KR101016915B1 - Aluminium alloy material with excellent surface stability and production method thereof - Google Patents

Abstract

An object of the present invention is to provide an aluminum alloy material having an excellent surface stability capable of maintaining good water wettability during chemical conversion, and a method for producing the same, together with the effect of press oil containing an ester component until degreasing of chemical conversion treatment.

The press oil containing an ester component is apply | coated to the surface of the Mg containing aluminum alloy material which has the phosphate or hydrogen phosphate hydrated phosphorus concentration of 2.0 atomic% or more on the surface.

Press oil, chemical treatment, water wettability, surface stability

Description

Aluminum alloy material with excellent surface stability and its manufacturing method {ALUMINIUM ALLOY MATERIAL WITH EXCELLENT SURFACE STABILITY AND PRODUCTION METHOD THEREOF}

The present invention is an aluminum alloy which is suitable for use in automobiles, in particular in automotive panels, and has excellent surface stability that can maintain good water wettability in chemical conversion, with the effect of press oil containing an ester component until degreasing of chemical conversion. It relates to ash and a method for producing the same. The aluminum alloy material used in the present invention refers to an aluminum alloy manufactured by various manufacturing methods such as a rolled plate, a rolled foil, an extruded shape member, a forging material, a casting material, and the like.

As is well known, various aluminum alloy materials (hereinafter, aluminum is also referred to as Al) for a vehicle, a ship, an aircraft, or a vehicle, a machine, an electric product, a building, a structure, an optical device, a member or a part of a vehicle, etc. conventionally. ) Is used universally according to the characteristics of each alloy.

In recent years, the improvement of the fuel efficiency by weight reduction of an automobile body is pursued with respect to the global environmental problem by exhaust gas. For this reason, instead of the steel material conventionally used, specific gravity is about 1/3 of iron, and the use of the aluminum material which has the outstanding energy absorption property to the motor vehicle body is increasing.

When using an aluminum alloy as an automotive panel, moldability, weldability, adhesiveness, chemical conversion treatment, corrosion resistance after coating, aesthetics, etc. are calculated | required. The method for manufacturing automobile panels using aluminum alloys includes: 1) molding (cutting to predetermined dimensions, press molding to a predetermined shape), 2) joining (welding and / or bonding), 3) chemical conversion treatment (using a detergent) Degreasing → Surface adjustment by colloidal titanate treatment, etc. → Zinc phosphate treatment), 4) Painting (primary coating → intermediate coating → finishing coating by electrodeposition coating), which is basically the same as when using conventional steel sheet Do.

On the other hand, the modularization of automobile parts is progressing, and after the aluminum alloy plate itself is manufactured, there is a tendency for the period from the above-described automotive panel to the vehicle body manufacturing process to be longer than ever.

The modularization of auto parts is a method of subassembly of individual parts that are directly installed in a car body in a car manufacturer and then installing them in the car body. The main purpose is to simplify production of automobiles and increase production efficiency. It also has the effect of shortening the production process and cutting down the products under manufacture. Although the burden on the parts company increases, it is effective in reducing the costs of the automobile company and the parts company as a whole, consequently contributing to the cost reduction of the automobile.

As for the conveyance path | route of the aluminum alloy plate for automobiles, the direct delivery system from a light pressure maker to an automobile maker was mainstream until now. However, if the modularization progresses, it is inevitably via the parts company, and the time from the manufacture of the aluminum alloy plate itself to the above-described manufacturing process is longer than ever. Therefore, the process of covering with oil is performed from a viewpoint of surface protection of an aluminum alloy plate.

However, in such a case, the surface characteristic of an aluminum alloy plate always changes with time, and in particular, it has become a problem that it has a bad influence on chemical conversion treatment property and paintability. Especially, it is known that degreasing property at the time of chemical conversion deteriorates with the change with time, and it becomes difficult to adhere to the chemical conversion coating, and, as a result, affects corrosion resistance.

For this reason, conventionally, it is focusing on improving chemical conversion treatment etc. by removing magnesium (Magnesium is Mg) from the surface of aluminum alloy containing magnesium (refer patent document 1-patent document 5). However, if only Mg is removed, it is not possible to obtain an excellent surface stability with a small change in surface characteristics over time.

In addition, in order to obtain an aluminum alloy sheet excellent in water wettability and adhesiveness after degreasing, in particular, the aluminum alloy for automobile body sheets in which the amount of Mg and OH of the surface coating of the aluminum alloy sheet was adjusted and coated with antirust oil within 14 days after the surface adjustment. A edition is also proposed (refer patent document 6). However, it is not possible to obtain an excellent surface stability with little change over time of surface properties as long as the surface is protected simply by applying antirust oil within 14 days after surface adjustment.

In addition, in order to make an aluminum alloy plate with little change in surface characteristics over time, the metal aluminum base of the aluminum alloy plate containing 2-10 weight% of Mg, the phosphate film of aluminum formed on this base material, and this phosphate film The formed aluminum oxide film and the aluminum alloy plate for automobile bodies to which antirust oil was apply | coated on this are also proposed (refer patent document 7). Moreover, the thing which covered the surface of aluminum alloy with the molding oil (press oil) containing the ester component for the purpose of preventing damage during conveyance of aluminum alloy, and drawing processability is also proposed (refer nonpatent literature 1).

[Patent Document 1] Japanese Unexamined Patent Application Publication No. 06-256980 (full text)

[Patent Document 2] Japanese Unexamined Patent Application Publication No. 06-256881 (full text)

[Patent Document 3] Japanese Unexamined Patent Application Publication No. 06-220564 (full text)

[Patent Document 4] Japanese Patent Application Laid-Open No. 04-214835 (full text)

[Patent Document 5] Japanese Patent Application Laid-open No. 02-115385 (full text)

[Patent Document 6] Japanese Patent Application Publication No. 2006-200007 (full text)

[Patent Document 7] Japanese Patent No. 2744697 (Professional)

[Non-Patent Document 1] Tanaka, Kobayashi, Kurata, "A Study on Degreasing Properties of Aluminum Surface Model Oxides", Outline of the Japan Light Metals Society 111th Fall Conference Lecture Summary, 167, 2006, p. 331-332

In the said patent document 7, in the Example, comparative evaluation is performed based on the material left to stand for one week after sample preparation. However, the change with time of the surface characteristics of the aluminum alloy mentioned above has the largest change amount just after sample preparation to about one week, and the change after that is comparatively small. Therefore, the stability of the target surface property is not guaranteed with the evaluation result disclosed by the said patent document 7. In addition, as disclosed in the above Non-Patent Document 1, the ester component in the press oil acts as an oil agent to improve the drawing workability of the alloy, but the degreasing property at the time of chemical conversion is lowered (that is, the surface stability is lowered). And the like).

In particular, in applications such as automobiles, water wetting stability, coating property, adhesion durability, welding stability, and the like in the chemical conversion treatment of aluminum alloy materials are required. In particular, the surface which can maintain favorable water wettability at the time of chemical conversion treatment with the effect of press oil, until aluminum alloy material is shipped from the manufacturer's factory, press molding etc., and degreasing at the chemical conversion treatment is performed. There is a demand for an aluminum alloy material having excellent stability.

MEANS TO SOLVE THE PROBLEM This invention solves the said subject, The Mg containing aluminum alloy material which is excellent in the surface stability which can maintain favorable water wettability at the time of chemical conversion treatment with the effect of the press oil containing an ester component until the degreasing of the chemical conversion treatment, and its manufacture It is an object to provide a method.

In order to achieve the above object, the invention described in claim 1 has an ester component on the surface of an Mg-containing aluminum alloy material having a phosphate or hydrogen phosphate of a phosphorus concentration of 2.0 atomic% or more. Since the press oil containing is applied, the aluminum alloy material which is excellent in the surface stability which can maintain favorable water wettability at the time of a chemical conversion treatment with the effect of the press oil containing an ester component until the degreasing of a chemical conversion treatment can be obtained.

The invention according to claim 2 comprises a step of treating an aluminum alloy material with an aqueous solution of dihydrogen phosphate having a pH adjusted to less than 4, and a press oil containing an ester component in the aluminum alloy material treated with the aqueous solution of dihydrogen phosphate. It is a structure provided with the process of apply | coating. Thereby, the aluminum alloy material excellent in the surface stability which can maintain the favorable water hygroscopicity at the time of chemical conversion treatment with the effect of the press oil containing an ester component until the degreasing of the chemical conversion treatment can be manufactured.

Invention of Claim 3 WHEREIN: In invention of Claim 2, it processes by the dihydrogen phosphate aqueous solution which pH was adjusted to 2.5 or more and 4 by adding phosphoric acid. Thereby, the aluminum alloy material which is excellent in the surface stability which can maintain the favorable water wettability at the time of chemical conversion treatment with the effect of the press oil containing an ester component until the degreasing | deoxidation of chemical conversion treatment can also be manufactured. When the hydrogen phosphate treatment is carried out, turbidity due to insoluble components does not occur in the aqueous dihydrogen phosphate solution (= transparent), the occurrence of clogging of the pipe is suppressed, and the frequency of maintenance can be reduced.

As described above, the invention according to claim 1 of the present invention is coated with press oil containing an ester component on the surface of an Mg-containing aluminum alloy material having a phosphate or hydrogen phosphate having a phosphorus concentration of 2.0 atomic% or more. Since it is a structure, the aluminum alloy material which is excellent in the surface stability which can maintain favorable water wettability at the time of chemical conversion treatment with the effect of the press oil containing an ester component until the degreasing of the chemical conversion treatment can be obtained.

Moreover, the invention of Claim 2 of this invention is a process of processing an aluminum alloy material with the dihydrogen phosphate aqueous solution which pH was adjusted to less than 4, and the ester component was made to the aluminum alloy material processed by the said dihydrogen phosphate aqueous solution. Since it is the structure provided with the process of apply | coating press oil containing, the aluminum alloy material which is excellent in the surface stability which can maintain favorable water wettability at the time of chemical conversion treatment with the effect of the press oil containing an ester component until the degreasing of chemical conversion treatment is carried out. It can manufacture.

In addition, the invention of Claim 3 of this invention WHEREIN: In the invention of Claim 2, since the structure is processed by the dihydrogen phosphate aqueous solution which adjusted pH to 2.5 or more and 4 by adding phosphoric acid, at the time of degreasing of a chemical conversion treatment, Along with the effect of the press oil containing the ester component, it is possible not only to produce an aluminum alloy material having excellent surface stability capable of maintaining good water wettability in the chemical conversion treatment, but also to the hydrogen phosphate treatment of the aluminum alloy material. Turbidity due to insoluble components does not occur in the aqueous solution of dihydrogen salt (= transparent), the occurrence of clogging of the pipe is suppressed, and the frequency of maintenance can be reduced.

EMBODIMENT OF THE INVENTION Hereinafter, it demonstrates in detail, demonstrating embodiment about this invention.

(Configuration of Aluminum Alloy Material Excellent in Surface Stability According to the Present Invention)

As for the aluminum alloy material excellent in the surface stability which concerns on this invention, the press oil containing an ester component is apply | coated to the surface of the Mg containing aluminum alloy material which has the phosphate or hydrogen phosphate which phosphate concentration is 2.0 atomic% or more, It features. Thereby, the aluminum alloy material excellent in the surface stability which can maintain the favorable water wettability at the time of chemical conversion treatment with the effect of the press oil containing an ester component until the degreasing of the chemical conversion treatment can be obtained.

Below, the reason which led to the said structure is explained in full detail.

MEANS TO SOLVE THE PROBLEM The present inventors noticed that the aluminum alloy material was recently shipped from the manufacturer's factory, press-molded, etc., and the whole period until degreasing at the time of chemical conversion is performed is long. That is, in view of the surface protection and the like of the aluminum alloy material, attention has been paid to the fact that the time covered by oil becomes long anyway. In addition, since the aluminum alloy material is subjected to press molding or the like before the chemical conversion treatment, it is also required that the oil has improved moldability. Even if the oil which satisfies both the surface protection property and the moldability is coated, does not an aluminum alloy material having excellent surface stability capable of sufficiently degreasing during chemical conversion treatment and maintaining good water wettability during chemical conversion treatment occurs? A polite review was made. As a result, the press oil containing an ester component is applied to the surface of the Mg containing aluminum alloy material which has the phosphate or hydrogen phosphate hydrated phosphate or hydrogen phosphate whose phosphorus concentration is 2.0 atomic% or more on the surface by studying the material and conditions of surface treatment of an aluminum alloy material. If so, it has been found for the first time that this object can be achieved.

By such a configuration, it is estimated that the above object can be achieved whether or not the properties of the surface of the aluminum alloy material as shown in FIG. 1 play a large role. That is, in Fig. 1, the aluminum alloy containing Mg (herein, the aluminum alloy is simply referred to as an aluminum alloy and, for example, an aluminum alloy material including Mg-Ox already present on its surface). When the surface is treated with an aqueous solution of dihydrogen phosphate (for example, an aqueous solution of aluminum dihydrogen phosphate) whose pH is adjusted to less than 4, a layer of hydrated phosphate is formed on the surface of the aluminum alloy material, and the hydrated phosphate or The hydrogen phosphate layer has a strong chemical bond through oxygen (-O-) between the aluminum alloy material, while on the opposite side to the aluminum alloy material, OH groups remain to form a moisturizing component, It is thought to inhibit adsorption.

Thereby, the phosphate hydrated on the surface of the aluminum alloy material and the press oil containing an ester component do not bond until the degreasing treatment, and a predetermined amount of press oil is stably held, so that the effect of the press oil can be maintained. In addition, since the press oil containing the ester component is not bound to the hydrated phosphate, it can be sufficiently removed at the time of degreasing to maintain good water wettability during chemical conversion. By the above, it is thought that the aluminum alloy material excellent in surface stability was realizable.

The present invention is described in detail below.

(Al alloy)

The Al alloy used in the present invention is defined by AA, JIS, or approximated to JIS, manufactured by various manufacturing methods, such as a rolled plate, a rolled foil, an extruded shape material, a forging material, and a casting material, depending on the use of the Al alloy material. Although an Al alloy can be used, it is essential to contain Mg. In this case, it is preferable to contain content of Mg 0.25weight% or more. Thereby, in the case of Al alloy with a small content of Mg, the subject which this invention tries to solve does not express.

Although there is no restriction | limiting in particular about the upper limit of content of Mg, In consideration of the balance of the various characteristics at the time of using as a structural member, up to 5.5 mass% is suitable.

For example, when using for automobiles, a high strength aluminum alloy material having a 0.2% yield strength of 100 MPa or more is preferable. As the aluminum alloy that satisfies such characteristics, it is a general-purpose alloy having a relatively high yield strength, such as 5000 series, 6000 series, and 7000 series, which is usually used for this kind of structural member, and a tempered aluminum alloy is suitably used if necessary. . It is preferable to use a 6000 series aluminum alloy from the point which is excellent in the recyclability and formability of scrap in the comparatively low age hardening ability and the amount of alloying elements.

(Hydrated phosphate)

The dihydrogen phosphate salt of the present invention is a generic term for salts containing dihydrogen phosphate (H ₂ PO ₄ ) in the salt. This dihydrogen phosphate salt is preferably a salt of at least one metal selected from Al, K, Ca, Mn, Li. More preferably Al is selected.

In addition, an oxide film of aluminum is necessarily formed on the surface of the aluminum alloy material, and the hydrated phosphate salt of the present invention is present or scattered on the oxide film or oxide film of the aluminum. Therefore, having hydrated phosphate on the surface of an aluminum alloy material as used in the present invention specifically refers to such a surface state.

(Adhesion method of hydrated phosphate to aluminum alloy material surface)

Adhesion of these hydrated phosphates to the surface of the aluminum alloy material is carried out in an aqueous solution containing dihydrogen phosphate (hereinafter collectively referred to as hydrogen phosphate treatment) during or outside the manufacturing process of the aluminum alloy material. This can be done by. In the manufacturing process of an aluminum alloy material, the cooling water after heat processing, such as a solution treatment and annealing, or the washing water in a washing | cleaning process is the aqueous solution containing (dissolved) these dihydrogen phosphates (henceforth generically, And dihydrogen phosphate aqueous solution).

The temperature of the aqueous solution of dihydrogen phosphate can be at room temperature, but may be heated. In addition, processing time is not specifically limited, What is necessary is just to select suitably according to the other treatment conditions, such as the density | concentration of aqueous solution, temperature, or a desired adhesion amount to the surface of an aluminum alloy material. For example, in the case of using aluminum dihydrogen phosphate {Al (H ₂ PO ₄ ) ₃ } as a medicine, and the aqueous solution concentration is 1 to 10 g / L (wherein "L" means liter). The aluminum alloy material may be immersed or sprayed in these aqueous solutions for 1 to 10 seconds. In the case where the aqueous solution concentration is 1 g / L, the pH is 3.4 and the pH is 2.4 in the case of 10 g / L, and in the present invention, the pH of the aqueous dihydrogen phosphate solution may be adjusted to be less than 4.

In addition, by adding phosphoric acid to an aqueous solution of dihydrogen phosphate and treating the aluminum alloy material using a liquid whose pH is adjusted to 2.5 or more and less than 4, an aluminum alloy having excellent surface stability capable of maintaining good water wettability during chemical conversion treatment Not only can ash be produced, but also when the aluminum phosphate is treated with hydrogen phosphate, it is not dissolved in the aqueous solution of dihydrogen phosphate, and turbidity due to components is not generated (= transparent). Can reduce the frequency of

In addition, at the time of adhesion of the hydrated phosphate to the surface of the aluminum alloy material, there is no need to remove the oxide film or magnesium of aluminum already formed on the surface of the aluminum alloy material by pretreatment such as cleaning accompanied by etching. However, in the manufacturing process of the above-mentioned aluminum alloy material, after removing the oxide film and magnesium of aluminum on the surface of aluminum alloy material by pretreatment, for example according to the other objective of a process, attaching hydrated phosphate to the surface of aluminum alloy material Of course it is allowed. Also in this case, since the oxide film of aluminum is immediately formed on the surface of the aluminum alloy material, it exists and is scattered in the hydrated phosphate of this invention, on the oxide film of this aluminum, or an oxide film.

(Method of applying press oil containing an ester component to an aluminum alloy material treated with an aqueous solution of dihydrogen phosphate)

Next, the method of apply | coating the press oil containing an ester component to the aluminum alloy material processed with the said dihydrogen phosphate aqueous solution is demonstrated. For example, the aluminum alloy material may be immersed in press oil containing ethyl oleate as an ester component. The method and conditions of apply | coating the press oil containing an ester component are not specifically limited, The method and conditions of apply | coating normal press oil are widely applicable. In addition, the ester component is not limited to ethyl oleate, and various things, such as butyl stearate and sorbitan monostearate, can be used.

(About surface stability)

Next, the surface stability of what apply | coated the press oil containing the said ester component is demonstrated. After leaving the press oil containing the ester component in a state of being coated for 6 months in an environment chamber of 50 to 90% RH at 15 to 35 ° C, degreasing with a conventional alkali degreasing agent to evaluate the water wetted area ratio is 100%. do. This is because even if the press oil containing the ester component satisfying the surface protection and press formability of the aluminum alloy material was shipped from the factory of the manufacturer of the aluminum alloy material and applied for a long time until degreasing of the chemical conversion treatment, good water wettability during the chemical conversion treatment was obtained. It has shown that it can provide the aluminum alloy material excellent in the surface stability with little maintainable change with time, and its manufacturing method.

Hereinafter, embodiments of the present invention will be described. As an aluminum alloy cold-rolled sheet (plate thickness 1mm) of the 60 type 606000 standard, the test piece of length 70mm x width 150mm was used. The aluminum alloy plate of this 6022 standard contains Mg: 0.55 mass% and Si: 0.95 mass%, and the 0.2% yield strength is 230 MPa.

In the case of pretreatment prior to hydrogen phosphate treatment, 1 to 10 mass% nitric acid or sulfuric acid at 50 to 90 ° C. after immersion or spraying at 60 to 90 ° C. for commercially alkaline degreasing solution for 1 to 10 seconds. It was immersed or sprayed for 10 to 10 seconds and then washed with water.

Under the pretreatment conditions, the aluminum oxide film or magnesium already formed on the surface of the test piece is removed. However, since the oxide film of aluminum is immediately formed on the test piece surface, the hydrated phosphate adhering to the test piece surface by the hydrogen phosphate treatment is present or scattered on the oxide film or oxide film of the aluminum.

For a test piece of an aluminum alloy subjected to such pretreatment or no pretreatment, an aluminum dihydrogen phosphate {Al (H ₂ PO ₄ ) ₃ } was used as the drug, and the concentration of an aqueous solution in which the test piece was immersed was 1 g / L. , 10 g / L were prepared. These are referred to as Examples 1 to 4 (see Table 1 below). PH of the aqueous solution at this time was 3.4, 2.4, 3.4, and 2.4, respectively. In addition, using the above-mentioned agent, phosphoric acid (85% purity reagent of Wako Pure Chemical) was added to the aqueous solution having a concentration of 0.1 g / L to 0.4 g / L, and the amount shown in Table 1 per 1 L of the aqueous solution, respectively, and the pH was 2.5. A dihydrogen phosphate aqueous solution adjusted to -3.8 was produced. These are referred to as the fifth to eighth embodiments.

In addition, the thing which does not immerse a test piece in the aqueous solution using the said chemical agent for comparison, and the thing of 0.1 g / L of aqueous solution concentration were produced, respectively. Let these be the 1st comparative example-the 4th comparative example (refer Table 2 below). PH of the aqueous solution of the 2nd comparative example and the 4th comparative example was all 6.4. Using the agent, phosphoric acid (85% purity reagent, Wako Junyakje Co., Ltd., 85% purity reagent) of the amount shown in Table 2 was added per 1 L of aqueous solution to an aqueous solution having a concentration of 0.1 g / L and an aqueous solution of 0.4 g / L, respectively. All the dihydrogen phosphate aqueous solution adjusted to 2.0 was produced. Let these be a 5th comparative example and a 6th comparative example. In 1st Example-8th Example, 2nd Comparative Example, and 4th Comparative Example-6th Comparative Example, the immersion time of the test piece was all set to 10 second.

In addition, the surfaces of the test pieces of the first to eighth examples and the first to sixth comparative examples where the predetermined hydrogen phosphate treatment was completed were analyzed by X-ray photoelectron spectroscopy. The measuring method and conditions are as follows. Here, the phosphorus concentration of the surface was analyzed by the composition of the depth direction from the surface to 200 nm in depth except the outermost surface, and the highest value of the phosphorus concentration (atomic%) analysis value was defined as the phosphorus concentration (atomic%) of the substrate surface layer. This is because the state of the outermost surface cannot be obtained precisely by contamination.

(Measurement method and condition)

Device: QuanteraSXM manufactured by Physical Electronics

Fully Automatic Scanning X-ray Photoelectron Spectroscopy

X-ray source: monochrome AlKa

X-ray output: 43.7 W

X-ray beam diameter: 200 μm

Optoelectronic extraction angle: 45 °

Ar ⁺ sputter rate: about 4.6 nm / min in terms of SiO ₂

In addition, the measuring method of surface phosphorus concentration is not limited to X-ray photoelectron spectroscopy (XPS), For example, besides XPS, analysis methods, such as a fluorescent X-ray and a high frequency glow discharge luminescent surface analysis (GDS), can be used.

As a result, as shown in Table 1, the surface phosphorus concentrations of the Examples are the first, second, third, fourth, fifth, sixth, and seventh embodiments. With respect to the example and the eighth embodiment, the ratios were 2.1 to 3.3, 2.4 to 4.4, 2.2 to 3.6, 2.4 to 4.5, 3.2 to 3.8, 2.8 to 3.3, 3.2 to 4.0 and 2.0 to 2.6, respectively. In addition, the surface phosphorus concentration of the comparative example is, as shown in Table 2 above, for the first comparative example, the second comparative example, the third comparative example, the fourth comparative example, the fifth comparative example and the sixth comparative example, respectively. 0.8 to 1.2, 1.1 to 1.6, 0.6 to 1.2, 1.3 to 1.6, 0.9 to 1.6, and 1.1 to 1.9.

In addition, the presence or absence of a non-hazardous component was judged by visually observing the turbidity state of the processing liquid after the predetermined hydrogen phosphate treatment was completed. As a result, in the treatment liquid of the Example 1-Example 4, the 2nd comparative example, and the 4th comparative example which performed hydrogen phosphate treatment using the dihydrogen phosphate aqueous solution which phosphoric acid was not added, it originates in a non-hazardous component. Haze was confirmed. This insoluble component was a mixture of crystalline and amorphous aluminum phosphate (AlPO ₄ ). On the other hand, in the treatment liquids of the fifth to eighth examples, the fifth comparative example, and the sixth comparative example, which were treated with hydrogen phosphate using an aqueous solution of dihydrogen phosphate to which phosphoric acid was added, turbidity due to insoluble components Was not confirmed (clear). In the fifth comparative example and the sixth comparative example, haze caused by the non-hazardous component was not confirmed, but as described later, an important water wet area ratio was significantly lower than 90% of the standard.

Next, the test piece (the first to eighth examples, the second comparative example and the fourth to sixth comparative examples) treated with the dihydrogen phosphate aqueous solution and the dihydrogen phosphate aqueous solution were not treated. The test piece (1st comparative example and 3rd comparative example) was immersed in the press oil containing ethyl oleate as ester component.

Next, the following test was done in order to investigate the time-lapse stability of the surface of the test piece to which the press oil containing the said ester component was apply | coated. The press oil containing the above ester component was left in an environment chamber of 50 to 90% RH at 15 to 35 ° C. for 6 months. After 6 months, the water wetting area ratio (one side only) of the area of the test piece when immersed in a commercially available weak alkali degreasing solution (temperature 40 ° C.) for 2 minutes was measured (the higher the number, the better). ) Thereby, the water wettability (stable chemical treatment property) at the time of chemical conversion treatment can be evaluated. As a result, the water-wetting area ratios of Examples 1 to 8 all cleared 90% of the reference (see Table 1 above). This indicates that the surface characteristics of the aluminum alloy material are stabilized without change over time even if it is left in a wet environment or prolonged for a long time due to the modularization of automobile parts described above. However, the water wetting area ratios of the first comparative example, the second comparative example, the third comparative example, the fourth comparative example, the fifth comparative example, and the sixth comparative example were 40%, 55%, 0%, 33%, 38, respectively. % And 52% (see Table 2 above) and significantly below 90% of baseline. This shows that the surface properties of the aluminum alloy material change over time.

As in the fifth to eighth embodiments described above, the concentration of the aqueous solution of aluminum dihydrogen phosphate is 0.1 g / L to 0.4 g / L, which is low in concentration. In the dihydrogen phosphate aqueous solution adjusted to less than, the equilibrium of the aqueous solution collapsed. In addition, dihydrogen phosphate (here, dihydrogen phosphate) in the free state (not dissociated, but dissolved), which is important for the reaction of this solution equilibrium to form hydrated phosphates or hydrogen phosphates on the surface of the aluminum alloy material Aluminum) led to an increase in concentration. Although the increase in the concentration of aluminum dihydrogen phosphate in this free state is low in the aqueous solution of aluminum dihydrogen phosphate before adding phosphoric acid, an aluminum alloy having excellent surface stability capable of maintaining good water wettability during chemical conversion treatment I think it was a good result of making ash. Further, by treating the aluminum alloy material with the dihydrogen phosphate aqueous solution as in the fifth embodiment to the eighth embodiment, the detailed mechanism in which turbidity due to the non-solvent component in the dihydrogen phosphate aqueous solution does not occur is present. Although unclear, it is presumed that some interaction occurred due to the addition of phosphoric acid to an aqueous solution of aluminum dihydrogen phosphate before the addition of phosphoric acid.

As described above, the press component containing the ester component is coated on the surface of the Mg-containing aluminum alloy material having a phosphate or hydrogen phosphate having a phosphorus concentration of 2.0 atomic% or more, thereby making the ester component until degreasing of chemical conversion treatment. Along with the effect of the press oil containing, an aluminum alloy material having excellent surface stability capable of maintaining good water wettability during chemical conversion can be obtained.

In the present Example, although the example which used the dihydrogen phosphate aqueous solution as the dihydrogen phosphate aqueous solution like Example 1-Example 4 mentioned above was demonstrated, it is not necessarily limited to this, Phosphoric acid in a salt It does not matter if it is a salt containing dihydrogen. By adjusting the pH of the aqueous solution of the salt containing dihydrogen phosphate in this salt to less than 4, and treating this aluminum alloy material with this aqueous solution, the aluminum alloy material excellent in the surface stability which can maintain favorable water wettability at the time of chemical conversion treatment is manufactured. can do.

Further, as in the fifth to eighth embodiments described above, the aluminum alloy is an aqueous solution in which a predetermined amount of phosphoric acid is added to an aqueous solution of dihydrogen phosphate of a predetermined amount, and the pH is adjusted to 2.5 or more and less than 4. By treating the ash, not only an aluminum alloy material having excellent surface stability capable of maintaining good water wettability in the chemical conversion treatment can be produced, but also insoluble in the dihydrogen phosphate aqueous solution when the aluminum alloy material is treated with hydrogen phosphate. Haze due to the component does not occur (= transparent), the occurrence of clogging of the pipe is suppressed, and the frequency of maintenance can be reduced.

BRIEF DESCRIPTION OF THE DRAWINGS The schematic diagram for considering the surface property of the aluminum alloy material after the hydrogen phosphate treatment and press oil application of this invention.

Claims (3)

An aluminum alloy material having excellent surface stability, wherein a press oil containing an ester component is applied to a surface of an Mg-containing aluminum alloy material having a phosphate or hydrogen phosphate having a phosphorus concentration of 2.0 atomic percent or more. A treatment step of treating the aluminum alloy material with an aqueous solution of dihydrogen phosphate having a pH adjusted to less than 4, and a coating step of applying a press oil containing an ester component to the aluminum alloy material treated with the aqueous solution of dihydrogen phosphate. The manufacturing method of the aluminum alloy material excellent in the surface stability characterized by the above-mentioned. The method for producing an aluminum alloy material having excellent surface stability according to claim 2, wherein in the treatment step, by adding phosphoric acid, treatment is performed with an aqueous solution of dihydrogen phosphate whose pH is adjusted to 2.5 or more and less than 4.

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