensing structure 2. The gas permeable layer 4 is a gas selective layer that allows a single corrosive gas or a predetermined group of corrosive gases to transfer to the surface of the atmospheric corrosion sensing structure 2 opposite to the insulating corrosion sensor substrate 3, thereby corroding it.

[0072] The corrosion sensing structure 2 is in the form of a metal film made of a corrodible metal or metal alloy, in particular copper, aluminum, iron, zinc, nickel, silver, steel and brass. However, other structures of the corrosion sensing structure 2 are possible, such as a metal plate.

[0073] The gas selective layer 4 may be, for example, an inorganic, polymer, mixed matrix or transport-facilitating layer. Examples of gas permeable layers permeable to corrosive SO2 are polymer layers such as 3533, 6FDA-HAB-DAM, cellulose triacetate (CTA) or polyacrylate. x gas, exemplary gas permeation layers are PSf, 5218, 6FDA-TMPDA, zeolite SSZ-13, PDMS, Fe0.8O3δ, ZSM-5 zeolite composite PTFE membrane layer.

[0074] The atmospheric corrosion sensor 1 also includes a groove layer 5 located between the corrosion sensing structure 2 and the gas permeable layer 4. The groove layer 5 can be made of a material with extremely high permeability but low selectivity, such as poly [(1-trimethylsilyl) -1-propyne] (PTMSP) and polydimethylsiloxane (PDMS), for example. However, the groove layer is completely optional and is not necessary for the operation of the sensor 1.

[0075] The gas selective layer transmits molecules of a single corrosive gas or a predetermined group of corrosive gases from the atmosphere to the surface corrosion sensing structure 2, and reduces the transmission of molecules of other gases. Thus, an atmospheric corrosion sensor that measures the corrosion rate of a specific gas or group of corrosive gases is provided. It can not only measure the corrosion rate of different corrosive gas concentrations, but also quantify the corrosiveness and composition of the atmosphere.

[0076] The electrical continuity of the corrosion sensing structure 2 can be verified by the same circuit as described in Example 1. Due to the reaction with a specific gas, the output signal (e.g., voltage or current) from the corrosion sensor changes with the corrosion process of the corrosion sensing structure 2, and the corrosion rate can be estimated.

[0077] Example 3

[0078] Figure 4 A third embodiment of an atmospheric corrosion sensor corresponding to the second embodiment is illustrated, however, it differs in that the atmospheric corrosion sensor 1 comprises two gas selective layers 4 located on top of each other. The gas selective layer 4a is permeable to gas molecules A and gas molecules B, and the gas selective layer 4b is permeable to gas molecules A and gas molecules D. Therefore, only gas molecules A can approach the corrosion sensing structure.

[0079] The two gas selective layers 4 can, for example, have the form of a double-layer membrane layer, such as, for example, a COF-LZU1-ACOF-1 membrane layer (Covalent Organic Framework - Covalent Organic Framework Double-Layer Membrane Layer for Highly Selective Gas Separation - Hongwei Fan, Alexander Mundstock, Armin Feldhoff, Alexander Knebel, Jiahui Gu, Hong Meng, and Jürgen Caro; Journal of the American Chemical Society 2018 140(32), 10094-10098lDOI: 10.1021 / jacs.8b0513).

[0080] Such combination of gas selective layers 4 allows a single corrosive gas or a predetermined group of corrosive gases to be transferred to the atmospheric corrosion sensing structure 2 if a particular gas selective layer is not available or is much more expensive than the group of layers.

[0081] Example 4

[0082] Figure 5A fourth embodiment of the atmospheric corrosion sensor corresponding to the second embodiment is shown, however, the difference is that the atmospheric corrosion sensor 1 includes a plurality of atmospheric corrosion sensing structures 2 having the same spatial dimensions. The atmospheric corrosion sensing structures 2 are covered by different gas selective layers 4, wherein the gas selective layers 4 allow different corrosive gases to be transferred to the atmospheric corrosion sensing structures 2. The gas selective layer 4a is permeable to gas molecules A (e.g., SO2), and the gas selective layer 4b is permeable to gas molecules B (e.g., NO x ), the gas selective layer 4c is permeable to gas molecules C (eg, H2S), and the gas selective layer 4d is permeable to gas molecules D (eg, gaseous Cl2).

[0083] In other embodiments of the present invention, the corrosion sensing structure 2 may be covered by different gas selective layers 4, thereby allowing different predetermined groups of corrosive gases to be transferred to the atmosphere corrosion sensing structure 2. In yet another embodiment of the present invention, the corrosion sensing structure 2 may also be covered by different combinations of gas selective layers 4, thereby allowing different corrosive gases or different predetermined groups of corrosive gases to be transferred to the atmosphere corrosion sensing structure 2.

[0084] Multiple such sensing structures covered by different gas selective permeation layers designed to transmit only molecules of specific corrosive gases and reduce the transmission of other molecules allow measuring corrosion rates relative to different corrosive gas concentrations and quantifying the corrosiveness and composition of the atmosphere.

[0085] Example 5

[0086] Figure 6 A fifth embodiment of an atmospheric corrosion sensor is illustrated, which corresponds to any of the previously discussed embodiments, and further includes a reference structure 6, wherein the corrosion sensing structure 2 and the reference structure 6 are made of a copper film placed on a common substrate (e.g., a printed circuit board). The reference structure 6 has the same spatial dimensions as the atmospheric corrosion sensing structure 2. In addition, the reference structure is covered with an impermeable protective layer 7 (e.g., a solder mask) that protects it from corrosion. The reference structure 6 covered with the impermeable protective layer 7 can be used together with the atmospheric corrosion sensing structure 2 to compensate for the effects of temperature and other environmental factors on the measurement.

[0087] Example 6

[0088] Figure 7 The sixth embodiment of the atmosphere corrosion sensor corresponding to the embodiment 1 is shown. The atmosphere corrosion sensor according to this embodiment includes a plurality of atmosphere corrosion sensing structures 2 having the same spatial dimensions. Figure 7As shown, each corrosion sensing structure 2 is covered by a gas permeable layer 4 of different thickness. The corrosion rate depends on the concentration of the molecules of the corrosive gas reaching the corrosion sensing structure 2. The corrosion sensing structure 2 covered by the thinnest layer will be destroyed like the first layer. On the other hand, the film covered by the thickest layer will break like the last layer. Therefore, the corrosion rate can be estimated based on the measurement of the time required to break the electrical continuity of the subsequent corrosion sensing structure 2.

[0089] Figure 8 The effect of atmospheric corrosion on three identical sensing membranes covered with a non-corrodible, gas-permeable layer of varying thickness is shown at discrete points in time.

[0090] Initially, all corrosion sensing structures 2 have the same resistance (R1=R2=R3). Once corrosive molecules begin to migrate from the atmosphere through the gas permeable layer to the surface of the corrosion sensing structure 2, corrosion occurs and the resistance of each corrosion sensing structure 2 begins to increase. The thicker the gas permeable layer, the lower the corrosion rate, and therefore the lower the resistance increase. If the corrosion continues for a long enough time, depending on the thickness of the gas permeable layer, the electrical continuity of each corrosion sensing structure 2 will be destroyed at some point in time. In other words, the corrosion sensing structure 2 will appear as an open circuit, which is easy to detect through the digital input of the logic device. Given the thickness of the gas permeable layer, the chemical composition of the corrosion sensing structure 2, and the time required to destroy the corrosion sensing structure 2, it is possible to estimate the corrosiveness of the atmosphere. Multiple such corrosion sensing structures 2 can be used to monitor atmospheric corrosion processes.

[0091] Example 7

[0092] An oscillator circuit for corrosion detection includes a plurality of atmospheric corrosion sensors 1 having corrosion sensing structures, or an atmospheric corrosion sensor 1 including a plurality of corrosion sensing structures 2 as described in any one of embodiments 1 to 6. The corrosion sensing structures 2 are connected to a plurality of reactive components (R-resistors, C-capacitors, L-inductors) of the oscillator circuit and form part of an oscillator feedback network ( Fig. 9 ).

[0093] The corrosion sensing structure 2 of the atmospheric corrosion sensor 1 is covered by a permeable layer and exposed to the corrosive atmosphere, and the reactive components are disconnected from the oscillator circuit. Once their electrical continuity is broken due to corrosion, the output frequency f of the oscillator o will change because the topology of its feedback network will also change.

[0094] Initially, all corrosion sensing structures 2 provide electrical continuity, so they can be represented by short circuits. Due to the corrosion process, the structures degrade until their continuity is destroyed. In this case, they can be represented by open circuits. The corrosion sensing structures have the same spatial dimensions, but are covered with different permeable layers, so the time required to destroy each structure due to corrosion is different.

[0095] Two embodiments of an oscillator including an atmospheric corrosion sensor 1 are proposed, wherein the corrosion sensing structure 2 is composed of Figures 9 to 13 The fuse symbol F in the diagram represents.

[0096] The first is the well-known RC oscillator based on a single Schmitt trigger inverter gate, such as Fig.10 It uses a single resistor R and multiple capacitors in the feedback network. Capacitor C0 is permanently connected to the inverter input, while the corrosion sensing structures F1, F2, F3, ..., F n When the electrical continuity of capacitors C1, C2, C3, ..., C n will be disconnected.

[0097] The output frequency of the oscillator is f o This can be calculated using the following formulas [1], [2]:

[0098]

[0099] C=C0+δ1C1+δ2C2+δ3C3+…+δ n Cn n [2]

[0100]

[0101] Where: V cc is the supply voltage of the Schmitt inverter, V T- and V T+ are the negative and positive input threshold voltages

[0102] Since the output frequency f o Inversely proportional to the feedback capacitance, once the fuse starts to cut off the capacitor, the output frequency f o Will increase gradually. Fig.11 An example output frequency variation over time due to corrosion of the sensing structure is depicted in FIG. n have the same value. The output frequency is an indicator of ongoing corrosion and can be measured by a frequency counter, easily implemented in most programmable logic devices and microcontrollers in use today.

[0103] The second embodiment is an example of a well-known Colpitts oscillator based on logic inverter gates, such as Fig.12 The feedback network consists of two capacitors, C1 and C2, connected to the input and output of the gate, respectively. The path between the input and output of the gate circuit is closed by a number of series-connected inductors. Inductor L0 is permanently connected, while inductors L1, L2, L3, ..., L n Fuse F1, F2, F3, ..., F n Short circuit. Once the fuse F i Fuse, L i The inductance will be added to the total feedback inductance of the oscillator.

[0104] The output frequency of the oscillator is f o This can be calculated using the following formulas [3], [4]:

[0105]

[0106] L=L0+δ1L1+δ2L2+δ3L3+…+δ n L n [4]

[0107]

[0108] Since the output frequency is inversely proportional to the square root of the feedback inductance, once the fuse Fn starts to blow, the inductance starts to increase and the output frequency will gradually decrease. Fig.13 An example output frequency variation over time due to corrosion of the sensing structure is depicted in FIG. n As in the previous embodiment, the output frequency fo, as an indicator of ongoing corrosion, can be measured by a frequency counter, which is easily implemented in most programmable logic devices and microcontrollers used today.

[0109] Example 8

[0110] An oscillator circuit for corrosion detection, an integrated circuit with an LM555 timer, includes a plurality of atmosphere corrosion sensors 1 with corrosion sensing structures or an atmosphere corrosion sensor 1 including a plurality of corrosion sensing structures as described in any one of embodiments 1 to 6.

[0111] Two embodiments of an oscillator having an LM555 timer integrated circuit including at least one atmospheric corrosion sensor 1 are proposed, wherein the corrosion sensing structure 2 is composed of Figure 14 to Figure 15 Fuse symbols on the N express.

[0112] according to Fig.14In the first embodiment presented, a plurality of resistors R P1 -R PN Series fuses F1…F N The arrangement (corrosion sensing structure 2) is connected in parallel with the resistor R1.

[0113] The equivalent resistance is given by the following formula [5]:

[0114]

[0115] The output frequency of the oscillator is f o It can be calculated as follows[6]:

[0116]

[0117] It can be seen that the output frequency f is inversely proportional to the equivalent resistance R1' o It will gradually decrease as the corrosion process progresses.

[0118] according to Fig.15 The second embodiment of Example 8 is presented in FIG. 1 , with the resistor R P1 …R PN Fuses F1…F connected in series N The arrangement of (corrosion sensing structure 2) is connected in parallel with resistor R2. The equivalent resistance is given by the following formula [7]:

[0119]

[0120] The output frequency of the oscillator is f o It can be calculated as follows[8]:

[0121]

[0122] It can be seen that the output frequency f is inversely proportional to the equivalent resistance R2' o It will gradually decrease as the corrosion process progresses.

[0123] Example 9

[0124] The circuit of the current source comprises a sensing element R_sens in the form of an atmospheric corrosion sensor 1 , which comprises a plurality of corrosion sensing structures 2 as described in any one of embodiments 1 to 6.

[0125] The corrosion sensing structure 2 of the sensing element R_sens controls the current I_set of the current source. The resistance of the corrosive element R_sens is used to set the value of the current source I_set, so the current at the output of the current source changes with the resistance of the sensing element R_sens. The changing resistance is reflected in the change of the output current of the current source controlled by the corrosion sensing structure 2.

[0126] An additional resistor R_limit may be used in series with the sensing element R_sens, so that the current can be limited to a reasonable value even if the resistance of the sensing element R_sens is very small.

[0127] Two implementations of this type of circuit are proposed.

[0128] Fig.16 The first embodiment presented in discloses a circuit having a fixed power supply Vdd and a fixed value of the control voltage Vin.

[0129] The output current value I_set can be calculated using the following formula [9]:

[0130]

[0131] The voltage output Vout across the load resistor R_load can also be calculated using the following formula

[10] :

[0132]

[0133] Another example of implementation is Fig.17 Given in.

[0134] The output current value I_set can be calculated using the following formula

[11] :

[0135]

[0136] The voltage output Vout across the load resistor R_load can also be calculated using the following formula

[12] :

[0137]

[0138] Furthermore, since the output signal of the current source is not affected by the length of the wire, it is possible to combine many such circuits including a current source of the sensing element R_sens in the form of the atmospheric corrosion sensor 1 with a single measurement unit (e.g., a measurement card accepting a signal range of 4 to 20 mA) capable of measuring the current generated by a single source. In this way, it is possible to establish a measurement system with distributed sensors and a universal measurement unit, such as Fig.18 shown.

[0139] Furthermore, such circuits including current sources of sensing elements R_sens in the form of atmospheric corrosion sensors 1 can be connected together and each Vin signal modulated with a different carrier frequency. In this case, the measurement unit can demodulate and extract corrosion data from the combined signal, so there is no need to use a source selection module such as Fig.19 shown.

[0140] Example 10

[0141] This embodiment relates to a current sink circuit including at least one atmosphere corrosion sensor 1 according to any one of embodiments 1 to 6. The corrosion sensing structure 2 of the atmosphere corrosion sensor 1 is Fig. 20 The resistor R S1 …R SN The emitter resistor RE and the fixed resistor R P1 …R PN The arrangement of corrosion sensing structures 2 connected in series is connected in parallel.

[0142] In this case, the corrosion sensing structure 2 of the atmospheric corrosion sensor 1 is intended to act as an electronic fuse, which exhibits a very low resistance in an initial state and a very high resistance after being corroded.

[0143] The equivalent resistance of the network can be expressed by the following formula

[13] :

[0144]

[0145] The output current IOUT can be calculated using the following formula

[14] :

[0146]

[0147] With the equivalent resistance R E The inversely proportional output current will gradually decrease as the corrosion process progresses.

[0148] Embodiment 11

[0149] This embodiment relates to a current source circuit including at least one atmosphere corrosion sensor 1 according to any one of embodiments 1 to 6. The corrosion sensing structure 2 of the atmosphere corrosion sensor 1 is Fig.21 The resistor R S1 …R SN Indicates. Emitter resistor R E and fixed resistor R P1 …R PN The arrangement of corrosion sensing structures 2 connected in series is connected in parallel.

[0150] In this case, the corrosion sensing structure 2 of the atmospheric corrosion sensor 1 is intended to act as an electronic fuse, which exhibits a very low resistance in an initial state and a very high resistance after being corroded.

[0151] The equivalent resistance of the network can be expressed by the following formula

[15] :

[0152]

[0153] Output current I OUTIt can be calculated by the following formula

[16] :

[0154]

[0155] Where - VDD - power supply voltage, Vref - reference voltage

[0156] With the equivalent resistance R E The inversely proportional output current will gradually decrease as the corrosion process progresses.

[0157] Example 12

[0158] This embodiment relates to a narrow band pass filter including an atmosphere corrosion sensor 1 according to any one of embodiments 1 to 6. The corrosion sensing structure 2 is used to control the center frequency of the narrow band pass filter. The resistance of the corrosion sensing structure 2 is used to set the center frequency of the narrow band pass filter. Therefore, the center frequency of the filter changes due to the change in the resistance of the atmosphere corrosion sensor 1.

[0159] Fig. 22 A multiple feedback narrow bandpass filter is presented. The corrosion sensing structure 2 of the atmosphere corrosion sensor 1 (in Fig. 22 In the figure, Rs is represented as Rs) and is connected in series with R2.

[0160] The center frequency is given by the following formula

[17] :

[0161]

[0162] The sensing element can also be placed in series with R1 or R5, which should then be changed appropriately in the above equation.

[0163] In order to check the center frequency of the narrow bandpass filter controlled by the corrosion sensor 1, signals of various frequencies must be generated and passed through the filter. The control unit, knowing the transmission frequency and amplitude of the signal received by the detector, can calculate the change in the resistance of the sensing element and, on this basis, provide information about the corrosion process. Fig.23 A measurement circuit for a filter based corrosion sensor 1 is presented.

[0164] like Fig. 22 The single-stage filter shown typically has a quality factor below 20, so its passband may be too wide. To obtain a narrower filter characteristic, it can be modified by adding a second op amp, such as Fig.24 As shown, this allows the quality factor (Q) to be increased even to values ​​of several hundred, thereby achieving narrower bandwidths.

[0165] Furthermore, it is possible to combine many filter-based sensors with a single measurement unit that is able to measure the frequency response of a single filter. In this way, it is possible to build a measurement system with distributed sensors and a universal measurement unit, such as Fig.25 shown.

[0166] Embodiment 13

[0167] This embodiment relates to a narrow band pass filter, which includes at least one atmosphere corrosion sensor 1 according to any one of embodiments 1 to 6. The corrosion sensing structure 2 of the atmosphere corrosion sensor 1 is Fig.26 The resistor R S1 …R SN The narrow bandpass filter circuit includes a resistor R2 connected in parallel with the arrangement of the corrosion sensing structure 2, and the corrosion sensing structure 2 is connected to the fixed resistor R P1 …R PN Series connection.

[0168] In this case, the corrosion sensing structure is designed to act as an electronic fuse, exhibiting a very low resistance in its initial state and a very high resistance after being corroded.

[0169] The equivalent resistance of the network can be expressed by the following formula

[18] :

[0170]

[0171] The center frequency fo of the filter is given by the following equation

[19] :

[0172]

[0173] The center frequency fo, which depends on R2', will gradually decrease as the corrosion process progresses.

[0174] Similar corrosion sensing structure networks can also be incorporated into high quality factor narrow bandpass filter circuits to obtain narrower frequency responses, such as Fig. 27 The center frequency of the filter depends on the equivalent resistance of the corrosion sensing structure network and will gradually change as the corrosion progresses.

Claims

1. An atmosphere corrosion sensor (1) for detecting corrosion of electrical equipment caused by corrosive gases, the atmosphere corrosion sensor comprising at least one atmosphere corrosion sensing structure (2) placed on at least one insulating corrosion sensor substrate (3), characterized in that: The atmospheric corrosion sensor (1) comprises at least one gas permeable layer (4) placed on the corrosion sensing structure (2), wherein the gas permeable layer (4) allows the molecules of the corrosive gas present in the atmosphere to be transferred to the surface of the sensing structure (2) opposite to the insulating corrosion sensor substrate (3), thereby corroding it.

2. The atmosphere corrosion sensor (1) according to claim 1, characterized in that: The gas permeable layer (4) is a gas selective layer that allows a single corrosive gas or a predetermined group of corrosive gases to transfer to the atmospheric corrosion sensing structure (2).

3. The atmosphere corrosion sensor (1) according to claim 2, characterized in that: The atmospheric corrosion sensor (1) comprises at least two gas selective layers (4) located on top of each other, wherein the combination of these gas selective layers (4) allows a single corrosive gas or a predetermined group of corrosive gases to be transferred to the atmospheric corrosion sensing structure (2).

4. The atmosphere corrosion sensor (1) according to claim 2 or 3, characterized in that: The atmosphere corrosion sensor (1) comprises at least two atmosphere corrosion sensing structures (2), preferably having the same spatial dimensions, wherein these atmosphere corrosion sensing structures (2) are covered by different gas selective layers (4) or different combinations of gas selective layers (4), wherein the gas selective layers (4) or the combination of gas selective layers (4) allow different corrosive gases or different predetermined groups of corrosive gases to be transferred to the atmosphere corrosion sensing structures (2).

5. The atmosphere corrosion sensor (1) according to any one of claims 1 to 3, characterized in that: The atmospheric corrosion sensor (1) comprises at least two atmospheric corrosion sensing structures (2) having the same spatial dimensions, wherein the sensing structures (2) are covered by the same type of gas permeable layers (4) having different thicknesses.

6. The atmospheric corrosion sensor (1) according to any one of the preceding claims, characterized in that The atmospheric corrosion sensor (1) comprises at least one reference structure (6) covered with an impermeable protective layer (7), wherein the reference structure (6) is made of the same material as the atmospheric corrosion sensing structure (2) and has the same spatial dimensions.

7. The atmospheric corrosion sensor (1) according to any one of the preceding claims, characterized in that The atmospheric corrosion sensor comprises a groove layer (5) located between the corrosion sensing structure (2) and the gas permeable layer (4).

8. The atmosphere corrosion sensor according to any one of the preceding claims, characterized in that The corrosion sensing structure (2) is made of a corrodible metal or metal alloy, in particular copper, aluminum, iron, zinc, nickel, silver, steel, brass.

9. The atmosphere corrosion sensor according to any one of the preceding claims, characterized in that The corrosion sensing structure (2) is made of a metal or metal alloy film.

10. A set of atmospheric corrosion sensors (1) according to any one of claims 1 to 9.

11. An electrical device for corrosion detection, comprising at least one atmosphere corrosion sensor (1) according to any one of claims 1 to 9 or at least one group of atmosphere corrosion sensors (1) according to claim 10.

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