Anti-corrosion treatment method for metal base material in extreme marine environment
By pre-treating the surface and applying multiple layers of coating, the corrosion problem of metal substrates in marine environments is solved, effectively resisting alternating wet and dry seawater and salt spray, thus improving corrosion resistance and durability.
Patent Information
- Application Number
- CN202410626000.6
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2024-05-20
- Publication Date
- 2025-11-21
AI Technical Summary
Existing anti-corrosion technologies have failed to effectively address the complex corrosion problems caused by alternating wet and dry seawater conditions and salt spray, resulting in insufficient corrosion resistance and durability of metal substrates in extreme marine environments.
The method employs surface pretreatment, thermal spraying of zinc, and anti-corrosion coating, including removing scale, rust, and oil stains to form a dense zinc layer, and applying multiple layers such as epoxy zinc-rich primer, epoxy micaceous iron oxide intermediate paint, and acrylic polyurethane topcoat to ensure that the coating adhesion and thickness meet the requirements.
It significantly improves the corrosion resistance and durability of metal substrates in extreme marine environments, resists the erosion of alternating wet and dry seawater and salt spray, extends service life, and provides lasting protection.
Smart Images
Figure CN120984535A_ABST
Abstract
Description
TECHNICAL FIELD
[0001] The application belongs to the technical field of metal corrosion prevention and relates to a method for preventing corrosion of a metal substrate in an extreme marine environment. BACKGROUND
[0002] In a complex marine environment, high salt and high humidity, dry-wet alternation, wind and wave impact, and bubbles in seawater have great destructive effects on the protective film and coating on the surface of the steel tower of an offshore wind turbine. After the aging and cracking of the paint film on the surface of the tower, the steel structure is exposed to harsh marine environments, so it is crucial to study the corrosion mechanism of the tower material.
[0003] Many studies have explored the corrosion behavior of different steels in simulated seawater or marine atmospheric environments. The results show that factors such as temperature, stirring speed, relative humidity, and alloy element content can affect the corrosion rate of the steel and the formation of surface corrosion products. For example, the corrosion rates of Q235 and Q345 steels in static seawater are close and increase with increasing temperature; the stirring speed has a significant effect on the corrosion behavior. In simulated marine atmospheric environments, salt spray corrosion tests of Q345 steel and weathering steels show that the main corrosion products are similar, but the different alloy element contents result in changes in the compactness of the surface corrosion products and the thickness of the rust layer. In addition, the temperature and relative humidity of the NaCl solution also affect the corrosion resistance of Q345 steel in simulated high-humidity and hot marine atmospheric environments.
[0004] Other studies have focused on the changes in the corrosion products of carbon steel in marine environments and found that the initial corrosion products are reducing Y-FeOOH, and the later-stage products are relatively stable ct-FeOOH, and the later-stage rust layer has a certain protective effect. At the same time, the corrosion kinetics and the changes in the corrosion products of carbon steel and weathering steel in different atmospheric environments are basically similar, but the corrosion mechanisms are significantly different. In particular, in marine atmospheres, the corrosion rate of carbon steel is extremely high.
[0005] However, current studies mostly focus on the corrosion behavior of materials in marine atmospheric or seawater environments, ignoring the effects of the dry-wet alternation of seawater and the interaction of salt spray on materials.
[0006] Periodic wetting and drying of seawater have a significant impact on the corrosion of metal material surfaces. However, current corrosion prevention techniques often only focus on corrosion problems in a single wet or dry state, and do not fully consider the complexity of corrosion behavior during the wet-dry alternating process. When seawater is wet, existing anti-corrosion coatings or surface treatments may not be able to effectively resist the erosion of seawater; and when seawater is dry, due to the lack of necessary water retention and salt mist resistance, salt accumulation and concentration on the surface of metal materials is easy to occur, further exacerbating corrosion. For salt mist, although there are some anti-salt mist corrosion coatings and materials, their corrosion resistance and durability still need to be improved. Especially in extreme salt mist environments, these corrosion-resistant materials may quickly fail and cannot provide adequate protection for metals. SUMMARY
[0007] In order to overcome the above-mentioned shortcomings of the prior art, the purpose of the present application is to provide a method for corrosion protection of metal substrates in extreme marine environments, which can improve the corrosion resistance and durability of metal substrates in extreme marine environments.
[0008] In order to achieve the above-mentioned purpose, the present application adopts the following technical solutions:
[0009] The present application discloses a method for corrosion protection of metal substrates in extreme marine environments, comprising the following steps:
[0010] Surface pretreatment of the surface of the metal substrate;
[0011] Thermal spraying of zinc on the surface of the metal substrate;
[0012] Anti-corrosion coating construction on the surface of the metal substrate;
[0013] Detection of the thickness of the anti-corrosion coating on the surface of the metal substrate, with at least 90% of the anti-corrosion coating thickness reaching the specified thickness, and the remaining 10% of the anti-corrosion coating thickness reaching 90% of the specified film thickness;
[0014] Detection of the adhesion of the anti-corrosion coating on the surface of the metal substrate, with the adhesion of the anti-corrosion coating being greater than or equal to 5 MPa.
[0015] Further, the surface pretreatment of the surface of the metal substrate is as follows:
[0016] Removing the oxide scale, rust, oil and burrs on the surface of the metal substrate, and correcting the non-continuous welds and pits of the metal substrate to ensure that the rust removal level of the surface of the metal substrate is Sa2.5 grade and the surface roughness is 40-60 um;
[0017] Rounding the corners of the surface of the metal substrate.
[0018] Further, the surface of the metal substrate is pre-treated by pickling and phosphating.
[0019] Further, the surface of the metal substrate is pre-treated by pickling and phosphating.
[0020] Further, the surface of the metal substrate is pre-treated by pickling and phosphating.
[0021] Further, the surface of the metal substrate is pre-treated by pickling and phosphating.
[0022] Further, the surface of the metal substrate is pre-treated by pickling and phosphating.
[0023] Further, the surface of the metal substrate is pre-treated by pickling and phosphating.
[0024] Further, the surface of the metal substrate is pre-treated by pickling and phosphating.
[0025] Further, the surface of the metal substrate is pre-treated by pickling and phosphating.
[0026] Further, the surface of the metal substrate is pre-treated by pickling and phosphating.
[0027] Further, the surface of the metal substrate is pre-treated by pickling and phosphating.
[0028] Further, the surface of the metal substrate is pre-treated by pickling and phosphating.
[0029] Further, the surface of the metal substrate is pre-treated by pickling and phosphating.
[0030] Further, the surface of the metal substrate is pre-treated by pickling and phosphating.
[0031] Further, the thickness of the anticorrosive coating of the stainless steel substrate is at least 80 microns, the thickness of the special primer for the substrate is at least 40 microns, and the thickness of the acrylic polyurethane topcoat is at least 40 microns.
[0032] Compared with the prior art, the present application has the following beneficial effects:
[0033] 1. The surface pretreatment of the metal substrate surface is beneficial to improve the coating adhesion, increase the contact area of the coating and the substrate, improve the anticorrosive effect of the coating, and reduce the construction difficulty.
[0034] 2. The thermal spraying of zinc on the surface of the metal substrate is beneficial to the long-term effective protection of the metal substrate from the erosion of the external environment, thereby significantly prolonging the service life of the metal and improving the anticorrosive performance and durability of the metal substrate in extreme marine environments.
[0035] 3. The anticorrosive coating construction on the surface of the metal substrate requires that at least 90% of the anticorrosive coating thickness reaches the specified thickness, and the remaining 10% of the anticorrosive coating thickness reaches 90% of the specified film thickness. The adhesion of the anticorrosive coating on the surface of the metal substrate is greater than or equal to 5 MPa, which ensures the stability of the anticorrosive performance of the metal substrate in harsh environments, provides long-term protection for the metal, and improves the anticorrosive performance and durability of the metal substrate in extreme marine environments. BRIEF DESCRIPTION OF DRAWINGS
[0036] Figure 1 The method flowchart of the present application. DETAILED DESCRIPTION
[0037] In order to better understand the present application by those skilled in the art, the technical solutions in the embodiments of the present application will be described clearly and completely below in conjunction with the drawings in the embodiments of the present application. Obviously, the described embodiments are only a part of the embodiments of the present application, not all. Based on the embodiments in the present application, all other embodiments obtained by those skilled in the art without creative labor should be within the scope of protection of the present application.
[0038] It is to be understood that the terminology used herein is for the purpose of describing particular embodiments only and is not intended to be limiting, unless the context clearly indicates otherwise. It will be further understood that the use of relational terms such as first and second, and the like are used solely to distinguish one from another entity without necessarily implying a relationship or order between such entities. Much of the detail of the embodiments described in this detailed description is intended to be illustrative and not restrictive. It is contemplated that the scope of the application is not limited to the embodiments set forth herein, but can be practiced with modification and alteration within the scope and spirit of the appended claims. Furthermore, the starting point of the steps recited in the claims does not have to be the starting point of the specific embodiments. Moreover, the grouping of data recited in the claims is only meant to be a limitation as to the scope of the embodiments and is not meant to limit the scope of possible embodiments to a specific group of data.
[0039] The application will be further described in conjunction with the drawings, in which:
[0040] Referring to Figure 1 The application discloses a method for corrosion protection of metal base material in extreme marine environment, comprising the following steps:
[0041] S1. Surface pretreatment is performed on the surface of the metal base material;
[0042] Preferably, the surface pretreatment of the surface of the metal base material is specifically as follows:
[0043] The oxide skin, rust, oil stain and burr on the surface of the metal base material are removed, and the discontinuous welding and pit of the metal base material are corrected, so that the rust removal level of the surface of the metal base material is ensured to be Sa2.5 level, and the surface roughness is 40um-60um.
[0044] Corner rounding is performed on the surface of the metal base material.
[0045] Preferably, when the surface of the metal base material is subjected to the surface pretreatment, the pickling and phosphating treatment is preferentially adopted for the long pipe type and the carbon steel sheet type base material with a thickness less than 4mm.
[0046] S2. Hot zinc spraying is performed on the surface of the metal base material;
[0047] Preferably, the hot zinc spraying on the surface of the metal base material is specifically as follows:
[0048] The metal zinc is heated to a molten state, and the molten metal zinc is sprayed to the surface of the metal base material after the pretreatment to form a coating.
[0049] Preferably, the hot zinc spraying work should be performed as soon as possible after the surface of the metal base material is pretreated, and the hot zinc spraying work is completed within 4 hours after the pretreatment is completed.
[0050] Preferably, the metal base material includes a carbon steel base material, a hot-dip galvanized base material, an aluminum alloy base material and a stainless steel base material.
[0051] S3. The surface of the metal substrate is subjected to anticorrosive coating construction;
[0052] Preferably, the surface of the metal substrate is subjected to anticorrosive coating construction as follows:
[0053] The anticorrosive coating construction process is carried out in a closed environment;
[0054] If the metal substrate is a carbon steel substrate, the anticorrosive coating comprises, from inside to outside, an epoxy zinc-rich primer, an epoxy micaceous iron intermediate paint and an acrylic polyurethane topcoat;
[0055] If the metal substrate is a hot-dip galvanized substrate, the anticorrosive coating comprises, from inside to outside, a special substrate-specific primer, an epoxy micaceous iron intermediate paint and an acrylic polyurethane topcoat;
[0056] If the metal substrate is an aluminum alloy substrate, the anticorrosive coating comprises, from inside to outside, a special substrate-specific primer and an acrylic polyurethane topcoat;
[0057] If the metal substrate is a stainless steel substrate, the anticorrosive coating comprises, from inside to outside, a special substrate-specific primer and an acrylic polyurethane topcoat.
[0058] Preferably, the anticorrosive coating of the carbon steel substrate has a thickness of at least 320 μm, the epoxy zinc-rich primer has a thickness of at least 60 μm, the epoxy micaceous iron intermediate paint has a thickness of at least 200 μm, and the acrylic polyurethane topcoat has a thickness of at least 60 μm.
[0059] Preferably, the anticorrosive coating of the hot-dip galvanized substrate has a thickness of at least 240 μm, the special substrate-specific primer has a thickness of at least 80 μm, the epoxy micaceous iron intermediate paint has a thickness of at least 200 μm, and the acrylic polyurethane topcoat has a thickness of at least 60 μm.
[0060] Preferably, the anticorrosive coating of the aluminum alloy substrate has a thickness of at least 120 μm, the special substrate-specific primer has a thickness of at least 60 μm, and the acrylic polyurethane topcoat has a thickness of at least 60 μm.
[0061] Preferably, the anticorrosive coating of the stainless steel substrate has a thickness of at least 80 μm, the special substrate-specific primer has a thickness of at least 40 μm, and the acrylic polyurethane topcoat has a thickness of at least 40 μm.
[0062] S4. The thickness of the anticorrosive coating on the surface of the metal substrate is detected, at least 90% of the anticorrosive coating thickness reaches the specified thickness, and the remaining 10% of the anticorrosive coating thickness reaches 90% of the specified film thickness;
[0063] S5. The adhesion of the anticorrosive coating on the surface of the metal substrate is detected, and the adhesion of the anticorrosive coating is greater than or equal to 5 MPa.
[0064] SeeFigure 1 In another possible embodiment of the present application, the following is adapted according to the situation. The surface of the metal substrate is subjected to surface pretreatment, which is beneficial to improve the adhesion of the coating, increase the contact area of the coating and the substrate, improve the corrosion protection effect of the coating, and reduce the construction difficulty. The surface of the metal substrate is subjected to thermal spraying of zinc, and the zinc layer can effectively protect the metal substrate from the erosion of the external environment for a long time, thereby significantly prolonging the service life of the metal. The metal surface treated by thermal spraying of zinc can remain stable in a high temperature environment and is not prone to deformation and corrosion, which can significantly improve the corrosion resistance and corrosion durability of the metal substrate in extreme marine environments. The surface of the metal substrate is subjected to corrosion protection coating construction, which is beneficial to ensure the stability of the corrosion resistance of the metal substrate in harsh environments and provide long-term protection for the metal. The thickness of the surface corrosion protection coating of the metal substrate is detected, at least 90% of the corrosion protection coating thickness reaches the specified thickness, and the remaining 10% of the corrosion protection coating thickness reaches 90% of the specified film thickness, further improving the corrosion resistance and corrosion durability of the metal substrate in extreme marine environments. The adhesion of the surface corrosion protection coating of the metal substrate is detected, and the adhesion of the corrosion protection coating is greater than or equal to 5 MPa, which can realize the long-term protection of the surface of the metal substrate by the corrosion protection coating and improve the corrosion resistance and corrosion durability of the metal substrate in extreme marine environments.
[0065] Example 1:
[0066] Referring to Figure 1 The present embodiment discloses a method for corrosion protection treatment of metal substrate in extreme marine environment, comprising the following steps:
[0067] S1. The surface of the metal substrate is pretreated and subjected to thermal spraying of zinc;
[0068] All burrs and corners of the metal substrate must be rounded, and non-continuous welding (dimple) and the like must be corrected; long pipe type and carbon steel sheet with a thickness of less than 4 mm are preferably subjected to pickling and phosphating treatment.
[0069] The surface of the metal substrate must be free of defects such as sharp corners, burrs and flash, and all corners must be chamfered; the chamfering R5 for steel plates with a thickness of not less than 10 mm, the chamfering R3 for the rest, and the rounding according to half of the thickness of the steel plate for less than R3; the chamfering R3 for the inside of the light hole;
[0070] The surface of the metal substrate is subjected to very thorough sandblasting to remove oxidation skin, grease, rust, dirt and paint and the like, and the surface should show uniform metal color; after sandblasting, the surface is cleaned with clean and dry compressed air or a clean brush, the rust removal level is Sa2.5, and the surface roughness is 40um-60um.
[0071] The surface of the metal substrate is subjected to thermal spraying of zinc, and the thermal spraying of zinc process scheme is as follows:
[0072] Hot zinc spraying process is a method of heating zinc to a molten state, and then spraying it to the surface of the pretreated body by means of a gas flow to form a coating. It is suitable for corrosion protection of transformer oil tank, oil tank accessories and other steel structures.
[0073] Hot zinc spraying work should be carried out as soon as possible after sandblasting the surface of the workpiece, and should be completed within 4 hours after sandblasting. Zinc spraying material uses high-quality zinc wire with a diameter of 3mm and a zinc content of not less than 99.99%, without oil stains.
[0074] S2. The surface of the metal substrate is coated with a corrosion-resistant coating, which is determined as follows:
[0075] Table 3.1 Carbon steel substrate coating system:
[0076]
[0077] Table 3.2 Hot dip galvanized (85μm) substrate coating system:
[0078]
[0079] Table 3.3 Aluminum alloy substrate coating:
[0080]
[0081] Table 3.4 Stainless steel 316L substrate coating:
[0082]
[0083] The metal substrate is closed and treated with a corrosion-resistant coating;
[0084] Sealing treatment is the last layer of corrosion-resistant process of hot spraying, in order to better and effectively achieve the protection purpose of the sprayed layer and prolong the service life of the substrate structure, sealing treatment must be carried out. The total thickness of the coating is not less than 300um.
[0085] S3. Film detection
[0086] The film thickness of any part shall not exceed 50% of the minimum thickness, 90% of the measurement points shall reach the specified thickness, and the remaining 10% of the measurement points shall reach 90% of the specified film thickness. The adhesion of the film shall not be less than 5MPa.
[0087] The quality detection requirements are as follows:
[0088] Zinc layer appearance inspection: no impurities, bubbles, substrate exposure, cavities and uneven particles and cracks, etc. The appearance of the coating is uniform, there are no unattached or weakly attached zinc particles and other defects that affect the service life and corrosion resistance of the coating.
[0089] Adhesion: The adhesion of the coating to the metal substrate was tested by cross-hatch testing. The cross-hatch area was 15mm*15mm, the cross-hatch spacing was 3mm, and the cross-hatch depth was required to break the coating to the base metal. The rest was operated according to the relevant test standards.
[0090] The method has the following advantages in dealing with seawater wet-dry alternation and salt spray:
[0091] Excellent corrosion resistance: The thermal sprayed zinc coating can provide a dense zinc layer for the metal substrate. When the seawater is wet, the zinc layer can act as an anode to provide cathodic protection to the substrate, effectively preventing corrosion of the substrate. When the seawater is dry, the zinc layer can form a stable oxide protective film, further resisting the erosion of salt spray.
[0092] Good weather resistance: The thermal sprayed zinc coating has good weather resistance and can maintain stable performance in extreme marine environments. It is not easily affected by seawater wet-dry alternation and salt spray, and can maintain long-term protection of the metal substrate.
[0093] Strong adhesion: The thermal sprayed zinc coating can form a strong metallurgical bond with the metal substrate, with strong adhesion. This bonding method makes the coating less likely to fall off or peel off, and even under the erosion of seawater wet-dry alternation and salt spray, it can maintain good adhesion performance.
[0094] Repairability: If the thermal sprayed zinc coating is damaged or destroyed in a local area, it can be repaired locally without replacing the entire coating. This repairability makes the thermal sprayed zinc coating maintain good economic and sustainable performance during long-term use.
[0095] Environmental friendliness: The thermal sprayed zinc process produces less waste during construction and can be recycled and reused, with less impact on the environment. At the same time, the thermal sprayed zinc coating does not release toxic and harmful substances during use, meeting environmental requirements.
[0096] In summary, the present application has excellent corrosion resistance, good weather resistance, strong adhesion, repairability and environmental friendliness in dealing with seawater wet-dry alternation and salt spray, and is an effective method for preventing corrosion of metal in marine environments.
[0097] The above content only illustrates the technical idea of the present application and cannot limit the protection scope of the present application. Any modification made according to the technical idea of the present application on the basis of the technical solution falls within the protection scope of the claims of the present application.
Claims
1. A method for corrosion protection of metal substrates in extreme marine environments, characterized in that, The method comprises the following steps: surface pretreatment of the surface of the metal substrate; thermal zinc spraying on the surface of the metal substrate; application of anticorrosive coating on the surface of the metal substrate; detection of the thickness of the anticorrosive coating on the surface of the metal substrate, at least 90% of the anticorrosive coating thickness reaching the specified thickness, and the remaining 10% of the anticorrosive coating thickness reaching 90% of the specified film thickness; detection of the adhesion of the anticorrosive coating on the surface of the metal substrate, the adhesion of the anticorrosive coating being greater than or equal to 5 MPa.
2. The method for corrosion protection of metal substrate in extreme marine environment according to claim 1, characterized in that, The surface pretreatment of the surface of the metal substrate is specifically as follows: removal of the oxide scale, rust, oil stains and burrs on the surface of the metal substrate, correction of the non-continuous weld and pits of the metal substrate, and ensuring that the rust removal level of the surface of the metal substrate is Sa2.5 and the surface roughness is 40-60 um; corner rounding of the surface of the metal substrate.
3. The method for corrosion protection of metal substrates in extreme marine environments according to claim 2, characterized in that, When the surface of the metal substrate is subjected to surface pretreatment, for long pipe type and carbon steel sheet type substrates with a thickness of less than 4 mm, acid pickling and phosphating are preferentially used.
4. The method for corrosion protection of metal substrate in extreme marine environment according to claim 1, characterized in that, The thermal zinc spraying on the surface of the metal substrate is specifically as follows: heating of the metal zinc to a molten state, and spraying of the molten metal zinc to the surface of the pretreated metal substrate to form a coating.
5. The method for corrosion protection of metal substrate in extreme marine environment according to claim 1, characterized in that, The metal substrate includes carbon steel substrate, hot-dip galvanized substrate, aluminum alloy substrate and stainless steel substrate.
6. The method of claim 1, wherein the method is characterized by: The application of the anticorrosive coating on the surface of the metal substrate is specifically as follows: The anticorrosive coating application process is carried out in a closed environment. If the metal substrate is a carbon steel substrate, the anticorrosive coating comprises, from inside to outside, an epoxy zinc-rich primer, an epoxy iron oxide intermediate coating and an acrylic polyurethane topcoat. If the metal substrate is a hot-dip galvanized substrate, the anticorrosive coating comprises, from inside to outside, a special substrate-specific primer, an epoxy iron oxide intermediate coating and an acrylic polyurethane topcoat. If the metal substrate is an aluminum alloy substrate, the anticorrosive coating comprises, from inside to outside, a special substrate-specific primer and an acrylic polyurethane topcoat. If the metal substrate is a stainless steel substrate, the anticorrosive coating comprises, from inside to outside, a special substrate-specific primer and an acrylic polyurethane topcoat.
7. The method of claim 6, wherein the method is characterized by: The thickness of the anticorrosive coating of the carbon steel substrate is at least 320 um, the thickness of the epoxy zinc-rich primer is at least 60 um, the thickness of the epoxy iron oxide intermediate coating is at least 200 um, and the thickness of the acrylic polyurethane topcoat is at least 60 um.
8. The method of claim 6, wherein the method is characterized by: The thickness of the anticorrosive coating of the hot-dip galvanized substrate is at least 240 um, the thickness of the special substrate-specific primer is at least 80 um, the thickness of the epoxy iron oxide intermediate coating is at least 200 um, and the thickness of the acrylic polyurethane topcoat is at least 60 um.
9. The method of claim 6, wherein the method is characterized by: The thickness of the anticorrosive coating of the aluminum alloy substrate is at least 120 um, the thickness of the special substrate-specific primer is at least 60 um, and the thickness of the acrylic polyurethane topcoat is at least 60 um.
10. The method of claim 6, wherein the method is characterized by: The thickness of the anticorrosive coating of the stainless steel substrate is at least 80 um, the thickness of the special substrate-specific primer is at least 40 um, and the thickness of the acrylic polyurethane topcoat is at least 40 um.