JPH07252636A - Zinc-titanium plated metallic material excellent in corrosion resistance after coating - Google Patents

Abstract

PURPOSE:To provide a plating material having corrosion resistance after coating, particularly excellent among Zn-Ti metallic materials. CONSTITUTION:In the metallic material plated with Zn-Ti, a multilayered plating is executed by forming 0.5-5g/m<2> of a plated layer composed of 0-8wt.% Ti and the balance Zn as a 1st layer, 5-60g/m<2> of a plated layer composed of 6-80wt.%, preferably 10-60wt.% Ti and the balance Zn as a 2nd layer and 0.2-3g/m<2> of a plated layer composed of 0-8wt.% Ti and the balance Zn as a 3rd layer respectively from plating surface side. The 1st layer, the 2nd layer and the 3rd layer can be plated so as to have a gradient composition by continuously changing the composition from the plating surface up to the boundary of the metallic material.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a Zn alloy-plated metal material which is required to have excellent corrosion resistance after painting, such as outer panels of automobiles and home electric appliances.

[0002]

2. Description of the Related Art Zn plating has hitherto been the most economical method for preventing corrosion of metal products in the atmosphere.
It is said to be effective and has been widely implemented.

In recent years, the requirements for rust prevention are becoming more and more strict, and various Zn alloy platings having improved corrosion resistance have already been used to prevent corrosion.

Among them, Zn-T having particularly excellent corrosion resistance
An i-plated steel sheet is disclosed (Japanese Patent Laid-Open No. 63-2473).
54, etc.).

[0005]

Since Zn-Ti plating has excellent corrosion resistance, it is expected to be applied to outer panels of automobiles and home electric appliances. For that purpose, excellent adhesion to metal materials is required. It is also necessary to have corrosion resistance after painting.

However, the previously disclosed Zn
The Ti-plated metal material is still insufficient in terms of adhesion and corrosion resistance after coating, and it is necessary to further improve these characteristics.

The present invention provides a Zn--Ti plated metal material having excellent adhesion and corrosion resistance after coating.

[0008]

The first object of the present invention, which has solved the above-mentioned problems, is to provide Ti: 0 as a first layer from the plating surface side.
˜8 wt%, 0.5 to 5 plating layer with balance Zn
g / m ² , 5 to 60 g / m ² for the second layer, Ti: 6 to 80 wt% and the balance Zn, and 5 to 60 g / m ² for the third layer, the Ti: 0 to 8 wt% and the balance Zn. 0.2 to 3 g / m ² Z with excellent corrosion resistance after coating
It is an n-Ti plated metal material.

In a second aspect of the present invention, in the above Zn—Ti plated metal material, the Ti composition of the first layer, the second layer and the third layer continuously changes from the plating surface to the interface with the metal material. Zn-Ti, which has excellent corrosion resistance after painting, characterized by
Gradient composition plated metal material.

Furthermore, a third aspect of the present invention is the above Zn--Ti.
The plated metal material or the Zn-Ti gradient composition plated metal material is characterized in that the lower layer of the third layer is further subjected to Ni pre-plating treatment in an amount of 0.05 to 1.5 g / m ² .

The metallic material to which the present invention is applied is Fe.
And Fe-based alloys, non-ferrous metals such as Al, and alloys thereof.

[0012]

In order to solve the above-mentioned problems, various studies have been made on the structure of Zn-Ti plating. As a result, it is possible to obtain excellent plating adhesion by changing the Ti concentration in the plating thickness direction with multilayer plating or with a graded composition. The present invention has been completed by finding out that it is possible to simultaneously secure the corrosion resistance and the corrosion resistance after painting.

The detailed structure will be described below.

The Zn-Ti alloy plating of the present invention is produced by a vapor phase plating method. The Zn—Ti plating layer cannot be formed by the electroplating method because of the difference in the deposition potential of Zn and Ti, and cannot be formed by the hot dipping method because of the difference in the melting points of Zn and Ti.

As the vapor phase plating method, a method such as a vacuum vapor deposition method, an ion plating method or a sputtering method can be adopted, and a wide range of compositions can be realized by controlling the evaporation amount, the evaporation source surface area and the like. You can

The Zn--Ti plating thus produced exhibits excellent corrosion resistance. However, if the concentration of Ti is increased to secure a high level of corrosion resistance, the plating layer becomes harder and The excellent corrosion resistance deteriorates the etching type chemical conversion treatment property.

Therefore, the inventors reduced the Ti concentration in the vicinity of the plating layer surface and in the vicinity of the plating layer-metal material interface and increased the Ti concentration in the intermediate layer of the plating to improve the plating adhesion, chemical conversion treatment property, and corrosion resistance. Tried to satisfy all of.

Here, the vicinity of the surface is the first layer and the intermediate layer is the second layer.
The layer, the plating layer, and the vicinity of the metal material interface are called the third layer.

The purpose of the first layer is to secure reactivity with an etching type chemical conversion treatment solution, the second layer to secure corrosion resistance, and the third layer to secure adhesion to a metal material.

As a result of various examinations, Ti: 0 to 8 was formed on the first layer.
wt%, 6-80 wt% of the second layer, preferably 10-6
The purpose could be achieved by setting 0 wt% and the third layer to 0 to 8 wt%.

The second layer is intended to ensure corrosion resistance, but if the Ti concentration is less than 6 wt%, the corrosion resistance is not sufficient, and if it exceeds 80 wt%, the sacrificial anticorrosive ability against the metal material is lost.

Desirably, the Ti content is about 10 to 60 wt% so that the anticorrosion performance is exhibited more reliably.

The unit weight is required to be 5 g / m ² or more in order to secure sufficient corrosion resistance, and if it exceeds 60 g / m ² , the plating layer becomes too thick and plating peeling occurs during processing.
Since the processing performance deteriorates, the basis weight of the second layer is 5 to 60 g.
/ M ²

However, when the corrosion resistance after coating, which is the final purpose, is evaluated by a salt spray test (according to JIS Z 2371) after putting a cross cut on the test piece, the first layer or the third layer When the basis weight of the layer is large, the first or third layer is selectively dissolved, the swelling width of the coating film is increased, and the corrosion resistance after coating is deteriorated.

Then, the weight per unit area was examined so as not to deteriorate the corrosion resistance. As a result, the first layer was 0.5 to 5 g / m ² , the third
By setting the layer to 0.2 to 3 g / m ² , it was possible to secure plating adhesion and chemical conversion treatment without deteriorating the corrosion resistance after coating.

If the basis weight of the first layer is less than 0.5 g / m ² and the basis weight of the third layer is less than 0.2 g / m ² , plating adhesion and chemical conversion treatment cannot be ensured.

On the other hand, if the basis weight of the first layer exceeds 5 g / m ² and the basis weight of the third layer exceeds 3 g / m ² , the first layer or the third layer
The selective dissolution of the layer occurs, the swelling width of the coating film becomes large, and the corrosion resistance after coating cannot be secured.

In the present invention, the above-mentioned first layer, second layer
The layer and the third layer do not need to be completely separated, and it is desirable to continuously change the concentration of Ti.

The main object of the present invention is to prevent the corrosion resistance after coating from deteriorating so that Ti is formed on the surface of the plating layer and the interface between the plating layer and the metal material.
By forming a part with a low concentration, it is necessary to secure plating adhesion and chemical conversion treatability at the same time.

To this end, a so-called gradient composition is used in which the Ti concentration in the middle of the plating layer is maximized from the surface of the plating layer to the interface between the plating layer and the metal material so that the Ti concentration is continuously changed. Is good.

FIG. 1 shows an example of the compositional change in the thickness direction of the Zn—Ti plated layer produced by the gradient composition method.

As described above, Zn--
A Zn-Ti plated metal material can be realized, but a Zn-Ti plated metal material that can withstand more difficult processing is required.
It is advisable to perform Ni pre-plating treatment on the base of plating.

Ni pre-plating 0.05-1.5 g / m
By performing Zn-Ti plating after applying the ^two, it is possible to secure a further excellent adhesion between the metal material and the Zn-Ti plated layer.

[0034] Although Ni is able to exert its effect if attached 0.05 g / m ^2, since the effect is but are not rise proportionally even exceed 1.5 g / m ^2, the basis weight The amount range is defined as 0.05 to 1.5 g / m ² .

[0035]

EXAMPLES The present invention will be described in more detail below with reference to examples.

Zn-Ti alloy plating was performed by a vacuum deposition method or an ion plating method using a cold-rolled steel sheet having a plate thickness of 0.7 mm or an Al alloy plate having a plate thickness of 1.0 mm as a metal substrate.

Table 1 shows the case where the multi-layer plating method is adopted,
Table 2 adopts the gradient composition method.

Tables 1 and 2 show the results of evaluation of plating adhesion, chemical conversion treatability, and corrosion resistance after coating. From these results, it can be seen that the inventive examples exhibit excellent performance.

The plating adhesion, chemical conversion treatment property, and corrosion resistance after coating were evaluated by the following methods.

Plating adhesion: Plating adhesion was evaluated by a tape peeling test after bending. Bending was performed 180 degrees so that the plated surface was on the inside (adhesive tape was previously attached to the bent portion), and the tape peeling test was used to make a determination.

No peeling of the plating was marked with ⊚, peeling width of less than 1 mm was marked with ◯, peeling width of 1 mm or more and less than 3 mm was marked with Δ, and peeling width of 3 mm or more was marked with x.

Chemical conversion treatment: As the chemical conversion treatment, Bt3080 (trade name) manufactured by Nippon Parker Co., Ltd. was immersed at 45 ° C. for 3 minutes and dried.

Corrosion resistance after coating: Corrosion resistance after coating was evaluated using a test piece which had been subjected to immersion phosphate treatment and cationic electrodeposition coating.
Phosphate treatment is performed with Bt3080 manufactured by Nippon Parker Co., Ltd., and a normal cold-rolled steel sheet has a coating amount of 2.5 to 3.0 g / m 2.
² and P were performed under standard processing conditions of 85% or more.

For the electrodeposition coating, Nippon Paint's cationic type electrodeposition coating U-80 was used, and the coating thickness after baking was 20 μm.
It was adjusted to be m.

For the post-painting corrosion resistance test, a cross-cut (5 cm × 5 cm) reaching the base material was put in this test piece, and a salt spray test (in accordance with JIS Z 2371) was conducted.
The swelling width of the coating film on the cut portion after the time lapse was measured. When the swelling width of the coating film was less than 3 mm, the corrosion resistance after coating was judged to be good.

[0046]

[Table 1]

[0047]

[Table 2]

[0048]

[Table 3]

[0049]

The Zn-Ti plated metal material constructed as in the present invention has very good corrosion resistance after painting.

[Brief description of drawings]

FIG. 1 is a diagram showing an example of a composition change in a thickness direction of a Zn—Ti plated layer produced by a gradient composition method.

Claims (3)

[Claims] 1. From the plating surface side, Ti:
0 to 8 wt%, the balance of the plating layer consisting of Zn 0.5 ~
6~80wt%, Ti plating layer and the balance being Zn 5 to 60 g / m ^2, as the third layer:: 5g / m ^2, Ti as the second layer 0~8wt%, the plating layer and the balance being Zn A Zn-Ti plated metal material having an excellent corrosion resistance after coating, which is produced in an amount of 0.2 to 3 g / m ² . 2. The Zn—Ti plated metal material according to claim 1, wherein the Ti composition of the first layer, the second layer, and the third layer changes continuously from the plating surface to the interface with the metal material. A Zn-Ti gradient composition plated metal material that has excellent corrosion resistance after painting. 3. The Zn-Ti plated metal material according to claim 1 or 2, wherein the lower layer of the third layer is further subjected to Ni pre-plating treatment in an amount of 0.05 to 1.5 g / m ^2. Zn-Ti plated metal material with excellent post-corrosion resistance.