DE102007013404A1 - A method for preventing corrosion of an aluminum-based metal component and a corrosion-resistant aluminum-based metal product produced by the method - Google Patents

Abstract

The present invention provides a method for preventing corrosion of an aluminum-based metal component which makes it easier to check the presence or absence of a chemically-formed film on the component, and a corrosion-resistant aluminum-based metal product produced by this method. In the method, the following treating agent (A) is contacted with the surface of an aluminum-based metal component to chemically form the following film (B) on the surface of the aluminum-based metal component: (A) a treating agent containing an aqueous solution of zinc sulfate; an aqueous solution of ammonium fluoride and an aqueous solution of sodium molybdate which are mixed together; (B) a chemically formed film (B) comprising zinc fluoride, molybdenum and aluminum fluoride. In this way, a corrosion-resistant aluminum-based metal product is produced.

Description

BACKGROUND OF THE INVENTION

1. Field of the invention

The The present invention relates to a method for avoiding corrosion a metal component based on aluminum or aluminum an aluminum alloy, and a manufactured by the method corrosion-resistant Aluminum product based on aluminum.

2. State of the art

in the Automotive sector, for example, is currently being attempted the weight of vehicles to reduce fuel costs (or to improve the environmental behavior). For weight reduction is aluminum or an aluminum alloy instead of iron as Metal material for vehicle parts like arm suspensions, Bushings, engines, engine mounts and body panels used.

Under such circumstances It is initially common chemical Films on aluminum and Aluminum alloy components through a chemical treatment (Surface treatment), such as a chromate treatment to avoid corrosion of the components to build. The treatment agent for the chromate treatment contains hexavalent Chromium, the human body and adversely affect the environment, causing problems.

Therefore, a recent trend is to refrain from using hexavalent chromium. The applicant of the present invention has recently proposed a method of avoiding corrosion as an alternative to chromate treatment (see Japanese Unexamined Patent Publication No. 2001-47515 ). In this process, an aluminum-based metal component consisting of aluminum or an aluminum alloy is etched with an acid, a base or a fluoride, and then chemically formed with a film by a chemical treatment using an alkali metal phosphate.

Yet is the chemically formed by the process of the prior art Film bright in color or colorless and transparent, which makes it difficult makes sure that the component was subjected to chemical treatment (film-forming Procedure) or not. This requires an improvement in terms of Production control.

in view of in the foregoing, it is an object of the present invention a method of avoiding corrosion of a metal component aluminum-based, it facilitates the presence or absence of a chemically formed film on the component to check and a corrosion resistant To provide aluminum-based metal product by this Procedure was made.

SUMMARY OF THE INVENTION

Corresponding The first aspect of the present invention is achieved of the aforementioned subject matter, a method for avoiding Corrosion of an aluminum-based metal component made of aluminum or an aluminum alloy is provided, wherein the Method comprises: contacting a treatment agent (A) with the surface an aluminum-based metal component for chemical forming of a film (B) on the surface the aluminum-based metal component; wherein the treatment agent (A) an aqueous Zinc sulphate solution, an aqueous one Ammonium fluoride solution and an aqueous one sodium molybdate which are mixed together; and where the chemical formed film (B) comprises zinc fluoride, molybdenum and aluminum fluoride.

Corresponding A second aspect of the present invention is a corrosion resistant metal product aluminum-based, comprising: a metal component based on aluminum, made of aluminum or an aluminum alloy consists; and chemically on a surface of the metal component Aluminum base according to the aforementioned method for avoiding Corrosion formed film (B).

The inventors of the present invention conducted a study on a new method for the Bil of a chemical film to make it easier to check the presence or absence of a film formed chemically on a surface of an aluminum-based metal component. As a result, the present inventors found that the aforementioned chemically formed film (B) is formed on the surface of the aluminum-based metal component by contacting the aforesaid treating agent (A) with the surface of the metal component to impart a sufficient anticorrosive property to the component and that the presence or absence of the chemically formed film (B) can be easily checked since the film (B) is colored. Thus, the present invention has been achieved.

• (a) eine wässrige Lösung, die 15 Gewichtsprozent Zinksulfat-Heptahydrat enthält;
• (b) eine wässrige Lösung, die 10 Gewichtsprozent Ammoniumfluorid enthält; und
• (c) eine wässrige Lösung, die 5 Gewichtsprozent Natriummolybdat-Dihydrat enthält.

According to the method of the invention for preventing corrosion of an aluminum-based metal component, the film (B) formed chemically by contacting the treating agent (A) with the surface of the aluminum-based metal component is colored. This makes it easy to check the presence or absence of the chemically formed film (B) on the surface. In particular, when the treating agent (A) comprises the following aqueous zinc phosphate solution (a), the following aqueous ammonium fluoride solution (b) and the following aqueous sodium molybdate solution (c), which are in a mass ratio of (a) / (b) / (c) = 7/3/2, the corresponding aqueous solutions are effective in the reaction for film formation at:

• (a) an aqueous solution containing 15% by weight of zinc sulfate heptahydrate;
• (b) an aqueous solution containing 10% by weight of ammonium fluoride; and
• (c) an aqueous solution containing 5% by weight of sodium molybdate dihydrate.

Further is the zinc of zinc fluoride, molybdenum and aluminum of aluminum fluoride in the chemically formed film (B) in a ratio of Contents of zinc / molybdenum / aluminum = 5/4/1 on a mass basis. Therefore, the chemically formed film is (B) in terms of adhesion and the anticorrosive property optimized.

If the treating agent (A) having a mass ratio of (a) / (b) / (c) = 7/3/2 35 to 175 g of the solution (a) 15 to 45 g of the solution (b) and 10 to 50 g of the solution (c), the formability of the film (B) is improved. Further the film (B) is excellent in anti-corrosive property and the adhesion.

If the treatment agent (A) has a temperature of 45 to 65 ° C and the surface the aluminum-based metal component with the treating agent (A) for a duration of 1 to 10 minutes is kept in touch Moldability of the film (B) further improved.

The Corrosion-resistant metal product according to the invention aluminum-based is avoided by the aforementioned method made of corrosion, and chemically on the surface of the Aluminum-based metal component (B) is colored. This makes it easier to detect the presence or absence of the chemical on the surface formed film (B) to check.

Especially is when zinc of zinc fluoride, molybdenum and aluminum of aluminum fluoride in the chemically formed film (B) in a ratio of Contents of zinc / molybdenum / aluminum = 5/4/1 on a mass basis, the chemically formed film (B) excellent in adhesion and gives the aluminum-based metal component excellent anti-corrosive property.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

embodiments The present invention will be described below in detail.

In the method according to the invention to avoid corrosion, a treating agent which will be described in detail later will, with the surface a metal component based on aluminum or aluminum an aluminum alloy is brought into contact, creating a Movie, later in detail chemically on the surface of the component to avoid is formed by corrosion of the aluminum-based metal component. The chemically formed film is yellow or sunny yellow. The color facilitates the presence or absence of the chemically formed Films on the surface to check the component.

In particular, the treating agent is a solution mixture obtained by mixing an aqueous solution of zinc sulfate, an aqueous solution of ammonium fluoride, and an aqueous solution of sodium molybdate. The treating agent (solution mixture) is prepared in the following manner. To form the film, an aqueous solution (a) containing 15% by weight of zinc sulfate heptahydrate, an aqueous solution (b) containing 10% by weight of ammonium fluoride, and an aqueous solvent solution (c) containing 5% by weight of sodium molybdate dihydrate, respectively, used as the aqueous zinc sulfate solution, aqueous ammonium fluoride solution and aqueous sodium molybdate solution. The aqueous solutions (a), (b) and (c) corresponding to the above-mentioned concentrations are mixed in a mass ratio of (a) / (b) / (c) = 7/3/2 to prepare the treating agent.

Of the Film chemically using the treating agent thus prepared is formed Zinc fluoride, molybdenum and aluminum fluoride (resulting from the reaction between ammonium fluoride and Aluminum in the aluminum-based metal component). Especially These are the zinc of zinc fluoride, molybdenum and aluminum of aluminum fluoride in the chemically formed film in a ratio of the contents of zinc / molybdenum / aluminum = 5/4/1 or in a ratio contents close to this ratio (4-6 / 3-6 / 0.5-2) on a mass basis.

The Composition (ratio the contents) of the chemically formed film is determined by ICP (inductive coupled plasma) emission spectrometry.

Especially the treating agent is prepared by mixing from 35 to 175 g of the aqueous Zinc sulfate solution (a) containing 15% by weight of zinc sulfate heptahydrate (or From 5.25 to 26.25 g of zinc sulfate heptahydrate based on the solute), 15 to 45 g of the aqueous Ammonium fluoride solution (b) containing 10% by weight of ammonium fluoride (or 1.5 to 4.5 g of ammonium fluoride based on the solved Stoffes) and 10 to 50 g of the aqueous sodium molybdate (c) containing 5% by weight of sodium molybdate dihydrate (or 0.5 to 2.5 g of sodium molybdate dihydrate based on the solute) produced. Consequently contains the resulting treatment agent the aqueous solution (a), the aqueous solution (b) and the watery Solution (c) in a mass ratio from (a) / (b) / (c) = 7/3/2. To improve the formability of the film is the temperature of the treating agent is preferably 45 to 64 ° C.

The surface The aluminum-based metal component is generally used with the treating agent by immersing the component in the treating agent brought into contact. Alternatively, the treatment agent may be applied to the surface of the Aluminum component sprayed or applied. When the treating agent at the aforementioned preferred temperature (45 to 65 ° C) is held, the aluminum-based metal component is preferable with the treatment agent for a duration (contact time) of 1 to 10 minutes by immersion or the like kept in contact.

After this the film chemically on the surface the aluminum-based metal component by dipping or the like was formed, the surface becomes the component is rinsed with water, with hot water rinsed and if necessary dried.

The Aluminum-based metal component usually has an oxide film on its surface. In the case of a conventional one chemical treatment using a phosphate of an alkali metal, it is necessary the oxide film before chemical treatment by etching remove. In the present invention, ammonium fluoride is for etching away an aluminum oxide film containing in the treating agent, so that the oxide film on the surface of the metal component on Aluminum base is dissolved by the treatment agent. This eliminates the Need of an etching step, which otherwise in the conventional method is required. Nevertheless, the etching step can be performed if necessary.

Of the thus chemically formed film is yellow or as described above sun yellow. Therefore, it can be checked at a glance if the movie is on the component is present or not. This facilitates the presence or absence of the film to check, thereby the efficiency of manufacturing control in the manufacturing process for a corrosion-resistant Aluminum-based metal product is improved.

The Aluminum and the aluminum alloy as material for the component aluminum-based ones are not particularly limited, but examples thereof shut down all aluminum-based metals including No. 1000 to No. 7000 Series, AC series and ADC series. The corrosion-resistant aluminum-based metal product is not particularly limited but close examples of this Vehicle components such as engine mounts, electrical components like camera body, constructive components such as aluminum sash frames, office furniture such as Desks and other products in different areas to be used.

When next Examples of the present invention will be described in connection with Example of the prior art described. It should be understood be that the invention is not limited to these examples.

example 1

Aluminum-based component

A Plate (25 mm × 60 mm × 3 mm (thickness)) of the aluminum alloy A6063 was prepared.

treatment agents

The Treating agent for forming the chemical film was prepared by mixing of 35.0 g of an aqueous Zinc sulfate solution (15 weight percent zinc sulfate heptahydrate containing), 15.0 g of an aqueous ammonium fluoride solution (10 Containing by weight ammonium fluoride) and 10.0 g of an aqueous sodium molybdate (Containing 5 weight percent sodium molybdate dihydrate) and diluting the resulting mixture, so that the zinc sulfate heptahydrate, the ammonium fluoride and the sodium molybdate dihydrate in concentrations corresponding to 5.25 g / liter, 1.5 g / liter and 0.5 g / liter in the Present treatment.

Formation of the chemical film

The Aluminum-based metal component was incorporated into the treatment agent for 20 Minutes immersed at 75 ° C, causing a film to chemically on the surface of the metal component Aluminum base was formed. The following was the result Component removed from the treatment agent, rinsed with water, with hot Water rinsed and dried. Thus, a corrosion-resistant aluminum-based metal product became produced.

Example 2

treatment agents

The Treating agent for forming the chemical film was prepared by mixing of 52.5 g of an aqueous Zinc sulfate solution (15 weight percent zinc sulfate heptahydrate containing), 22.5 g of an aqueous ammonium fluoride solution (10 Containing by weight ammonium fluoride) and 15.0 g of an aqueous sodium molybdate (Containing 5 weight percent sodium molybdate dihydrate) and mixing prepared the resulting mixture so that the zinc sulfate heptahydrate, the ammonium fluoride and the sodium molybdate dihydrate in concentrations corresponding to 7.875 g / liter, 2.25 g / liter and 0.75 g / liter in the treatment agent.

Formation of the chemical film

The Aluminum-based metal component was incorporated into the treatment agent for 10 Minutes immersed at 65 ° C, causing a film to chemically on the surface of the metal component Aluminum base was formed. The following became the component taken from the treatment agent, rinsed with water, with hot Water rinsed and dried. Thus, a corrosion-resistant aluminum-based metal product became produced.

Example 3

treatment agents

The Treatment agent for Forming the chemical film was accomplished by mixing 70.0 g of an aqueous Zinc sulfate solution (15 weight percent zinc sulfate heptahydrate containing), 30.0 g of an aqueous ammonium fluoride solution (10 Containing by weight ammonium fluoride) and 20.0 g of an aqueous sodium molybdate (Containing 5 weight percent sodium molybdate dihydrate) and mixing of the resulting mixture, so that the zinc sulfate heptahydrate, the Ammonium fluoride and the sodium molybdate dihydrate according to in Concentrations of 10.5 g / liter, 3.0 g / liter and 1.0 g / liter in the treatment agent.

Formation of the chemical film

The aluminum-based metal component was immersed in the treating agent at 55 ° C for 5 minutes, thereby chemically forming a film on the surface of the aluminum-based metal component it was. Subsequently, the component was removed from the treating agent, rinsed with water, rinsed with hot water and dried. Thus, a corrosion-resistant aluminum-based metal product was produced.

Example 4

treatment agents

The Treatment agent for the formation of the chemical film was carried out by mixing 87.5 g of an aqueous Zinc sulfate solution (15 weight percent zinc sulfate heptahydrate containing), 37.5 g of an aqueous ammonium fluoride solution (10 Containing by weight ammonium fluoride) and 25.0 g of an aqueous sodium molybdate (Containing 5 weight percent sodium molybdate dihydrate) and mixing prepared the resulting mixture so that the zinc sulfate heptahydrate, the ammonium fluoride and the sodium molybdate dihydrate, respectively in concentrations of 13.125 g / liter, 3.75 g / liter and 1.25 g / liter present in the treatment agent.

Formation of the chemical film

The Aluminum-based metal component was incorporated into the treatment agent for 1 minute at 45 ° C immersed, causing a film chemically on the surface of the Metal component based on aluminum was formed. following the component was removed from the treatment, with water rinsed, with hot water rinsed and dried. Thus, a corrosion-resistant aluminum-based metal product became produced.

Example 5

treatment agents

The Treating agent for forming the chemical film was prepared by mixing of 105.0 g of an aqueous Zinc sulfate solution (15 weight percent zinc sulfate heptahydrate containing), 45.0 g of an aqueous ammonium fluoride solution (10 Containing by weight ammonium fluoride) and 30.0 g of an aqueous sodium molybdate (Containing 5 weight percent sodium molybdate dihydrate) and mixing prepared the resulting mixture so that the zinc sulfate heptahydrate, the ammonium fluoride and the sodium molybdate dihydrate, respectively in concentrations of 15.75 g / liter, 4.5 g / liter and 1.5 g / liter present in the treatment agent.

Formation of the chemical film

The Aluminum-based metal component was incorporated into the treatment agent for 30 Seconds (0.5 minutes) at 35 ° C immersed, causing a film chemically on the surface of the Metal component based on aluminum was formed. following the component was removed from the treatment, with water rinsed, with hot Water rinsed and dried. Thus, a corrosion-resistant aluminum-based metal product became produced.

Example 6

treatment agents

The Treating agent for forming the chemical film was prepared by mixing of 175.0 g of an aqueous Zinc sulfate solution (15 weight percent zinc sulfate heptahydrate containing), 45.0 g of an aqueous ammonium fluoride solution (10 Containing by weight ammonium fluoride) and 50.0 g of an aqueous sodium molybdate (Containing 5 weight percent sodium molybdate dihydrate) and mixing of the resulting mixture, so that the zinc sulfate heptahydrate, the Ammonium fluoride and the sodium molybdate dihydrate according to in Concentrations of 26.25 g / liter, 4.5 g / liter and 2.5 g / liter in the treatment agent.

Formation of the chemical film

The aluminum-based metal component was immersed in the treating agent for 30 seconds (0.5 minutes) at 35 ° C, whereby a film was chemically deposited on the surface of the metal component on Alumi niumbasis was formed. Subsequently, the component was removed from the treating agent, rinsed with water, rinsed with hot water and dried. Thus, a corrosion-resistant aluminum-based metal product was produced.

Example 1 of the prior art

The surface An aluminum-based metal component was subjected to an etching process and then subjected to a chemical method in the following manner Film formation using a phosphate of an alkali metal.

etching

One acid etchant JCB-7030 (available from Japan C.B.Chemical Co., Ltd.) was concentrated of 200 g / liter diluted with water and the aluminum-based metal component became the resulting etchant for 5 minutes at 60 ° C immersed.

Process of chemical film formation

CHEMIBONDER 5701 (Japan C.B.Chemical Co., Ltd.), which is essentially sodium dihydrogen phosphate contains was diluted to a concentration of 120 g / liter with water and the etched Aluminum-based metal component was used in the resulting Treatment agent for 5 minutes at 60 ° C immersed, causing a film chemically on the surface of the Component was formed. Then the component was removed from the treatment removed, rinsed with water, with hot water rinsed and dried. Thus, a corrosion-resistant aluminum-based metal product became produced.

Check the chemically formed film

The aluminum-based corrosion-resistant metal products prepared in Examples 1 to 6 and Example 1 of the prior art were respectively checked for the presence or absence of a chemically formed film. As a result, it was found that the surfaces of the products of Examples 1 to 6 were yellow or sunny yellow. Therefore, the formation of the film was detected at a glance. On the other hand, the chemically formed film of the aluminum-based corrosion-resistant metal product of Example 1 of the prior art was not visually observed because the surface of the product was colorless and transparent. The surface of the aluminum-based corrosion-resistant metal product of Example 1 of the prior art was analyzed with an ICP emission spectrometer (OPTIMA 4300DV, available from Perkin Elmer Corporation), and as a result, it was confirmed that the product had a chemically formed film on its surface. The aluminum-based corrosion-resistant metal products of Examples 1 to 6 were also analyzed by the ICP emission spectrometer. The analysis shows that the products each had a yellow or sun yellow chemically formed film on their surface. Further, the compositions (content ratio) of the films were analyzed. The results of the analysis are shown in Table 1.

Claims (7)

Method for avoiding corrosion of a metal component based on aluminum, made of aluminum or an aluminum alloy which method comprises: bring one in contact Treatment agent (A) with the surface of a metal component aluminum base for chemically forming a film (B) on the surface the aluminum-based metal component; wherein the treatment agent (A) an aqueous Zinc sulphate solution, an aqueous one Ammonium fluoride solution and an aqueous one sodium molybdate which are mixed together; being the chemical formed film (B) comprises zinc fluoride, molybdenum and aluminum fluoride. The method of claim 1, wherein the treating agent (A) 5.25 to 26.25 g / liter of zinc sulfate heptahydrate, 1.5 to 4.5 g / liter Ammonium fluoride and 0.5 to 2.5 g / liter of sodium molybdate dihydrate contains. The method of claim 1 or 2, wherein the treatment agent (A) the following aqueous Zinc sulfate solution (a), the following aqueous Ammonium fluoride solution (b) and the following sodium molybdate solution (c), which in a mass ratio of (a) / (b) / (c) = 7/3/2; (a) an aqueous solution containing 15% by weight of zinc sulfate heptahydrate; (b) an aqueous solution containing Contains 10% by weight of ammonium fluoride, (C) an aqueous one Solution, containing 5% by weight of sodium molybdate dihydrate, the zinc of the Zinc fluoride, the molybdenum and the aluminum of the aluminum fluoride in the chemically formed Film (B) in a ratio the contents of zinc / molybdenum / aluminum = 5/4/1 on a mass basis. The method of claim 3, wherein the treatment agent (A) a mass ratio of (a) / (b) / (c) = 7/3/2 and 35 to 175 g of the solution (a), 15 to 45 g of the solution (b) and 10 to 50 g of the solution (c). Method according to one of claims 1 to 4, wherein the treatment agent (A) a temperature of 45 to 65 ° C has and the surface the aluminum-based metal component with the treating agent (A) for one Duration of 1 to 10 minutes is kept in contact. corrosion resistant Aluminum-based metal product comprising: a metal component based on aluminum, made of aluminum or an aluminum alloy consists; and a chemically on a surface of the Aluminum-based metal component according to a method according to one the claims 1 to 4 formed film (B), the zinc fluoride, molybdenum and aluminum fluoride includes. corrosion resistant The aluminum-based metal product according to claim 6, wherein the zinc of zinc fluoride, molybdenum and the aluminum of the aluminum fluoride in the chemically formed Film (B) in a ratio the contents of zinc / molybdenum / aluminum = 5/4/1 on a mass basis.