阅读说明：本技术 一种可用于航空铝合金的表面处理液及其使用方法 (Surface treatment liquid for aviation aluminum alloy and use method thereof ) 是由 薛文利 雷力明 黄佳华 周正刚 于 2018-06-25 设计创作，主要内容包括：本发明涉及一种可用于航空铝合金的表面处理液及其使用方法。该处理液为酸的水溶液,其含有,铬酸,以CrO<Sub>3</Sub>计的浓度为35～45g/L；硝酸,浓度为70～100g/L；氢氟酸,浓度为2～10g/L；和磷酸,浓度为2～10g/L。该铝合金处理液的使用周期长,效果好。(The invention relates to a surface treatment liquid for aviation aluminum alloy and a using method thereof. The treatment liquid is an aqueous acid solution containing chromic acid and CrO 3 The measured concentration is 35-45 g/L; nitric acid with the concentration of 70-100 g/L; hydrofluoric acid with the concentration of 2-10 g/L; and phosphoric acid with the concentration of 2-10 g/L. The aluminum alloy treatment fluid has long service life and good effect.)

1. A surface treatment liquid for an aluminum-based material, which is an aqueous acid solution, contains,

chromic acid, in CrO₃The measured concentration is 35-45 g/L;

nitric acid with the concentration of 70-100 g/L;

hydrofluoric acid with the concentration of 2-10 g/L; and

the concentration of the phosphoric acid is 2-10 g/L.

2. The surface treatment fluid for aluminum-based materials as claimed in claim 1, which has one or more of the following characteristics:

the concentration of chromic acid is 38-42 g/L;

the concentration of the nitric acid is 80-90 g/L;

the concentration of the hydrofluoric acid is 4-6 g/L;

the concentration of the phosphoric acid is 4-6 g/L;

the mass ratio of the hydrofluoric acid to the phosphoric acid is 0.8-1.2: 0.8 to 1.2;

the aluminum-based material is pure aluminum or an aluminum alloy.

3. The surface treatment liquid for aluminum-based materials as claimed in claim 1, which is composed of:

chromic acid, nitric acid, hydrofluoric acid, phosphoric acid, and water.

4. Use of the surface treatment liquid for aluminum-based materials according to any one of claims 1 to 3 for surface treatment of aluminum-based materials.

5. The use according to claim 4, for the pretreatment of an aluminum-based material to be chemically converted.

6. A method for pretreating an aluminum-based material, comprising the steps of:

a) immersing an aluminum-based material in the surface treatment liquid for an aluminum-based material according to any one of claims 1 to 5;

optionally, step a) is followed by a step of washing the aluminum-based material with water.

7. The method for pretreating aluminum-based materials of claim 6, wherein,

and soaking the aluminum-based material in the aluminum-based material surface treatment solution for 5-20 minutes.

8. The method for pretreating aluminum-based materials according to claim 7, further comprising, prior to step a), one or more of:

-mechanically grinding the aluminum-based material;

-washing the aluminum-based material with an organic solvent;

-washing the aluminum-based material with an alkaline solution;

washing the aluminum-based material with water.

9. The method for pretreatment of aluminum-based materials as claimed in claim 6, further comprising one or more of:

detecting the corrosion rate of the aluminum-based material surface treatment liquid on the aluminum-based material, and if the corrosion rate is less than x mm/surface/hour, adding phosphoric acid and hydrofluoric acid into the aluminum-based material surface treatment liquid to enable the corrosion rate to reach more than x mm/surface/hour, wherein x is 0.015-0.025;

detecting the concentration of each component in the aluminum-based material surface treatment liquid, and if the concentration of any component is found to deviate from the formula, performing an operation of adjusting the concentration of the component so that the concentration of the component is brought back into the formula range.

10. The aluminum-based material pretreatment method of claim 9, having one or more of the following characteristics:

the mass ratio of phosphoric acid to hydrofluoric acid added to the aluminum-based material surface treatment liquid is 0.8-1.2: 0.8 to 1.2;

-detecting the concentration of chromic acid and/or nitric acid in the surface treatment liquid for the aluminum-based material, and if the concentration of chromic acid and/or nitric acid deviates from the recipe, performing the step of adding acid or water to bring the concentration of chromic acid and/or nitric acid back into the recipe range

The aluminum-based material is aluminum or an aluminum alloy, such as a 2XXX series aluminum alloy.

11. The method for pretreating an aluminum-based material according to claim 9, wherein the surface treatment liquid for an aluminum-based material has a lifetime of 3 months or more.

12. A method for forming a chemical conversion coating on the surface of an aluminum-based material, comprising the steps of:

pretreating an aluminium-based material using a method according to any one of claims 6 to 11;

and immersing the pretreated aluminum-based material into a chemical conversion solution.

Technical Field

The invention belongs to the field of aluminum alloy surface treatment, and particularly relates to an aluminum alloy surface treatment liquid and a surface treatment method.

Background

The chemical conversion coating technology is a technology for forming a stable compound coating on the surface of a metal by chemical or electrochemical means, namely, passivating the metal. The chemical conversion film is mainly used for rust prevention, wear resistance, coating, galvanic corrosion prevention, insulation and decoration of metal. The metal is contacted with a specific corrosive liquid phase, and a chemical reaction is carried out under a certain condition, so that a product film layer with good adhesive force and difficult solubility is formed on the surface of the metal. These film layers either protect the base metal from water and other corrosive media or improve the adhesion and aging resistance of the organic coating film.

In order to obtain a good chemical conversion film, before chemical conversion, surface pretreatment is generally performed.

Disclosure of Invention

In some aspects, there is provided an aluminum-based material surface treatment fluid which is an aqueous acid solution containing,

chromic acid (H)₂CrO₄) With CrO₃The measured concentration is 35-45 g/L;

nitric acid (HNO)₃) The concentration is 70-100 g/L;

hydrofluoric acid (HF) with a concentration of 2-10 g/L; and

phosphoric acid (H)₃PO₄) The concentration is 2-10 g/L.

The surface treating liquid for aluminum-based material is prepared from water, nitric acid, hydrofluoric acid, phosphoric acid and CrO₃Is prepared by the following steps.

In some embodiments, the concentration of chromic acid in the aluminum-based material surface treatment solution is 38 to 42 g/L.

In some embodiments, the concentration of nitric acid in the surface treatment liquid for aluminum-based materials is 80 to 90 g/L.

In some embodiments, the concentration of hydrofluoric acid in the surface treatment solution for aluminum-based materials is 4 to 6 g/L.

In some embodiments, the concentration of phosphoric acid in the surface treatment liquid for aluminum-based materials is 4 to 6 g/L.

In some embodiments, the mass ratio of hydrofluoric acid to phosphoric acid in the surface treatment liquid for the aluminum-based material is 0.8 to 1.2: 0.8 to 1.2.

In some embodiments, the mass ratio of hydrofluoric acid to phosphoric acid in the surface treatment liquid for the aluminum-based material is 0.9 to 1.1: 0.9 to 1.1.

In some embodiments, the aluminum-based material surface treatment fluid consists of: chromic acid, nitric acid, hydrofluoric acid, phosphoric acid, and water.

The aluminum-based material surface treatment liquid is an aqueous solution of an acid, wherein the acid is a combination of chromic acid, nitric acid, hydrofluoric acid and phosphoric acid.

In some embodiments, the aluminum-based material surface treatment liquid refers to a solution for surface treatment of an aluminum-based material.

In some embodiments, the pitting ability of the aluminum-based material treatment fluid is tested. For example, the pitting and intergranular corrosion capability test is carried out by using 2024-T3 bare aluminum test piece, namely, the 2024-T3 bare aluminum test piece (the size is 125mm multiplied by 80mm multiplied by 1mm) is placed in the surface treatment liquid of the aluminum-based material, and the test piece is observed after 30 minutes of corrosion. The results show that the surface treatment fluid for aluminum-based materials meets the following criteria: the pitting depth of the end of the crystal grain is not more than 0.025 mm.

In some embodiments, the intergranular corrosion capability of an aluminum-based material treatment fluid is tested. For example, the intergranular corrosion ability test is carried out by using a 2024-T3 bare aluminum test piece, namely, a 2024-T3 bare aluminum test piece (the size is 125mm x 80mm x 1mm) is placed in the surface treatment liquid of the aluminum-based material, and the test piece is observed after 30 minutes of corrosion. The results show that the surface treatment fluid for aluminum-based materials meets the following criteria: no intergranular corrosion or intergranular corrosion depth less than 0.005 mm.

In some embodiments, the frequency of detecting pitting and intergranular corrosion capabilities of the aluminum-based material treatment fluid may be one or more checks per day, week, month, or quarter.

In some aspects, there is provided a use of an aluminum-based material surface treatment liquid for surface treatment of an aluminum-based material.

In some embodiments, the aluminum-based material surface treatment solution is used to pretreat an aluminum-based material to be chemically converted.

In some aspects, a method for pretreating an aluminum-based material is provided, comprising the steps of:

a) an aluminum-based material is immersed in the aluminum-based material surface treatment liquid of the present disclosure.

Optionally, step a) is followed by a step of washing the aluminum-based material with water.

In some embodiments, the aluminum-based material is immersed in the surface treatment solution for 5 to 20 minutes.

In some embodiments, step a) is preceded by the step of mechanically abrading the aluminum-based material.

In some embodiments, step a) is preceded by the step of washing the aluminum-based material with an organic solvent.

In some embodiments, step a) is preceded by the step of washing the aluminum-based material with an alkaline solution.

In some embodiments, step a) is preceded by the step of washing the aluminum-based material with water.

In some embodiments, a method of pretreatment of an aluminum-based material comprises: detecting the corrosion rate of the aluminum-based material surface treatment liquid on the aluminum-based material, and if the corrosion rate is less than 0.020 mm/surface/hour, adding phosphoric acid and hydrofluoric acid into the aluminum-based material surface treatment liquid to enable the corrosion rate to reach 0.020-0.025 mm/surface/hour.

In some embodiments, if the etching rate is less than 0.020 mm/surface/hr, the phosphoric acid and the hydrofluoric acid are added to the aluminum-based material surface treatment liquid at a mass ratio of 0.8 to 1.2: 0.8 to 1.2.

In some embodiments, a method of pretreatment of an aluminum-based material comprises: when the concentration of each component in the surface treatment liquid for aluminum-based materials is detected and the concentration of any component is found to deviate from the recipe, the concentration of the component is adjusted so that the concentration of the component falls within the recipe range.

In some embodiments, the frequency of detecting components may be one or more checks per day, week, month, or quarter.

In some embodiments, when a formula value is a numerical point, deviating from the formula means deviating from the formula value by more than 1%, such as more than 5%, such as more than 10%. When a formula value is a numerical range, deviation from the formula means exceeding the formula numerical range.

In some embodiments, a method of pretreatment of an aluminum-based material comprises: and detecting the concentration of chromic acid and/or nitric acid in the surface treatment solution of the aluminum-based material, and if the concentration of chromic acid and/or nitric acid deviates from the formula, performing the step of adding acid or water to return the concentration of chromic acid and/or nitric acid to the formula range.

In some embodiments, the aluminum-based material pretreatment method further comprises the steps of: detecting the corrosion rate of the aluminum-based material surface treatment liquid to the aluminum-based material, and if the corrosion rate is less than x mm/surface/hour, adding the aluminum-based material surface treatment liquid with the mass ratio of 0.8-1.2: 0.8-1.2 phosphoric acid and hydrofluoric acid, so that the etching rate is more than x mm/surface/hour, wherein x is 0.015-0.025.

In some embodiments, the frequency of detecting the rate of corrosion may be one or more checks per day, week, month, or quarter.

In some embodiments, the aluminum-based material pretreatment method further comprises the steps of: detecting the corrosion rate of the aluminum-based material surface treatment liquid to the aluminum-based material, and if the corrosion rate is less than x mm/surface/hour, adding the aluminum-based material surface treatment liquid with the mass ratio of 0.8-1.2: 0.8 to 1.2 phosphoric acid and hydrofluoric acid, so that the etching rate reaches x to x + y mm/surface/hour, wherein x is 0.015 to 0.025, and y is 0.005 to 0.01.

In some embodiments, the aluminum-based material pretreatment method further comprises the steps of: detecting the corrosion rate of the aluminum-based material surface treatment liquid to the aluminum-based material, and if the corrosion rate is less than 0.020 mm/surface/hour, adding the aluminum-based material surface treatment liquid with the mass ratio of 0.8-1.2: 0.8-1.2 phosphoric acid and hydrofluoric acid to reach a corrosion rate of 0.020-0.025 mm/surface/hour.

In some embodiments, the average daily amount of aluminum-based material treated per 1000 liters of aluminum alloy acid treatment fluid over the trial period is about 5m based on the surface area of the aluminum-based material²Below, for example, about 3m²The following.

In some embodiments, the aluminum-based material surface treatment fluid has a lifetime of 3 months or more, such as 6 months or more, such as 9 months or more, such as 12 months or more, such as 15 months or more, such as 18 months or more, such as 24 months or more.

In some aspects, a method of forming a chemical conversion film on a surface of an aluminum-based material is provided, comprising the steps of:

pretreating an aluminum-based material using the aluminum-based material pretreatment method of the present disclosure;

and immersing the pretreated aluminum-based material into a chemical conversion solution.

In some embodiments, the chemical conversion solution is a liquid capable of forming a good adhesion and insoluble product film on the surface of the aluminum-based material after contacting the aluminum-based material. The chemical conversion solution is, for example, Alodine1200 chemical conversion solution.

In some embodiments, chemical conversion of the aluminum-based material refers to the reaction of the surface of the aluminum-based material with a chemical oxidant in solution in a chemical conversion solution, rather than by applying an electrical voltage to form a chemical conversion film.

In the present invention, unless otherwise specified, scientific and technical terms used herein have the meanings that are commonly understood by those skilled in the art. Also, the laboratory procedures referred to herein are all conventional procedures widely used in the corresponding field. Meanwhile, in order to better understand the present invention, the definitions and explanations of related terms are provided below.

In some embodiments, the aluminum-based material is pure aluminum or an aluminum alloy.

In some embodiments, the aluminum alloy is a 1XXX series aluminum alloy, i.e., greater than 99% pure aluminum series, such as 1050, 1100; 2XXX series aluminum alloys, i.e., the aluminum-copper alloy series, such as 2014; 3XXX series aluminum alloys, i.e., aluminum-manganese alloy series, such as 3003; 4XXX series aluminum alloys, i.e., aluminum-silicon alloy series, such as 4032; 5XXX series aluminum alloys, i.e., aluminum-magnesium alloy series, such as 5052; 6XXX series aluminum alloys, i.e., aluminum-magnesium-silicon alloy series, such as 6061, 6063; 7XXX series aluminum alloys, i.e., aluminum-zinc alloy series aluminum alloys, such as 7001; 8XXX series aluminum alloys, i.e., alloy systems other than those described above.

In some embodiments, the aluminum alloy refers to a 2XXX series aluminum alloy, such as the aluminum alloys having designations 2024, 2a16(LY16), or 2a02(LY 6).

In some embodiments, the aluminum alloy is an aerospace aluminum alloy.

In some embodiments, the aluminum content in the aluminum alloy is greater than or equal to 50 wt.%, such as greater than or equal to 60 wt.%, such as greater than or equal to 70 wt.%, such as greater than or equal to 80 wt.%, such as greater than or equal to 90 wt.%, such as greater than or equal to 95 wt.%, such as greater than or equal to 99 wt.%.

The corrosion rate of the aluminum alloy acid treatment liquid to the test piece is controlled to be 0.020-0.025 mm/surface/hour by adding hydrofluoric acid and phosphoric acid (optionally, the mass ratio of the hydrofluoric acid to the phosphoric acid is 0.8-1.2-0.8-1.2) to the aluminum alloy acid treatment liquid (the test piece material is 2024-T3 aluminum-coated test piece).

The 2024-T3 aluminum clad test pieces are industry standard test pieces well known in the art. The method is characterized in that a high-purity aluminum layer with the thickness not less than 4% is metallurgically bonded on the surface of the 2024 aluminum alloy and is used as an anode of the core alloy to improve the corrosion resistance of the core alloy.

2024-T3 bare aluminum coupons are industry standard coupons known in the art. It is an aluminum alloy with an outer layer not containing an aluminum coating layer.

Chromic acid is H₂CrO₄From CrO₃Dissolving in water. The nitric acid is HNO₃. Phosphoric acid is H₃PO₄. The hydrofluoric acid is HF.

Advantageous effects

The present disclosure has one or more of the following benefits:

1. the aluminum-based material surface treatment liquid has long service life, for example, up to two years;

2. the pretreatment method for the surface of the aluminum-based material has good effect, if intergranular corrosion does not occur;

3. the surface chemical conversion treatment effect of the aluminum-based material is good, such as no corrosion point in a salt spray test;

4. the method for pretreating the surface of the aluminum-based material has low cost, and the treatment liquid is continuously used without frequently replacing the treatment liquid;

5. the chemical conversion treatment cost of the surface of the aluminum-based material is low.

Embodiments of the present invention will be described in detail below with reference to the drawings and examples, but those skilled in the art will understand that the following drawings and examples are only for illustrating the present invention and are not to be construed as limiting the scope of the present invention. Various objects and advantageous aspects of the present invention will become apparent to those skilled in the art from the accompanying drawings and the following detailed description of the preferred embodiments.

Drawings

FIG. 1 is a photograph of test pieces of 9 th and 10 th aluminum alloys of comparative example 2;

FIG. 2 is a photograph of the 9 th and 10 th aluminum alloy test pieces of example 2;

FIG. 3 is a photograph of the 30 th and 31 th aluminum alloy test pieces of comparative example 2;

FIG. 4 is a photograph of the 30 th and 31 th aluminum alloy test pieces of example 2;

FIG. 5 is a metallographic picture (magnification 500) of an aluminum alloy test piece treated with the aluminum alloy acid treatment solution of example 1;

FIG. 6 is a photograph of the aluminum alloy test piece of example 3 after being subjected to a salt spray test.

Detailed Description

Embodiments of the present invention will be described in detail below with reference to examples, but those skilled in the art will appreciate that the following examples are only illustrative of the present invention and should not be construed as limiting the scope of the present invention. The examples, in which specific conditions are not specified, were conducted under conventional conditions or conditions recommended by the manufacturer. The reagents or instruments used are not indicated by the manufacturer, and are all conventional products commercially available.

Comparative example 1

The aluminum alloy acid treatment liquid A is an aqueous acid solution and consists of chromic acid, nitric acid and hydrofluoric acid, wherein: chromic acid (in CrO)₃Calculated) 40g/L, 85g/L nitric acid and 5g/L hydrofluoric acid, and the total amount is 2L.