Method for evaluating blackening tendency of organic passivation magnesium-containing coating steel plate
By combining aging and damp heat tests with ultraviolet light and high temperature and humidity environment to simulate natural conditions, color difference values are obtained to determine the blackening tendency of magnesium-coated steel plates, solving the problem of darkening of steel plate surface color and achieving more accurate evaluation.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2025-12-05
- Publication Date
- 2026-03-13
AI Technical Summary
Magnesium-coated steel sheets are prone to darkening (blackening) during storage and use, and there is a lack of effective evaluation methods.
By obtaining the initial surface color parameters, an aging damp heat test is conducted. By combining ultraviolet light and high temperature and humidity environment to simulate natural conditions, the color difference value is calculated to determine the tendency of blackening.
It improves the accuracy and reliability of blackening evaluation, overcomes the limitations of traditional single damp heat test, simulates the actual environment more closely, and enhances the scientific nature of the evaluation results.
Smart Images
Figure CN121656155A_ABST
Abstract
Description
Technical Field
[0001] This application relates to the field of steel corrosion technology, and in particular to a method for evaluating the tendency of blackening of organically passivated magnesium-coated steel plates. Background Technology
[0002] Hot-dip galvanized steel sheets are widely used in the automotive, home appliance, and construction industries due to their excellent corrosion resistance and cost advantages. To further improve corrosion resistance, magnesium is added to the coating to form magnesium-coated steel sheets. However, during actual storage and use, the surface of these magnesium-coated sheets is prone to gradual darkening, a phenomenon known as "blackening," which seriously affects the appearance quality of the product. Therefore, there is an urgent need for a method to evaluate the blackening tendency of organically passivated magnesium-coated steel sheets to address the aforementioned problem. Summary of the Invention
[0003] The summary section introduces a series of simplified concepts, which will be further explained in detail in the detailed description section. This summary section is not intended to limit the key and essential technical features of the claimed technical solutions, nor is it intended to determine the scope of protection of the claimed technical solutions.
[0004] Firstly, this application provides a method for evaluating the tendency of organic passivated magnesium-containing coated steel sheets to turn black, including: Obtain the initial surface color parameters of the organic passivated magnesium-coated steel sheet to be tested; An aging damp heat test was conducted on the organic passivated magnesium-containing coated steel sheet to be tested. Obtain the surface color parameters of the tested organic passivated magnesium-coated steel sheet after the aging damp heat test; The color difference value is calculated based on the initial surface color parameters and the surface color parameters after the experiment; Based on the color difference value, the tendency of the tested organic passivated magnesium-coated steel sheet to turn black is determined.
[0005] In some embodiments, the initial surface color parameters include initial brightness, initial red-green hue, and initial blue-yellow hue; the post-test surface color parameters include post-test brightness, post-test red-green hue, and post-test blue-yellow hue.
[0006] In some embodiments, the aging and damp heat test includes multiple test cycles, each test cycle including an aging test and a damp heat test.
[0007] In some implementations, the number of test cycles is a first preset number, and the duration of each test cycle is a first preset duration.
[0008] In some embodiments, the aging test includes irradiating the organic passivated magnesium-coated steel sheet to be tested with an ultraviolet light source, wherein the irradiation temperature is controlled within a first preset temperature range and the irradiation intensity is controlled within a first preset intensity range.
[0009] In some embodiments, the ultraviolet light source is a UVA 340 ultraviolet fluorescent lamp with a peak wavelength of 340 nm.
[0010] In some embodiments, the damp heat test includes placing the organic passivated magnesium-coated steel sheet to be tested in a damp heat environment, wherein the damp heat temperature is controlled within a second preset temperature range and the relative humidity is controlled within a first preset humidity range.
[0011] In some embodiments, in each test cycle, the proportion of the duration of the aging test to the duration of each test cycle is a first preset proportion, the proportion of the duration of the damp heat test to the duration of each test cycle is a second preset proportion, and the proportion of the transition duration between the aging test and the damp heat test to the duration of each test cycle is a third preset proportion, and the sum of the first preset proportion, the second preset proportion, and the third preset proportion is 1.
[0012] In some embodiments, calculating the color difference value based on the initial surface color parameters and the post-test surface color parameters includes: The brightness difference is determined based on the initial brightness and the brightness after the test; The red-green color difference is determined based on the initial red-green color and the red-green color after the test; The difference in blue-yellow hue is determined based on the initial blue-yellow hue and the blue-yellow hue after the test; The color difference value is calculated based on the brightness difference, the red-green hue difference, and the blue-yellow hue difference.
[0013] In some embodiments, determining the blackening tendency of the tested organic passivated magnesium-coated steel sheet based on the color difference value includes: The color difference value is compared with a preset blackening evaluation threshold to obtain the comparison result; Based on the comparison results, the tendency of the tested organic passivated magnesium-coated steel sheet to turn black was determined.
[0014] Secondly, this application proposes a device for evaluating the tendency of blackening of organically passivated magnesium-coated steel sheets, comprising: The initial parameter acquisition unit acquires the initial surface color parameters of the organic passivated magnesium-coated steel sheet to be tested. The aging and damp heat test unit is used to conduct aging and damp heat tests on the organic passivated magnesium-containing coated steel sheet to be tested. The test parameter acquisition unit is used to acquire the surface color parameters of the tested organic passivated magnesium-coated steel sheet after the aging damp heat test; A surface color difference calculation unit is used to calculate the color difference value based on the initial surface color parameters and the surface color parameters after the test; A blackening tendency evaluation unit is used to determine the blackening tendency of the tested organic passivated magnesium-coated steel sheet based on the color difference value.
[0015] Thirdly, an electronic device includes: a memory, a processor, and a computer program stored in the memory and executable on the processor, wherein the processor executes the computer program stored in the memory to implement the steps of the method for evaluating the blackening tendency of organic passivated magnesium-coated steel sheets according to any one of the first aspects.
[0016] Fourthly, this application also proposes a computer-readable storage medium having a computer program stored thereon, wherein when the computer program is executed by a processor, it implements the steps of the method for evaluating the blackening tendency of organic passivated magnesium-coated steel sheets according to any one of the first aspects.
[0017] In summary, this application provides a method for evaluating the blackening tendency of organically passivated magnesium-coated steel sheets. The method involves obtaining the initial surface color parameters of the sample and conducting a comprehensive test combining aging and damp heat treatment. The surface color parameters are then measured again after the test, and the color difference value is calculated. Finally, the blackening tendency is objectively determined based on this color difference value. This method effectively overcomes the limitations of traditional single damp heat tests by simultaneously simulating light aging and damp heat conditions in a laboratory environment. This makes the accelerated test conditions closer to the actual environment, thereby improving the accuracy and reliability of the blackening tendency evaluation results. Attached Figure Description
[0018] Various other advantages and benefits will become apparent to those skilled in the art upon reading the following detailed description of preferred embodiments. The accompanying drawings are for illustrative purposes only and are not intended to limit this specification. Furthermore, the same reference numerals denote the same parts throughout the drawings. In the drawings: Figure 1 This is a schematic flowchart of a method for evaluating the blackening tendency of organic passivated magnesium-coated steel plates, provided in an embodiment of this application. Figure 2 A schematic diagram of one cycle of the aging damp heat test process A provided in the embodiments of this application; Figure 3 A schematic diagram of one cycle of the aging damp heat test process B provided in the embodiment of this application; Figure 4 A schematic diagram of one cycle of the aging damp heat test process C provided in the embodiments of this application; Figure 5 A schematic diagram of a device for evaluating the blackening tendency of organic passivated magnesium-coated steel plates provided in this application embodiment; Figure 6 This is a schematic diagram of an electronic device for evaluating the blackening tendency of an organically passivated magnesium-coated steel plate, as provided in an embodiment of this application. Detailed Implementation
[0019] The terms "first," "second," "third," "fourth," etc. (if present) in the specification, claims, and accompanying drawings of this application are used to distinguish similar objects and are not necessarily used to describe a specific order or sequence. It should be understood that such data can be interchanged where appropriate so that the embodiments described herein can be implemented in a sequence other than that illustrated or described herein. Furthermore, the terms "comprising" and "having," and any variations thereof, are intended to cover non-exclusive inclusion; for example, a process, method, system, product, or apparatus that comprises a series of steps or units is not necessarily limited to those steps or units explicitly listed, but may include other steps or units not explicitly listed or inherent to such processes, methods, products, or apparatus. The technical solutions of the embodiments of this application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only a part of the embodiments of this application, and not all of them.
[0020] Please see Figure 1 This is a schematic diagram of a method for evaluating the blackening tendency of organic passivated magnesium-coated steel plates according to an embodiment of this application, which may specifically include: S110. Obtain the initial surface color parameters of the organic passivated magnesium-coated steel sheet to be tested. For example, in step S110, the surface of the organic passivated magnesium-coated steel sheet to be tested is measured using a colorimeter or similar colorimetric device to obtain its initial color parameters. These color parameters are typically characterized using the internationally recognized Lab color space, where the L component represents lightness, the a component represents chromaticity in the red-green direction, and the b component represents chromaticity in the yellow-blue direction. The purpose of obtaining the initial surface color parameters is to establish an accurate benchmark for subsequent evaluation of the tendency to darken, ensuring that the quantitative comparison of color changes before and after the test is scientific and repeatable.
[0021] S120. An aging damp heat test was conducted on the organic passivated magnesium-containing coated steel sheet to be tested. For example, the aging damp heat test in step S120 aims to simulate the synergistic effect of sunlight and humidity in a natural atmospheric environment. This test accelerates the aging process of the organic passivation film and induces potential blackening of the coating surface through alternating periods of ultraviolet (UV) irradiation and high-temperature, high-humidity environments. UV irradiation primarily simulates the UV band in solar radiation that is highly destructive to organic components, inducing photodegradation of the passivation film; while the high-temperature, high-humidity environment provides the necessary conditions for the electrochemical corrosion and discoloration reaction of the coating itself. These accelerated test conditions more realistically reflect the performance evolution of the sample under actual outdoor exposure.
[0022] S130. Obtain the surface color parameters of the organic passivated magnesium-coated steel sheet to be tested after the aging damp heat test. For example, in step S130, after completing the aging and damp heat test, a colorimeter of the same model and configuration as in step S110 is used again to measure the color at the same location on the surface of the same organic passivated magnesium-coated steel sheet to be tested. This measurement aims to obtain the surface color state of the sample after accelerated aging and environmental effects. The obtained post-test surface color parameters will be characterized in the same color space system as the initial parameters, providing an accurate data basis for subsequent calculations of color change.
[0023] S140. Calculate the color difference value based on the initial surface color parameters and the surface color parameters after the test; For example, in step S140, the color difference value between the two is calculated by comparing the surface color parameters measured after the test with the initial surface color parameters. This color difference value is an objective indicator that quantifies the degree of surface color change of the sample after undergoing an aging and damp heat test. Its calculation is based on a comprehensive calculation of the differences of each component in the color space. The calculation result directly reflects the color deviation of the sample surface caused by the test conditions and can accurately characterize the darkening of the surface color caused by the aging and damp heat test.
[0024] S150. Based on the color difference value, determine the blackening tendency of the organic passivated magnesium-coated steel sheet to be tested.
[0025] For example, in step S150, the tendency of the organically passivated magnesium-coated steel sheet to blacken is determined based on the calculated color difference value. This color difference value objectively quantifies the degree of color change that occurs on the sample surface before and after undergoing a comprehensive aging damp heat test. Generally, an increase in the color difference value directly reflects a decrease in the brightness of the sample surface and a trend of color shifting towards a darker tone. This change is consistent with the blackening phenomenon observed in actual storage and use environments. Therefore, by comparing the calculated color difference value with an evaluation standard or threshold range established in advance through the accumulation of a large amount of experimental data and experience, an objective evaluation of the blackening tendency of the tested sample can be made, thus providing a key basis for judging the weather resistance performance of the material.
[0026] In summary, this application uses the initial surface color parameters of the sample as a benchmark, followed by a comprehensive test combining ultraviolet aging and high-temperature, high-humidity environments. This simulates the synergistic effect of sunlight and humidity in the actual atmospheric environment. After the test, the surface color parameters are measured again and the color difference value is calculated. Finally, based on this color difference value, the blackening tendency of the material is objectively quantified and determined. This method effectively reproduces the key influencing factors that cause blackening of organic passivated magnesium-coated steel sheets in the natural environment under laboratory conditions. It overcomes the limitations of traditional single humidity and heat tests that ignore the effects of photoaging, making the accelerated test conditions closer to the real environment of the material. This significantly improves the accuracy and reliability of the blackening tendency evaluation results, providing a scientific basis for product quality control, material process optimization, and service life prediction.
[0027] In some instances, the initial surface color parameters include initial brightness, initial red-green hue, and initial blue-yellow hue; the post-test surface color parameters include post-test brightness, post-test red-green hue, and post-test blue-yellow hue.
[0028] For example, in steps S110 and S130, the Lab color space is chosen instead of other color systems such as RGB to characterize the initial and post-experiment surface color parameters. This is because the Lab color space is a device-independent color model based on human visual perception. Specifically, the Lab color space decomposes color into lightness (L component), red-green hue (a component), and yellow-blue hue (b component). Its design allows the Euclidean distance in the color space to approximately correspond to the color differences perceived by the human eye. Compared to the RGB color system, which depends on the photoelectric characteristics of specific devices, the Lab color system provides an absolute and uniform color scale, ensuring the comparability and repeatability of color data obtained under different measurement devices and ambient light sources. Furthermore, the Lab color space exhibits higher sensitivity and accuracy in characterizing color changes, especially for the decrease in lightness (i.e., blackening) and accompanying chromaticity shifts on metal coating surfaces caused by corrosion or oxidation. The L component directly and linearly reflects the lightness and darkness changes of the sample surface, while the a and b components effectively capture subtle tonal shifts that may accompany the blackening process. Therefore, the Lab color space is used to quantify the surface color parameters, providing a color data basis for subsequent accurate calculation of color difference values and objective evaluation of blackening tendency.
[0029] In summary, by obtaining initial and post-experimental surface color parameters based on the Lab color space, this application ensures that subsequent color difference calculations accurately reflect surface color changes perceptible to the human eye, particularly the decrease in lightness directly related to blackening. The device-independent nature of this color model guarantees the consistency and comparability of measurement data under different instruments and conditions, thus improving the reliability of the evaluation results.
[0030] In some instances, the aging and damp heat test comprises multiple test cycles, each cycle including an aging test and a damp heat test. The number of test cycles is a first preset number, and the duration of each test cycle is a first preset duration.
[0031] For example, in an aging and damp heat test, the test comprises multiple consecutive test cycles, each containing both an aging test phase and a damp heat test phase. This multi-cycle structure is designed to more realistically simulate the alternating effects of sunlight and damp heat conditions in a natural environment. The total duration of each test cycle is set as a first preset duration, which preferably aligns with the natural day cycle, such as 24 hours, to match the basic environmental cyclical rhythm experienced by the material in a real environment. The total number of test cycles is set as a first preset number, determined based on the cumulative stress level required to sufficiently accelerate material aging and induce measurable blackening; the first preset number is 8.
[0032] In some instances, the aging test involves irradiating the organic passivated magnesium-coated steel sheet under test with an ultraviolet light source, wherein the irradiation temperature is controlled within a first preset temperature range, the irradiation intensity is controlled within a first preset intensity range, and the ultraviolet light source is a UVA 340 ultraviolet fluorescent lamp with a peak wavelength of 340 nm.
[0033] For example, during the aging test, an ultraviolet (UV) light source is used to irradiate the organic passivated magnesium-coated steel sheet under test. The UV light source is preferably a UVA 340 UV fluorescent lamp with a peak wavelength of 340 nm. This wavelength is chosen because it highly overlaps with the UV band in outdoor sunlight, especially the UV band that significantly affects the aging of organic materials, thus ensuring that the laboratory lighting conditions can effectively simulate the UV radiation in natural sunlight. During irradiation, the irradiation intensity is controlled within a first preset intensity range, specifically 0.5 W / m² at 340 nm. 2 Up to 1.2 W / m 2 This range is set with reference to a midday summer solar radiation intensity of approximately 0.55 W / m². 2The 340nm wavelength is designed to simulate real-world solar ultraviolet irradiation levels. If the irradiation intensity is below the lower limit of this range, the aging and destructive effects of midday sunlight on the organic passivation film cannot be adequately simulated, resulting in a smaller induced color difference value and insufficient evaluation sensitivity. If the irradiation intensity is above the upper limit of this range, it may introduce atypical destructive mechanisms beyond the actual environment, leading to a larger color difference value and distorted evaluation results. Simultaneously, the ambient temperature during the irradiation process is controlled within a first preset temperature range, specifically 30℃ to 50℃. This temperature range also considers the characteristics of summer ambient temperatures, aiming to provide a temperature field that accelerates aging without causing thermal decomposition or excessive reactions in the material. Too low a temperature will slow down the photochemical reaction rate, resulting in a smaller color difference value and a conservative evaluation; too high a temperature may trigger a non-photoaging-dominated thermal aging mechanism, leading to a larger color difference value and also distorted evaluation results. By controlling the type, peak wavelength, irradiation intensity, and ambient temperature of the ultraviolet light source within the aforementioned specific ranges, aging tests can effectively and reliably simulate the aging effect of outdoor sunlight, especially ultraviolet radiation, on organic passivation films under laboratory conditions. This provides photo-aging stress conditions for inducing and evaluating the tendency of coatings to blacken, and ensures that the resulting color changes are comparable to real environmental exposure.
[0034] In summary, this embodiment of the application uses a UVA 340 ultraviolet fluorescent lamp as the light source, and precisely controls its irradiation intensity and ambient temperature to 0.5 W / m². 2 Up to 1.2 W / m 2 Within a specific temperature range of 30°C to 50°C, this aging test phase effectively and controllably simulates natural sunlight ultraviolet radiation and typical ambient temperature conditions in the laboratory. This refined parameter control ensures that the photoaging process experienced by the organic passivation film has a sufficient acceleration factor to shorten the test cycle, while avoiding distortion caused by overstress conditions. This allows the surface color changes induced by the aging test to accurately reflect the performance degradation trend of the material under actual use conditions due to light exposure. This design improves the simulation fidelity and reliability of the aging test phase, and ensures a significant improvement in simulating real-world environmental factors compared to traditional single damp heat tests.
[0035] In some instances, the damp heat test involves placing the organic passivated magnesium-coated steel sheet to be tested in a damp heat environment, with the damp heat temperature controlled within a second preset temperature range and the relative humidity controlled within a first preset humidity range.
[0036] For example, during the damp heat test, the organic passivated magnesium-coated steel sheet to be tested is placed in a damp heat chamber with controllable environmental parameters to create and maintain a stable high-temperature and high-humidity environment. The temperature of the damp heat environment is controlled within a second preset temperature range, which is 40°C to 60°C; simultaneously, the relative humidity of the environment is controlled within a first preset humidity range, which is 70% to 90%. The setting of the second preset temperature range and the first preset humidity range is based on simulating the typical storage environment of magnesium-coated steel sheets and achieving effective and accelerated evaluation. If the damp heat temperature is below 40℃ or the relative humidity is below 70%, the environmental conditions are too mild, making it difficult to effectively induce a significant blackening reaction on the coating surface within a reasonable test period, resulting in an excessively long evaluation cycle and low efficiency. Conversely, if the damp heat temperature is above 60℃ or the relative humidity is above 90%, the environmental conditions are too harsh, easily leading to the rapid formation of secondary corrosion products such as white rust on the coating surface. The coverage of these products can interfere with or even obscure the true blackening phenomenon, increasing the difficulty of judging the degree of blackening. Furthermore, these extreme conditions differ significantly from the actual storage environment, potentially leading to distorted evaluation results. Therefore, by limiting the temperature and humidity parameters of the damp heat test to the aforementioned specific range, a simulated environment that is both sufficiently accelerated for the occurrence of coating blackening can be provided, while avoiding the introduction of interfering factors, ensuring that the test can effectively and reliably induce and exhibit a blackening tendency consistent with actual storage conditions.
[0037] In summary, this embodiment of the application effectively simulates the typical humid and hot environment faced by magnesium-coated steel sheets during actual storage by precisely controlling the ambient temperature and relative humidity of the damp heat test within specific ranges of 40°C to 60°C and 70% to 90%, respectively. This parameter setting provides the necessary accelerating force for the occurrence of blackening of the coating under laboratory conditions, ensuring that measurable color changes are induced within a reasonable test period, while avoiding interference from side reactions such as surface white rust caused by overly harsh conditions. This improves the relevance and effectiveness of the damp heat test stage in simulating real-world environmental stress.
[0038] In some instances, the proportion of the duration of the aging test to the duration of each test cycle is a first preset proportion, the proportion of the duration of the damp heat test to the duration of each test cycle is a second preset proportion, and the proportion of the transition time between the aging test and the damp heat test to the duration of each test cycle is a third preset proportion. The sum of the first preset proportion, the second preset proportion, and the third preset proportion is 1.
[0039] For example, in each test cycle, the proportion of the aging test duration to the total test cycle duration is set as a first preset proportion, the proportion of the damp heat test duration is set as a second preset proportion, and the proportion of the transition time consumed between the aging test and the damp heat test stages is set as a third preset proportion. These three proportion parameters satisfy the constraint that they sum to 1, and together define the time allocation structure of a test cycle. The specific range of the first preset proportion is set to 20% to 40%. This range is established based on the reality that the actual sunshine duration in the natural environment accounts for approximately the proportion of the entire day, aiming to ensure that the aging test stage can effectively simulate the aging effect of daytime ultraviolet light on the organic passivation film. If this proportion is too low, the cumulative dose of ultraviolet radiation will be insufficient, failing to fully simulate the damage of sunlight to the passivation film, resulting in a smaller induced color difference value and a decrease in evaluation sensitivity. The second preset ratio is set within a range of 60% to 80%, reflecting the characteristics of prolonged humid and hot conditions outside of intermittent sunlight in the natural environment. This ensures sufficient time during the humid and hot test phase to simulate the promoting effect of atmospheric moisture and temperature on the blackening process of the coating. If this ratio is too low, the induction effect of the humid and hot environment on coating corrosion and blackening will be insufficient, which will also lead to a smaller measured color difference value. The third preset ratio is strictly limited to no more than 5%. Its purpose is to minimize the time occupied by non-test states (i.e., process transitions), ensure the proportion of effective test time in each cycle, and avoid the dilution of the actual intensity of the aging and humid and hot environmental stresses due to excessively long transition time, thereby causing the color difference measurement results to be smaller and the evaluation inaccurate. By precisely defining and constraining these three time ratio parameters and their interrelationships, it is ensured that the two key environmental stresses of aging and humid and hot are applied to the sample in a preset pattern that closely resembles the natural rhythm within each test cycle.
[0040] In summary, this application's embodiments define the duration of aging, damp heat, and transition phases within a test cycle as specific ranges of 20%-40%, 60%-80%, and no more than 5%, respectively, ensuring that the sum of the three is 1. This design enables the comprehensive aging and damp heat test to faithfully reproduce the real-world scenario of alternating solar aging and damp heat environments under laboratory conditions in a manner closely resembling natural diurnal rhythms. This avoids the problem of insufficient accelerated stress caused by insufficient exposure time of a single environmental factor and minimizes the encroachment of non-test conditions on effective environmental exposure time. This time management ensures that the two environmental stresses of aging and damp heat act on the sample with intensity and timing consistent with actual environmental exposure characteristics, thereby improving the simulation fidelity and stress application accuracy of the accelerated test.
[0041] In some instances, color difference values are calculated based on initial surface color parameters and post-experiment surface color parameters, including: The brightness difference is determined based on the initial brightness and the brightness after the test; The difference in red-green hue is determined based on the initial red-green hue and the red-green hue after the experiment; The difference in blue-yellow hue was determined based on the initial blue-yellow hue and the blue-yellow hue after the experiment; The color difference value is calculated based on the difference in brightness, the difference in red-green hue, and the difference in blue-yellow hue.
[0042] For example, in calculating the color difference value based on the initial surface color parameters and the post-experiment surface color parameters, the arithmetic difference between the initial luminance component in the initial surface color parameters and the post-experiment luminance component in the post-experiment surface color parameters is first calculated to determine the luminance difference. Next, the arithmetic difference between the initial red-green hue component in the initial surface color parameters and the post-experiment red-green hue component in the post-experiment surface color parameters is calculated to determine the red-green hue difference. Simultaneously, the arithmetic difference between the initial blue-yellow hue component in the initial surface color parameters and the post-experiment blue-yellow hue component in the post-experiment surface color parameters is calculated to determine the blue-yellow hue difference. Finally, the determined luminance difference, red-green hue difference, and blue-yellow hue difference are used as inputs, and the CIELab color difference formula is applied for synthesis calculation. Specifically, the square root of the sum of the squares of the above three differences is calculated to ultimately calculate the color difference value used to quantify the degree of surface color change.
[0043] In summary, this application's embodiment, through the aforementioned step-by-step calculation and synthesis of brightness difference, red-green hue difference, and blue-yellow hue difference to determine the final color difference value, achieves the quantification of color changes on the surface of organically passivated magnesium-coated steel sheets. This calculation strategy ensures that the evaluation index can comprehensively capture the decrease in surface brightness and possible accompanying color shift caused by the aging damp heat test, making the final color difference value a comprehensive and objective characterization parameter. This parameter effectively reflects the overall color difference of the sample surface before and after the test in terms of human visual perception.
[0044] In some instances, the tendency of organically passivated magnesium-coated steel sheets to blacken is determined based on color difference values, including: The color difference value is compared with the preset blackening evaluation threshold to obtain the comparison result; Based on the comparison results, the tendency of blackening of the organic passivated magnesium-coated steel sheet to be tested was determined.
[0045] For example, the calculated color difference value is compared with a preset blackening evaluation threshold determined through extensive experimental data accumulation and correlation analysis. This preset blackening evaluation threshold consists of one or more critical values used to classify different levels of blackening tendency. Its setting comprehensively considers the acceptance standards for product appearance quality in practical applications and the correspondence between laboratory accelerated testing results and long-term outdoor exposure data. Based on the comparison results, the blackening tendency is qualitatively or semi-quantitatively graded according to preset judgment rules. For example, when the color difference value is below the first threshold, it is judged as a slight blackening tendency; when it is between the first and second thresholds, it is judged as a moderate blackening tendency; and when it is above the second threshold, it is judged as a severe blackening tendency. This judgment process transforms the objective physical quantity of color difference into an evaluation conclusion of the product's appearance stability risk under actual use conditions, providing a decision-making basis for material selection, process optimization, and quality control.
[0046] The technical solution of this application will be further described in detail below through specific embodiments. To verify the effectiveness and accuracy of the method for evaluating the blackening tendency of organically passivated magnesium-coated steel sheets proposed in this application, a series of comparative experiments were designed and implemented. Organically passivated magnesium-coated steel sheets with different magnesium contents (1%, 3%, and 6%) were selected as test samples. The organic passivation films of all samples were prepared using the same process, with a film thickness of approximately 1 micrometer. The basic formulation of the passivation solution included components such as polytetrafluoroethylene, zirconium nitrate, lanthanum nitrate, zinc borate, phytic acid, sodium metasilicate, zinc sulfate, and thiosulfate complexing agents. The evaluation benchmark was the surface color difference measured after three months of field exposure of the same batch of samples in a typical atmospheric environment, denoted as the true ΔE. The laboratory evaluation objective was to make the experimental ΔE value measured by this method as close as possible to the true ΔE value.
[0047] It should be noted that the passivation solution formula is 6-20 g / L polytetrafluoroethylene, 5-10 g / L zirconium nitrate, 3-8 g / L lanthanum nitrate, 5-12 g / L zinc borate, 3-12 g / L phytic acid, 3-7 g / L sodium metasilicate, 4-10 g / L zinc sulfate, and 3-10 g / L thiosulfate complexing agent.
[0048] This application employs three different aging and damp heat test procedures, labeled as procedures A, B, and C, respectively. Their specific time allocation and conversion relationships are as follows: Figure 2 , Figure 3 and Figure 4 As shown in Table 1, the data clearly demonstrate the evaluation results under different test conditions and magnesium content in the coating. Examples 1 to 3 adopted Process A, in which the aging time accounted for 25%, the damp heat time accounted for 70%, the transition time accounted for 5%, the aging test temperature was 30℃, and the light intensity was 0.7 W / m². 2The damp heat test temperature was 50℃, and the relative humidity was 70%. Test results showed that for samples with magnesium contents of 1%, 3%, and 6%, the experimental ΔE values were 4.2, 5.6, and 11.8, respectively. Compared with the corresponding true ΔE values of 4.0, 5.5, and 12.0, the deviations were extremely small, at +0.2, +0.1, and -0.2, respectively, proving that process A can provide highly accurate evaluation results at different magnesium content levels. Examples 4 to 6 used process B, with the parameters adjusted as follows: aging time 22%, damp heat time 75%, transition time 3%, aging temperature increased to 50℃, and light intensity increased to 1.2 W / m². 2 The humidity was reduced to 40°C and the damp heat temperature was increased to 80%. The experimental ΔE values for samples with magnesium contents of 1%, 3%, and 6% were measured to be 4.5, 5.2, and 12.3, respectively, with deviations from the true values of 4.0, 5.5, and 12.0 of +0.5, -0.3, and +0.3, respectively. Although there were slight fluctuations, good consistency was maintained, demonstrating the applicability of the method under another set of parameters. Examples 7 to 9 adopted process C, characterized by a significantly increased aging time proportion to 39%, a reduced damp heat time proportion to 60%, a strictly controlled transition time of 1%, an aging temperature of 40°C, and a light intensity of 0.5 W / m². 2 The temperature was raised to 60℃ and the humidity to 90%. Under these conditions, the experimental ΔE values for samples with magnesium contents of 1%, 3%, and 6% were measured to be 3.8, 5.8, and 11.6, respectively, with deviations from the true values of -0.2, +0.3, and -0.4. This further verifies that the method can obtain reliable data that closely matches the outdoor exposure under different time distributions and stress level combinations.
[0049] To highlight the superiority of the method presented in this application, several comparative examples were set up for comparison. Comparative examples 1 to 4 only underwent traditional single damp heat tests, without introducing any ultraviolet aging process. The results showed that regardless of whether the damp heat conditions were mild (Comparative examples 1 and 2) or severe (Comparative examples 3 and 4), the measured experimental ΔE was lower than the true ΔE, with deviations ranging from -1.5 to -2.1, severely underestimating the tendency of the samples to darken, confirming that ignoring photo-aging factors leads to inaccurate evaluation. Comparative examples 5 to 9 attempted the aging damp heat test mode of this application, but the key parameters exceeded the preferred range set by this application. For example, Comparative examples 5 and 6 had excessively low ultraviolet light intensity (0.1 W / m²). 2 Or the aging temperature is too low (20℃) and the light intensity is too high (1.9 W / m²). 2The excessively low humidity (25℃, 30℃) and excessively low damp-heat conditions (40%), coupled with an excessively long transition time (15%), resulted in experimental ΔE values that were either too low (-1.8) or too high (+2.5), leading to distorted evaluations. Comparative Examples 7 and 8, due to excessively low damp-heat temperatures (25℃, 30℃) or excessively low humidity (40%), and excessively long transition times (15%), also resulted in experimental ΔE values (3.5) that were significantly lower than the true value (5.5), with a deviation of -2.0.
[0050] In summary, the evaluation method provided in this application, through multi-cycle comprehensive aging and damp heat tests within a set parameter range (such as aging time accounting for 20-40%, damp heat time accounting for 60-80%, transition time ≤5%, and corresponding temperature, humidity, and light intensity ranges), enables the laboratory accelerated evaluation results to be highly consistent with the results of outdoor natural exposure for up to three months. The deviation between the test ΔE and the actual ΔE is significantly smaller than that of traditional methods or test schemes with inappropriate parameters, fully demonstrating the effectiveness and superiority of this method in accurately and rapidly evaluating the blackening tendency of organic passivated magnesium-coated steel sheets.
[0051] Table 1 Evaluation results under different test conditions and magnesium content of the coating.
[0052] Please see Figure 5 The diagram below illustrates the structure of a device for evaluating the blackening tendency of organically passivated magnesium-coated steel plates, as provided in this application embodiment. The device includes: Initial parameter acquisition unit 21 acquires the initial surface color parameters of the organic passivated magnesium-coated steel sheet to be tested; Aging and damp heat test unit 22 is used to conduct aging and damp heat tests on the organic passivated magnesium-containing coated steel sheet to be tested. Test parameter acquisition unit 23 acquires the surface color parameters of the organic passivated magnesium-coated steel sheet to be tested after the aging damp heat test; The surface color difference calculation unit 24 is used to calculate the color difference value based on the initial surface color parameters and the surface color parameters after the test; The blackening tendency evaluation unit 25 is used to determine the blackening tendency of the organic passivated magnesium-coated steel sheet under test based on the color difference value.
[0053] Please see Figure 6 This application also provides an electronic device 300, including a memory 310, a processor 320, and a computer program 311 stored in the memory 310 and executable on the processor. When the processor 320 executes the computer program 311, it implements the steps of the method for evaluating the blackening tendency of organic passivated magnesium-coated steel plates.
[0054] Since the electronic device described in this embodiment is the device used to implement the device for evaluating the blackening tendency of an organic passivated magnesium-coated steel plate in this application embodiment, those skilled in the art can understand the specific implementation method and various variations of the electronic device in this embodiment based on the method described in this application embodiment. Therefore, how the electronic device implements the method in this application embodiment will not be described in detail here. Any device used by those skilled in the art to implement the method in this application embodiment is within the scope of protection of this application.
[0055] In practice, when the computer program 311 is executed by the processor, it can implement any of the embodiments corresponding to the first aspect.
[0056] It should be noted that the descriptions of each embodiment in the above embodiments have different focuses. For parts that are not described in detail in a certain embodiment, please refer to the relevant descriptions in other embodiments.
[0057] Those skilled in the art will understand that embodiments of this application can provide methods, systems, or computer program products. Therefore, this application can take the form of a completely hardware embodiment, a completely software embodiment, or an embodiment combining software and hardware aspects. Furthermore, this application can take the form of a computer program product embodied on one or more computer-readable storage media containing computer-readable program code.
[0058] This application is described with reference to flowchart illustrations and / or block diagrams of methods, apparatus (systems), and computer program products according to embodiments of this application. It will be understood that each block of the flowchart illustrations and / or block diagrams, and combinations of blocks in the flowchart illustrations and / or block diagrams, can be implemented by computer program instructions. These computer program instructions can be provided to a processor of a general-purpose computer, special-purpose computer, embedded computer, or other programmable data processing apparatus to produce a machine, such that the instructions, which execute via the processor of the computer or other programmable data processing apparatus, create a machine for implementing the flowchart illustrations and / or block diagrams. Figure 1 One or more processes and / or boxes Figure 1 A device that provides the functions specified in one or more boxes.
[0059] These computer program instructions may also be stored in a computer-readable storage medium that can direct a computer or other programmable data processing device to function in a particular manner, such that the instructions stored in the computer-readable storage medium produce an article of manufacture including instruction means, which are implemented in a process Figure 1 One or more processes and / or boxes Figure 1 The function specified in one or more boxes.
[0060] These computer program instructions may also be loaded onto a computer or other programmable data processing equipment to cause a series of operational steps to be performed on the computer or other programmable equipment to produce a computer-implemented process, thereby providing instructions that execute on the computer or other programmable equipment for implementing the process. Figure 1 One or more processes and / or boxes Figure 1 The steps of the function specified in one or more boxes.
[0061] This application also provides a computer program product, which includes computer software instructions that, when executed on a processing device, cause the processing device to perform... Figure 1 The flowchart of a method for evaluating the blackening tendency of organic passivated magnesium-coated steel plates in the corresponding embodiment.
[0062] A computer program product includes one or more computer instructions. When the computer program instructions are loaded and executed on a computer, all or part of the flow or function according to the embodiments of this application is generated. The computer may be a general-purpose computer, a special-purpose computer, a computer network, or other programmable device. The computer instructions may be stored in a computer-readable storage medium or transferred from one computer-readable storage medium to another. For example, computer instructions may be transferred from one website, computer, server, or data center to another website, computer, server, or data center via wired or wireless means. The computer-readable storage medium may be any usable medium that a computer can store or a data storage device such as a server or data center that integrates one or more usable media. The usable medium may be a magnetic medium, an optical medium, or a semiconductor medium, etc.
[0063] Those skilled in the art will clearly understand that, for the sake of convenience and brevity, the specific working processes of the systems, devices, and units described above can be referred to the corresponding processes in the foregoing method embodiments, and will not be repeated here.
[0064] In the several embodiments provided in this application, it should be understood that the disclosed devices, apparatuses, and methods can be implemented in other ways. For example, the apparatus embodiments described above are merely illustrative; multiple units or components may be combined or integrated into another system, or some features may be omitted or not performed. Furthermore, the mutual couplings or direct couplings or communication connections shown or discussed may be indirect couplings or communication connections through some interfaces, devices, or units, and may be electrical, mechanical, or other forms.
[0065] The units described as separate components may or may not be physically separate. The components shown as units may or may not be physical units; that is, they may be located in one place or distributed across multiple network units. Some or all of the units can be selected to achieve the purpose of this embodiment according to actual needs.
[0066] Furthermore, the functional units in the various embodiments of this application can be integrated into one processing unit, or each unit can exist physically separately, or two or more units can be integrated into one unit. The integrated units described above can be implemented in the form of hardware and / or software functional units.
[0067] If the integrated unit is implemented as a software functional unit and sold or used as an independent product, it can be stored in a computer-readable storage medium. Based on this understanding, the technical solution of this application, in essence, or the part that contributes to the prior art, or all or part of the technical solution, can be embodied in the form of a software product. This computer software product is stored in a storage medium and includes several instructions to cause a computer device to execute all or part of the steps of the methods in the various embodiments of this application. The aforementioned storage medium includes various media capable of storing program code, such as USB flash drives, portable hard drives, read-only memory, magnetic disks, or optical disks.
[0068] The above embodiments are only used to illustrate the technical solutions of this application, and are not intended to limit them. Although this application has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some of the technical features. Such modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the spirit and scope of the technical solutions of the embodiments of this application.
[0069] Although preferred embodiments have been described in this specification, those skilled in the art, upon learning the basic inventive concept, can make other changes and modifications to these embodiments. Therefore, the appended claims are intended to be interpreted as including the preferred embodiments as well as all changes and modifications that fall outside the scope of this specification.
[0070] Obviously, those skilled in the art can make various modifications to this specification without departing from its spirit and scope. Therefore, this specification also intends to include any modifications that fall within the scope of the claims and their equivalents.
Claims
1. A method for evaluating the tendency of blackening in organically passivated magnesium-containing coated steel sheets, characterized in that, include: Obtain the initial surface color parameters of the organic passivated magnesium-coated steel sheet to be tested; An aging damp heat test was conducted on the organic passivated magnesium-containing coated steel sheet to be tested. Obtain the surface color parameters of the tested organic passivated magnesium-coated steel sheet after the aging damp heat test; The color difference value is calculated based on the initial surface color parameters and the surface color parameters after the experiment; Based on the color difference value, the tendency of the tested organic passivated magnesium-coated steel sheet to turn black is determined.
2. The method according to claim 1, characterized in that, The initial surface color parameters include initial brightness, initial red-green hue, and initial blue-yellow hue; the post-test surface color parameters include post-test brightness, post-test red-green hue, and post-test blue-yellow hue.
3. The method according to claim 1, characterized in that, The aging and damp heat test includes multiple test cycles, each of which includes an aging test and a damp heat test.
4. The method according to claim 3, characterized in that, The number of test cycles is a first preset number, and the duration of each test cycle is a first preset duration.
5. The method according to claim 3, characterized in that, The aging test includes irradiating the organic passivated magnesium-coated steel sheet to be tested with an ultraviolet light source, wherein the irradiation temperature is controlled within a first preset temperature range and the irradiation intensity is controlled within a first preset intensity range.
6. The method according to claim 5, characterized in that, The ultraviolet light source is a UVA 340 ultraviolet fluorescent lamp with a peak wavelength of 340 nm.
7. The method according to claim 3, characterized in that, The damp heat test involves placing the organic passivated magnesium-coated steel sheet to be tested in a damp heat environment, wherein the damp heat temperature is controlled within a second preset temperature range and the relative humidity is controlled within a first preset humidity range.
8. The method according to claim 3, characterized in that, In each test cycle, the proportion of the duration of the aging test to the duration of each test cycle is a first preset proportion, the proportion of the duration of the damp heat test to the duration of each test cycle is a second preset proportion, and the proportion of the transition time between the aging test and the damp heat test to the duration of each test cycle is a third preset proportion. The sum of the first preset proportion, the second preset proportion, and the third preset proportion is 1.
9. The method according to claim 2, characterized in that, The calculation of the color difference value based on the initial surface color parameters and the post-test surface color parameters includes: The brightness difference is determined based on the initial brightness and the brightness after the test; The red-green color difference is determined based on the initial red-green color and the red-green color after the test; The difference in blue-yellow hue is determined based on the initial blue-yellow hue and the blue-yellow hue after the test; The color difference value is calculated based on the brightness difference, the red-green hue difference, and the blue-yellow hue difference.
10. The method according to claim 1, characterized in that, The determination of the blackening tendency of the tested organic passivated magnesium-coated steel sheet based on the color difference value includes: The color difference value is compared with a preset blackening evaluation threshold to obtain the comparison result; Based on the comparison results, the tendency of the tested organic passivated magnesium-coated steel sheet to turn black was determined.