JPH03153863A - Zn-ti alloy plated metallic material having excellent phosphate treatability - Google Patents

Abstract

PURPOSE:To produce the Zn-Ti alloy plated material which is excellent in both of a rust preventive effect and phosphate treatability by gradually decreasing the content of Ti from the surface of a metallic material, such as steel sheet, toward the upper part in the thickness direction of the plating layer at the time of forming the Zn-Ti alloy plating layer on the surface of the metallic material. CONSTITUTION:A crucible 2a contg. molten Ti and a crucible 2b contg. molten Zn are disposed under the steel sheet or other metallic sheet 1 while the steel sheet 1 is progressed in an arrow direction and the Ti and Zn are deposited by evaporation on the lower surface of the steel sheet 1. The crucible 2a for the Ti and the crucible 2b for the Zn are disposed on the upstream in the progressing direction of the steel sheet 1 in this case. The Ti is first deposited by evaporation on the steel sheet 1 and the vapor deposition rate of the Zn increases gradually as the steel sheet progresses in the arrow direction to form the compsn. of the part where the Zn-Ti alloy layer 3 comes into contact with the steel sheet as the Zn-Ti alloy contg. 10 to 60wt.% Ti. The content. of the Ti decreases gradually and the compsn. in the uppermost layer part is formed of the Zn-Ti alloy layer contg. <10wt.% Ti. The alloy layer is thus formed to such quality that the content of the Ti decreases from the steel sheet surface toward the upper part. The Zn-Ti alloy plated steel sheet which is excellent in both of the rust preventiveness and phosphate treatability is thereby produced.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Application Field] The present invention relates to a Zn-Ti alloy plated metal material that has excellent rust prevention effects and phosphate treatment properties as a base for electrodeposition coating. Plating materials are useful for the outer and inner panels of vehicles, the outer panels of household electrical appliances, and various building materials.

The metal materials to which the present invention is applied include Fe and Fe.
In addition to the base alloy, non-ferrous metals such as Cu and A1, and their alloys are included, and the shape may be flat, corrugated, tubular, rod, or an irregular rod with an L-shaped or H-shaped cross section. However, in the following explanation, the most typical plate-shaped steel material, that is, a steel plate, will be mainly explained.

[Prior Art] Zn plating has conventionally been generally used as a plating method with a high rust prevention effect. However, in recent years, there has been a demand for better rust prevention effects, and in response to this demand, various alloy platings have been developed. Among these, Zn-Ti alloy plating is one of the most effective in preventing rust.

[Problem to be solved by the invention 1 In plating materials used for the above-mentioned purposes,
Along with rust prevention, paintability is also an important required property. In other words, when performing phosphate treatment as a pretreatment for painting, a sufficient zinc phosphate film must be formed;
In the case of Zn-Ti alloy plating materials, there is a problem in that a zinc phosphate film is difficult to form.

Figure 3 shows the Ti content in the Zn-Ti alloy plating layer and 5%.
This is a graph showing the relationship between red rust generation time in salt spray test (SST), and the preferable Ti content from the viewpoint of rust prevention effect is 10 to 60% by weight (hereinafter expressed as %), more preferably 10 to 40%. %It can be seen that it is. Also the fourth
The figure is a graph showing the relationship between the amount of zinc phosphate film and the Ti content during phosphate treatment. When the Ti content is 10% or more, the zinc phosphate film is less than 137 m2, and in practice it is rarely formed. It is determined that this has not been done. In this way, Zn-T
In the case of i-alloy plating, there is no Ti content range that satisfies both rust prevention and phosphate treatment properties.

[Means for Solving the Problems] The present inventors have conducted extensive research with the aim of obtaining a matting material that is excellent in both rust prevention effect and phosphate treatment properties, and have completed the present invention having the following structure. did. That is, in the Zn-Ti plated material according to the present invention, the Ti content on the interface side with the metal material in the plating layer is 10 to 60%, and the Ti content on the outermost layer is less than 10%. There is a point to it.

[Function] As mentioned above, Zn-Ti alloy plating does not have a Ti content range that satisfies both the rust prevention effect and phosphate treatability, so the conventional uniform plating layer does not have the rust prevention effect. Since the phosphate treatment properties are both excellent, the next step cannot be obtained. Therefore, the present inventors conducted research focusing on the thickness of the plating layer, and as a result, the Ti content was changed in the thickness direction of the plating layer. Therefore, if the Ti content is lowered in the surface area to ensure phosphate treatability, and the Ti content is increased in the deeper layer to ensure rust prevention, the rust prevention effect and phosphate The present invention was completed by discovering that a Zn-Ti alloy plating with excellent processability can be obtained.

In this case, the Ti content on the boundary side with the metal material is 10 to 60%, more preferably 10 to 60%, as shown in FIG.
It needs to be within the range of 40%.

If the Ti content is higher or lower than this range, a sufficient rust prevention effect cannot be obtained.On the other hand, if the Ti content in the outermost layer is
It should be less than 10% as shown in the figure. Tl
The content is preferably as low as possible, and may be 0%, but 10
% or more, zinc phosphate film will hardly be formed and should be avoided.

The concentration of Ti in the plating layer is decreased stepwise or continuously toward the surface side of the plating layer to form a concentration gradient.

As mentioned above, Z has a concentration gradient of Ti content in the thickness direction.
The most preferable method for forming the n-Ti alloy plating layer is a vacuum deposition method. It is not possible to form a Zn-Ti alloy plating layer using normal electroplating methods, and it is difficult to form a concentration gradient in the alloy plating layer using hot-dip plating methods because the melting points of Zn and Ti are significantly different. . On the other hand, in the vacuum evaporation plating method, an example of which is shown in FIG. 1, a concentration gradient of Ti content can be easily formed. As shown in the figure, steel plate 1 traveling in the direction of the arrow
Two crucibles 2 are installed along the running direction of the steel plate 2 at the lower part of the
a and 2b are arranged, and Ti is charged into the crucible 2a on the upstream side in the running direction, and Zn is charged into the crucible 2b on the downstream side. Then, Ti and Zn are heated and evaporated, respectively, and vapor deposition is performed while the respective vapor atmospheres are lapped. Then, vapor having the highest Ti vapor ratio is first deposited on the steel plate 1, and as the steel plate 1 moves, vapor having a gradually lower Ti vapor ratio is deposited. As a result, T at the boundary with the steel plate
A Zn-Ti alloy plating layer is formed which has a gentle concentration gradient in which the Ti content is highest in the surface layer and the Ti content in the surface layer is the lowest. ? The degree of lA can be freely controlled by the heating conditions of the crucibles 2a and 2b and the degree of vacuum.

The thickness of the plating layer can also be arbitrarily set by adjusting the running speed of the steam steel plate 1. Any means can be used to heat each metal; in particular, Zn has a low melting point and high vapor pressure, so general electric resistance heating can serve the purpose well, but Ti has a high melting point and a high vapor pressure. It is preferable to use a high-energy beam such as an electron beam, which has a high thermal focusing property, for heating.

In the example shown in FIG. 1, two crucibles are used, but depending on the case, three or more crucibles may be used to finely control the concentration change. In addition, we have adopted the ion brating method, which ionizes metal vapor and applies a negative voltage to the base steel plate to deposit the metal vapor.
It is also possible to further improve the performance of the plating layer, such as preventing pinholes, making the alloy composition uniform in the width direction, and improving adhesion to the base steel plate.

FIG. 2 shows an example of the composition change in the thickness direction of the plating layer obtained by the above-mentioned vacuum evaporation method. Plating layer
The Ti content at the boundary between the steel plates is approximately 25%, which has an excellent rust prevention effect, and the Ti content decreases toward the surface layer, reaching approximately 5% at the outermost layer, which provides excellent phosphate treatment properties. rate.

[Example] A Zn-Ti alloy plating layer was formed on a cold-rolled steel sheet whose surface had been cleaned by washing with water after electrolytic degreasing in accordance with the method shown in FIG. At this time, by controlling the amount of evaporation of Zn and Ti, the Ti content in the outermost layer of the plating layer can be adjusted to 10
%, and the Ti content at the substrate boundary was adjusted to be 10 to 60%. The amount of plating deposited is 20 g/m.
2, and plating materials with different Ti contents were also created as comparative examples.

Table 1 shows the results of investigating the Ti content, rust prevention effect, and phosphate treatment properties of each Zn-Ti alloy plating material. I investigated the method.

(Rust prevention effect) A spray test of 5% saline was continued at room temperature, and evaluation was made based on the time until red rust appeared.

◎: Excellent ○: Good ×: Poor (phosphate treatment properties) After applying a cationic electrodeposition coating of 20 μm to each plated steel plate, a cross cut was made in the coating film, and a 5% saline solution was sprayed with 3i10.
Evaluation was made based on the state of peeling of the coating film after 00 hours.

◎: Excellent O: Good X: Poor As is clear from Table 1, the Ti content in the surface layer is 10
% or more shows an excellent rust prevention effect, but has poor phosphate treatment properties (Comparative Example 1.2.3), and those with a Ti content of 10% or less in the surface layer and the boundary between the base material and Although the salt treatment property is excellent, the rust prevention effect is poor (Comparative Example 4.5),
On the other hand, Examples (1 to 4) are excellent in both rust prevention effect and phosphate treatment properties.

[Effects of the Invention] The present invention is constructed as described above, and uses Zn-T that has excellent rust prevention effects and phosphate treatment properties as a base for electrodeposition coating.
i-alloy plated metal material can be obtained.

[Brief explanation of the drawing]

Fig. 1 is a conceptual diagram illustrating the vapor deposition plating method according to the present invention, Fig. 2 is a graph showing an example of the composition change in the thickness direction of the plating layer obtained by the present invention, and Fig. 3 is a graph showing an example of the composition change in the thickness direction of the plating layer obtained by the present invention.
A graph showing the relationship between the Ti content in the alloy plating layer and the red rust generation time. Figure 4 shows the relationship between the Ti content in the Zn-TL gold alloy plating layer and the amount of zinc phosphate film during phosphate treatment. This is a graph showing. 1... Steel plate 2a... Ti crucible 2b... Zn crucible 3... Zn-Ti alloy plating layer

Claims (1)

[Claims] A Zn-Ti alloy plating material, in which the Ti content on the interface side with the metal material in the plating layer is 10 to 60% by weight, and the Ti content in the outermost layer is less than 10% by weight. Zn-Ti with excellent phosphate treatment properties characterized by
Alloy plated metal material.