CN108330476B - Aluminum alloy surface metal-organic framework film for washing-free ship - Google Patents

Abstract

The invention relates to the technical field of metal surface treatment, in particular to a washing-free marine aluminum alloy surface metal-organic framework film. The framework film is obtained by treating the surface of the marine aluminum alloy with a treatment liquid, wherein the treatment liquid is prepared from the following components in parts by weight: 0.1 to 4 weight percent of fluozirconic acid with the concentration of 45 percent, 0.5 to 3.5 weight percent of fluotitanic acid with the concentration of 50 percent, 0.2 to 1 weight percent of hydrofluoric acid with the concentration of 50 percent, 0.5 to 2.5 weight percent of silane coupling agent, 0.02 to 0.1 weight percent of phytic acid with the concentration of 50 percent, and the balance of water. According to the invention, the aluminum alloy is endowed with good corrosion resistance by coating the treatment liquid on the surface of the aluminum alloy, the treatment liquid takes fluozirconic acid and fluotitanic acid as main raw materials, organic matter components such as silane coupling agent, phytic acid and the like are added to act on the surface of the aluminum alloy, a chromium-free treatment process is adopted, the treatment liquid is safe and environment-friendly, the pollution to the environment is greatly reduced, and the prepared framework film is beneficial to improving the corrosion resistance of the surface of the aluminum alloy and the adhesiveness of the surface to powder coating.

Description

A water-free metal-organic framework film for marine aluminum alloy surface

technical field

The invention relates to the technical field of metal surface treatment, in particular to a metal-organic skeleton film on the surface of an aluminum alloy that is not washed with water.

Background technique

Aluminum alloys are widely used in ship structural materials due to their good corrosion resistance, weldability and mechanical properties. However, due to the thin oxide film of the aluminum alloy itself, the substrate will be corroded under the erosion of seawater and the humid and hot ocean atmosphere, which will affect its appearance and the adhesion of the organic coating. At present, most of the aluminum alloy surfaces are chemically treated to improve their corrosion resistance. Most of the treatment solutions containing chromium such as chromic acid-chromate directly contact the surface of the metal material, so that the chromate film is precipitated. Or coat it on the metal surface, and after drying, a chromate film is precipitated to protect the aluminum alloy surface. However, since hexavalent chromium is extremely harmful to the human body and the environment, it will not only cause pollution during the treatment process, but also the hexavalent chromium in the conversion film will also cause secondary pollution to the environment when the treated product is used and discarded in the future. The use of chromium chemical conversion treatment technologies is increasingly restricted.

At present, countries are developing more effective and environmentally friendly chromium-free metal surface treatment fluids. For example, the Chinese invention patent with the announcement number CN1123649C discloses a similar chromium-free surface treatment fluid, which contains titanium, zirconium or their mixtures, phosphates and fluorides. As the main component, adjust the acidic solution with pH value of 1.5-4.0. The solution has no sediment and harmful chromium ions, but when the solution is sprayed on the surface of metal materials in a short time (15 to 30 seconds), the resulting coating is uneven, showing unstable corrosion resistance and resistance to paints or coatings. Uneven adhesion. The Chinese invention patent with publication number CN102409324A discloses a chromium-free and phosphorus-free nanoscale chemical conversion solution, which is composed of titanium salt, zirconium salt, silicon compound, accelerator, pH adjuster, surfactant, etc., and is completely free of chromium ions and phosphoric acid. However, in the preparation of the nano-chemical conversion film, after chemical conversion, a water washing step is required to remove impurities such as acid and alkali on the surface of the film, which increases the industrial production cost, and the corrosion resistance of the conversion film does not last for a long time. narrower.

Therefore, it is a technical problem to be solved urgently in the art to provide a chromium-free aluminum alloy surface film layer with good corrosion resistance and adhesion.

SUMMARY OF THE INVENTION

The purpose of the present invention is to provide a chromium-free, water-free marine aluminum alloy surface metal-organic framework film with good corrosion resistance and good adhesion, optimize the preparation process of the framework film, and reduce industrial production costs.

The present invention adopts following technical scheme:

A metal-organic framework film on the surface of a water-free marine aluminum alloy, the framework film is obtained by treating the surface of the marine aluminum alloy with a treatment solution, and the treatment solution is prepared from the following components: a concentration of 45% Fluorozirconic acid 0.1-4wt%, 50% fluorotitanic acid 0.5-3.5wt%, 50% hydrofluoric acid 0.2-1wt%, silane coupling agent 0.5-2.5wt%, 50% concentration Phytic acid is 0.02-0.1wt%, and the balance is water.

Further, the pH value of the treatment solution is 2-5.

Further, the treatment solution is diluted with water during use, and the content of the treatment solution in the diluted solution is 2.5-4 wt %.

Further, the film forming process of the metal-organic framework film is as follows:

(1) Surface pretreatment of aluminum alloy: Polish the aluminum alloy surface with silicon carbide water sandpaper until the surface roughness is below 10 μm, soak it in an acidic degreasing and degreasing water solution for 2-6 minutes, rinse it with clean water, and repeat the operation twice Naturally air-dry or air-dry;

(2) Chemical conversion treatment of aluminum alloy: soak the aluminum alloy in the treatment solution, or spray the treatment solution directly on the surface of the aluminum alloy, or coat the treatment solution on the surface of the aluminum alloy, and the treatment time is 40s-10min;

(3) Drying: the aluminum alloy subjected to the chemical conversion treatment in step (2) is directly air-dried or dried.

Further, in step (2), the aluminum alloy is soaked in the treatment solution for a treatment time of 2-10 min.

Further, in step (2), the treatment time for directly spraying the treatment liquid on the surface of the aluminum alloy is 1-3min, and the spraying pressure is 0.08-0.18KPa.

Further, in step (2), the treatment time for coating the aluminum alloy surface with the treatment liquid is 40-70s.

Further, in step (3), the drying temperature is 40-120° C., and the drying time is 10-15 min.

The metal-organic framework film of the present invention imparts good corrosion resistance to the aluminum alloy by coating the surface of the aluminum alloy with the treatment liquid. Among them, the treatment liquid uses fluorozirconic acid and fluorotitanic acid as the main raw materials, supplemented by silane coupling agent, phytic acid and other organic components to act on the surface of the aluminum alloy, and the formed skeleton film uses Zr-Ti composite inorganic matter as the main film-forming salt. With silane coupling agent and phytic acid as auxiliary film-forming substances, a binary structure oxide with Zr-Ti as the main salt element and a chromium-free passivation film combined with organic matter can be quickly formed on the surface of aluminum alloy, and then Improve the corrosion resistance of aluminum alloy surfaces and good adhesion to powder coatings.

When using the treatment solution of the present invention to treat the surface of the aluminum alloy, according to the cathode film-forming mechanism, due to the existence of different potential phases and impurity atoms on the surface of the aluminum alloy, countless galvanic cells are formed in the surface micro-region and electrochemical reactions occur: the micro-anode region Metal dissolution occurs: M-ze ^- →M ^z+ (M represents the metal element in the aluminum alloy), H ₂ precipitation occurs in the micro-cathode region: 2H ⁺ +2e ^- → H ₂ or O ₂ reduction: O ₂ +2H ₂ O+ 4e ^- → 4OH ^- , so that the concentration of OH ^- ions in the micro-cathode area increases and the pH value increases, creating favorable conditions for the deposition of aluminum oxides. The reaction equation is as follows:

2Al+6H ⁺ +3ZrF ₆ ^2- +5H ₂ O→2AlOF.3ZrOF ₂ +10HF+3H ₂

2Al+6H ⁺ +3TiF ₆ ^2- +5H ₂ O→2AlOF.3TiOF ₂ +10HF+3H ₂

The formation of the film layer of zirconium and titanium, on the one hand, improves the adhesion between the passivation film and the powder coating, and at the same time increases the density of the skeleton film microscopically and improves its corrosion resistance.

At the same time, by adding organic components such as silane coupling agents to the treatment solution, the unsaturated bonds in the organic raw materials will combine with the metal bonds hydrolyzed by fluorozirconic acid and fluorotitanic acid to form a chemical bond skeleton, which provides a basis for the deposition of aluminum oxides. To effectively improve the corrosion resistance of metal-organic framework films. Further, the addition of organic components such as silane coupling agents enables the treatment solution to be directly dried after being coated on the surface of the aluminum alloy without water washing, which simplifies the fabrication process of the skeleton film and reduces industrial water consumption. The agent solution can be uniformly retained on the surface of the conversion film. During the curing process after coating powder or paint, the silane will hydrolyze and bond between the organic resin and the inorganic interface, which promotes the fusion of the interface and enhances the bonding force between the interfaces.

The water-free marine aluminum alloy surface metal-organic framework film of the present invention has the following beneficial effects:

(1) The metal-organic framework film on the surface of the water-free marine aluminum alloy of the present invention, by coating the surface of the aluminum alloy with a treatment solution, gives the aluminum alloy good corrosion resistance, and the treatment solution is fluorozirconic acid and fluorotitanic acid. The main raw materials, supplemented by silane coupling agent, phytic acid and other organic components act on the surface of the aluminum alloy, and the chromium-free treatment process is adopted, which is safe and environmentally friendly, and minimizes environmental pollution. Corrosion resistance of alloy surfaces and adhesion to powder coatings.

(2) The metal-organic skeleton film on the surface of the water-free marine aluminum alloy of the present invention adopts organic raw materials such as a silane coupling agent. On the surface of the conversion coating, during the curing process after coating powder or paint, the silane will be hydrolyzed, bonding between the organic resin and the inorganic interface, which promotes the fusion of the interface and improves the bonding force between the interfaces. The manufacturing process of the skeleton film improves the production efficiency, and on the other hand saves water resources and reduces the production cost.

(3) The metal-organic framework film on the surface of the water-free marine aluminum alloy of the present invention can make the tertiary powder coating have excellent adhesion performance on the surface of the marine aluminum alloy material, which is similar to the existing chromium-free passivation film on the aluminum alloy surface. It has a wider application range and can better adapt to the humid environment of the shipbuilding industry, which makes the corrosion resistance of aluminum alloy materials, the adhesion of powder coatings, impact resistance, toughness and other mechanical properties significantly improved.

Detailed ways

The technical solutions of the present invention will be clearly and completely described below with reference to specific embodiments. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative work fall within the protection scope of the present invention.

Metal materials used in the following examples:

The domestic aluminum-magnesium alloy profile 6061 with a thickness of 1mm, its main components are Fe: 0.35%, Mg: 0.8-0.9%, Si: 0.65-0.75%, Cu: 0.85-0.95%, Mn: 0.15-0.25%, the rest is Al.

According to the acidic degreasing and degreasing water solution of patent CN201010206660.7 or CN201010543878.1, the surface of the above metal material is cleaned, and then used for the surface treatment in the following examples.

Example 1

A metal-organic framework film on the surface of a water-free marine aluminum alloy, the framework film is obtained by treating the surface of the marine aluminum alloy with a treatment solution. In this embodiment, the treatment solution is prepared from the following components: the concentration is 45% 0.1wt% of fluorozirconic acid, 1wt% of fluorotitanic acid with a concentration of 50%, 0.8wt% of hydrofluoric acid with a concentration of 50%, 1wt% of silane coupling agent, 0.05wt% of phytic acid with a concentration of 50%, and the rest The amount is water, and the pH value of the treatment solution is adjusted to 2. The treatment solution was diluted with water during use, and the content of the treatment solution in the diluted solution was 4 wt %.

The film forming process of the skeleton film in this embodiment is as follows:

(1) Surface pretreatment of aluminum alloy: Take a sample piece from a 6061 large-size aluminum alloy profile, grind it with silicon carbide water sandpaper until the surface roughness is below 10 μm, soak it in an acidic degreasing and degreasing solution for 2 minutes, and then rinse it with water Clean, dry naturally or air dry after repeating the operation twice;

(2) Chemical conversion treatment of aluminum alloy: soak the aluminum alloy in the treatment solution for 4 minutes, or spray the treatment solution directly on the surface of the aluminum alloy with a spray pressure of 0.08KPa and a treatment time of 3 minutes, or coat the treatment solution on the surface of the aluminum alloy. Aluminum alloy surface, treatment time is 60s;

(3) Drying: the aluminum alloy after chemical conversion treatment in step (2) is directly and naturally dried.

Example 2

A metal-organic framework film on the surface of a water-free marine aluminum alloy, the framework film is obtained by treating the surface of the marine aluminum alloy with a treatment solution. In this embodiment, the treatment solution is prepared from the following components: the concentration is 45% Fluorozirconic acid 0.4wt%, 50% fluorotitanic acid 2.5wt%, 50% hydrofluoric acid 0.4wt%, silane coupling agent 1.5wt%, 50% phytic acid 0.02wt% , the balance is water. The pH of the treatment solution was adjusted to 3.6. The treatment solution was diluted with water during use, and the content of the treatment solution in the diluted solution was 3.2 wt %.

The film forming process of the skeleton film in this embodiment is as follows:

(1) Surface pretreatment of aluminum alloy: Take the sample piece from 6061 large-size aluminum alloy profile, grind it with silicon carbide water sandpaper until the surface roughness is below 10 μm, soak it in an acidic degreasing and degreasing solution for 6 minutes, and then rinse it with water Clean, dry naturally or air dry after repeating the operation twice;

(2) Chemical conversion treatment of aluminum alloy: soak the aluminum alloy in the treatment solution for 6 minutes, or spray the treatment solution directly on the surface of the aluminum alloy with a spray pressure of 0.12KPa and a treatment time of 1min, or coat the treatment solution on the surface of the aluminum alloy. Aluminum alloy surface, treatment time is 40s;

(3) Drying: directly drying the aluminum alloy after chemical conversion treatment in step (2), the drying temperature is 40° C., and the drying time is 15 minutes.

Example 3

A metal-organic framework film on the surface of a water-free marine aluminum alloy, the framework film is obtained by treating the surface of the marine aluminum alloy with a treatment solution. In this embodiment, the treatment solution is prepared from the following components: the concentration is 45% Fluorozirconic acid 1.0wt%, 50% fluorotitanic acid 2.4wt%, 50% hydrofluoric acid 0.2wt%, silane coupling agent 2.5wt%, 50% phytic acid 0.1wt% , the balance is water. Adjust the pH of the treatment solution to 5. The treatment liquid is diluted with water during use, and the content of the treatment liquid in the solution after dilution is 2.5 wt %.

The film forming process of the skeleton film in this embodiment is as follows:

(1) Surface pretreatment of aluminum alloy: Take the sample piece from the 6061 large-size aluminum alloy profile, grind it with silicon carbide water sandpaper until the surface roughness is below 10 μm, soak it in an acidic degreasing and degreasing solution for 4 minutes, and then rinse it with water Clean, dry naturally or air dry after repeating the operation twice;

(2) Chemical conversion treatment of aluminum alloy: soak the aluminum alloy in the treatment solution for 2 minutes, or spray the treatment solution directly on the surface of the aluminum alloy with a spray pressure of 0.1KPa and a treatment time of 2 minutes, or apply the treatment solution to the surface of the aluminum alloy. Aluminum alloy surface, treatment time is 50s;

(3) Drying: directly drying the aluminum alloy after chemical conversion treatment in step (2), the drying temperature is 120° C., and the drying time is 10 min.

Example 4

A metal-organic framework film on the surface of a water-free marine aluminum alloy, the framework film is obtained by treating the surface of the marine aluminum alloy with a treatment solution. In this embodiment, the treatment solution is prepared from the following components: the concentration is 45% Fluorozirconic acid 1.2wt%, 50% fluorotitanic acid 0.5wt%, 50% hydrofluoric acid 1wt%, silane coupling agent 0.5wt%, 50% phytic acid 0.08wt%, The remainder is water. The pH of the treatment solution was adjusted to 4. The treatment liquid is diluted with water during use, and the content of the treatment liquid in the solution after dilution is 3 wt %.

The film forming process of the skeleton film in this embodiment is as follows:

(1) Surface pretreatment of aluminum alloy: Take the sample piece from 6061 large-size aluminum alloy profile, grind it with silicon carbide water sandpaper until the surface roughness is below 10 μm, soak it in an acidic degreasing and degreasing solution for 6 minutes, and then rinse it with water Clean, dry naturally or air dry after repeating the operation twice;

(2) Chemical conversion treatment of aluminum alloy: soak the aluminum alloy in the treatment solution for 10min, or spray the treatment solution directly on the surface of the aluminum alloy, the spray pressure is 0.18KPa, the treatment time is 1.5min, or the treatment solution is coated On the aluminum alloy surface, the treatment time is 70s;

(3) Drying: the aluminum alloy after chemical conversion treatment in step (2) is directly and naturally dried.

The aluminum alloy materials obtained in Examples 1-4 were electrostatically sprayed with a three-level powder coating, and then cured. The curing temperature was 210° C. and the curing time was 15 minutes. The cured materials were subjected to acid salt spray test, constant temperature condensed water test, SO ₂ resistance test and filiform corrosion test. The specific test conditions are as follows:

(1) Acid salt spray test

The test basis is ISO 9227:2012, the test equipment is Q-FOG/SSP1100, the test time is 2000 hours, the technical requirements are based on QUALICOAT 14 edition: the foaming level is based on ISO 4628-2: ≤2(S2); ≤16mm ² /10cm; single maximum penetration length along the grid: ≤4mm.

(2) Constant temperature condensate test

Test based on ISO 6270-2: 2005, test equipment LIEBISCH K300, test duration 2000 hours, technical requirements based on QUALICOAT 14th edition: Foaming level based on ISO 4628-2: ≤2(S2); single maximum penetration length along the grid: ≤1mm.

(3) Resistance to SO ₂ test

Test according to DIN EN ISO 3231, test equipment A-SC KBG 400 Co.Liebsche, test duration 24cycles, technical requirements according to QUALICOAT 14th edition: no discoloration or foaming according to ISO 4628-2: ≤2(S2); The maximum penetration length of a single grid: ≤1mm.

(4) Filiform corrosion test

The test is based on DIN EN ISO 4623-2:2004, the test equipment Climate Chamber Co Binder, the test time is 1000 hours, the technical requirements are based on the QUALICOAT 14 edition: the maximum length of filamentous corrosion: ≤4mm, the average length of filamentous corrosion: ≤2mm, the wire Corrosion number: ≤20/10cm.

The test results of Examples 1-4 are shown in Tables 1-4.

Table 1 Results of acid salt spray test

Table 2 Test results of constant temperature condensate

Table 3 Test results of SO ₂ resistance

Discoloration or blistering grade Single maximum penetration length/mm Example 1 0(S0) 0 Example 2 0(S0) 0 Example 3 0(S0) 0 Example 4 0(S0) 0

Table 4 Filiform corrosion test results

It can be seen from Tables 1-4 that the metal-organic skeleton film on the surface of the water-free marine aluminum alloy of the present invention enables the aluminum alloy material to have good corrosion resistance to the tertiary powder coating and high adhesion to the powder coating. Compared with the primary and secondary powder coatings, the first-grade powder coating has stronger mechanical properties such as toughness and impact resistance, so that the metal-organic framework film on the surface of the water-free marine aluminum alloy of the present invention can play an excellent role in the marine aluminum alloy material. Protective effects. At the same time, the metal-organic framework film on the surface of the water-free marine aluminum alloy of the present invention does not need to be washed with water after chemical conversion in the film-forming process, and can be directly dried, which simplifies the production process, saves water resources, and reduces production costs.

The present invention has been further described above with the help of specific embodiments, but it should be understood that the specific description herein should not be construed as a limitation on the spirit and scope of the present invention. Various modifications made in the embodiments all belong to the protection scope of the present invention.

Claims (8)

1. a metal-organic skeleton film on the surface of a water-free aluminum alloy for ships, characterized in that, the skeleton film is obtained by utilizing a treatment solution on the surface of the aluminum alloy for ships, and the treatment solution is formulated from the components of the following contents : 45% fluorozirconic acid 0.1-4wt%, 50% fluorotitanic acid 0.5-3.5wt%, 50% hydrofluoric acid 0.2-1wt%, silane coupling agent 0.5-2.5wt% , the concentration is 50% phytic acid 0.02-0.1wt%, and the balance is water. 2 . The metal-organic framework film on the surface of aluminum alloy for marine use without water washing according to claim 1 , wherein the pH value of the treatment solution is 2-5. 3 . 3 . The metal-organic framework film on the surface of aluminum alloy for boats without water washing according to claim 2 , wherein the treatment solution is diluted with water during use, and the content of the treatment solution in the diluted solution is 2.5-4 wt %. 4 . 4. water-free marine aluminum alloy surface metal-organic framework film according to claim 3, is characterized in that, the film forming process of described framework film is as follows: (1) Surface pretreatment of aluminum alloy: Polish the aluminum alloy surface with silicon carbide water sandpaper until the surface roughness is below 10 μm, soak it in an acidic degreasing and degreasing water solution for 2-6 minutes, rinse it with clean water, and repeat the operation twice Naturally air-dry or air-dry; (2) Chemical conversion treatment of aluminum alloy: soak the aluminum alloy in the treatment solution, or spray the treatment solution directly on the surface of the aluminum alloy, or coat the treatment solution on the surface of the aluminum alloy, and the treatment time is 40s-10min; (3) Drying: the aluminum alloy after chemical conversion treatment in step (2) is directly dried or dried naturally. 5. The metal-organic skeleton film on the surface of the aluminum alloy for boats without water washing according to claim 4, is characterized in that, in the step (2), the processing time of the aluminum alloy being immersed in the treatment solution is 2-10min. 6. water-free marine aluminum alloy surface metal-organic framework film according to claim 4, is characterized in that, in step (2), the treatment time that the treatment liquid is directly sprayed on the aluminum alloy surface is 1-3min, and the spray pressure is 1-3min. It is 0.08-0.18KPa. 7 . The metal-organic framework film on the surface of aluminum alloy for marine use without water washing according to claim 4 , wherein, in step (2), the treatment time during which the treatment solution is applied to the surface of the aluminum alloy is 40-70s. 8 . 8. The metal-organic framework film on the surface of aluminum alloy for boats without water washing according to claim 4, characterized in that, in step (3), the drying temperature is 40-120° C., and the drying time is 10-15 min.