A method for constructing and applying a solid surface wetting model considering salt deliquescence effect

Abstract

The application discloses a kind of construction method and application method and system of solid surface wetting model considering salt deliquescence effect, belong to material surface engineering and atmospheric corrosion simulation field.For the problems that traditional pure water wetting model cannot reflect marine salt fog deposition, deliquium phase change, dry-wet cycle salt redistribution and the like, by dew point correction, surface tension correction, equivalent curvature radius correction, contact angle correction and salt density deposition amount correction, a unified condensation amount equation coupling temperature, humidity, salt composition, salt deposition amount and material surface characteristics is constructed;The critical condition of condensation can be accurately determined, the condensation amount per unit area can be calculated, the growth of liquid film and the wetting state can be described, and the corrosion risk level can be output.The application is suitable for typical marine engineering materials such as galvanized steel and silicone rubber, has the advantages of high precision, strong universality, easy to land engineering, etc., and can be used for environmental adaptability design of marine equipment, early warning and life assessment of corrosion.

Description

Technical Field

[0001] This invention belongs to the technical field of materials surface engineering and atmospheric corrosion simulation, specifically relating to a method for constructing and applying a solid surface wetting model that considers the salt deliquescence effect. Background Technology

[0002] The marine atmospheric environment is characterized by high temperature, high humidity, high salt spray, large diurnal temperature range, and frequent alternation of dry and wet conditions. In the South China Sea, East China Sea, coastal industrial areas, and island equipment environments, key materials such as galvanized steel, aluminum alloys, silicone rubber, and epoxy coatings are exposed to the elements for extended periods. Their surfaces undergo continuous coupled physicochemical processes, including salt spray particle deposition, hygroscopic deliquescence, water vapor condensation, liquid film growth, moisture evaporation, and salt crystallization and redistribution. Soluble salts in the marine atmosphere, primarily NaCl, rapidly absorb water vapor when relative humidity reaches the deliquescence threshold, forming ionic electrolyte microfilms. This significantly alters the wettability, interfacial energy, contact angle, and thermal conductivity and insulation properties of solid surfaces, directly inducing subfilm electrochemical corrosion, coating blistering, decreased adhesion, insulation degradation, and tracking, severely reducing equipment reliability and service life.

[0003] Current solid surface wetting and condensation models are mostly based on pure water vapor systems, with classical Kelvin equations, Young's equations, Fick's diffusion law, Laplace equations, and Magnus-Tetens dew point formulas as their core framework. These models have certain applicability in clean, dry, or salt-free atmospheric environments, but they have significant technical limitations in humid, hot, and salty marine environments. (1) The coupling correction of salt deliquescence on dew point, saturated vapor pressure and gas-liquid interfacial tension was not considered, and the physical nature of the decrease in vapor pressure, increase in dew point and change in surface tension caused by salt ion dissolution was ignored. The calculation deviation of the critical condition for condensation exceeded 20%. (2) No quantitative mapping between the contact angle change caused by salt deliquescence and the equivalent radius of curvature has been established, so the influence of the salt solution film spreading on the wetting morphology cannot be described. (3) The cyclic enhancement mechanism of salt deposition density and local salt concentration increase caused by salt crystallization, migration and redistribution under wet and dry cycles is not included, making it difficult to predict the wetting behavior and corrosion evolution during long-term service. (4) Temperature, relative humidity, salt density deposition, material surface energy, contact angle, and salt type are not uniformly incorporated into the coupling equation. The input is singular and the output is limited, which cannot meet the engineering prediction requirements of multiple scenarios. (5) There is a lack of dedicated test calibration methods and parameter libraries for typical marine engineering materials such as galvanized steel and silicone rubber, resulting in poor model versatility and high difficulty in engineering implementation.

[0004] Existing condensation models mostly focus on scenarios such as refrigeration, HVAC, and power insulators, with very few models addressing the entire chain of salt deliquescence-wetting-condensation-corrosion in humid and hot marine environments. However, humid and hot marine environments are complex systems formed by the coupling of multiple factors and the superposition of various phenomena. Currently, research on the environmental effects and transmission mechanisms that induce damage to power transmission equipment is lacking both domestically and internationally. The evolution process of equipment defects and failures caused by the environment is difficult to analyze in detail, affecting the effectiveness of precise prevention and control. Therefore, constructing a solid surface wetting model that couples the salt deliquescence effect, covers the entire evolution process, allows for quantifiable calculation of condensation and wetting states, and is adaptable to multiple materials, has significant theoretical and engineering value for improving the environmental adaptability design level of marine equipment and achieving early corrosion warning and accurate life assessment. Summary of the Invention

[0005] The purpose of this section is to outline some aspects of embodiments of the present invention and to briefly describe some preferred embodiments. Simplifications or omissions may be made in this section, as well as in the abstract and title of this application, to avoid obscuring the purpose of these documents; however, such simplifications or omissions should not be construed as limiting the scope of the invention.

[0006] In view of the problems existing in the above and / or prior art, the present invention is proposed.

[0007] Therefore, the purpose of this invention is to overcome the shortcomings of the prior art and provide a solid surface wetting model that takes into account the salt deliquescence effect.

[0008] To solve the above-mentioned technical problems, the present invention provides the following technical solution: the model consists of a condensation thermodynamic critical determination model corrected for salt deliquescence and a condensation quantity basic model based on Kelvin equation and diffusion kinetics; The basic model of condensation is based on the Kelvin equation, combined with water vapor diffusion flux and droplet growth dynamics, to derive the formula for calculating the condensation of pure water. The dew point, surface tension, equivalent radius of curvature, and redistribution of salt in the dry-wet cycle are coupled and corrected by salt deliquescence to obtain the calculation model of condensation per unit area as shown in formula (1). (1); In equation (1), k5 and k6 are model fitting coefficients, and P0(T) is the saturated vapor pressure at temperature T; θ s γ is the contact angle of the salt solution; sv For solid-gas interface energy; s RH(T) represents the amount of salt deposited; T represents the thermodynamic temperature; and RH(T) represents the relative humidity.

[0009] As a preferred embodiment of the solid surface wetting model considering the salt deliquescence effect described in this invention, wherein: the salt deliquescence-corrected condensation thermodynamic critical determination model T d,salt The expression is shown in equation (2); T d,salt = T d + ΔT (2; In equation (2), T d The dew point is pure water, and the calculation formula is shown in the Magnus-Tetens formula of formula (4); ΔT is the dew point increase, and the calculation formula is shown in formula (3); ΔT≈k·C salt (3); In equation (3), k is the salt characteristic constant; C salt The salt mass fraction is used as the criterion for condensation occurrence; the solid surface temperature T is used as the criterion for condensation occurrence. s <T d,salt ; Among them, pure water-based condensate T d The calculation module uses the Magnus-Tetens formula as shown in equation (4); (4); In equation (4), A = 17.27℃; B = 237.7℃; T is the ambient temperature; and RH is the relative humidity.

[0010] As a preferred embodiment of the solid surface wetting model considering the salt deliquescence effect described in this invention, wherein: the surface tension coupling correction introduces the salt density deposition amount s Surface tension of salt solution γ salt Satisfying equation (5); γ salt =γ lv +k4· s (5); In equation (5), γ lv The surface tension is the liquid-gas interfacial tension of pure water, which is derived from the Neumann equation, as shown in equation (6); k4 is the surface tension correction coefficient. (6); In equation (6), γ sv Let θ be the solid-gas interface energy, and θ be the contact angle of pure water.

[0011] As a preferred embodiment of the solid surface wetting model considering the salt deliquescence effect described in this invention, the coupling correction of the equivalent radius of curvature is based on the droplet volume conservation, resulting in the corrected equivalent radius of curvature r. s The calculation formula is shown in formula (7); (7); In equation (7), θ is the contact angle of pure water; θ s This represents the contact angle of the salt solution.

[0012] As a preferred embodiment of the solid surface wetting model considering the salt deliquescence effect described in this invention, the dry-wet cycle salt redistribution includes water evaporation and salt crystallization accumulation under low humidity conditions. s Increased humidity; under high humidity, salt particles deliquesce again, increasing solution concentration, decreasing contact angle, and intensifying condensation.

[0013] Another object of the present invention is to provide an application method for a solid surface wetting model that takes into account the salt deliquescence effect.

[0014] To solve the above-mentioned technical problems, the present invention provides the following technical solution: including, Obtain environmental and material parameters, including ambient temperature T, relative humidity RH, and solid surface temperature T. s Solid-gas interface energy γ sv Contact angle θ of pure water, contact angle θ of salt solution s Salt density sedimentation ; Calculate the dew point T of pure water using the Magnus-Tetens formula d By combining the salt characteristic constant and the salt mass fraction correction, the deliquescence correction T is obtained. d,salt Based on the solid surface temperature T s With deliquescence correction dew point T d,salt The size relationship determines whether condensation has occurred; If T s <T d,salt If condensation occurs, the environmental and material parameters are substituted into the calculation model of condensation per unit area shown in formula (1) to calculate the condensation per unit area and output the wetting state of the material surface to determine the corrosion risk level.

[0015] As a preferred embodiment of the application method of the solid surface wetting model considering the salt deliquescence effect described in this invention, the solid surface wetting model is suitable for predicting the wetting behavior of materials in marine atmospheric environments, early warning of corrosion, and life assessment.

[0016] As a preferred embodiment of the application method of the solid surface wetting model considering the salt deliquescence effect described in this invention, the materials include galvanized steel sheet, silicone rubber, epoxy coating, aluminum alloy, and stainless steel.

[0017] Beneficial effects of this invention: (1) By coupling salt deliquescence multi-dimensional correction, the calculation error of condensation critical condition and condensation amount is ≤10%, and the prediction accuracy is significantly improved.

[0018] (2) It fully simulates the six-stage process of salt deposition, deliquescence, condensation, evaporation, recrystallization and re-deliquescence, and can predict the evolution of wetting and corrosion over a long period of time.

[0019] (3) It is applicable to typical marine equipment materials such as galvanized steel plate, silicone rubber, epoxy coating, aluminum alloy, and stainless steel, and has strong versatility.

[0020] (4) It is equipped with a complete parameter acquisition, test calibration, coefficient fitting and verification process, which can be directly used for equipment environmental adaptability design.

[0021] (5) It can output condensation judgment, condensation amount, surface wetting status and corrosion risk level, and support early warning of corrosion and accurate life assessment. Attached Figure Description

[0022] To more clearly illustrate the technical solutions of the embodiments of the present invention, the drawings used in the description of the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort. Wherein: Figure 1 This is a diagram illustrating the six-stage evolution mechanism of the condensation model constructed based on the salt deliquescence effect in this invention.

[0023] Figure 2 This is a schematic diagram illustrating the effect of salt redistribution during wet-dry cycles on condensation. Detailed Implementation

[0024] To make the above-mentioned objects, features and advantages of the present invention more apparent and understandable, the specific embodiments of the present invention will be described in detail below with reference to the examples in the specification.

[0025] Many specific details are set forth in the following description in order to provide a full understanding of the invention. However, the invention may also be practiced in other ways different from those described herein, and those skilled in the art can make similar extensions without departing from the spirit of the invention. Therefore, the invention is not limited to the specific embodiments disclosed below.

[0026] Secondly, the term "one embodiment" or "embodiment" as used herein refers to a specific feature, structure, or characteristic that may be included in at least one implementation of the present invention. The phrase "in one embodiment" appearing in different places in this specification does not necessarily refer to the same embodiment, nor is it a single or selective embodiment that is mutually exclusive with other embodiments.

[0027] Example 1 Reference Figure 1 The six evolution stages of a solid surface wetting model that takes into account the salt deliquescence effect include: (1) Solid materials are placed in a humid and hot marine atmospheric environment; (2) Marine salt spray particles deposit on solid surfaces to form salt nuclei; (3) Salt nuclei deliquesce to form a liquid film and trigger water vapor condensation; (4) In low humidity environments, water evaporates, salt crystallizes, and is spatially redistributed; (5) In high humidity environments, salt crystals deliquesce again, and the amount of condensation increases further; (6) The formation of high-concentration electrolyte can induce under-film corrosion or material deterioration; Based on this evolutionary stage, this embodiment provides a method for constructing a solid surface wetting model that considers the salt deliquescence effect, specifically: The model consists of a critical condensation thermodynamic determination model corrected for salt deliquescence and a basic condensation amount model based on Kelvin equations and diffusion kinetics. 1) Critical condensation thermodynamic determination model corrected for salt deliquescence: Based on the Magnus-Tetens pure water dew point formula shown in equation (4): (4); In equation (4), A = 17.27℃; B = 237.7℃; T is the ambient temperature; and RH is the relative humidity.

[0028] In marine environments, the dew point rises due to the decrease in saturated vapor pressure caused by salt dissolution. Therefore, a correction factor ΔT is introduced. ΔT≈k·C salt (3); k is the salt characteristic constant; C salt This represents the salt mass fraction; in the NaCl system, k ≈ 0.3℃ / % The final revised thermodynamic criticality determination model for condensation is shown in equation (2): T d,salt = T d + ΔT (2; The criterion for condensation is the solid surface temperature T. s <T d,salt .

[0029] 2) Basic model for condensation: S1: Basic model for condensation rate based on pure water; The core is the Kelvin equation shown in equation (8): (8); In equation (8), P sat(T) is the surface vapor pressure, P is the actual vapor pressure, and γ lv It is the gas-liquid interfacial tension, V m is the liquid molar volume, r is the radius of curvature of the droplet, T is the temperature, and R is the gas constant.

[0030] Combining water vapor diffusion flux and droplet growth kinetics, the condensation rate of pure water is derived as shown in equation (9); (9); In equation (9), k2 is the derivation process coefficient, P0(T) is the vapor pressure, and γ lv It is the gas-liquid interfacial tension, V m is the liquid molar volume, r is the radius of curvature of the droplet, T is the temperature, RH is the relative humidity, and V is the condensation droplet volume.

[0031] S2: Salt deliquescence surface tension correction; Increased salt concentration leads to increased interfacial tension, resulting in increased salt density deposition. s The surface tension γsalt of a salt solution satisfies equation (5); γ salt =γ lv +k4· s (5); The calculation formula shown in equation (6) is derived by combining the Neumann equation: (6); In equation (5), γ lv The surface tension is the liquid-gas interfacial tension of pure water, which is derived from the Neumann equation, as shown in equation (6); k4 is the surface tension correction coefficient. S3: Equivalent radius of curvature correction; Since the contact angle changes due to salt deliquescence, based on volume conservation, we know that: (7); In equation (7), θ is the contact angle of pure water; θ s This represents the contact angle of the salt solution.

[0032] S4: Correction for salt redistribution in wet-dry cycles.

[0033] like Figure 2 As shown, low humidity evaporation and crystallization lead to increased salt density; high humidity re-deliquescence leads to increased concentration, decreased contact angle, and enhanced condensation, ultimately resulting in a change in salt density deposition. See the detailed equations and processes below. Figure 2 .

[0034] S5: Basic model for final condensation amount; By combining all the correction terms, we obtain the condensation per unit area considering salt deliquescence: (1); In equation (1), k5 and k6 are model fitting coefficients; P0(T) is the saturated vapor pressure at temperature T; θ s γ is the contact angle of the salt solution; sv For solid-gas interface energy; s RH(T) represents the amount of salt deposited; T represents the thermodynamic temperature; and RH(T) represents the relative humidity.

[0035] Example 2 This embodiment provides a method for applying the model of Embodiment 1, specifically: 1. Experimental materials: (1) Metal sample: hot-dip galvanized steel sheet, 50mm×50mm×1mm, Ra≤0.8μm; (2) Insulation sample: methyl vinyl silicone rubber, 2 mm thick; (3) Reagents: Analytical grade NaCl, deionized water, and anhydrous ethanol; (4) Auxiliary materials: dust-free paper, high-precision weighing paper. 2. Test equipment: Constant temperature and humidity chamber, high-precision temperature and humidity acquisition instrument, contact angle measuring instrument, electronic analytical balance, conductivity meter, and saturated salt solution equilibrium humidity testing device.

[0036] 3. Verification experiment of the thermodynamic criticality determination model for condensation corrected for salt deliquescence: Orthogonal experiments were conducted on galvanized steel (D) and silicone rubber (G) metal samples under the conditions of temperatures T=25 / 45 / 65 / 85℃ and RH=60% / 70% / 80% / 90%. The results were recorded. s Verify T with condensation state s <T d,salt The accuracy rate was 100%.

[0037] 4. Verification test of the basic model for condensation amount: At T=75 / 85℃, RH=80% / 90%, different s The P0(T) and θ of the test sample s V salt The fitting yielded k5 and k6, where k5 = 9 × 10⁻⁶. -5 k6 = 0.74; 5. Equilibrium humidity (RH) of saturated salt solution salt (T) test; (1) Heat deionized water to the target temperature; (2) Add excess NaCl to prepare a saturated solution; (3) Seal the container, circulate a gentle breeze, and read the RH after stabilization.

[0038] 6. Example of model calculation; Input: T=85℃, RH=90%, s =0.005kg / m 2 γ sv =0.032 N / m, θ s =45° Output: V salt =8.6×10 -6 m 3 / m 2 (1) Condensation occurs: Yes; (2) Condensation V salt =8.6×10 -6 m 3 / m 2 .

[0039] In summary, this invention addresses the shortcomings of traditional pure water wetting models in reflecting marine salt spray deposition, deliquescence phase transition, and salt redistribution during wet-dry cycles. By correcting for dew point, surface tension, equivalent radius of curvature, contact angle, and salt density deposition, a unified condensation equation is constructed that couples temperature, humidity, salt composition, salt deposition amount, and material surface properties. The model covers the six-stage evolution mechanism of salt deposition-deliquescence-condensation-evaporation-recrystallization-redeliquescence, accurately determining critical condensation conditions, calculating condensation per unit area, describing liquid film growth and wetting status, and outputting corrosion risk levels. This invention is applicable to typical marine engineering materials such as galvanized steel and silicone rubber, possessing advantages such as high precision, strong versatility, and ease of engineering implementation. It can be used for environmental adaptability design of marine equipment, early corrosion warning, and life assessment.

[0040] It should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and are not intended to limit it. Although the present invention has been described in detail with reference to preferred embodiments, those skilled in the art should understand that modifications or equivalent substitutions can be made to the technical solutions of the present invention without departing from the spirit and scope of the technical solutions of the present invention, and all such modifications or substitutions should be covered within the scope of the claims of the present invention.

Claims

1. A solid surface wetting model considering the salt deliquescence effect, characterized in that: The model consists of a critical condensation thermodynamic determination model corrected for salt deliquescence and a basic condensation amount model based on Kelvin equations and diffusion kinetics. The basic model of condensation is based on the Kelvin equation, combined with water vapor diffusion flux and droplet growth dynamics, to derive the formula for calculating the condensation of pure water. The dew point, surface tension, equivalent radius of curvature, and redistribution of salt in the dry-wet cycle are coupled and corrected by salt deliquescence to obtain the calculation model of condensation per unit area as shown in formula (1). （1）; In equation (1), k5 and k6 are model fitting coefficients; P0(T) is the saturated vapor pressure at temperature T; θ s γ is the contact angle of the salt solution; sv For solid-gas interface energy; s RH(T) represents the amount of salt deposited; T represents the thermodynamic temperature; and RH(T) represents the relative humidity.

2. The solid surface wetting model considering the salt deliquescence effect as described in claim 1, characterized in that: The salt deliquescence-corrected thermodynamic criticality determination model T d,salt The expression is shown in equation (2); T d,salt = T d + ΔT (2); In equation (2), T d The dew point is pure water, and the calculation formula is shown in the Magnus-Tetens formula of formula (4); ΔT is the dew point increase, and the calculation formula is shown in formula (3); ΔT≈k·C salt (3); In equation (3), k is the salt characteristic constant; C salt The salt mass fraction is used as the criterion for condensation occurrence; the solid surface temperature T is used as the criterion for condensation occurrence. s <T d,salt ; Among them, pure water-based condensate T d The calculation module uses the Magnus-Tetens formula as shown in equation (4); （4）； In equation (4), A = 17.27℃; B = 237.7℃; T is the ambient temperature; and RH is the relative humidity.

3. The solid surface wetting model considering the salt deliquescence effect as described in claim 1, characterized in that: The surface tension coupling correction introduces salt density deposition. s Surface tension of salt solution γ salt Satisfying equation (5); c salt =c lv +k4· s (5); In equation (5), γ lv The surface tension is the liquid-gas interfacial tension of pure water, which is derived from the Neumann equation, as shown in equation (6); k4 is the surface tension correction coefficient. （6）； In equation (6), γ sv Let θ be the solid-gas interface energy, and θ be the contact angle of pure water.

4. The solid surface wetting model considering the salt deliquescence effect as described in claim 1, characterized in that: The coupling correction of the equivalent radius of curvature is based on the droplet volume conservation, resulting in the corrected equivalent radius of curvature r. s The calculation formula is shown in formula (7); （7）； In equation (7), θ is the contact angle of pure water; θ s This represents the contact angle of the salt solution.

5. The solid surface wetting model considering the salt deliquescence effect as described in claim 1, characterized in that: The dry-wet cycle salt redistribution includes water evaporation and salt crystallization and aggregation under low humidity conditions. s Increased humidity; under high humidity, salt particles deliquesce again, increasing solution concentration, decreasing contact angle, and intensifying condensation.

6. A method for applying the solid surface wetting model according to any one of claims 1 to 5, characterized in that: include, Obtain environmental and material parameters, including ambient temperature T, relative humidity RH, and solid surface temperature T. s Solid-gas interface energy γ sv Contact angle θ of pure water, contact angle θ of salt solution s Salt density sedimentation ρ s ; Calculate the dew point T of pure water using the Magnus-Tetens formula d By combining the salt characteristic constant and the salt mass fraction correction, the deliquescence correction T is obtained. d,salt Based on the solid surface temperature T s With deliquescence correction dew point T d,salt The size relationship determines whether condensation has occurred; If T s <T d,salt If condensation occurs, the environmental and material parameters are substituted into the calculation model of condensation per unit area shown in formula (1) to calculate the condensation per unit area and output the wetting state of the material surface to determine the corrosion risk level.

7. The method for applying the solid surface wetting model as described in claim 6, characterized in that: The solid surface wetting model is applicable to predicting the wetting behavior of materials in marine atmospheric environments, early warning of corrosion, and lifetime assessment.

8. The method for applying the solid surface wetting model as described in claim 7, characterized in that: The materials include galvanized steel sheet, silicone rubber, epoxy coating, aluminum alloy, and stainless steel.

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