Surface coating treatment method for stainless steel support assembly

Abstract

The invention provides a surface coating treatment method for a stainless steel bracket assembly, which comprises the following steps: degreasing and removing oil on the bracket assembly, cleaning with ionized water to remove oil stain on the surface, then pickling and passivating, increasing the material surface energy, uniformly spreading a passivation solution on the surface of a base material to form a passivation film with uniform thickness, and further coating primer, intermediate paint and finish paint to obtain the surface coating treatment of the stainless steel bracket assembly. According to the method, the stainless steel part with excellent coating adhesive force can be obtained, the adhesive force level is 0 level, meanwhile, the appearance quality and the corrosion resistance are greatly improved, the weather resistance is high, the technical requirements of special vehicles in the ultralow-temperature complex service environment can be met, and the method can be applied to other stainless steel parts and is good in application prospect.

Description

Technical Field

[0001] The invention belongs to the technical field of component surface coating treatment, and in particular relates to a stainless steel bracket assembly surface coating treatment method. Background Art

[0002] Stainless steel is widely used in various industries due to its good corrosion resistance, excellent appearance, high strength and high temperature resistance. In the past, special vehicle stainless steel parts only used surface passivation treatment to meet product protection and use requirements, and there was no surface coating treatment process for stainless steel.

[0003] The service conditions of special vehicles are complex and changeable. The service environment includes both land and glacial seawater. The environmental characteristics are high humidity, high heat, extremely low temperature and strong corrosion. The service temperature range is wide, from -70℃ to 45℃. Therefore, the surface performance requirements of parts are extremely strict, especially the protection performance. Therefore, the parts need to be painted while using stainless steel materials.

[0004] At present, the pre-treatment of coating mainly includes shot peening, degreasing, surface adjustment, phosphating, passivation, etc., which are used to remove oil stains and floating rust and increase the bonding strength between the substrate and the coating. Figure 1 As shown, shot peening cannot completely clean all surfaces of parts, leaving dead corners in some areas. Especially for the bracket assembly made of 12Cr18Ni9, the phosphating treatment does not form a film, and the surface cannot be evenly spread, resulting in uneven thickness, which significantly reduces the adhesion of the coating after painting, and causes shedding during use, reducing the service life. The epoxy coating and fluorocarbon coating currently used are new coatings with high weather resistance and corrosion resistance, and are applied to special vehicles for the first time. Therefore, the surface coating process of epoxy coatings and fluorocarbon coatings and improving the bonding strength between stainless steel substrates and coatings have become the focus of research, in order to provide strong support for improving the overall life of the bracket assembly. Summary of the invention

[0005] 1. Technical issues to be resolved

[0006] The present invention provides a surface coating treatment method for a stainless steel bracket assembly to solve the technical problem of how to improve the anti-corrosion performance and service life of the bracket assembly with respect to a new coating.

[0007] (II) Technical solution

[0008] In order to solve the above technical problems, the present invention proposes a surface coating treatment method for a stainless steel bracket assembly, which uses epoxy zinc-rich primer, epoxy micaceous iron intermediate paint and fluorocarbon coating topcoat to sequentially coat the surface of the bracket assembly.

[0009] Furthermore, the bracket assembly adopts stainless steel 12Cr18Ni9.

[0010] Furthermore, the surface coating treatment method comprises the following steps:

[0011] S1. Degreasing: Soak the stainless steel bracket assembly in a degreasing agent, clean the surface of the bracket assembly, and remove the organic matter and oil residue on the surface;

[0012] S2. Deionized water cleaning: Soak the degreased bracket assembly in deionized water to remove the surface degreasing agent;

[0013] S3. Pickling and passivation: Place the stainless steel bracket assembly in a pickling and passivation tank and hang it with a hanger to pickle the oxides on the stainless steel surface and eliminate the heat affected zone after welding. Under the action of the passivation liquid, a dense passivation film is formed on the surface of the bracket assembly;

[0014] S4. Cleaning: Place the pickled and passivated bracket assembly in running water for cleaning to remove residual passivation liquid and impurities;

[0015] S5. Drying: The cleaned bracket assembly is placed in a dry environment for drying;

[0016] S6. Primer coating: The dried surface of the bracket assembly is coated with primer, and then sent to a curing furnace for curing and drying until the surface of the bracket assembly reaches a surface dry state;

[0017] S7. Intermediate paint coating: The bracket assembly coated with primer is coated with intermediate paint, and then sent to a curing furnace for curing and drying until the surface of the bracket assembly reaches a solid dry state;

[0018] S8. Topcoat painting: The bracket assembly that has been coated with intermediate paint is coated with topcoat, and then sent to a curing furnace for curing and drying until the surface of the bracket assembly reaches a solid dry state.

[0019] Furthermore, in step S1, the degreasing agent is sodium hydroxide, the concentration is 5% to 10%, the temperature is 80 to 100° C., and the soaking time is 10 to 20 minutes.

[0020] Furthermore, in step S3, the components of the pickling passivation solution are 20% sulfuric acid, 30% nitric acid, and the rest are Na2Cr2O7·2H2O and additives; the passivation temperature is 25-35°C, the passivation time is 2-3min, and the passivation film thickness is 0.5-3μm.

[0021] Furthermore, in step S6, the curing temperature is 75-85°C; and the drying is performed at 80°C±5°C for ≥40 min.

[0022] Furthermore, in step S7, the curing temperature is 75-85°C; and the drying is performed at 80°C±5°C for ≥2h.

[0023] Furthermore, in step S8, the curing temperature is 75-85°C; and the drying is performed at 80°C±5°C for ≥2h.

[0024] Furthermore, the coating thickness of the primer is 40 to 80 μm; the coating thickness of the intermediate paint is 80 to 160 μm; and the coating thickness of the topcoat is 50 to 85 μm.

[0025] (III) Beneficial effects

[0026] The present invention proposes a surface coating treatment method for a stainless steel bracket assembly. The bracket assembly is degreased and deoiled, and the surface oil is removed by ion water cleaning, and then pickling and passivation are performed. The surface energy of the material is increased, and the passivation liquid is evenly spread on the surface of the substrate to form a passivation film of uniform thickness. Then, primer, intermediate paint, and topcoat are further applied to obtain stainless steel parts with excellent coating adhesion, and the adhesion level is 0. At the same time, the appearance quality and anti-corrosion performance are greatly improved, and the weather resistance is strong, which can meet the technical requirements of special vehicles in ultra-low temperature and complex service environments. The method can be applied to other stainless steel parts and has good application prospects. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] Figure 1 This is a cross-sectional view of the stainless steel bracket assembly targeted by the present invention;

[0028] Figure 2 The present invention is a flow chart of the surface coating treatment method of the stainless steel bracket assembly. DETAILED DESCRIPTION

[0029] In order to make the purpose, content and advantages of the present invention more clear, the specific implementation methods of the present invention are further described in detail below in conjunction with the drawings and examples.

[0030] This embodiment provides a surface coating treatment method for a stainless steel bracket assembly. The bracket assembly uses stainless steel 12Cr18Ni9, and the coating uses epoxy zinc-rich primer, epoxy micaceous iron intermediate paint and fluorocarbon coating topcoat to coat the surface of the bracket assembly. The process is as follows: Figure 2 As shown, the specific steps include:

[0031] S1. Degreasing: Soak the stainless steel bracket assembly in a degreasing agent to clean the bracket assembly surface and remove the organic matter and oil residue on the surface. The degreasing agent is sodium hydroxide with a concentration of 5% to 10%, a temperature of 80 to 100°C, and a soaking time of 10 to 20 minutes.

[0032] S2. Deionized water cleaning: Soak the degreased bracket assembly in deionized water to remove the surface degreasing agent to ensure that there is no residue. The cleaning time is 20 to 30 seconds.

[0033] S3. Pickling and passivation: Place the stainless steel bracket assembly in the pickling and passivation tank, hang it with a hanger, pickle the oxide on the stainless steel surface and eliminate the heat affected zone after welding. Under the action of the passivation liquid, a dense passivation film is formed on the surface of the bracket assembly. The pickling and passivation liquid contains 20% sulfuric acid, 30% nitric acid, and the rest is Na2Cr2O7·2H2O and additives; the passivation temperature is 25-35℃, the passivation time is 2-3min, and the passivation film thickness is 0.5-3μm.

[0034] S4. Cleaning: Place the pickled and passivated bracket assembly in running water for cleaning to remove residual passivation solution and impurities. The cleaning time is 40 to 50 seconds.

[0035] S5. Drying: Place the cleaned bracket assembly in a dry environment and use an air duct to blow dry until the surface of the parts is dry;

[0036] S6. Primer coating: Apply primer to the dried surface of the bracket assembly, and then send it into the curing furnace for curing at a curing temperature of 75-85°C; after applying the primer, dry it at 80°C±5°C for ≥40 minutes until the surface of the bracket assembly reaches a dry state (no fingerprints when pressed with the tip of the finger). Among them, the primer is an epoxy zinc-rich primer. Stir component A (including epoxy resin film-forming material, zinc powder, anti-rust pigment, additives, and solvent) evenly, and then mix them in a mass ratio of component A: component B (amine curing agent) = 10:1, stir evenly again, add diluent, adjust the viscosity to 10-25s, spray at a uniform speed, spray ≥1 coat, and the primer coating thickness is 40-80μm.

[0037] S7. Intermediate paint coating: The bracket assembly coated with primer is coated with intermediate paint, and then sent to the curing furnace for curing at a curing temperature of 75-85°C; after the intermediate paint is applied, it is dried at 80°C±5°C for ≥2h until the surface of the bracket assembly reaches a solid dry state. Among them, the intermediate paint is epoxy micaceous iron intermediate paint, and component A (including epoxy resin film-forming material, pigments such as micaceous iron oxide and fillers, solvents, and additives) is stirred evenly, and then mixed in a mass ratio of component A: component B (polyamide curing agent) = 9.3:1, and then stirred evenly again, matured for 20-40min, added with diluent, adjusted the viscosity to 15-35s, and sprayed at a uniform speed using an air pressure spray gun, spraying ≥2 coats, and the intermediate paint coating thickness is 80-160μm.

[0038] S8. Topcoat: Apply topcoat to the bracket assembly that has been coated with intermediate paint, and then send it into a curing furnace for curing at a curing temperature of 75 to 85°C; after applying the topcoat, dry it at 80°C±5°C for ≥2h until the surface of the bracket assembly reaches a solid dry state. Among them, the topcoat is a white matte flexible fluorocarbon coating topcoat. Stir component A (including fluorocarbon resin, pigment and filler, solvent, and additive) evenly, and then mix them in a mass ratio of component A: component B (polyamide curing agent) = 8:1, stir evenly again, add diluent, adjust the viscosity to 15 to 30s, use an air pressure spray gun to spray at a uniform speed, spray ≥2 coats, and the topcoat coating thickness is 50 to 85μm.

[0039] The coating of the stainless steel bracket assembly after surface coating according to the above embodiment was subjected to adhesion test and salt spray test, and the test results showed that the adhesion level was 0 and the salt spray test could last up to 720h. It can be seen that the appearance quality and anti-corrosion performance of the stainless steel bracket assembly are greatly improved after adopting this method, which can meet the performance requirements of special vehicles in extreme environments.

[0040] The above is only a preferred embodiment of the present invention. It should be pointed out that for ordinary technicians in this technical field, several improvements and modifications can be made without departing from the technical principles of the present invention. These improvements and modifications should also be regarded as the scope of protection of the present invention.

Claims

1. A method for surface coating of a stainless steel bracket assembly, characterized in that: The surface coating treatment method of the stainless steel bracket assembly uses epoxy zinc-rich primer, epoxy micaceous iron intermediate paint and fluorocarbon coating topcoat to sequentially coat the surface of the bracket assembly.

2. The surface coating treatment method of the stainless steel bracket assembly according to claim 1, characterized in that: The bracket assembly is made of stainless steel 12Cr18Ni9.

3. The surface coating treatment method of the stainless steel bracket assembly according to claim 1, characterized in that: The surface coating treatment method comprises the following steps: S1. Degreasing: Soak the stainless steel bracket assembly in a degreasing agent, clean the surface of the bracket assembly, and remove the organic matter and oil stains remaining on the surface; S2. Deionized water cleaning: Soak the degreased bracket assembly in deionized water to remove the surface degreasing agent; S3. Pickling and passivation: Place the stainless steel bracket assembly in a pickling and passivation tank and hang it with a hanger to pickle the oxides on the stainless steel surface and eliminate the heat affected zone after welding. Under the action of the passivation liquid, a dense passivation film is formed on the surface of the bracket assembly; S4. Cleaning: Place the pickled and passivated bracket assembly in running water for cleaning to remove residual passivation liquid and impurities; S5. Drying: The cleaned bracket assembly is placed in a dry environment for drying; S6. Primer coating: The dried surface of the bracket assembly is coated with primer, and then sent to a curing furnace for curing and drying until the surface of the bracket assembly reaches a surface dry state; S7. Intermediate paint coating: The bracket assembly coated with primer is coated with intermediate paint, and then sent to a curing furnace for curing and drying until the surface of the bracket assembly reaches a solid dry state; S8. Topcoat coating: The bracket assembly that has been coated with intermediate paint is coated with topcoat, and then sent to a curing furnace for curing and drying until the surface of the bracket assembly reaches a solid dry state.

4. The surface coating treatment method of the stainless steel bracket assembly according to claim 3 is characterized in that: In step S1, the degreasing agent is sodium hydroxide, the concentration is 5% to 10%, the temperature is 80 to 100° C., and the soaking time is 10 to 20 minutes.

5. The surface coating treatment method of the stainless steel bracket assembly according to claim 3, characterized in that: In step S3, the components of the pickling passivation solution are 20% sulfuric acid, 30% nitric acid, and the rest are Na2Cr2O7·2H2O and additives; the passivation temperature is 25-35°C, the passivation time is 2-3min, and the passivation film thickness is 0.5-3μm.

6. The surface coating treatment method of the stainless steel bracket assembly according to claim 3, characterized in that: In step S6, the curing temperature is 75-85°C; and the drying is performed at 80°C±5°C for ≥40 min.

7. The surface coating treatment method of the stainless steel bracket assembly according to claim 3, characterized in that: In step S7, the curing temperature is 75-85°C; and the drying is performed at 80°C±5°C for ≥2h.

8. The surface coating treatment method of a stainless steel bracket assembly according to claim 3, characterized in that: In step S8, the curing temperature is 75-85°C; the drying is performed at 80°C±5°C for ≥2h.

9. The surface coating treatment method of a stainless steel bracket assembly according to claim 3, characterized in that: The coating thickness of the primer is 40 to 80 μm; the coating thickness of the intermediate paint is 80 to 160 μm; and the coating thickness of the topcoat is 50 to 85 μm.

Images