Corrosion damage evaluation method for part anticorrosion organic coating protection system
Through tape peeling method and energy spectrometer analysis combined with video microscope three-dimensional imaging, the problem that traditional methods cannot accurately evaluate coating bubble damage is solved, and the rapid, convenient and accurate corrosion damage evaluation of coating bubble areas is achieved. .
Patent Information
- Application Number
- CN202411500190.3
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2024-10-25
- Publication Date
- 2025-02-18
AI Technical Summary
The traditional organic coating corrosion damage evaluation method cannot accurately evaluate the actual damage situation in the bubble area, and it is destructive and complex, making it difficult to apply to parts that are costly or need to continue to use.
The surface coating was removed by tape peeling, the corrosion product components were analyzed in combination with the energy spectrometer, and the corrosion depth was measured through the three-dimensional stereo imaging function of the video microscope, and the corrosion damage degree rating assessment method was established at the bubbling of the organic coating.
Accurate analysis and evaluation of corrosion damage in the bubbling area of the coating is achieved, irreversible damage is avoided, and is suitable for parts with large sizes or cannot be placed in the electron microscope, improving the convenience and accuracy of evaluation.
Smart Images
Figure CN119470230A_ABST
Abstract
Description
Technical Field
[0001] The present invention belongs to the technical field of corrosion protection, and relates to a method for evaluating corrosion damage of a part anti-corrosion organic coating protection system, and in particular to a method for evaluating corrosion damage when aging corrosion such as bubbling occurs on the organic coating on the surface of a part during field use or after a corrosion test. Background Art
[0002] In the environment with strong corrosive effects such as the ocean or in the corrosive environment test, the surface of parts made of materials such as aluminum alloy, copper alloy, and steel with poor corrosion resistance is often protected by anti-corrosion organic coating. Under the action of the corrosive environment, the coating may show corrosion aging phenomena such as discoloration, blistering, and rust. When blistering occurs in the coating, it often indicates that the protective performance of the coating has been significantly reduced, and further serious coating performance degradation phenomena such as coating damage and peeling may occur. At this time, it is necessary to test and analyze the interface where the blister appears, the composition of the corrosion product, the corrosion depth, etc., so as to determine the cause of the aging corrosion damage and comprehensively evaluate the degree of corrosion damage. Traditional methods for evaluating corrosion damage of organic coatings include comprehensive rating, electrochemical impedance testing, cutting and dissecting microscopic analysis, etc. The comprehensive rating method is to observe the appearance of the organic coating, count the number and size of blistering, cracking, rusting and other parts, and complete the rating of the degree of coating degradation. This method only counts the number and size of blisters, does not conduct in-depth analysis on the blistering problem, and cannot accurately evaluate the actual damage of the blistering part. When the electrochemical method is used, the degradation change of the coating is analyzed by electrical signals, and the results cannot intuitively determine the corrosion site below the blister, the composition of the corrosion products, and the corrosion depth. The cutting and dissecting microanalysis method is to cut the blister site, prepare the cross-sectional sample, and perform corrosion damage analysis under a scanning electron microscope. This method requires the destruction of the test piece and sample preparation, and the process is relatively complicated and destructive to the test piece. It is not suitable for parts with high costs or parts that still need to be used later. In addition, when cutting the microanalysis sample, it is difficult to get the deepest corrosion site during cutting and sample preparation because the corrosion site is blocked by the coating. In this way, the maximum corrosion depth of the alloy matrix or metal protective coating below the blister cannot be accurately obtained, and the degree of corrosion cannot be accurately evaluated. In order to prevent the coating from blocking, the coating can be removed by solvent, but the solvent may contaminate the blister site, which is not convenient for subsequent corrosion product composition analysis. In summary, the traditional coating blister site damage evaluation methods have disadvantages, so it is necessary to provide a new method for corrosion damage evaluation suitable for the blister site of the coating of parts. Summary of the invention
[0003] Purpose of the invention: The present invention proposes a corrosion damage evaluation method for an anti-corrosion organic coating protection system. The method is fast and convenient, will not cause irreversible damage to parts during the test process, and can accurately analyze the cause and extent of coating corrosion damage, thereby accurately evaluating the corrosion resistance of the coating system.
[0004] The technical solution of the present invention is a method for evaluating corrosion damage of a part anti-corrosion organic coating protection system, comprising the following steps:
[0005] (1) Use the tape stripping method to remove the surface coating of the blister area of the test piece;
[0006] (2) Corrosion damage test and grade assessment: see Table 1
[0007] Table 1 Corrosion damage level of organic coating blister
[0008]
[0009] Before removing the surface coating of the bubbling part of the test piece, the test piece is gently cleaned with deionized water on the parts with organic coating bubbling under the action of the corrosive environment to remove the dust, salt and impurities on the surface, and after cleaning, the surface moisture is blown dry with cold air from a hair dryer;
[0010] The method for selecting the tape is as follows: select the unbubbled area and the bubbled area, use several tapes with different peeling strengths, stick one side to the unbubbled area, and leave the other side suspended, lift the tape on the unsticked side to above 90°C, quickly tear off the tape, and select the tape that can just stick the coating as the tape with the most suitable peeling strength.
[0011] The corrosion product composition test uses an energy spectrometer to analyze the corrosion product composition.
[0012] The test piece is of a size that can be placed in a scanning electron microscope test chamber, and the test piece can be directly used to perform microscopic morphology and composition analysis of corrosion products.
[0013] If the test piece cannot be placed in the test chamber, use wooden tweezers or sharp tools to gently scrape up a small amount of corrosion product, then use conductive glue to pick up a small amount of corrosion product powder, stick the conductive glue with corrosion products to the scanning electron microscope test bench, and use an energy spectrometer to perform component analysis.
[0014] The corrosion depth is determined by selecting a corresponding corrosion product removal paste according to the type of base material, and applying it to the area where corrosion products accumulate. After 10 minutes to 30 minutes, the area is wiped with soft gauze to observe whether there are still corrosion products on the corrosion area. If so, the above process is repeated until the corrosion products are completely removed. Then, the three-dimensional imaging function of the video microscope is used to test the corrosion pits at the area where the corrosion products are removed to obtain a three-dimensional image of the corrosion pits and the corrosion depth.
[0015] The corrosion product paste is a chemical containing acid.
[0016] The characteristics and beneficial effects of the present invention are:
[0017] The present invention mainly designs a new corrosion damage evaluation method for the blistering part of the traditional anti-corrosion organic coating protection system, which is often inaccurate, cumbersome or destructive. The present invention adopts a tape stripping method to remove the surface coating. The method is simple and easy to operate, and does not pollute the surface after stripping, which is convenient for subsequent corrosion damage analysis. For parts of large size that cannot be placed in an electron microscope, a corrosion product sampling method is designed to avoid destructive operations such as cutting parts, which is convenient for subsequent maintenance and reuse of parts. For the corrosion products exposed after removing the coating, a method of removing the corrosion products using a paste is designed to facilitate the subsequent three-dimensional morphology and depth measurement of the corrosion pit. The traditional method for removing corrosion products is to immerse the test piece as a whole in a chemical reagent such as an acid solution, heat it to a certain temperature and keep it for a certain time, and the chemical reagent dissolves the corrosion products. The corrosion product removal paste has the characteristics of viscosity and non-flowing, can be applied locally, and quickly removes local corrosion products. It is mainly used in field repair and maintenance processes. The present invention uses the corrosion product removal paste in the corrosion damage analysis process, which effectively avoids the corrosion and pollution of other parts of the parts by the corrosion product removal solvent. By designing a series of test and analysis methods, the corrosion damage conditions of the coating blistering area were obtained, and a corrosion damage grade assessment method for the organic coating blistering area was developed based on the corrosion damage conditions, so as to accurately evaluate the corrosion damage degree.
[0018] The corrosion damage evaluation method for the blistering part of the anti-corrosion organic coating protection system established in the above manner can evaluate the degree of corrosion damage conveniently, accurately and without causing irreversible damage. BRIEF DESCRIPTION OF THE DRAWINGS
[0019] Figure 1 Bubble morphology on the spring surface;
[0020] Figure 2 The surface of the spring after the paint layer is removed from the bubbling area;
[0021] Figure 3 Suspected corrosion morphology of the substrate surface after the paint layer was removed from the blister area;
[0022] Figure 4 Normal surface morphology of the substrate after removing the paint layer in the non-bubbled area;
[0023] Figure 5 Energy spectrum results of corrosion products exposed after the coating was peeled off at the blister of the spring. DETAILED DESCRIPTION
[0024] The technical solution of the present invention is further described in detail below in conjunction with embodiments:
[0025] A method for evaluating corrosion damage of a part anti-corrosion organic coating protection system comprises the following steps:
[0026] (1) Preparation of test pieces
[0027] a) Use deionized water to gently clean the parts with organic coating bubbles in a corrosive environment to remove dust, salt and impurities on the surface. After cleaning, use a hair dryer to blow dry the surface moisture;
[0028] b) Select typical non-bubbled areas and bubbled areas, use several tapes with different peel strengths, stick one side to the non-bubbled area, and leave the other side hanging. Lift the tape on the non-bonded side to above 90°, quickly tear off the tape, and select the tape that can just stick the coating as the tape with the most suitable peel strength. Use the selected tape to perform the above operation on the bubbled area, quickly and conveniently remove the coating at the bubble, and expose the damage under the bubble.
[0029] (2) Corrosion damage test
[0030] a) If only the primer is exposed after the bubble area is torn off, and there are no obvious corrosion products, it means that the internal damage occurs at the interface between the topcoat and the primer; if only the metal protective layer is exposed after the bubble area is torn off, and there are no obvious corrosion products, it means that the internal damage occurs at the interface between the primer and the metal protective layer; if corrosion products are accumulated on the surface of the bubble area after it is torn off, it means that the base alloy or the metal protective layer is corroded, and the specific corrosion location needs to be further analyzed to determine the composition of the corrosion products.
[0031] b) For test pieces with corrosion products, an energy spectrometer is required to further analyze the composition of the corrosion products. If the test piece is small and can be placed in the SEM test chamber, the microscopic morphology and composition analysis of the corrosion products can be performed directly on the test piece. If the test piece is large and cannot be placed in the test chamber, use wooden tweezers or sharp tools to gently scrape up a small amount of corrosion products, then use conductive glue to take a small amount of corrosion product powder, and stick the conductive glue with corrosion products to the SEM test bench, and use an energy spectrometer to perform composition analysis. Determine the location of corrosion based on the composition of the corrosion products.
[0032] c) If the above test determines that the substrate has been corroded, the depth of substrate corrosion needs to be further tested. Select the corresponding corrosion product removal paste according to the type of substrate material and apply it to the area where corrosion products accumulate. After 10 to 30 minutes, wipe with soft gauze to observe whether there are still corrosion products in the corroded area. If so, continue to repeat the above process until the corrosion products are completely removed. Then use the three-dimensional imaging function of the video microscope to test the corrosion pits in the area where the corrosion products are removed to obtain a three-dimensional image and corrosion depth of the corrosion pits. The corrosion product paste is an acid-containing chemical, such as: steel corrosion product removal paste, aluminum corrosion product removal paste.
[0033] (3) Evaluation of corrosion damage
[0034] Combined with the test results, the corrosion damage was determined and the corrosion degree evaluation of the organic coating blister was given. The specific evaluation levels are shown in Table 1.
[0035] Table 1 Corrosion damage level of organic coating blister
[0036]
[0037]
[0038] Embodiment 1,
[0039] (1) Preparation of test pieces
[0040] a) A spring part is made of aluminum alloy, and the surface is cadmium plated and then coated with an organic coating. During the field service, the surface organic coating has bubbling phenomenon (such as Figure 1 ). Use deionized water to gently clean the spring parts to remove dust, salt and other impurities on the surface. After cleaning, use a hair dryer to blow dry the surface moisture.
[0041] b) Select 4 non-bubbled areas and 3 relatively obvious bubbling areas on the surface of the part. Use 4 tapes with different peel strengths, stick one side to the non-bubbled area, and leave the other side hanging. Lift the tape on the non-stick side to above 90°, quickly tear off the tape, and select the tape that can just stick the coating as the tape with the most suitable peel strength. Use the selected tape to perform the above operation on the 3 bubbling areas to remove the coating at the bubbling areas. Figure 2 shown.
[0042] (2) Corrosion damage test
[0043] a) After removing the paint layer of the spring bubble area, the test piece was placed in the SEM test chamber, and a small number of white spots were found on the surface. The shape was round or oval, similar to the bubble shape. After magnification, these white spots appeared loose on the surface, suspected to be corrosion products. Figure 3This morphology is different from the surface micromorphology of the normal area, see Figure 4 .
[0044] b) Use an energy spectrometer to test the composition of the suspected corrosion product white spot area. The test results are as follows Figure 5 The corrosion products mainly contain Cd, O and other components, indicating that the chrome plating layer has been corroded.
[0045] (3) Evaluation of corrosion damage
[0046] According to the test and analysis results, after the coating was removed from the blister area, corrosion products appeared on the exposed surface. After testing the composition of the corrosion products, it was determined that the corrosion site was the chrome plating layer, that is, the metal protective layer was corroded. According to the corrosion damage grade assessment method in Table 1, the degree of corrosion damage was grade 3.
Claims
1. A method for evaluating corrosion damage of a part anti-corrosion organic coating protection system, characterized in that: The following steps are involved: (1) Use the tape stripping method to remove the surface coating of the blister area of the test piece; (2) Corrosion damage test and grade assessment: see Table 1 Table 1 Corrosion damage level of organic coating blister 2. The corrosion damage evaluation method of the parts anti-corrosion organic coating protection system according to claim 1 is characterized in that: Before removing the surface coating of the bubbling part of the test piece, the test piece is gently cleaned with deionized water on the parts with organic coating bubbling under the action of the corrosive environment to remove surface dust, salt and impurities. After cleaning, the surface moisture is blown dry with cold air from a hair dryer.
3. The corrosion damage evaluation method of the parts anti-corrosion organic coating protection system according to claim 1 is characterized in that: The method for selecting the tape is as follows: select the unbubbled area and the bubbled area, use several tapes with different peeling strengths, stick one side to the unbubbled area, and leave the other side suspended, lift the tape on the unsticked side to above 90°C, quickly tear off the tape, and select the tape that can just stick the coating as the tape with the most suitable peeling strength.
4. The corrosion damage evaluation method of the parts anti-corrosion organic coating protection system according to claim 1 is characterized in that: The corrosion product composition test uses an energy spectrometer to analyze the corrosion product composition.
5. The corrosion damage evaluation method of the parts anti-corrosion organic coating protection system according to claim 1 is characterized in that: The test piece is of a size that can be placed in a scanning electron microscope test chamber, and the test piece can be directly used to perform microscopic morphology and composition analysis of corrosion products.
6. The corrosion damage evaluation method of the parts anti-corrosion organic coating protection system according to claim 1 is characterized in that: If the test piece cannot be placed in the test chamber, use wooden tweezers or sharp tools to gently scrape up a small amount of corrosion product, then use conductive glue to pick up a small amount of corrosion product powder, stick the conductive glue with corrosion products to the scanning electron microscope test bench, and use an energy spectrometer to perform component analysis.
7. The corrosion damage evaluation method of the parts anti-corrosion organic coating protection system according to claim 1 is characterized in that: The corrosion depth is determined by selecting a corresponding corrosion product removal paste according to the type of base material, and applying it to the area where corrosion products accumulate. After 10 minutes to 30 minutes, the area is wiped with soft gauze to observe whether there are still corrosion products on the corrosion area. If so, the above process is repeated until the corrosion products are completely removed. Then, the three-dimensional imaging function of the video microscope is used to test the corrosion pits at the area where the corrosion products are removed to obtain a three-dimensional image of the corrosion pits and the corrosion depth.
8. The corrosion damage evaluation method of the parts anti-corrosion organic coating protection system according to claim 1 is characterized in that: The corrosion product paste is a chemical containing acid.