Construction method of ternary gas impurity control threshold model in high-temperature inert environment

Abstract

The invention discloses a method for constructing a ternary gas impurity control threshold model in a high-temperature inert environment, which comprises the following steps of: analyzing the types of impurity corrosion reactions possibly occurring in a material, and establishing a single impurity and temperature two-dimensional critical partial pressure map; the impurity partial pressure is changed under the equal total pressure, and dominant corrosion reaction types of different ratio combinations are determined; selecting a representative impurity gas proportion point in the dominant reaction area, performing high-temperature corrosion reaction on the material, and analyzing an actual dominant corrosion reaction type; carrying out normalization processing on theoretical and actual dominant corrosion reactions, and constructing a ternary impurity ratio and corrosion reaction type response model; and setting a failure critical condition, and obtaining a ternary impurity control threshold model by taking a corrosion reaction type as a criterion. According to the method, the critical partial pressure relation of an oxidation-carbonization-volatilization-stability region is defined through the influence rule of different impurity combinations on the type, thickness and diffusion depth of corrosion products on the surface of refractory alloy, and the method can be used for calculating the key impurity control threshold value of the high-temperature alloy material.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of material-working medium interface compatibility in nuclear energy and high-temperature power systems, and in particular, relates to a method for constructing a ternary gas impurity control threshold model under a high-temperature inert gaseous working medium environment. BACKGROUND

[0002] Currently, advanced nuclear energy systems and high-efficiency energy conversion systems using high-temperature inert gaseous working media as heat transfer media are becoming an important development direction in the energy field. High-temperature inert gases (such as helium, argon, xenon gas or mixtures thereof) become the preferred working medium for closed Brayton cycle and high-temperature gas cooled reactor systems due to their good thermophysical properties and chemical stability. At the same time, in order to further improve the thermal efficiency, realize the miniaturization of the reactor and long-term operation, the system operating temperature is rising, and some have reached or exceeded 1500K. Under such extremely high temperature conditions, although the inert gas itself has extremely low chemical reactivity, due to process limitations and operating environment, trace impurities such as H2O, O2, CO, CO2, etc. will inevitably exist in the working medium. These impurities can cause serious oxidation, carbonization, decarburization and even vapor corrosion reactions at the ppm level, especially when the structural material uses Mo, Nb, W and other ultra-high temperature refractory alloys. Taking Mo alloy as an example, it can work stably at low oxygen partial pressure, but when the temperature exceeds 1200K, even 5ppm of H2O or O2 impurities can induce the volatilization of surface MoO3 oxide, thereby causing rapid failure of the material.

[0003] Currently, international projects such as HTTR (Japan), HTR-PM (China), NASA nuclear thermal propulsion reactor (NTP) have developed gas impurity control specifications for helium cooled reactors, but these specifications are mostly based on the operating experience of graphite cores and traditional high-temperature alloys (such as Ni-based alloys). The control limits and theoretical models are not applicable to the new generation of systems using refractory metal materials, higher temperatures, and more complex working media. In particular, most of the existing specifications are based on empirical rules or single-factor corrosion experiments, and lack a deep understanding of the synergistic reaction mechanism between impurities. For example, O2 may inhibit the carbonization of CH4 under certain conditions, while the coexistence of CO2 and H2O may cause instability of the oxidation layer, resulting in material peeling. This "synergistic corrosion" phenomenon between multiple impurities is particularly complex under ultra-high temperature conditions, resulting in large prediction deviations based on traditional thermodynamic models.

[0004] In summary, in the face of super-high temperature inert gas environment, the existing material corrosion evaluation and impurity limit setting method cannot meet the needs of the system for long-term operation safety and material life prediction. Therefore, it is urgent to develop a gas impurity control threshold value construction method that can be applied to high-temperature inert gaseous working medium environment, considering the synergistic reaction effect between multiple impurities, and combining theoretical modeling and experimental data.

[0005] Therefore, the present application is proposed. SUMMARY

[0006] To solve the above technical problems, the present application provides a method for constructing a ternary gas impurity control threshold model in a high-temperature inert gaseous working medium environment. By studying the influence of different impurity combinations on the corrosion product type, thickness, and diffusion depth on the surface of refractory alloys, the quantitative relationship between impurity concentration, composition ratio, temperature, and material reaction is determined, and a thermodynamic boundary map between temperature, impurity partial pressure, and material corrosion reaction type is constructed. The critical partial pressure relationship of the "oxidation-carbonization-volatilization-stabilization" region can be used to calculate the key impurity control threshold values for different high-temperature alloy materials.

[0007] The present application is realized by the following technical solutions: The present application provides a method for constructing a ternary gas impurity control threshold model in a high-temperature inert environment, comprising the following steps: S1, analyze the possible impurity corrosion reaction types of alloy materials in a high-temperature inert atmosphere, and establish a two-dimensional critical partial pressure map of single impurity and temperature; change the three impurity partial pressures under the same total pressure to determine the dominant corrosion reaction type of different ternary ratio combinations, and obtain a theoretical dominant reaction region map; S2, select a representative impurity gas ratio point for each dominant reaction region, and perform high-temperature corrosion reaction on the alloy material; characterize the surface of the alloy material after corrosion, and analyze the actual dominant corrosion reaction type; S3, normalize the theoretical dominant reaction region map and the actual dominant corrosion reaction type to construct a response model of ternary impurity ratio and corrosion reaction type; taking the corrosion reaction type as the criterion, and combining the "failure critical condition" of the working condition, the ternary impurity control threshold model is obtained by back calculation.

[0008] The present application studies the influence of different impurity combinations on the corrosion product type, thickness, and diffusion depth on the surface of refractory alloys, determines the quantitative relationship between impurity concentration, composition ratio, temperature, and material reaction, and constructs a thermodynamic boundary map between temperature, impurity partial pressure, and material corrosion reaction type. The critical partial pressure relationship of the "oxidation-carbonization-volatilization-stabilization" region can be used to calculate the key impurity control threshold values for different high-temperature alloy materials.

[0009] The present application breaks through the limitation of single-factor empirical rule in traditional nuclear working medium management through efficient cooperation of multiple experiments and theoretical modeling, can build a highly reliable and universal impurity control threshold model, significantly improves the scientificity, pertinence and engineering adaptability of impurity limit setting, and provides a scientific, accurate and engineering practical technical means for corrosion prevention and control of high-temperature inert gas cooling system materials In a specific embodiment, in step S1, the impurity corrosion reaction type includes oxidation reaction, carbonization reaction and evaporation reaction.

[0010] In a specific embodiment, in step S1, the specific method for establishing a two-dimensional critical partial pressure map of a single impurity and temperature is as follows: The thermodynamic database is used to obtain the ΔH 0 , ΔS 0 and ΔG 0 data of each reaction; The temperature dependence of ΔG of each reaction is analyzed by the Gibbs minimum free energy principle; The critical reaction partial pressure expression is derived by using the thermodynamic equilibrium equation, the critical partial pressure of impurities for each reaction is determined, and the partial pressure critical curve at different temperatures of a single impurity is established.

[0011] In a specific embodiment, in step S1, the establishment method of the theoretical dominant reaction region map is as follows: Under the condition of constant total pressure, three impurity partial pressures are changed, and the ΔG expression of each reaction is substituted into each ratio combination to calculate the reaction thermodynamic conditions under each impurity ratio; The dominant corrosion reaction type of all ratio combinations is determined, and it is mapped to the corresponding ternary coordinate point; According to the dominant corrosion reaction type, a theoretical dominant reaction region map is drawn.

[0012] In a specific embodiment, in step S2, the data characterized includes corrosion layer thickness, phase composition, surface morphology and element diffusion depth.

[0013] The present application combines density functional theory and experimental fitting formula to establish the Gibbs energy model of corrosion reaction and the function relationship of impurity partial pressure, realizes the quantification and calculation of impurity control, and directly reverses the upper limit of impurity control according to the operating temperature on the engineering, and provides target parameters for the coolant purification system In a specific embodiment, in step S2, the judgment conditions of the actual dominant corrosion reaction type include: a) The corrosion layer thickness is greater than 3 μm, and the main component is oxide, then it is determined that the oxidation reaction is dominant; b) There is obvious carbide phase of alloy and C element enrichment, then it is determined that the carbonization reaction is dominant; c) if the corrosion morphology is pitting or surface loss, and alloy oxide or alloy species gaseous signals are found, then it is determined that evaporation reaction is dominant; d) if the material mass loss is very small, the corrosion layer is discontinuous or amorphous, then it is determined that it is inert and stable.

[0014] In a specific embodiment, the response model is constructed using multivariate regression, response surface method (RSM) or artificial neural network (ANN).

[0015] In a specific embodiment, the specific construction method of the response model is to construct it by taking the impurity partial pressure ratio and temperature as input variables and the corrosion rate or corrosion layer thickness of the alloy material as response output variables.

[0016] In a specific embodiment, the construction method of the ternary impurity control threshold model is as follows: Based on the output results of the response model, the ternary impurity space is globally simulated, and the dominant reaction region map is drawn; Set a clear "failure critical condition", take the corrosion rate and corrosion layer thickness as the criterion, and inversely solve the corresponding impurity control threshold line; Combine theoretical calculation with experimental verification results to accurately draw the impurity control threshold map in the ternary impurity system, and clearly define the accurate boundaries of the oxidation dominant region, the carbonization dominant region, the evaporation dominant region and the inert and stable region.

[0017] In a specific embodiment, the construction method of the impurity control threshold model further comprises step S4, iterative optimization of the impurity control threshold model: Select points near the boundary of the ternary map or the junction area as an extended experimental group to verify the accuracy of the impurity threshold model constructed by the model, and ensure that the model prediction error is controlled within ±10%; If the model prediction error exceeds the specified range, additional experimental data collection and theoretical calculation optimization are performed, and the model parameters are repeatedly iterated until the model error is within an acceptable range.

[0018] Compared with the prior art, the present application has the following advantages and beneficial effects: 1. The construction method of the ternary gas impurity control threshold model in a high-temperature inert environment provided by the embodiment of the present application clearly determines the synergistic mechanism of the influence of multi-impurities on the corrosion behavior (oxidation, carbonization, evaporation) of super-high-temperature refractory materials under super-high-temperature (>1000℃) conditions, and determines the critical impurity partial pressure conditions for each type of reaction to occur. 2. The method for constructing a ternary gas impurity control threshold model in a high-temperature inert environment provided by the embodiment of the present application can divide the "oxidation dominant zone", "carbonization dominant zone", "evaporation dominant zone" and "inert safe zone" of material service behavior by constructing a corrosion boundary map of ternary atmosphere, thereby providing a safety window map based on temperature and impurity concentration for engineering design; 3. The method for constructing a ternary gas impurity control threshold model in a high-temperature inert environment provided by the embodiment of the present application can break through the limitation of the traditional single-factor empirical rule in nuclear engineering quality management through efficient cooperation of multivariate experiments and theoretical modeling, can construct a highly reliable and universal impurity control threshold model, and significantly improves the scientificity, pertinence and engineering adaptability of impurity limit setting, thereby providing a scientific, accurate and engineering practical technical means for corrosion prevention and control of materials in a high-temperature inert gas cooling system; 4. The method for constructing a ternary gas impurity control threshold model in a high-temperature inert environment provided by the embodiment of the present application combines density functional theory and experimental fitting formula, establishes a relationship between the Gibbs energy model of corrosion reaction and the impurity partial pressure function, realizes quantitative and calculable control of impurities, and can directly back-calculate the upper limit of impurity control according to the operating temperature on the engineering, thereby providing target parameters for a coolant purification system; 5. The method for constructing a ternary gas impurity control threshold model in a high-temperature inert environment provided by the embodiment of the present application has material independence and atmosphere adjustability, is not only suitable for a variety of inert gaseous working medium systems such as helium, helium-xenon and CO2, but also can be popularized to new application fields such as a supercritical CO2 energy conversion system, a deep space nuclear thermal propulsion system and an aviation nuclear energy power system. DETAILED DESCRIPTION

[0019] In order to make the objects, technical solutions and advantages of the present application clearer, further detailed description will be made to the present application in combination with embodiments, and the illustrative embodiments of the present application and the description thereof are only used to explain the present application, but not limit the present application.

[0020] In the following description, a large number of specific details are set forth in order to provide a thorough understanding of the present application. However, it is apparent that one of ordinary skill in the art can practice the present application without these specific details. In other instances, well-known materials or methods have not been described in detail in order to avoid obscuring the present application.

[0021] Reference throughout this specification to "one embodiment", "an embodiment", "one design", or "a design" means that a particular feature, structure, or characteristic described in connection with the embodiment or design is included in at least one embodiment or design of the present application. Thus, appearances of the phrases "one embodiment", "an embodiment", "one design", or "a design" in various places throughout this specification are not necessarily all referring to the same embodiment or design. Furthermore, the particular features, structures, or characteristics can be combined in any suitable

[0022] "ranges" disclosed herein are defined as being inclusive of the recited starting and ending range values, and are independently combinable, i.e., any of the recited ranges can be combined with any other recited range to create a new range. For example, if a range of 60-120 and a range of 80-110 are recited, a range of 60-110 and a range of 80-120 are also contemplated. Furthermore, if a minimum range value of 1 and 2 are recited, and a maximum range value of 3, 4, and 5 are recited, then the following ranges are all contemplated: 1-3, 1-4, 1-5, 2-3, 2-4, and 2-5. In this application, numerical ranges are generally inclusive of the recited endpoints, unless otherwise specifically indicated. For example, a numerical range of "0-5" means that all real combinations of "0-5" are contemplated, even though the numbers 0 and 5 are included in the range. Similarly, if a parameter is stated to be an integer of >2, then it is equivalent to state that the parameter is an integer of, for example, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, etc.

[0023] If not otherwise specified, all steps of the application can be performed in any order, preferably in the order as specified. For example, the method comprises steps (a) and (b) means that the method can comprise steps (a) and (b) in the order as specified, but also steps (b) and (a) in the order as specified. For example, the method can further comprise step (c) means that step (c) can be added to the method in any order, for example, the method can comprise steps (a), (b) and (c), but also steps (a), (c) and (b), but also steps (c), (a) and (b), etc. Embodiment

[0024] The embodiment of the application provides a method for constructing a threshold model of ternary gas impurities in a high-temperature inert environment, comprising the following steps: S1, theoretically calculate the initial impurity threshold model S11, corrosion reaction type analysis Select typical refractory metal and alloy material system, clear its high temperature inert conditions may occur corrosion reaction type, select the representative O2-H2O-CO2 ternary impurity system, and Mo alloy as the research object, as follows: (1) oxidation path: Mo + O2→ MoO2(solid) Mo + H2O→ MoO2+ H2 (2) carbonization path: Mo + CO2→ Mo2C + O2(generate carbide) Mo + CO→ Mo2C + O (3) evaporation path: MoO2(s) ⇌ MoO2(g) MoO2(s) + 1 / 2O2→ MoO3(g) S12, thermodynamic parameter collection and calculation platform construction (1) Use standard thermodynamic database, such as JANAF, NIST, FACTPS database, to obtain the ΔH 0 , ΔS 0 , ΔG 0 data of each reaction, and calibrate the effectiveness of the database in the target temperature range; (2) Then use thermodynamic calculation software such as FactSage, Thermo-Calc, etc., input each reaction equation, calculate the specific value of the standard Gibbs free energy change (ΔG) of each reaction in the specific temperature range through the principle of Gibbs minimum free energy, and determine the thermodynamic spontaneous condition of each reaction; (3) Derive the critical reaction partial pressure expression through the thermodynamic equilibrium equation, for example: ΔG = ΔG 0 + RT ln(pO2), and then inversely solve pO2 = exp[(ΔG-ΔG 0 ) / RT]; (4) Finally, based on the reaction thermodynamic equilibrium condition (ΔG = 0), determine the impurity critical partial pressure of each reaction type at different temperatures, form a two-dimensional critical partial pressure map of single impurity and temperature, and preliminarily judge the critical corrosion condition; S13, ternary impurity space thermodynamic mapping (1) Define the coordinate normalization rule in the ternary impurity space, x O2+ x H2O+ xCO2=1, ensuring that any mixing ratio has the ability to be visually expressed on a triangular projection map, i.e. any impurity ratio can be expressed in a triangular coordinate system, and the impurity concentration (pO2, pH2O, pCO2) of any point is converted into a normalized concentration ratio (pO2 / pCO2, pH2O / pCO2, pCO2 / pCO2) x O2, x H2O, x CO2); (2) On the basis of single impurity critical partial pressure, it is extended to ternary impurity system. By changing the partial pressure of three impurities under the condition of equal total pressure, a large number of possible impurity ratio combinations are substituted into the ΔG expression of each reaction, the ΔG value of each possible reaction is calculated, and the dominant reaction type (oxidation, carbonization, evaporation or inert stability) of each impurity combination point is determined according to the principle of minimum energy; (3) Construct a data processing program to automatically identify the dominant corrosion reaction type for all ratio combinations and map it to the corresponding ternary coordinate point; (4) According to the classification of the dominant corrosion reaction type, a theoretical ternary impurity corrosion dominant region map is initially drawn to clearly define the theoretical boundaries of the oxidation dominant region, the carbonization dominant region, the evaporation dominant region and the inert stability region; (5) Finally, use MATLAB or Python (Matplotlib + Numpy) to identify the region and smooth the boundary of the ternary impurity corrosion dominant region map, and further refine the temperature level map (such as 1200 K, 1400 K, 1600 K respectively) by combining the critical partial pressure calculation results.

[0025] S2, verify the model using actual corrosion experiment data of alloy materials under different impurity ratio atmospheres S21, impurity ratio point design (1) Refer to the theoretical ternary impurity corrosion dominant region map, select representative impurity ratio points from each dominant reaction region, select not less than 3 points in each region to ensure uniform distribution and comprehensive coverage of experimental data in each corrosion region; (2) Use the D-Optimal design principle to consider the multi-level combination of temperature, ratio and reaction pressure to generate a comprehensive experimental matrix (3) All experimental points are normalized to form a triangular coordinate point distribution map, and are compared with the theoretical ternary impurity corrosion dominant region map to test the scientificity of the points.

[0026] S22, experimental design and corrosion experiment (1) Experimental device composition: A high-precision temperature control high-temperature tube furnace is used, and a 2-point thermocouple is arranged in the experimental section for real-time temperature measurement, and a pressure real-time monitoring and overpressure relief device is arranged to ensure the stability of the furnace temperature and prevent the high-temperature tube furnace from being broken due to overpressure; a mass flow controller (MFC) is configured to control the flow of the gas introduced; an online gas monitoring unit is arranged for measuring the cleaning effect of the system before the experiment and monitoring the real-time gas changes; the flanges at the inlet and outlet of the tube furnace are water-cooled flanges connected to a water-cooled machine for cooling, effectively avoiding air leakage and high-temperature deformation of the sealing ring; the material of the experimental section is avoided to be used for materials that are easy to react with impurity gases or high-temperature impurity gases, and the EP-grade electrolytic polishing pipeline is used in the low-temperature section to prevent gas adsorption interference with the experimental results.

[0027] (2) System purification steps: Before the experiment, use 99.999% high-purity He to flush for not less than 3 rounds, each round lasting 30 minutes; intermittently heat the sample section to about 100°C while using a high-vacuum pump to wash the system (the final vacuum degree is <10 Pa) to completely remove the residual impurity gases in the system; use the online gas monitoring unit to monitor the exhaust concentration curve and real-time monitor the cleaning effect of the experimental system, and when the O2, CO2, H2O concentrations are stable and below 0.1 ppm for 20 minutes, the reaction atmosphere can be enabled; the flow rates of all process gases and the composition of the atmosphere are recorded and archived in real time to ensure traceability of the data.

[0028] (3) Sample preparation: Mo alloy material is selected and processed into a uniform shape to ensure consistent exposed surface area. The cutting method of ultra-high-temperature refractory alloy should use turning, slow wire or diamond wire, and should not use wire cutting method; at the same time, alcohol cleaning is used to avoid water washing as much as possible. After drying, it is packaged in a vacuum storage tank for standby to avoid oxidation or moisture absorption.

[0029] (4) Experimental condition setting: The specified temperature and flow rate are set, and the corrosion time under each impurity combination is fixed to be not less than 500 hours; three parallel samples are set for each experimental group to enhance the repeatability statistics; at the same time, a control group (only He environment) is set for normalization of corrosion behavior comparison; samples are taken at regular intervals during the experiment, and the sample mass change is recorded. After the experiment, SEM, EDS, XPS, XRD, FIB-TEM and other analysis techniques are used to quantitatively characterize the corrosion layer thickness, phase composition, surface morphology and element diffusion depth.

[0030] S23, corrosion product analysis and dominant reaction discrimination (1) Morphology and structure analysis: SEM is used to observe the surface morphology characteristics after corrosion, and EDS is used to obtain the element distribution information of the surface scan; XRD is used to determine the main phase composition of the corrosion layer to judge whether it is an oxide (such as MoO2, MoO3) or a carbide (Mo2C); XPS is used to analyze the chemical state change of Mo element to identify the oxidation state (Mo 4+ / Mo6+ ) or carbonization bonding (Mo-C).

[0031] (2) Interface and diffusion analysis: FIB was used to prepare cross-section samples, and TEM high-resolution analysis was used to analyze the corrosion layer thickness and interface continuity; line scanning EDS was used to analyze the element distribution along the vertical direction to determine whether oxygen or carbon penetrated into the matrix.

[0032] (3) Quantitative judgment method of corrosion reaction dominant type: By comparing the data obtained by different analysis techniques, the following indicators were extracted: a) Corrosion layer thickness > 3 pm, and mainly oxide, then judged as oxidation dominant; b) There are obvious Mo2C phase and C element enrichment, then judged as carbonization dominant; c) Corrosion morphology is pitting or surface loss, and MoO3 or Mo species gaseous signal is found, then judged as evaporation dominant; d) If the mass loss is very small (<0.2 mg / cm 2 ), the corrosion layer is discontinuous or amorphous: it can be classified as inert stable region.

[0033] The dominant reactions of all samples were numbered for subsequent response surface model construction and ternary diagram classification.

[0034] S3, accurate construction of impurity control threshold model by combining experiment and theory Based on the completion of theoretical calculation and corrosion experiment, the fusion analysis of experiment and theory was carried out, so as to construct the impurity control threshold model with quantitative ability and regional judgment function, as follows: S31, data normalization and integration (1) Compare the corrosion reaction dominant region map (such as oxidation / carbonization / evaporation boundary) obtained by theoretical calculation with the corrosion dominant behavior type determined by experiment, verify the accuracy of theoretical model, adjust and optimize the theoretical model based on experimental data, and unify the normalization of impurity ratio (conversion of triangular coordinates).

[0035] (2) Number and classify the corrosion reaction dominant type of all experimental points (for example, 1 represents oxidation dominant, 2 for carbonization dominant, 3 for evaporation dominant, and 0 for inert stable), forming a labeled data set.

[0036] S32, response model construction Based on experimental data, the impurity partial pressure ratio (P x O2, x H2O, xCO2) and temperature as input variables, and corrosion reaction type, corrosion layer thickness or quantitative corrosion rate as response output variables, using multivariate regression, response surface method (RSM), artificial neural network (ANN) and other algorithms, a high-precision quantitative corrosion response model is constructed, and a mapping relationship between "impurity ratio-reaction type" or "impurity ratio-corrosion rate" is established.

[0037] S33, boundary determination and ternary impurity control threshold map generation (1) Based on the output results of the response model, the global simulation of the entire ternary impurity space (O2-H2O-CO2) is carried out, the dominant reaction interval map (thermodynamics + experimental correction version) is drawn, and the actual experimental points are superimposed.

[0038] (2) Combined with the working condition requirements, a clear failure critical condition (such as corrosion rate >1mg / cm 2 ·h or corrosion layer thickness >5µm) is set, and the corrosion rate, corrosion depth and other criteria are used to back-calculate the corresponding impurity control threshold line.

[0039] (3) The theoretical calculation and experimental verification results are combined to accurately draw the complete ternary impurity control threshold map, clearly define the accurate boundaries of the oxidation dominant region, carbonization dominant region, evaporation dominant region and inert stable region, identify different corrosion reaction dominant regions, and clearly delineate the engineering allowable range and failure risk area.

[0040] S4, model iteration optimization and verification closed loop To ensure that the constructed threshold model has sufficient engineering applicability and prediction accuracy, a closed-loop verification and iteration mechanism needs to be established, as follows: S41, verification data expansion (1) Select points near the boundary of the ternary map or the intersection region as the expanded experimental group to obtain new data to enhance the model boundary recognition ability.

[0041] (2) Use the new experimental data for "blind prediction", and compare the model prediction results and deviations with the actual corrosion reaction.

[0042] S42, model error analysis and adjustment (1) Calculate the prediction error (such as reaction mechanism recognition accuracy, corrosion rate residual error mean square deviation, etc.) (2) Re-evaluate the representativeness of the thermodynamic calculation model parameters and experimental boundary points in the high-deviation area, and update the model weight or region subdivision training.

[0043] S43, repeated iteration and stable convergence (1) Compare the updated map of the model with the original model, if the prediction accuracy is improved and the boundary tends to be stable, the model is considered to be converged.

[0044] (2) If the error is still greater than 10%, continue to introduce new experimental points or adjust the modeling strategy until the model error is controlled within ±10%.

[0045] S44, engineering application adaptability verification (1) The finally constructed model is embedded in a high-temperature power system to quickly determine the corrosion risk with actual service atmosphere parameter input.

[0046] (2) Long-term operation test is carried out in the actual application scene, the service performance of the sample is continuously tracked, the model is further iteratively corrected, and the precision requirement of the actual engineering application is met.

[0047] The above specific embodiments further specifically describe the purposes, technical solutions and beneficial effects of the present application. It should be understood that the above description is only a specific embodiment of the present application and is not used to limit the protection scope of the present application. Any modification, equivalent replacement, improvement, etc. within the spirit and principles of the present application should be included in the protection scope of the present application.

Claims

1. A method for constructing a control threshold model of ternary gas impurities in a high-temperature inert environment, characterized in that, The method comprises the following steps: S1, analyzing the types of impurity corrosion reactions that may occur to the alloy material in a high-temperature inert atmosphere, establishing a two-dimensional critical partial pressure map of a single impurity and temperature, changing three impurity partial pressures under the condition of constant total pressure, determining the dominant corrosion reaction type of different ternary ratio combinations, and obtaining a theoretical dominant reaction region map; S2, selecting a representative impurity gas ratio point of each dominant reaction region, and performing high-temperature corrosion reaction on the alloy material; and performing characterization on the alloy material surface after corrosion, and analyzing the actual dominant corrosion reaction type; S3, performing normalized processing on the theoretical dominant reaction region map and the actual dominant corrosion reaction type, constructing a response model of ternary impurity ratio and corrosion reaction type; taking the corrosion reaction type as a criterion, and combining a working condition "failure critical condition", a ternary impurity control threshold model is reversely obtained.

2. The method of claim 1, wherein the method is characterized by: In step S1, the impurity corrosion reaction types include oxidation reaction, carbonization reaction and evaporation reaction.

3. The method of claim 1, wherein the method is characterized by: In step S1, the specific method for establishing the two-dimensional critical partial pressure map of a single impurity and temperature is as follows: Thermodynamic database is used to obtain ΔH 0 , ΔS 0 , ΔG 0 data for each reaction; Perform temperature dependence analysis on ΔG of each reaction through the Gibbs minimum free energy principle; Deduce a critical reaction partial pressure expression by using a thermodynamic equilibrium equation, determine the impurity critical partial pressure at which each reaction occurs, and establish a partial pressure critical curve at different temperatures of a single impurity.

4. The method of claim 1, wherein, In step S1, the establishment method of the theoretical dominant reaction region map is as follows: Under the condition of constant total pressure, change three impurity partial pressures, and in each ratio combination, substitute ΔG expression of each reaction to calculate the reaction thermodynamic condition under each impurity ratio; Determine the dominant corrosion reaction type of all ratio combinations, and map it to the corresponding ternary coordinate point; According to the dominant corrosion reaction type, a theoretical dominant reaction region map is drawn.

5. The method of claim 1, wherein, In step S2, the data of characterization includes corrosion layer thickness, phase composition, surface morphology and element diffusion depth.

6. The method of claim 1, wherein, In step S2, the judgment conditions of the actual dominant corrosion reaction type include: a) If the corrosion layer thickness is greater than 3 μm and mainly composed of oxides, it is determined that the oxidation reaction is dominant; b) If there is an obvious carbide phase of the alloy and the element C is enriched, it is determined that the carbonization reaction is dominant; c) If the corrosion morphology is pit corrosion or surface loss, and the alloy oxides or alloy species gaseous signal is found, it is determined that the evaporation reaction is dominant; d) If the material mass loss is extremely small, the corrosion layer is discontinuous or amorphous, it is determined that the reaction is inert and stable.

7. The method of claim 1, wherein, The response model is constructed by using multivariate regression, response surface method (RSM) or artificial neural network (ANN).

8. The method of claim 7, wherein the method is characterized by: The specific construction method of the response model is that the impurity partial pressure ratio and temperature are taken as input variables, and the corrosion rate or corrosion layer thickness of the alloy material is taken as response output variable for construction.

9. The method of claim 7, wherein the method is characterized by: The construction method of the ternary impurity control threshold model is as follows: Based on the output results of the response model, the ternary impurity space is globally simulated, and a dominant reaction region map is drawn; A clear "failure critical condition" is set, and the corrosion rate and corrosion layer thickness are taken as criteria to reversely solve the corresponding impurity control threshold line. Theoretical calculation and experimental verification results are combined to accurately draw the impurity control threshold map in the ternary impurity system, and the accurate boundaries of the oxidation dominant region, carbonization dominant region, evaporation dominant region and inert stable region are determined.

10. The method of claim 7, wherein the method is characterized by: The step S4 of iterative optimization of the impurity control threshold model is further included. Points or intersection regions near the boundaries of the ternary map are selected as an extended experimental group to verify the accuracy of the constructed impurity threshold model prediction, and to ensure that the model prediction error is controlled within ±10%; If the model prediction error exceeds the specified range, additional experimental data collection and theoretical calculation optimization are performed, and the model parameters are repeatedly iterated until the model error is within an acceptable range.