An in-situ method for measuring a corrosion product film and a corrosion depth

Abstract

The application discloses a kind of corrosion product film and in-situ measurement method of corrosion depth, first determine sample preparation method after sample preparation, set hardness mark point and carry out position correspondence, utilize the optimal test parameter continuous collection mark area initial surface fluctuation data, sample is carried out mask covering treatment, after film coating, corrosion test is carried out, after test, corrosion product film and the surface data acquisition of uncorrosion area are carried out, after removing corrosion product, surface data acquisition of corrosion area and uncorrosion area is carried out again;In later data processing process, by increasing data mask, hardness mark point, excluding surface initial fluctuation degree data influence, finally using weight loss method to calculate material uniform corrosion depth, white light test result is verified.The application ensures the accuracy of nm level corrosion height data, also carries out statistics to surface mm level range height data, eliminates the error of single field of view, realizes in-situ film layer thickness and corrosion depth quantitative characterization in large size range.

Description

Technical Field

[0001] This invention relates to the field of corrosion resistance evaluation technology, and in particular to an in-situ measurement method for corrosion product film and corrosion depth. Background Technology

[0002] High-throughput characterization and service behavior evaluation technologies, as an important development direction in high-throughput experimental techniques within "materials genome engineering," aim to construct the connections between atomic arrangement and phase formation, and between microstructure and macroscopic service performance of materials. This establishes a material composition-structure-performance mapping relationship, advancing the research and application of advanced materials and structures. The microstructural characteristics of materials and their performance evolution during service are key research areas in this direction, determining the functional integrity and service safety of materials under specific service conditions. Currently, how to correlate the composition and properties of micro-regions with the all-time and all-space service performance of materials and structures remains a bottleneck in the development of high-throughput characterization.

[0003] A high-throughput statistical spatial mapping characterization method based on original location statistical distribution analysis offers a feasible solution to the bottlenecks in the development of high-throughput characterization. This method performs high-throughput and cross-scale statistical distribution characterization of samples based on the identification of the inherent heterogeneity of materials, rapidly and accurately obtaining the precise locational correspondences between macroscopic-mesoscopic-microscopic components, structures, and properties. It establishes spatial mapping relationships between datasets, thereby obtaining the correlations between composition, structure, and properties.

[0004] Currently, methods for characterizing material corrosion behavior mainly focus on electrochemical analysis and weight loss calculations, with a significant lack of methods for characterizing micro-area corrosion features. While methods like SEM are commonly used to acquire two-dimensional information, they lack feedback on the height of corrosion characteristics. AFM, often used to characterize height, cannot acquire height information over a large field of view in a short time. Optical profilometers, employing the white light interferometry principle, offer high precision, high efficiency, and repeatability, enabling efficient and convenient testing and analysis. Combining optical profilometers with in-situ techniques can lead to the development of new methods for large-scale corrosion characterization, allowing for the exploration of corrosion processes and corrosion resistance mechanisms. Summary of the Invention

[0005] In order to overcome the above-mentioned problems in the prior art, the present invention proposes an in-situ measurement method for corrosion product film and corrosion depth.

[0006] The technical solution adopted by this invention to solve its technical problem is: an in-situ measurement method for corrosion product film and corrosion depth, comprising the following steps:

[0007] S1. Select a flat sample to be tested, polish it with sandpaper to make its upper and lower surfaces flat and smooth, use diamond polishing paste to mechanically polish the surface of the sample to be tested, clean it and then electropolish the sample. After electropolishing, store it for later use.

[0008] S2, Select the optimal test parameters for the instrument, use the optimal test parameters to continuously collect the height information of the sample under the same field of view, and obtain the instrument accuracy through height error and roughness error;

[0009] S3. Different sample preparation methods are used to prepare samples. The appropriate sample preparation method is selected according to the uniformity of the surface data collected by white light and the application requirements.

[0010] S4. Prepare the sample using the sample preparation method selected in S3. Use a microhardness tester to set in-situ marking points on the sample. Set no less than two in-situ corresponding areas on the surface of each sample.

[0011] S5, cover the sample obtained in S4 with a mask, immerse the covered sample in the solution for etching; take out the sample, remove the mask and collect height and roughness data, pickle the sample after collecting height and roughness data, and collect height and roughness data again after pickling.

[0012] S6 processes the original surface data of the sample before corrosion, the surface data of the sample after corrosion, and the surface data of the sample after pickling obtained in S5. The data correction is initially achieved through data masking and flattening.

[0013] S7 uses hardness markers to establish positional correspondence between measurement data before and after corrosion, and further corrects the data by using the in-situ corresponding initial height difference to obtain the thickness of the corrosion product film on the surface after corrosion and the corrosion thinning height after pickling.

[0014] S8. The accuracy of the test method was verified by calculating the corrosion thinning height using the weight loss method after immersion for the same duration.

[0015] The above-mentioned in-situ measurement method for corrosion product film and corrosion depth, the specific method for selecting the optimal test parameters of the instrument in step 2 is as follows: set up an orthogonal experiment including magnification, fluctuation range and scanning time, collect surface information under various combination conditions, statistically analyze the capture rate, relative standard deviation within the 95% confidence interval and scanning time, and select reasonable magnification and fluctuation range test parameters.

[0016] The above-mentioned in-situ measurement method for corrosion product film and corrosion depth includes the following different preparation methods in S3:

[0017] Method 1: Select the sample to be tested obtained from S1, place the sample directly in the three-dimensional profilometer, and collect surface height and roughness data.

[0018] Method 2: Select the sample to be tested obtained from S1, fix the sample on a thick glass slide with metallographic clay, then manually flatten it, and place it in a three-dimensional profilometer to collect surface height and roughness data.

[0019] Method 3: Select the sample to be tested obtained in S1, embed the sample with AB glue, clean the sample and polish it with sandpaper to make its upper and lower surfaces flat and smooth, use diamond polishing paste to mechanically polish the surface of the sample to be tested, and collect the surface height and roughness data of the sample after polishing.

[0020] Method 4: Select the sample to be tested obtained in S1, embed the sample in a thick glass plate with silicone rubber, and collect the surface height and roughness data of the sample.

[0021] The above-mentioned in-situ measurement method for corrosion product film and corrosion depth, wherein the selection of the sample preparation method in S3 is specifically as follows: the sample to be tested obtained in S1 is placed in a three-dimensional profilometer to collect surface height and roughness data; metallographic tape is used to cover the samples obtained by different sample preparation methods with a mask, and the covered samples are immersed in the solution for corrosion; the sample is taken out, the mask is removed, and height and roughness data are collected; and a suitable sample preparation method is selected according to the uniformity of the surface data collected by white light and the application requirements.

[0022] The above-mentioned in-situ measurement method for corrosion product film and corrosion depth includes, in step S6, data correction specifically: the corrosion height in the area near the boundary of the corrosion zone is lower than that in the normal corrosion zone, and this needs to be excluded during calculation to reduce error; the corrosion height in the area near the boundary of the mask zone is higher than that in the normal mask zone, and this needs to be excluded during calculation to reduce error.

[0023] The above-mentioned in-situ measurement method for corrosion product film and corrosion depth, wherein the S6 data correction incorporates the undulation of the sample before corrosion, the original undulation Δh = h 腐蚀初始 -h 掩膜初始 The thickness of the corrosion-produced film Δh1 = h 膜 -h 掩膜 The corrosion thinning data after pickling is Δh2=h 掩膜 -h 腐蚀 .

[0024] In the above-mentioned in-situ measurement method of corrosion product film and corrosion depth, during the S7 data correction, the positional correspondence of the measurement data before and after corrosion is realized by using hardness marker points, and the data correction is further realized by using the undulation error of the sample before corrosion. The corrected product film thickness is Δh1'=Δh1+Δh, and the corrected corrosion thinning is Δh2'=Δh2+Δh.

[0025] The beneficial effects of the present invention are: (1) The current corrosion height is mainly characterized by the height after corrosion. This method does not take into account the height fluctuation of the sample itself before corrosion. When the corrosion height is at the micrometer level, the fluctuation of the sample itself will lead to a large measurement error. When the corrosion height is at the nanometer level, the fluctuation of the sample itself is greater than the height change caused by corrosion, resulting in abnormal data measurement. The present invention sets in-situ markers to eliminate the initial height fluctuation of the height after corrosion in the same area, thereby achieving accurate acquisition of nanometer-level corrosion product film and corrosion thinning height.

[0026] (2) The current corrosion height is measured by a local field of view, and the observed field area and statistical results are limited. This invention greatly eliminates the error of a single field of view by averaging the data of corrosion product film, corrosion thinning area after pickling and surface height of uncorroded area within a millimeter range, and the data is more reliable. Attached Figure Description

[0027] The present invention will be further described below with reference to the accompanying drawings and embodiments.

[0028] Figure 1 This is a flowchart of the present invention;

[0029] Figure 2 This is the height distribution data after manual flattening;

[0030] Figure 3 This is the height distribution data after manual flattening;

[0031] Figure 4 Data showing the height distribution of the surface after silicone rubber inlay;

[0032] Figure 5 This is the height line distribution data after silicone rubber inlay;

[0033] Figure 6 This refers to the initial surface height data of the sample.

[0034] Figure 7 This refers to the surface height data of the sample after corrosion.

[0035] Figure 8 This refers to the surface height data of the sample after acid washing;

[0036] Figure 9 This is a graph showing the relationship between the calculated weight loss data of the sample and the white light test data. Detailed Implementation

[0037] To enable those skilled in the art to better understand the technical solution of the present invention, the present invention will be described in detail below with reference to the accompanying drawings and specific embodiments.

[0038] like Figure 1As shown, this embodiment discloses an in-situ measurement method for corrosion product film and corrosion depth, which specifically includes the following steps: S1, select copper-nickel alloy pipe, grind the surface with 200-5000 grit sandpaper, mechanically polish the surface of the test sample with 5μm-1μm diamond polishing paste, clean the sample and then electropolish it, and store it for later use.

[0039] S2. Optimal instrument test parameters were selected by setting up an orthogonal experiment for magnification, data capture rate, and acquisition time. Based on the data standard deviation, the optimal combination of test parameters was determined. The relationship between the fluctuation range and the information capture rate is shown in Table 1. Analysis of the test results showed that the magnification was 20×1, and the fluctuation range was -400μm to 100μm.

[0040] Table 1. Fluctuation Range and Information Capture Rate

[0041] Range of fluctuations ±50μm ±200μm ±300μm ±500μm ±600μm ±700μm ±1000μm Information capture rate 67.35％ 80.76％ 97.29％ 98.41％ 98.41％ 98.41％ 98.41％

[0042] S3. Without changing any parameters, using the optimal test parameters, continuously collect sample height information, height error, and roughness error under the same field of view. The average height error is shown in Table 2. Within the 95% confidence interval, the height error is ±22 to ±66 nm, and the roughness error is ±0.07 to ±0.32 nm.

[0043] Table 2 Average height error of sample surface

[0044]

[0045]

[0046] S4. Screen the optimal sample preparation method, select the sample after electropolishing, and place the sample directly in the three-dimensional profilometer to collect surface height and roughness data.

[0047] S5. Screen the optimal sample preparation method, select the sample after electrolytic polishing, fix the sample on a thick glass slide with metallographic clay, and then manually flatten it to collect the sample surface height and roughness data.

[0048] S6. Select the optimal sample preparation method, choose a flat sample to be tested, and mount the sample with AB glue. After cleaning the sample, polish it with 1-5000 grit sandpaper to make its upper and lower surfaces flat and smooth. Mechanically polish the surface of the sample to be tested with 5μm~1μm diamond polishing paste, and collect the surface height and roughness data of the polished sample.

[0049] S7. Screen the optimal sample preparation method, select the sample after electrolytic polishing, embed the sample on a thick glass plate with silicone rubber, and collect the sample surface height and roughness data.

[0050] S8. Use metallographic tape to cover the three types of samples, then immerse the covered samples in the etching solution. Remove the samples, remove the mask, and collect height and roughness data. Because manual grinding and polishing cannot guarantee uniform sample height, resulting in an arc-shaped surface that is higher in the middle and lower around the edges, there will be a micrometer-level height difference between the masked area and the etching observation area. This can lead to significant errors, especially when the initial thinning thickness is small. Manual flattening cannot guarantee the consistency of the sample's reference height before and after etching. Furthermore, uneven force causing sample tilting also introduces errors. See [link to documentation]. Figure 2-3 The sample is mounted on a thick glass slide using silicone rubber or AB glue. The height difference before and after etching allows for point-to-point detection of height changes, avoiding errors caused by manual flattening. See [link to documentation]. Figure 4-5 Embedding silicone rubber onto a thick glass slide allows for initial characterization of the sample's composition or structure, followed by corrosion performance testing. Since this invention focuses on corrosion morphology testing, the AB glue embedding method was chosen for sample preparation.

[0051] S9. Use a microhardness tester to set in-situ marking points, with no less than two corresponding in-situ areas set on each sample surface.

[0052] S10, After preparation, sample surface data were collected using the optimal combination. See [link / reference] Figure 6 .

[0053] S11, a metallographic tape was used to cover the sample, which was then immersed in the etching solution for etching. The sample was removed, the mask was removed, and data on the masked area and the etching product film were collected. Figure 7 The collected samples were acid-washed, and surface data of the masked and etched areas were collected again after acid washing. (See attached image) Figure 8 .

[0054] S12 involves processing the original surface data of the sample before corrosion, the surface data of the sample after corrosion, and the surface data of the sample after pickling. Hardness markers are used to establish the positional correspondence of the measurement data before and after corrosion, and a data mask is used for flattening to achieve data correction.

[0055] S13, process the original surface data of the sample before corrosion, the surface data of the sample after corrosion, and the surface data of the sample after pickling. Original surface height Δh = h 腐蚀初始 -h 掩膜初始 The height of the corrosion-produced film Δh1 = h 膜 -h 掩膜 The height difference data after pickling and thinning is Δh2=h 掩膜 -h 腐蚀By using hardness markers, the positional correspondence of measurement data before and after corrosion is achieved. The data is further corrected by the undulation error of the sample before corrosion. The corrected product film height data is Δh1'=Δh1+Δh, and the corrected corrosion thinning data is Δh2'=Δh2+Δh.

[0056] S14. Due to the presence of the mask, the corrosion height in the area near the boundary of the corrosion zone is lower than that in the normal corrosion zone. This area needs to be excluded during calculation to reduce errors.

[0057] S15. Due to the presence of the mask, the corrosion height in the area near the boundary of the mask area is higher than that in the normal mask area. This area needs to be excluded during calculation to reduce errors.

[0058] S16, the accuracy of the test method is verified by calculating the corrosion thinning height using the weight loss method after immersion for the same duration. See [link to relevant documentation]. Figure 9 The measurements from both methods correspond to the trends, demonstrating that this method can test the height variations of nanoscale surfaces.

[0059] The above embodiments are merely exemplary embodiments of the present invention and are not intended to limit the present invention. The scope of protection of the present invention is defined by the claims. Those skilled in the art can make various modifications or equivalent substitutions to the present invention within its spirit and scope of protection, and such modifications or equivalent substitutions should also be considered to fall within the scope of protection of the present invention.

Claims

1. A method for in-situ measurement of corrosion product film and corrosion depth, characterized in that, Includes the following steps: S1. Select a flat sample to be tested, polish it with sandpaper to make its upper and lower surfaces flat and smooth, use diamond polishing paste to mechanically polish the surface of the sample to be tested, clean it and then electropolish the sample. After electropolishing, store it for later use. S2, Select the optimal test parameters for the instrument, use the optimal test parameters to continuously collect the height information of the sample under the same field of view, and obtain the instrument accuracy through height error and roughness error; S3. Different sample preparation methods are used to prepare samples. The appropriate sample preparation method is selected according to the uniformity of the surface data collected by white light and the application requirements. S4. Prepare the sample using the sample preparation method selected in S3. Use a microhardness tester to set in-situ marking points on the sample. Set no less than two in-situ corresponding areas on the surface of each sample. S5, cover the sample obtained in S4 with a mask, immerse the covered sample in the solution for etching; take out the sample, remove the mask and collect height and roughness data, pickle the sample after collecting height and roughness data, and collect height and roughness data again after pickling. S6 processes the original surface data of the sample before corrosion, the surface data of the sample after corrosion, and the surface data of the sample after pickling obtained in S5. The data correction is initially achieved through data masking and flattening. S7 uses hardness markers to establish positional correspondence between measurement data before and after corrosion, and further corrects the data by using the in-situ corresponding initial height difference to obtain the thickness of the corrosion product film on the surface after corrosion and the corrosion thinning height after pickling. S8. The accuracy of the test method was verified by calculating the corrosion thinning height using the weight loss method after immersion for the same duration. The data correction in step S6 specifically includes: the corrosion height of the area near the boundary of the corrosion zone is lower than that of the normal corrosion zone, and it needs to be excluded during calculation to reduce error; the corrosion height of the area near the boundary of the mask zone is higher than that of the normal mask zone, and it needs to be excluded during calculation to reduce error. The S6 data correction incorporates the undulation of the sample before corrosion, with the original undulation ∆h=h 腐蚀初始 -h 掩膜初始 The thickness of the corrosion-produced film ∆h1=h 膜 -h 掩膜 After pickling, the corrosion thinning data ∆h2=h 掩膜 -h 腐蚀 ; During the S7 data correction, the positional correspondence of the measured data before and after corrosion is achieved through hardness marker points. The data correction is further achieved through the fluctuation error of the sample before corrosion. The corrected product film thickness is ∆h1'=∆h1+∆h, and the corrected corrosion thinning is ∆h2'=∆h2+∆h.

2. The in-situ measurement method for corrosion product film and corrosion depth according to claim 1, characterized in that, The specific method for selecting the optimal test parameters of the instrument in step 2 is as follows: set up an orthogonal experiment including magnification, fluctuation range, and scanning time; collect surface information under various combinations of conditions; statistically analyze the capture rate, relative standard deviation within the 95% confidence interval, and scanning time; and select reasonable magnification and fluctuation range test parameters.

3. The in-situ measurement method for corrosion product film and corrosion depth according to claim 1, characterized in that, The different preparation methods in S3 specifically include the following: Method 1: Select the sample to be tested obtained from S1, place the sample directly in the three-dimensional profilometer, and collect surface height and roughness data. Method 2: Select the sample to be tested obtained from S1, fix the sample on a thick glass slide with metallographic clay, then manually flatten it, and place it in a three-dimensional profilometer to collect surface height and roughness data. Method 3: Select the sample to be tested obtained in S1, embed the sample with AB glue, clean the sample and polish it with sandpaper to make its upper and lower surfaces flat and smooth, use diamond polishing paste to mechanically polish the surface of the sample to be tested, and collect the surface height and roughness data of the sample after polishing. Method 4: Select the sample to be tested obtained in S1, embed the sample in a thick glass plate with silicone rubber, and collect the surface height and roughness data of the sample.

4. The in-situ measurement method for corrosion product film and corrosion depth according to claim 3, characterized in that, The specific method for selecting the sample preparation method in S3 is as follows: the sample to be tested obtained in S1 is placed in a three-dimensional profilometer to collect surface height and roughness data; metallographic tape is used to cover the samples obtained by different sample preparation methods with a mask, and the covered samples are immersed in a solution for etching; the sample is taken out, the mask is removed, and height and roughness data are collected. The appropriate sample preparation method is selected according to the uniformity of the surface data collected by white light and the application requirements.

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