Atmospheric environmental corrosion monitoring system

Abstract

The application provides an atmospheric environment corrosion monitoring system, comprising a double electrode sensor, a current-voltage IV conversion circuit, a secondary amplification circuit, an analog-digital conversion circuit, a range switching circuit and a processor, the input end of the IV conversion circuit is connected with the double electrode sensor, the output end is connected with the first input end of the analog-digital conversion circuit through the secondary amplification circuit and is connected with the second input end of the analog-digital conversion circuit; the output end and the enable control end of the analog-digital conversion circuit are respectively connected with the corresponding ports of the processor; the output end of the range switching circuit is connected with the connection end of the IV conversion circuit, and the enable control end of the range switching circuit is connected with the corresponding port of the processor. The application has a wide measurement range, high precision and a simple measurement method.

Description

Technical Field

[0001] This invention belongs to the field of natural environment testing and monitoring technology, and specifically relates to an atmospheric environment corrosion monitoring system. Background Technology

[0002] Atmospheric corrosion refers to the corrosion phenomenon that occurs in materials and their products in the atmospheric environment, and it is the most common form of atmospheric corrosion. Currently, research on the atmospheric corrosion behavior and patterns of materials mainly relies on analyzing the mass changes and morphology of samples from outdoor exposure and accelerated indoor testing. While these methods can directly reflect atmospheric corrosion behavior, they involve long testing cycles, limited data, and are prone to significant experimental errors. Furthermore, they cannot obtain information on the process of corrosion changes over time, posing challenges to atmospheric corrosion research and failing to meet the current application requirements for real-time monitoring. To achieve continuous automated detection and reduce human error, it is necessary to develop new testing technologies for studying the corrosion behavior of materials in the atmospheric environment.

[0003] Metal materials and their products in the atmosphere undergo evaporation, condensation, and adsorption processes due to changes in environmental factors such as temperature, humidity, and rainfall, forming a thin liquid film on the metal surface. Electrochemical corrosion occurs under this thin liquid film. At the corrosion potential, although the net current on the electrode is zero, the corrosion reaction still proceeds at a certain rate. At this point, the anodic current and the cathodic current are opposite in direction and equal in magnitude; this current is called the corrosion current (A). Therefore, the corrosivity of a metal can be detected by measuring the corrosion current. This method is more sensitive and convenient, highly operable, and low-cost.

[0004] Because the corrosion rate of samples varies depending on the type and atmospheric environment, the corrosion current typically ranges from 100 pA to 10 mA, spanning eight orders of magnitude. Therefore, achieving a wide range of corrosion current measurements is a crucial technical challenge when measuring atmospheric corrosion phenomena based on corrosion current. Currently, while atmospheric corrosion monitoring systems based on corrosion current can expand the measurement range to some extent, their measurement accuracy remains low and the methods are relatively complex. For example, invention patent application number 201710819468.7 provides an atmospheric corrosion monitoring system and its monitoring method. Figure 3As shown, the system uses three sampling resistors to convert the corrosion current into an analog voltage. These three sampling resistors are connected in series, with two of them connected in parallel to a transistor. By adjusting the conduction state of the transistors, the corresponding sampling resistor in the series chain is connected to a signal operational amplifier conditioning circuit. In addition, the patent mentions a method for measuring corrosion current based on the three sampling resistors. This method compares the corrosion current measured with different sampling resistors with different preset current values. There are multiple preset current values, and the design logic of the entire measurement method is quite complex. Summary of the Invention

[0005] This invention provides an atmospheric corrosion monitoring system to solve the problems of narrow measurement range, low measurement accuracy, and complex measurement methods in current atmospheric corrosion monitoring systems.

[0006] According to a first aspect of the present invention, an atmospheric corrosion monitoring system is provided, comprising a dual-electrode sensor, a current-to-voltage (IV) conversion circuit, a two-stage amplifier circuit, an analog-to-digital converter circuit, a range switching circuit, and a processor. The input terminal of the IV conversion circuit is connected to the dual-electrode sensor, and the output terminal is connected to the first input terminal of the analog-to-digital converter circuit via the two-stage amplifier circuit, and also connected to the second input terminal of the analog-to-digital converter circuit. The output terminal and the enable control terminal of the analog-to-digital converter circuit are respectively connected to corresponding ports of the processor. The output terminal of the range switching circuit is connected to the connection terminal of the IV conversion circuit, and the enable control terminal of the range switching circuit is connected to the corresponding port of the processor.

[0007] The dual-electrode sensor detects the corrosion current on the surface of the test sample in the atmospheric environment;

[0008] The IV conversion circuit converts the corrosion current into an analog voltage U1 and amplifies it in one stage. The amplified U1 is then converted into a digital signal K1 by the analog conversion circuit and transmitted to the processor.

[0009] The processor determines, based on the digital signal K1, whether it is necessary to adjust the amplification resistor provided by the range switching circuit to the IV conversion circuit, so as to adjust the range segment corresponding to the amplification resistor to the range segment where the corrosion current is located. The voltage values ​​obtained by multiplying each amplification resistor by the current value in its corresponding range segment are all within the same voltage value range. When U1 is not within the voltage value range, the amplification resistor needs to be adjusted.

[0010] When U1 is within the voltage range, there is no need to adjust the amplification resistor. At this time, the processor enables the first input terminal of the analog-to-digital converter circuit, so that U1 after the first stage of amplification is amplified by the second stage of the amplification circuit to form an analog voltage U2, which is then transmitted to the analog-to-digital converter circuit. The analog-to-digital converter circuit converts U2 into a digital signal K2.

[0011] The processor deduces the corrosion current based on the digital signal K2.

[0012] In one alternative implementation, the analog voltage U1 = -IR n Where I represents corrosion current, R n This represents the amplification resistor; the analog voltage is U2 = U1A, where A is the second amplification factor of the second-stage amplifier circuit;

[0013] The processor deduces the corrosion current I based on the digital signal K2 using the following formula: Where m is the number of bits in the analog-to-digital converter circuit.

[0014] In another alternative implementation, the total corrosion current range is subdivided into multiple range segments that are continuous;

[0015] When increasing the total range of corrosion current without changing the number of bits m and the secondary amplification factor A of the analog-to-digital converter circuit, a new range segment that is continuous with the original maximum or minimum range segment is added on the basis of the original range segment, and an amplification resistor corresponding to the new range segment is added at the same time.

[0016] To improve the measurement accuracy of each range segment without changing the total range of the corrosion current, at least one of the following three methods can be used: increasing the number of range segments subdivided from the total range; increasing the number of bits m in the analog-to-digital conversion circuit; and increasing the secondary amplification factor A.

[0017] In another optional implementation, when U1 is not within the voltage range, the processor controls the amplifying resistor in the range switching circuit that has a larger or smaller resistance value than the current amplifying resistor to be connected to the IV conversion circuit in order of resistance value from small to large or from large to small.

[0018] In another optional implementation, a temperature and humidity sensor and a clock module connected to the processor are also included. After the processor deduces the corrosion current each time, it reads the temperature and humidity information output by the temperature and humidity sensor and the time information output by the clock module, and stores the corrosion current, temperature and humidity information and time information in the memory.

[0019] In another alternative implementation, the processor initiates a low-power mode after each data storage operation until the next operation; the processor employs an adaptive filtering algorithm to process the corrosion current to suppress the effects of circuit noise and offset voltage.

[0020] In another alternative implementation, a communication circuit connected to the processor is also included, through which the processor communicates with the host computer.

[0021] In another optional implementation, the IV conversion circuit includes a first operational amplifier. The inverting input of the first operational amplifier is connected to the output of the dual-electrode sensor through resistor R53 and grounded through resistor R56. The connection point between the output of the dual-electrode sensor and resistor R53 is grounded through capacitor C59. The non-inverting input of the first operational amplifier is grounded through resistor R58. The positive power supply of the first operational amplifier is connected to a corresponding positive power supply and grounded through positive polarity capacitors C49 and C51, respectively. The negative power supply is connected to a corresponding negative power supply and grounded through negative polarity capacitors C63 and C65, respectively. Two protection terminals are grounded. The inverting input and output of the first operational amplifier serve as two ports in the IV conversion circuit connected to the range switching circuit: a first connection terminal IN Rxl+ and a second connection terminal INRxl-. The output of the first operational amplifier serves as the output of the IV conversion circuit through node IN2 after resistor R54, and is connected to the input of the secondary amplifier circuit and the second input of the analog-to-digital converter circuit, respectively.

[0022] In another optional implementation, the second-stage amplifier circuit includes a second operational amplifier. The inverting input of the second operational amplifier is connected to the output of the IV conversion circuit and grounded through capacitor C60 and resistor R57, respectively. The non-inverting input of the second operational amplifier is grounded through resistor R59. The positive power supply of the second operational amplifier is connected to a corresponding positive power supply and grounded through positive polarity capacitors C50 and C52, respectively. The negative power supply is connected to a corresponding negative power supply and grounded through negative polarity capacitors C64 and C66, respectively. The inverting input of the second operational amplifier is connected to its output through resistor R44. The output of the second operational amplifier is connected to the first input of the analog-to-digital converter circuit via node IN3 after resistor R55.

[0023] In another optional implementation, the range switching circuit includes a multiplexing chip. The eight source terminals S1 to S8 of the multiplexing chip are connected to the first connection terminal IN Rxl+ of the IV conversion circuit through amplification resistors of different sizes. The eight source terminals S1 to S8 are also connected to the first connection terminal IN Rxl+ of the IV conversion circuit through their respective capacitors. The drain terminal D of the multiplexing chip is connected to the second connection terminal INRxl- of the IV conversion circuit. The enable control terminals A1 and A2 are connected to the corresponding control ports of the processor.

[0024] The beneficial effects of this invention are:

[0025] 1. In atmospheric corrosion monitoring, this invention subdivides the total range of the corrosion current into multiple continuous range segments. A corresponding amplification resistor is set for each range segment, ensuring that the voltage values ​​obtained by multiplying the corrosion current within each amplification resistor's corresponding range segment are within the same voltage range. When the processor detects that the first voltage is outside this range (i.e., the voltage value obtained by multiplying the corrosion current by the amplification resistor currently connected to the IV conversion circuit is outside this range), it indicates that the range segment corresponding to the current amplification resistor does not include the corrosion current. Therefore, the current amplification resistor and its corresponding range segment need to be adjusted. When the range segment corresponding to the amplification resistor is adjusted to match the range segment containing the corrosion current, the corrosion current can be detected. Furthermore, the IV conversion circuit in this invention not only converts the corrosion current into voltage but also performs amplification during the voltage conversion process, ensuring that the voltage values ​​obtained by multiplying the current value within each amplification resistor's corresponding range segment are all within the same voltage range.

[0026] When the number of bits m in the analog-to-digital converter circuit is fixed, the number of data N that the system of this invention can collect is fixed, where N is an integer greater than 1. In this invention, the total range of corrosion current is subdivided into multiple continuous range segments. For each range segment, when switching to that range segment, that range segment becomes the system's range. The system of this invention can collect N data points within that range segment. Thus, for the total range of corrosion current, the number of data points that can be collected is N * the number of range segments. It is evident that this invention can significantly improve the measurement accuracy of the total range of corrosion current. This invention can further improve the measurement accuracy of corrosion current by setting up a two-stage amplification circuit. When increasing the total range of corrosion current, this invention only needs to add a new range segment that is continuous with the original range segment, and simultaneously add a resistor corresponding to the newly added range segment. The method of expanding the total range is simple, and it can achieve an expansion of the total range of arbitrary width. Therefore, it is evident that this invention has a wide measurement range, high measurement accuracy, and both are adjustable.

[0027] In this invention, when adjusting the amplification resistor, the analog voltage U1 formed after the IV conversion circuit is transmitted to the analog-to-digital conversion circuit. After being converted into a digital signal K1 by the analog-to-digital conversion circuit, the processor compares U1 with a voltage range to determine whether the amplification resistor connected to the IV conversion circuit needs adjustment. During the gradual adjustment process, the first voltage obtained by the processor only needs to be compared with the same voltage range. Adjustment of the amplification voltage is not required only when U1 falls within the voltage range. The entire measurement method is very simple, and even with an increasing number of measurement ranges, the required comparison parameters do not increase, nor does the complexity of the measurement method increase. Because this invention has a large corrosion current measurement range, high measurement accuracy, and a simple measurement method, it can achieve continuous automatic monitoring of atmospheric corrosion, obtaining corrosion data over the entire cycle. It is particularly suitable for electrochemical research under thin liquid films.

[0028] 2. In addition to monitoring corrosion current, this invention can also collect temperature, humidity and time information corresponding to the corrosion current.

[0029] 3. Through the communication circuit, this invention can also send the collected corrosion current, temperature and humidity information, and time information to the host computer;

[0030] 4. When the system does not need to collect corrosion current, the hardware of the collection section is powered off and enters a low-power mode. The processor starts the low-power silent mode through software control and wakes it up through a timer. By combining software and hardware, the power consumption problem of the system is solved and energy consumption is reduced. In addition, the processor of the present invention can also use an adaptive filtering algorithm to process the corrosion current to suppress the influence of circuit noise and offset voltage. Attached Figure Description

[0031] Figure 1 This is a circuit block diagram of an embodiment of the atmospheric environment corrosion monitoring system of the present invention;

[0032] Figure 2 This is a circuit diagram of an embodiment of the IV conversion circuit and the two-stage amplifier circuit of the present invention;

[0033] Figure 3 This is a circuit diagram of an embodiment of the range switching circuit of the present invention;

[0034] Figure 4 This is a circuit diagram of an embodiment of the analog-to-digital conversion circuit of the present invention;

[0035] Figure 5 This is a circuit block diagram of another embodiment of the atmospheric environmental corrosion monitoring system of the present invention;

[0036] Figure 6This is a circuit diagram of one embodiment of the communication circuit of the present invention;

[0037] Figure 7 This is the circuit diagram of the reference circuit of the present invention;

[0038] Figure 8 This is a schematic diagram of an embodiment of the atmospheric environment corrosion monitoring system of the present invention;

[0039] Figure 9 This is a flowchart of the atmospheric environment corrosion monitoring system of the present invention;

[0040] Figure 10 (a) and (b) are respectively the top view and side view of the metal electrode in the dual-electrode sensor of the present invention;

[0041] Figure 11 A schematic diagram of laboratory measurement data errors in the system of this invention;

[0042] Figure 12 This is a schematic diagram of the measured current, temperature, and humidity curves of the system of this invention. Detailed Implementation

[0043] To enable those skilled in the art to better understand the technical solutions in the embodiments of the present invention, and to make the above-mentioned objectives, features and advantages of the embodiments of the present invention more apparent and understandable, the technical solutions in the embodiments of the present invention will be further described in detail below with reference to the accompanying drawings.

[0044] In the description of this invention, unless otherwise specified and limited, it should be noted that the term "connection" should be interpreted broadly. For example, it can be a mechanical connection or an electrical connection, or it can be a connection between two internal components. It can be a direct connection or an indirect connection through an intermediate medium. Those skilled in the art can understand the specific meaning of the above term according to the specific circumstances.

[0045] See Figure 1 This is a circuit block diagram of an embodiment of the atmospheric environmental corrosion monitoring system of the present invention. The atmospheric environmental corrosion monitoring system may include a dual-electrode sensor, a current-to-voltage (IV) conversion circuit, a two-stage amplifier circuit, an analog-to-digital converter circuit, a range switching circuit, and a processor. The input terminal of the IV conversion circuit is connected to the dual-electrode sensor, and its output terminal is connected to the first input terminal of the analog-to-digital converter circuit via the two-stage amplifier circuit, and also connected to the second input terminal of the analog-to-digital converter circuit. The output terminal and enable control terminal of the analog-to-digital converter circuit are respectively connected to the corresponding ports of the processor. The output terminal of the range switching circuit is connected to the connection terminal of the IV conversion circuit, and the enable control terminal of the range switching circuit is connected to the corresponding port of the processor.

[0046] The dual-electrode sensor detects the corrosion current on the surface of the test sample in the atmospheric environment. The IV conversion circuit converts the corrosion current into an analog voltage U1 and amplifies it in one stage. The amplified analog voltage U1 is then converted into a digital signal K1 by the analog-to-digital converter and transmitted to the processor. The processor determines, based on the digital signal K1, whether it is necessary to adjust the amplification resistor provided by the range switching circuit to the IV conversion circuit to adjust the range segment corresponding to the amplification resistor to the range segment where the corrosion current is located. The voltage values ​​obtained by multiplying each amplification resistor by the current value in its corresponding range segment are all within the same voltage range. When U1 is not within the voltage range, the amplification resistor needs to be adjusted. When U1 is within the voltage range, the amplification resistor does not need to be adjusted. In this case, the processor enables the first input terminal of the analog-to-digital converter, so that the amplified analog voltage U1 is amplified in two stages by the second-stage amplification circuit to form an analog voltage U2, which is then transmitted to the analog-to-digital converter. The analog-to-digital converter converts U2 into a digital signal K2. The processor deduces the corrosion current based on the digital signal K2.

[0047] In this embodiment, the analog voltage U1 = -IR n Where I represents corrosion current, R n The resistor represents the amplification resistance; the analog voltage U2 = U1A, where A is the second amplification factor of the second-stage amplifier circuit; the processor deduces the corrosion current I based on the digital signal K2 using the following formula: Where m is the number of bits in the analog-to-digital converter circuit.

[0048] The inverse formula derived from the above corrosion current It can be seen that the larger the secondary amplification factor A and the number of bits m in the analog-to-digital converter circuit, the smaller the change in corrosion current after a unit change in K2, meaning that even very subtle changes in corrosion current can be detected. In other words, increasing the amplification factor of the secondary amplifier circuit and / or the number of bits in the analog-to-digital converter circuit can improve the accuracy of corrosion current measurement. When the number of bits m in the analog-to-digital converter circuit is fixed, the number of data points N that the system can collect is fixed, where N is an integer greater than 1. In this invention, the total range of corrosion current is subdivided into multiple continuous range segments. For each range segment, when switching to that range segment, that range segment becomes the system's range. The system can collect N data points within that range segment. Thus, for the total range of corrosion current, the number of data points that can be collected is N * the number of range segments. It is evident that this invention subdivides the total range of corrosion current into multiple continuous range segments, and selecting the corresponding range segment as the system's range can significantly improve the accuracy of the total range measurement of corrosion current.

[0049] This invention, while increasing the total range of the corrosion current without changing the measurement accuracy of each range segment (including without changing the number of bits m and the secondary amplification factor A of the analog-to-digital converter circuit), can add a new range segment that is continuous with the original maximum or minimum range segment, and simultaneously increase the amplification resistor corresponding to the new range segment. To improve the measurement accuracy of each range segment without changing the total range of the corrosion current, at least one of the following three methods can be used: (1) increasing the number of range segments subdivided from the total range; (2) increasing the number of bits m of the analog-to-digital converter circuit; (3) increasing the secondary amplification factor A. In this invention, when the analog voltage U1 is not within the voltage range, the processor can control the amplification resistor in the range switching circuit that has a larger or smaller resistance value than the current amplification resistor to be connected to the IV conversion circuit in order of increasing or decreasing resistance value.

[0050] As can be seen from the above embodiments, when monitoring atmospheric corrosion, this invention subdivides the total range of the corrosion current into multiple continuous range segments. A corresponding amplification resistor is set for each range segment, ensuring that the voltage values ​​obtained after multiplying the corrosion current within each amplification resistor's corresponding range segment are within the same voltage range. When the processor detects that U1 is not within this voltage range—that is, when the voltage value obtained after multiplying the corrosion current by the amplification resistor currently connected to the IV conversion circuit is not within this range—it indicates that the range segment corresponding to the current amplification resistor does not include the corrosion current. Therefore, it is necessary to adjust the current amplification resistor and its corresponding range segment. When the range segment corresponding to the amplification resistor is adjusted to match the range segment containing the corrosion current, the corrosion current can be detected. Furthermore, the IV conversion circuit in this invention not only converts the corrosion current into voltage but also performs amplification during the voltage conversion process, ensuring that the voltage values ​​obtained after multiplying the current value within each amplification resistor's corresponding range segment are all within the same voltage range.

[0051] When the number of bits m in the analog-to-digital converter circuit is fixed, the number of data N that the system of this invention can collect is fixed, where N is an integer greater than 1. In this invention, the total range of corrosion current is subdivided into multiple continuous range segments. For each range segment, when switching to that range segment, that range segment becomes the system's range. The system of this invention can collect N data points within that range segment. Thus, for the total range of corrosion current, the number of data points that can be collected is N * the number of range segments. It is evident that this invention can significantly improve the measurement accuracy of the total range of corrosion current. This invention can further improve the measurement accuracy of corrosion current by setting up a two-stage amplification circuit. When increasing the total range of corrosion current, this invention only needs to add a new range segment that is continuous with the original range segment, and simultaneously add a resistor corresponding to the newly added range segment. The method of expanding the total range is simple and can achieve an expansion of the total range of any width. Therefore, this invention has a wide measurement range, high measurement accuracy, and both are adjustable.

[0052] In this invention, when adjusting the amplification resistor, the analog voltage U1 formed after the IV conversion circuit is transmitted to the analog-to-digital conversion circuit. After being converted into a digital signal K1 by the analog-to-digital conversion circuit, the processor compares U1 with a voltage range to determine whether the amplification resistor connected to the IV conversion circuit needs adjustment. During the gradual adjustment process, the first voltage obtained by the processor only needs to be compared with the same voltage range. Adjustment of the amplification voltage is not required only when U1 falls within this voltage range. The entire measurement method is very simple, and even with an increasing number of measurement ranges, the required comparison parameters do not increase, thus not increasing the complexity of the measurement method. Because this invention has a large corrosion current measurement range, high measurement accuracy, and a simple measurement method, it can achieve continuous automatic monitoring of atmospheric corrosion, obtaining corrosion data over the entire cycle. It is particularly suitable for electrochemical research under thin liquid films.

[0053] See Figure 2This is a circuit diagram of an embodiment of the IV conversion circuit and the two-stage amplifier circuit of the present invention. The IV conversion circuit may include a first operational amplifier. The inverting input of the first operational amplifier is connected to the output of the dual-electrode sensor through resistor R53 and grounded through resistor R56. The connection point between the output of the dual-electrode sensor and resistor R53 is grounded through capacitor C59. The non-inverting input of the first operational amplifier is grounded through resistor R58. The positive power supply of the first operational amplifier is connected to the corresponding positive power supply +5VCC and grounded through positive polarity capacitors C49 and C51, respectively. The negative power supply is connected to the corresponding negative power supply -5VCC and grounded through negative polarity capacitors C63 and C65, respectively. The two protection terminals are grounded. The inverting input and output of the first operational amplifier serve as two ports in the IV conversion circuit connected to the range switching circuit: the first connection terminal IN Rxl+ and the second connection terminal IN Rxl-. The output of the first operational amplifier serves as the output of the IV conversion circuit through node IN2 after resistor R54, and is connected to the input of the secondary amplifier circuit and the second input of the analog-to-digital converter circuit, respectively. The first operational amplifier can be an ADA4530-1, and the analog voltage output from the IN2 terminal of the IV conversion circuit is U1 = -IR. n Where I represents corrosion current, R n This indicates the amplification resistor.

[0054] Additionally, the secondary amplifier circuit may include a second operational amplifier. The inverting input of this second operational amplifier is connected to the output of the IV converter circuit (node ​​IN2) and grounded through capacitor C60 and resistor R57. The non-inverting input of the second operational amplifier is grounded through resistor R59. The positive power supply of the second operational amplifier is connected to the corresponding positive power supply +5VCC and grounded through positive polarity capacitors C50 and C52. The negative power supply is connected to the corresponding negative power supply -5VCC and grounded through negative polarity capacitors C64 and C66. The inverting input of the second operational amplifier is connected to its output through resistor R44. The output of the second operational amplifier, via node IN3 after resistor R55, serves as the output of the secondary amplifier circuit and is connected to the first input of the analog-to-digital converter circuit. The second operational amplifier may be an LMC6001, and the analog voltage output from the output terminal IN3 of the secondary amplifier circuit is... A is the second amplification factor of the second-stage amplifier circuit, R 44 and R 55 These are the resistance values ​​of resistors R44 and R55, respectively.

[0055] See Figure 3This is a circuit diagram of an embodiment of the range switching circuit of the present invention. The range switching circuit may include a multiplexing chip. The eight source terminals S1 to S8 of the multiplexing chip are respectively connected to the first connection terminal IN Rxl+ of the IV conversion circuit through amplifying resistors of different sizes. The eight source terminals S1 to S8 are also respectively connected to the first connection terminal IN Rxl+ of the IV conversion circuit through their corresponding capacitors. The Vss port of the multiplexing chip is grounded through resistor R43. The drain terminal D of the multiplexing chip is connected to the second connection terminal IN Rxl- of the IV conversion circuit. The enable control terminals A1 and A2 are respectively connected to the corresponding control ports of the processor. The multiplexing chip can be model ADG708. When the total range of the corrosion current is 0.1nA to 10mA, the total range can be subdivided into 8 range segments: 1mA to 10mA, 100uA to 1mA, 10uA to 100uA, 1uA to 10uA, 100nA to 1uA, 10nA to 100nA, 1nA to 10nA, and 0.1nA to 1nA. Assuming the absolute value range of the voltage is 10mV to 100mV, the corresponding amplification resistors connected to the 8 source terminals S1 to S8 of the multiplexing chip can be 10Ω, 100Ω, 10KΩ, 10KΩ, 100KΩ, 1MΩ, 10MΩ, and 100MΩ. Resistors with a temperature coefficient better than 1ppm / ℃ and an accuracy better than 0.01% can be selected as amplification resistors.

[0056] See Figure 4 This is a circuit diagram of an embodiment of the analog-to-digital converter (ADC) circuit of the present invention. The ADC circuit includes an ADC first channel serving as the second input terminal of the ADC, grounded through resistor R30 and capacitor C34, and connected to the output terminal IN2 of the IV converter circuit through resistor R28; the ADC second channel serving as the first input terminal of the ADC, grounded through resistor R31 and capacitor C35, and connected to the output terminal IN3 of the secondary amplifier circuit through resistor R29; the ADC output terminal DOUT is connected to the corresponding port of the processor, and the ADC input terminal DIN serves as the enable control terminal of the ADC and is connected to the corresponding port of the processor. The ADC model can be ADS1256, and it can be a 24-bit ADC. The processor can be a microcontroller, and the microcontroller model can be STM32F103RET6.

[0057] Additionally, see Figure 5 This is a circuit block diagram of another embodiment of the atmospheric environmental corrosion monitoring system of the present invention. Figure 5 and Figure 1The difference in the atmospheric corrosion monitoring system shown is that it may also include a temperature and humidity sensor and a clock module connected to the processor. After the processor deduces the corrosion current each time, it reads the temperature and humidity information output by the temperature and humidity sensor and the time information output by the clock module, and stores the corrosion current, temperature and humidity information and time information in the memory.

[0058] The memory can be a Flash memory chip, specifically a W25Q128JVSIQTR with a capacity of 128MB. This Flash memory chip can communicate with the processor via SPI (Serial Peripheral Interface). When the processor needs to store data, it first selects the corresponding storage location in the Flash memory chip and then stores the corrosion current, temperature and humidity information, and time information into the Flash memory chip. The clock module can be a DS3231, which can read the time information from the clock module via IIC communication.

[0059] Figure 5 and Figure 1 The difference in the atmospheric corrosion monitoring system shown is that it may also include a communication circuit connected to the processor, through which the processor communicates with a host computer. This communication circuit can be an RS485 communication circuit. When the host computer needs to access data stored in the Flash memory chip, it can first send a read data command to the processor via the RS485 communication circuit. After receiving the read data command, the processor reads the corresponding data from the Flash memory chip and uploads the read data to the host computer in .txt text format via the RS485 communication circuit. The host computer can be a computer, etc. An embodiment of the communication circuit is shown in the circuit diagram below. Figure 6 As shown.

[0060] Figure 5 and Figure 1The difference in the atmospheric corrosion monitoring system shown is that it may also include a power module connected to a processor. The power conversion circuit may include a lithium battery, an isolation circuit, and a reference voltage circuit connected in sequence. The lithium battery transmits power to the reference voltage circuit via the isolation circuit. The reference voltage circuit generates three types of voltages: the first type of voltage output is connected to the power supply of the IV conversion circuit and the secondary amplifier circuit via a relay; the second type of voltage output is connected to the corresponding power supply of the analog-to-digital conversion circuit; and the third type of voltage output is connected to the corresponding power supply of the analog-to-digital conversion circuit and the processor. The relay is connected to the processor. After each data storage operation, the processor controls the relay to open and close, stopping the power supply to the IV conversion circuit and the secondary amplifier circuit, thereby initiating a low-power mode until the next (e.g., timed) return to operating mode. When the system does not need to collect corrosion current, the hardware of the acquisition section is powered off, entering a low-power mode. The processor initiates a low-power silent mode via software control and wakes it up via a timer. This combination of software and hardware solves the system's power consumption problem and reduces energy consumption. The processor uses an adaptive filtering algorithm to process the corrosion current to suppress the effects of circuit noise and offset voltage. One embodiment of the reference voltage circuit is shown in the circuit diagram below. Figure 7 As shown.

[0061] Furthermore, the structure of the atmospheric environmental corrosion monitoring system of the present invention can be as follows: Figure 8As shown, the system may include a top cover 1 and a base 9. The system's power supply 4 (e.g., a lithium battery) is mounted on the base 9 and can be fixed with epoxy resin. The data acquisition module 8 (including an IV conversion circuit, a two-stage amplification circuit, a range switching circuit, an analog-to-digital conversion circuit, and a processor) can be fixed to the base 9 with fixing screws 5. The temperature and humidity sensor 2 and the dual-electrode sensor 3 are fixed to the top cover 1 and can be sealed with epoxy resin. The aviation connector 6 and the contact switch 7 are both mounted on the base 9. The aviation connector 6 is connected to the power supply 4 and the data acquisition module 8. The contact switch 7 is connected to the power supply 4 and is used to control the power supply on and off. When the system needs to be charged, the contact switch 7 is turned off, the aviation connector 6 is switched to be connected to the power supply 4, and the charger is connected to the aviation connector 6. The base plate 9 can be fixed in the corresponding position with connecting bolts 10. The input end of the data acquisition module 8 is connected to the dual-electrode sensor 3. Under normal non-charging conditions, connector 6 is not connected to power supply 4. When connector 6 is connected to the RS485 communication interface, the data acquisition module connects to the host computer sequentially via connector 6 and the RS485 communication interface. After software configuration on the host computer, data acquisition can begin. The data acquisition interval can be set according to actual needs; real-time or interval-based acquisition is possible. After data acquisition is complete, the host computer can read the data stored in the FLASH memory chip of the data acquisition module via the RS485 communication interface. The system workflow is as follows: Figure 9 As shown.

[0062] Specifically, the workflow of the atmospheric environment corrosion monitoring system of the present invention may include the following steps:

[0063] Step S110: The processor controls the relay coil to be energized, supplying power to the IV conversion circuit and the second-stage amplifier circuit;

[0064] Step S120: The processor controls the analog-to-digital conversion circuit to collect the voltage value of the power module and determines whether the collected voltage is normal. If it is normal, proceed to step S130; otherwise, cut off the power supply.

[0065] Step S130: The processor controls the range switching circuit to connect the amplifying resistor with the smallest resistance value in the amplifying resistor group to the IV conversion circuit.

[0066] In step S140, after the corresponding amplification resistor is connected, the IV conversion circuit outputs an analog voltage U1 = -IR. n Where I represents corrosion current, R n This represents the amplification resistor, and U1 is provided to the analog-to-digital converter circuit, which converts it into a digital signal K1 and provides the digital signal K1 to the processor.

[0067] Step S150: The processor determines whether U1 is greater than the lower limit voltage value within the set voltage range. If so, proceed to step S170; otherwise, proceed to step S160.

[0068] Step S160: Determine the resistor in the amplifying resistor group that has a larger resistance value than the current amplifying resistor, and find the amplifying resistor with the smallest difference from the current amplifying resistor from the determined resistors. Control the range switching circuit to connect the found amplifying resistor into the IV conversion circuit, and return to execute step S140.

[0069] Step S170: The processor enables the first input terminal of the analog-to-digital converter circuit, so that U1 is amplified by the two-stage amplifier circuit to form an analog voltage U2 = U1A, where A is the second amplification factor of the two-stage amplifier circuit; the analog voltage U2 is transmitted to the analog-to-digital converter circuit, which converts it into a digital signal K2 and provides the digital signal K2 to the processor.

[0070] Step S180: The processor deduces the corrosion current I based on the digital signal K2 using the following formula: Where m is the number of bits in the analog-to-digital converter circuit.

[0071] In this invention, the structural schematic diagram of the dual-electrode sensor can be combined with... Figure 10 As shown in (a) and (b), the dual-electrode sensor may comprise metal electrodes and an insulating sheet stacked on top of each other. Each metal electrode has an electrode lead. The metal electrodes are made of two different materials arranged alternately, and the two metal electrodes are fixed together using M3 polyethylene nuts and screws. The schematic diagram of laboratory measurement data errors and the schematic diagram of measured current, temperature, and humidity curves of the system of this invention are shown below. Figure 11 and Figure 12 As shown.

[0072] Other embodiments of the invention will readily occur to those skilled in the art upon consideration of the specification and practice of the invention disclosed herein. This application is intended to cover any variations, uses, or adaptations of the invention that follow the general principles of the invention and include common knowledge or customary techniques in the art not disclosed herein. The specification and examples are to be considered exemplary only, and the true scope and spirit of the invention are indicated by the following claims.

[0073] It should be understood that the present invention is not limited to the precise structure described above and shown in the accompanying drawings, and various modifications and changes can be made without departing from its scope. The scope of the invention is defined solely by the appended claims.

Claims

1. An atmospheric environmental corrosion monitoring system characterized by, The system includes a dual-electrode sensor, a current-to-voltage (IV) conversion circuit, a two-stage amplifier circuit, an analog-to-digital (ADC) conversion circuit, a range switching circuit, and a processor. The input terminal of the IV conversion circuit is connected to the dual-electrode sensor, and its output terminal is connected to the first input terminal and the second input terminal of the ADC circuit via the two-stage amplifier circuit. The output terminal and enable control terminal of the ADC circuit are respectively connected to the corresponding ports of the processor. The output terminal of the range switching circuit is connected to the connection terminal of the IV conversion circuit, and the enable control terminal of the range switching circuit is connected to the corresponding port of the processor. The dual-electrode sensor detects the corrosion current on the surface of the test sample in the atmospheric environment; The IV conversion circuit converts the corrosion current into an analog voltage U1 and amplifies it in one stage. The amplified U1 is then converted into a digital signal K1 by the analog conversion circuit and transmitted to the processor. The processor determines, based on the digital signal K1, whether it is necessary to adjust the amplification resistor provided by the range switching circuit to the IV conversion circuit, so as to adjust the range segment corresponding to the amplification resistor to the range segment where the corrosion current is located. The voltage values ​​obtained by multiplying each amplification resistor by the current value in its corresponding range segment are all within the same voltage value range. When U1 is not within the voltage value range, the amplification resistor needs to be adjusted. When the voltage value of U1 is within the specified range, there is no need to adjust the amplification resistor. At this time, the processor enables the first input terminal of the analog-to-digital converter circuit, so that the first-stage amplified U1 is amplified by the second-stage amplification circuit to form an analog voltage U2, which is then transmitted to the analog-to-digital converter circuit. The analog-to-digital converter circuit converts U2 into a digital signal K2. The processor deduces the corrosion current based on the digital signal K2.

2. An atmospheric environmental corrosion monitoring system according to claim 1, characterised in that, The analog voltage U1 = -IR n where I represents the corrosion current, R n represents the amplification resistance; the analog voltage is U2 = U1A, A being the amplification factor of the second amplification circuit; The processor inversely deduces the corrosion current I according to the digital signal K2 according to the following formula: Wherein m is the bit number of the analog-digital conversion circuit.

3. An atmospheric environmental corrosion monitoring system according to claim 1 or 2, characterised in that, The total corrosion current range is subdivided into multiple continuous range segments; When increasing the total range of corrosion current without changing the number of bits m and the secondary amplification factor A of the analog-to-digital converter circuit, a new range segment that is continuous with the original maximum or minimum range segment is added on the basis of the original range segment, and an amplification resistor corresponding to the new range segment is added at the same time. To improve the measurement accuracy of each range segment without changing the total range of the corrosion current, at least one of the following three methods can be used: increasing the number of range segments subdivided from the total range; increasing the number of bits m in the analog-to-digital conversion circuit; and increasing the secondary amplification factor A.

4. The atmospheric environmental corrosion monitoring system of claim 1, wherein, When U1 is not within the voltage range, the processor controls the amplifying resistor in the range switching circuit that has a larger or smaller resistance value than the current amplifying resistor to be connected to the IV conversion circuit in order of resistance value from small to large or from large to small.

5. The atmospheric environmental corrosion monitoring system according to claim 1, characterized in that, It also includes a temperature and humidity sensor and a clock module connected to the processor. Each time the processor deduces the corrosion current, it reads the temperature and humidity information output by the temperature and humidity sensor and the time information output by the clock module, and stores the corrosion current, temperature and humidity information and time information in the memory.

6. The atmospheric environmental corrosion monitoring system according to claim 1 or 5, characterized in that, After each data storage operation, the processor initiates a low-power mode until it enters the working mode again. The processor employs an adaptive filtering algorithm to process the corrosion current in order to suppress the effects of circuit noise and offset voltage.

7. The atmospheric environmental corrosion monitoring system according to claim 6, characterized in that, It also includes a communication circuit connected to the processor, through which the processor communicates with the host computer.

8. The atmospheric environmental corrosion monitoring system according to claim 1, characterized in that, The IV conversion circuit includes a first operational amplifier. The inverting input of the first operational amplifier is connected to the output of the dual-electrode sensor through resistor R53 and grounded through resistor R56. The connection point between the output of the dual-electrode sensor and resistor R53 is grounded through capacitor C59. The non-inverting input of the first operational amplifier is grounded through resistor R58. The positive power supply of the first operational amplifier is connected to a corresponding positive power supply and grounded through positive polarity capacitors C49 and C51, respectively. The negative power supply is connected to a corresponding negative power supply and grounded through negative polarity capacitors C63 and C65, respectively. Two protection terminals are grounded. The inverting input and output of the first operational amplifier serve as two ports in the IV conversion circuit connected to the range switching circuit: a first connection terminal IN Rxl+ and a second connection terminal IN Rxl-. The output of the first operational amplifier, through node IN2 after resistor R54, serves as the output of the IV conversion circuit and is connected to the input of the secondary amplifier circuit and the second input of the analog-to-digital converter circuit, respectively.

9. The atmospheric environmental corrosion monitoring system according to claim 1, characterized in that, The second-stage amplifier circuit includes a second operational amplifier. The inverting input of the second operational amplifier is connected to the output of the IV converter circuit and grounded through capacitor C60 and resistor R57. The non-inverting input of the second operational amplifier is grounded through resistor R59. The positive power supply of the second operational amplifier is connected to the corresponding positive power supply and grounded through positive polarity capacitors C50 and C52. The negative power supply is connected to the corresponding negative power supply and grounded through negative polarity capacitors C64 and C66. The inverting input of the second operational amplifier is connected to its output through resistor R44. The output of the second operational amplifier is connected to the first input of the analog-to-digital converter circuit via node IN3 after resistor R55.

10. The atmospheric environmental corrosion monitoring system according to claim 1, characterized in that, The range switching circuit includes a multiplexing chip. The eight source terminals S1 to S8 of the multiplexing chip are connected to the first connection terminal IN Rxl+ of the IV conversion circuit through amplification resistors of different sizes. The eight source terminals S1 to S8 are also connected to the first connection terminal IN Rxl+ of the IV conversion circuit through their respective capacitors. The drain terminal D of the multiplexing chip is connected to the second connection terminal IN Rxl- of the IV conversion circuit. The enable control terminals A1 and A2 are connected to the corresponding control ports of the processor.

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