WO2004024988A1

WO2004024988A1 - CORROSION-RESISTANT Al-BASED STRUCTURAL MEMBER AND METHOD FOR MANUFACTURE THEREOF

Info

Publication number: WO2004024988A1
Application number: PCT/JP2003/010225
Authority: WO
Inventors: Junichi Sato
Original assignee: Keihin Corporation
Priority date: 2002-08-12
Filing date: 2003-08-11
Publication date: 2004-03-25
Also published as: TW200528579A; AU2003254940A1; JP2004076041A; EP1544322A1; CN1675410A; US20060110619A1; TWI249590B

Abstract

A corrosion-resistant Al based structural member (1) having an Al based structural member (1o), an undercoat layer (2) closely attached on the surface thereof, and a corrosion-resistant coating film (3) closely attached on the surface of the undercoat layer (2), wherein the undercoat layer (2) comprises Zn, and the corrosion-resistant coating film (3) comprises a chromate coating film for Zn which contains trivalent Cr. The corrosion-resistant Al based structural member is advantageous in that it has a pollution-free and hexavalent chromium-free corrosion-resistant coating film.

Description

DESCRIPTION Corrosion resistance A 1-based structural member and method for producing the same

The present invention relates to a corrosion resistant Al-based structural member and a method of manufacturing the same. Here, the A 1 -based structural members include both structural members consisting of pure A 1 and structural members consisting of A 1 alloy.

Background art

Heretofore, as this type of A 1-based structural member, one provided with an anticorrosive film comprising a chromate film has been known (see, for example, Japanese Patent Publication No. 60-35423). However, conventional chromate film contains hexavalent C r because those formed using a treatment liquid to C R_〇 ₃ as an essential component. As well known, hexavalent Cr is an element harmful to the human body, so it is desirable that the anticorrosion coating does not contain hexavalent Cr in order to prevent pollution.

Disclosure of the invention

An object of the present invention is to provide the above-mentioned corrosion resistant Al-based structural member provided with a non-polluting corrosion-resistant coating free of hexavalent chromium.

According to the present invention to achieve the above object, according to the present invention, it has an underlayer adhering to the surface of the A1 system structural member and an anticorrosive coating adhering to the surface of the underlayer, the underlayer consisting of Z n The coating is provided with a corrosion resistant Al-based structural member comprising a chromate coating for Z n containing trivalent Cr.

The anticorrosion coating has excellent corrosion resistance and is free from harmful hexavalent Cr which is harmful to the human body, and thus is useful for preventing pollution. The chromate film for Z n containing trivalent Cr does not adhere directly to the surface of the A 1 type structural member, but sufficient adhesion to the underlayer consisting of Z n, that is, to the surface of the Z n underlayer Demonstrate. Furthermore, it is easy to form a Z n underlayer closely on the surface of the A1 system structural member, such as by applying a known zincate treatment. Another object of the present invention is to provide the above-mentioned manufacturing method which can easily mass-produce the corrosion resistant Al-based structural member of the above-mentioned constitution.

In order to achieve the above object, according to the present invention, zincate is used on the surface of the A 1-based structural member. A process to form an underlayer consisting of Z n, that is, an Z underlayer, and a chromate treatment using a trivalent chromate agent on the surface of the Z n underlayer, a chromate for trivalent Cr containing zr There is provided a method for producing a corrosion resistant A 1-based structural member using the step of forming an anticorrosive film comprising a film.

According to the manufacturing method, it is possible to easily and reliably obtain the corrosion resistant Al-based structural member having the above-mentioned configuration. Moreover, since both the zincate treatment and the chromate treatment are performed by applying the immersion method, productivity can be improved by using both treatments as an in-line process.

The processing time required for the zincate treatment is set to a value that can increase the amount of Zn deposition on the surface of the A1 system structural member to obtain a Zn underlayer of the required thickness, for example, T ≥ 0 3 0 s Ru. On the other hand, the treatment time t ₂ required for the chromate treatment is that the thickness of the z n underlayer is secured despite the dissolution of the z n underlayer by the chromate treatment, and then the trivalent surface of the z n underlayer is The value that can reliably form a chromate film for Z n containing C r, for example, t ₂ ≤1 5 s is set. However, the thickness of the Zn underlayer is insufficient for chromate treatment when the treatment time of zinc oxide treatment is 30 s, while the treatment time of chromate treatment t ₂ is 2 n when t ₂ > 15 3. Dissolution of the underlying layer may progress to expose the surface of the A 1 -based structural member.

Brief description of the drawings

Fig. 1 is a front view of corrosion resistance A1 alloy vaporizer main body, and Fig. 2 is an enlarged cross sectional view of corrosion resistance A 1 alloy metal vaporizer main body.

BEST MODE FOR CARRYING OUT THE INVENTION

Figure 1 shows a corrosion resistant vaporizer main body 1 made of an A1 alloy as a corrosion resistant A1 system structural member. This corrosion resistant vaporizer main body 1 is a vaporizer main body 1 obtained by die casting using J I S AD C 12 as shown in Fig. 2. The surface of the unprotected surface is provided with the underlayer 2 in close contact with the surface and the anticorrosive film 3 in contact with the surface of the underlayer 2. The underlayer 2 is made of Zn, while the anticorrosion film 3 is made of a chromate film for Zn containing trivalent Cr.

This anticorrosion coating 3 has excellent corrosion resistance and is useful for pollution control because it does not contain hexavalent Cr which is harmful to the human body. In addition, chromate film for Z n containing trivalent Cr is A Vaporizer main body consisting of 1 alloy 1. Although not in direct contact with the surface, it exhibits sufficient adhesion to the underlying layer of Zn, that is, the surface of the Zn underlayer 2. It is equal to applying known Jinke Ichito process, it is easy still in close contact forming a Zn base layer 2 to the vaporizer body 1 ₀ surface consisting of A 1 alloy.

Corrosion Resistant Vaporizer Main Body 1 First, after die casting, the vaporizer main body 1. The well-known pretreatment, namely, hot water washing, degreasing, water washing, activation, water washing and hot water washing, are sequentially applied to the Then, pre-treatment vaporizer main body 1. The process of forming Zn underlayer 2 by zincate treatment on the surface, the water washing process, and the chromate treatment with trivalent chromate agent on the surface of Zn underlayer 2 from the chromate film for Zn containing trivalent Cr The step of forming the anticorrosion coating 3, the step of washing with water, and the step of drying are sequentially performed.

According to the manufacturing method, the corrosion resistant vaporizer main body 1 of the above configuration can be obtained easily and surely. In addition, since both the zincate treatment and the chromate treatment are performed by applying the immersion method, it is possible to improve productivity by using both treatments as an in-line process.

The treatment time required for zincate treatment is mainly vaporizer1. For example, 値 30 s is set to a value that can increase the Zn deposition amount on the surface and obtain the required thickness of the Zn underlayer 2. On the other hand, the processing time t ₂ required for the chromate treatment is, despite securing the thickness of the z n underlayer 2 despite the dissolution of the Zn underlayer 2 by the chromate treatment, the surface of the z n underlayer 2 A value that can reliably form a chromate film for Zn containing trivalent Cr, for example, t ₂ ≤ 15 s.

[Example]

As a main component of the zincate treatment solution, a Zn substitution solution (trade name: K1 102, manufactured by NIPPON SHOKEN CO., LTD.) Was selected. This zinc substitution solution contains 18.6 wt% NaOH, 3. 1 wt% Z η θ, 7. 8 wt% organic acid and minor additives. The concentration of this solution was adjusted to 22 mL to obtain a gin gate treatment solution.

A trivalent chromate agent (trade name: Dipsol ZT-444A, liquid, manufactured by Dipsol) was selected as the main component of the chromate treatment solution. This trivalent chromate is 14-16 wt% (Cr ³⁺ : 4) chromium nitrate [Cr (NO) ₃ · · 9H ₂ O], 2 to 4 wt% cobalt nitrate [Co (N0 ₃ ) ₂ ] and the rest common substances, which are existing chemicals. The concentration of this solution was adjusted to 6 OmL / L to prepare a chromate treatment solution.

The same A1 alloy vaporizer as above (JIS ADC 12, die cast product) 1. A plurality of samples were prepared and subjected to the same pretreatment as above. Then, using the above-mentioned Zin gate treatment solution at 30 ° C., forming the Zr underlayer 2 with variously changed treatment time, washing with water, using the above chromate treatment solution at 30 ° C., variously changed the treatment time t ₂ Anticorrosion coating 3 was formed, washed with water and dried sequentially to obtain various corrosion resistant vaporizer main bodies 1.

The salt spray test was carried out on the corrosion resistant vaporizer main body 1, and the area ratio A of the white product (product by corrosion of the A1 alloy) after 48 hours from the start of the test, that is, A = (white product Area / total surface area of main body of vaporizer) x 100 (%) was obtained.

Table 1 shows the treatment time t _x of zincate treatment, the treatment time t _{2 of} chromate treatment, and the area ratio A of the white product for the examples 1 to 6 of the corrosion resistant vaporizer main body 1.

【table 1】

Corrosion resistance Zincate treatment Chromium ώ CJ ft I Area ratio of treatment time to treatment time of the product vaporizer A Main component t 1 (S) t Δ 2 (S) '(\% / U) Example 1 50 1 5 1 Example 2 3 0 1 5 3 Example 3 1 5 1 5 1 0 Example 4 1 5 30 30 Example 5 1 5 50 70

As is clear from Table 1, as shown in Examples 1 and 2, the processing time for the ging treatment is ti! If A = 30 s and the chromate treatment time t ₂ is t ₂ s 15 s, A1 alloy vaporizer main body 1 with excellent corrosion resistance can be obtained. In the case of Example 35, the processing time t _{2 of the} chromate treatment is t ₂ = 15 s although the processing time of the gin gate treatment is 15 s, even though the underlying layer 2 is relatively thin. <t 2 = from 30 s <be a t 2 = 50 s, example 3, the corrosion resistance is also seen a child worse in this order by the exposure amount of the carburetor main body 1 ₀ surface in the order of example 4 example 5 is increased.

The A1 system structural member is not limited to the vaporizer made mainly of the A1 alloy, but includes a slot pod made of the A1 alloy, a solenoid valve main body, a compressor housing, etc., and also includes a structural member made of pure A1. .

Claims

The scope of the claims

1. A 1-based structural member (1.) A base layer (2) in close contact with the surface and an anticorrosion coating (3) in close contact with the base layer (2), the base layer (2) is made of Zn The corrosion resistant A 1-based structural member is characterized in that the anticorrosion film (3) is made of a chromate film for Zn containing trivalent Cr.

2. A 1-based structural member (1.) A process of forming an underlayer (2) of Zn by zincate treatment, and a chromate using a trivalent chromate agent on the surface of the underlayer (2) And a step of forming a corrosion-resistant film (3) comprising a chromate film for Zn containing trivalent C r by the grit treatment.

3. The treatment time required for the zincate treatment is: the A 1-based structural member (1.

The above-mentioned underlayer of Zn of the required thickness by increasing the amount of Zn deposition on the surface

(2) is set to a value that can be obtained, and the treatment time t ₂ required for the chromate treatment is the thickness of the underlayer (2) despite the dissolution of the underlayer (2) by the chromate treatment The corrosion resistance A 1 -based structural member according to claim 2, wherein the corrosion resistance A 1 -based structural member according to claim 2 is set to a value capable of reliably forming the chromate film for Zn containing trivalent Cr on the surface of the underlayer (2). Manufacturing method.

4. The corrosion resistant Al-based structural member according to claim 3, wherein the treatment time required for the zincate treatment is ≥ 30 s, and the treatment time t ₂ required for the chromate treatment is t ₂ ≤ 15 s. Manufacturing method.