JPH05239685A - Zinc double layer plated al alloy sheet excellent in lubricity - Google Patents

Abstract

PURPOSE:To obtain a Zn double layer plated Al alloy sheet excellent in lubricity by coating one side or both sides of an Al alloy sheet with a lower layer of a Zn alloy plating layer and an upper layer of a Zn-Fe plating layer having a specified compsn. with specified coating weight. CONSTITUTION:One side or both sides of an Al alloy sheet are coated with a Zn alloy plating layer with 0.1 to 60g/m<2> coating weight. This Zn alloy plating layer preferably contains, as alloy elements, about 1 to 90% of one or more kinds among Fe, Ni, Co, Cr, Al and Mn. Furthermore, as an upper layer, Zn-Fe plating layer contg. 40 to 95% Fe is provided by 0.1 to 10g/m<2>. In this way, the objective Zn double layer plated Al alloy sheet excellent in external rushing resistance and lubricity can be obtd.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a Zn-based two-layer plated Al alloy plate, and more specifically, it has excellent lubricity and can be used for various purposes, for example, an Al alloy plate for automobiles.
The present invention relates to an n-based two-layer plated Al alloy plate.

[0002]

2. Description of the Related Art Generally, not only the bare corrosion resistance but also the coating corrosion resistance, that is, the coating adhesion, the perforation resistance, the hot water immersion adhesion of the coating, and the red rust resistance are not only the corrosion resistance of automobile steel sheets in a corrosive environment. Etc. are required. Furthermore, particularly good lubricity is essential at the time of work forming of a steel sheet. For example, Shokoku Sho 5
No. 0-29821, Zn-Ni plated steel sheet, Japanese Patent Publication No. 56-133488, Zn-
Conventionally used plated steel sheets such as the Fe2 layer plated steel sheet have excellent lubricity, but there is no example of coating with such a plating on the Al alloy plate. As the level of sophistication increases, there is room for improvement in the plating to be coated, in terms of external surface rust resistance and lubricity during processing. Further, a single-layer-plated composite plated steel sheet found in Japanese Patent Publication No. 58-247984 is proposed, but application to an Al alloy sheet is disclosed in JP-A-61-157693.
Although it is partially found in the publication, the present situation is that the lubricity is not always sufficient.

[0003]

Means for Solving the Problems In view of the above situation, the present inventors have conducted various experiments, and as a result, coat the surface of an Al alloy plate with Zn alloy plating and, as an upper layer, Zn—Fe plating. It was found that the steel sheet has better external surface rust resistance and lubricity during processing than the conventional alloy plating. The reason for this is as follows. Regarding the external surface rust resistance, Zn-based alloy plating coated on the Al alloy plate suppresses the thread rust peculiar to the Al alloy plate, and at the same time, improves the corrosion resistance of the plating, thereby suppressing the rust width. I was seen. Regarding lubricity, performance can be improved by increasing the surface hardness by coating the Zn-based alloy as the lower layer plating, and at the same time, by providing the Zn-Fe alloy plating on the upper layer, lubrication is achieved by the synergistic effect with the lower layer. It was also found that the sex is significantly improved. The present invention is
The present invention was made based on the above knowledge, and the gist thereof is that a Zn-based alloy plating layer having a plating adhesion amount of 0.1 to 60 g / m ² is provided as an underlayer on one or both surfaces of an Al alloy plate. A Zn-based two-layer plated Al alloy plate is characterized by having Zn-Fe plating containing 40 to 95% Fe as an upper layer in an amount of 0.1 to 10 g / m ² .

The present invention will be described in detail below. First, in the present invention, the Zn-based composite plating Al alloy plate is composed of two layers of Zn-based alloy plating and Zn-Fe alloy plating, which will be described later, and has a two-layer structure. This is because the drastic improvement in lubricity was taken into consideration as described above. Here, the Zn-based alloy plating of the lower layer refers to a Zn-based alloy plating containing one or more kinds of alloying elements such as Fe, Ni, Co, Cr, Al, and Mn. Is 1 to 90%. The reason for using these platings is that Al and Fe tend to cause thread rust, whereas Zn-based plating generally does not show thread rust and has better corrosion resistance than Zn single plating. It also has excellent suppression effect. Therefore, the Al alloy plate has Z
The coating with the n-based alloy plating is effective in improving the outer surface rust resistance. Further, Zn-based alloy plating generally has a higher surface hardness than Zn single plating, and the friction coefficient tends to decrease. This effect is remarkable as compared with the original aluminum alloy plate.

The amount of Zn-based alloy plating deposited as the lower layer is 0.1 considering the dissolution in the chemical conversion treatment bath.
The lower limit is g / m ² , and the effect is saturated even if it exceeds 60 g / m ² , so this is the upper limit. Further, in order to achieve a drastic improvement in lubricity, 40 to 9 Fe was added on the plating.
Zn-Fe plating containing 5% was applied. Zn in the upper layer
-The lower limit of Fe concentration during Fe plating is 40% to ensure hardness.
Is required, and the upper limit is set to 95% in consideration of resistance to outer surface rust. The adhesion amount of the upper layer plating was limited to 0.1 to 10 g / m ² from the viewpoint of the external surface rust resistance and lubricity. Hereinafter, the effects of the present invention will be described more specifically with reference to Examples.

[0006]

EXAMPLES The production of the plated Al alloy plate of the present invention was conducted at pH 1
˜3 fluoride bath or pH 13.5-14.5 alkaline bath and pH 1-3 sulphate bath,
It is possible to perform electroplating using a chloride bath.
A part of the plating was produced by heat treatment for alloying.
The base Al alloy plate was mainly based on 5000 series and 6000 series. On the other hand, the upper layer plating was performed by electroplating using a sulfate bath or a chloride bath having a pH of 1 to 3. As the evaluation test, a flat plate pull-out test (friction coefficient measurement) and an outer surface rust resistance test (rust width measurement) were performed. The test conditions are shown below.

[Plate drawing test conditions] Specimen size: 1.0 mm x 30 mm x 300 mm Pressing force: 450 kgf Drawing speed: 200 mm / min Tool contact area: 900 mm ² (30 mm x 30 mm)

[Test conditions for outer surface rust resistance] Specimen size: 1.0 mm x 70 mm x 150 mm Sample preparation: A plating aluminum plate was subjected to chemical conversion treatment + 3 coats, and then scratches reaching the groundwork were added to the coating. Test environment: salt spray + wet environment.

Furthermore, the evaluation criteria of each test are as follows.

[0010] However, outer surface rust occurs as a coating swell from the cut scratches.

Among the present invention, lower layer Zn alloy plating / upper layer Z
FIG. 1 shows the relationship between the Fe content in the upper layer plating and each evaluation result under the n-Fe alloy plating structure condition. Furthermore, the Zn-based alloy plating composition of the lower layer, the adhesion amount and the Zn-Fe (40%) of the upper layer
Table 1 shows the results of each evaluation test in which the amounts of Zn-Fe (95%) alloy plating deposited were changed independently. In the table, the upper grade with (humidity) indicates lubricity, and the lower grade with (rust) indicates external rust resistance. In FIG. 1, 40% or more of Fe in the upper plating is desirable from the viewpoint of lubricity, and 95% or less is considered to be appropriate from the viewpoint of external surface rust resistance. Therefore, the Fe content in the upper layer plating that satisfies both performances is 40 to 95%. It is considered that this is because if the Fe content in the upper layer plating is less than 40%, the hardness is low, and if it exceeds 95%, the upper layer plating itself is easily corroded.

In Table 1, when the lower layer plating has a low adhesion amount, the outer surface rust resistance is very poor regardless of the presence or absence of the upper layer.
It becomes good when the amount of adhesion is 0.1 g / m ² or more. If there is no plating on the upper layer, the lubricity is not sufficient regardless of the presence or absence of plating. Although the lubricity is improved due to the increase in the amount of coating on the upper layer,
If the amount of adhesion is too large, the lubricating performance tends to decrease. From the above, the Zn-based alloy plating is phenomenally 0.1 to 60 g / m ^{2 as} the lower layer, and Fe is 40 to 95% as the upper layer.
It was confirmed that the structure in which the contained Zn-Fe plating was coated in an amount of 0.1 to 10 g / m ² was suitable for improving the lubricity and outer surface rust resistance of the Al alloy plate.

[0013]

[Table 1]

[0014]

[Table 2]

[0015]

Industrial Applicability As described above, the present invention is a Zn-based two-layer plated Al alloy plate having excellent lubricity after plating coating of the Al alloy plate, and is particularly applicable as a lightweight automotive Al alloy plate. , Industrially, it is extremely significant.

[Brief description of drawings]

FIG. 1 is a diagram showing a relationship between evaluation results of lubricity and outer surface rust resistance with respect to Fe content in upper layer plating according to the present invention.

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Akira Takahashi Akira Takahashi 20-1 Shintomi, Futtsu-shi, Chiba Nippon Steel Co., Ltd. Technology Development Division (72) Inventor Kazuhiko Honda 20-1 Shintomi, Futtsu-shi, Chiba Made by Nippon Steel (72) Inventor Shoji Saito, 1351 Uenodai, Fukaya City, Saitama Prefecture Sky Alminium Co., Ltd. Technical Research Laboratory (72) Inventor Michio Kobayashi 1351, Uenodai, Fukaya City, Saitama Prefecture Sky Alminium Technology Research Co., Ltd. In-house

Claims (1)

[Claims] 1. A Zn-Fe alloy having a Zn-based alloy plating layer having a coating weight of 0.1 to 60 g / m ² as a lower layer and 40 to 95% Fe as an upper layer on one surface or both surfaces of an Al alloy plate. A Zn-based two-layer plated Al alloy plate having excellent lubricity, which has 0.1 to 10 g / m ^{2 of} plating.