JPS60194091A - Double-electroplated steel sheet having superior resistance to sliding and falling - Google Patents

Abstract

PURPOSE:To obtain a double-electroplated steel sheet having superior resistance to sliding and falling by depositing a thin layer of a Zn-Ni or Zn-Fe alloy on a Zn layer formed on a steel sheet by galvanizing. CONSTITUTION:One side or both sides of a steel sheet are galvanized, and a film of a Zn-Ni alloy contg. 5-20wt% Ni or a Zn-Fe alloy contg. 5-40wt% Fe is formed on the resulting Zn layer as a surface layer by electroplating by 0.1- 5g/m<2>. When the double-electroplated steel sheet is slit to a proper size, it is pressed from the front and rear sides with pads of felt or the like and undergoes sliding deformation. Little dust falls from the Zn and alloy layers in spite of the deformation, and the steel sheet has superior resistance to sliding. The double plated steel sheet has superior work withstanding properties.

Description

[Detailed Description of the Invention] (Prior Art and Problems) Electrolytic Zn-plated steel sheets have excellent properties in terms of adhesion to the substrate, resistance to plastic deformation, corrosion resistance, etc., and are suitable for use in automobiles. It is widely used in fields such as home appliances, light electrical appliances, and building materials.

Such an electrolytic Zn-plated steel sheet is usually wound into a coil and threaded, and processed into three/slits to appropriate dimensions by the customer. At this time, a device is often used that applies tension to the strip by pressing a pad made of felt, nylon, or the like with hydraulic pressure from both sides of the strip.

However, the electrolytic Zn plating layer has the disadvantage of being prone to adhesive wear due to such sliding deformation.
Fine powder is detached, accumulates in the tension pad material, and aggregates.
Furthermore, since scratches are generated in the plating layer, there are problems of deterioration of quality such as deterioration of surface appearance and promotion of white rust formation.

Therefore, the following methods (a) or (b) have been used as a means to reduce adhesive wear of the electrolytic Zn plating layer, but each of these methods has its own problems, and there is no way to solve them. However, this was considered to be a technical issue.

(a) High current density (high overvoltage) plating If the Zn crystals are made finer by high current density plating,
Increases surface hardness and improves sliding resistance. However, it is necessary to strengthen the plating solution flow (a huge plating solution circulation pump), and power loss due to plating solution resistance increases.
The plating power consumption rate (KWH/T) deteriorates and is uneconomical.

(b) Use of organic additives A small amount of starch such as pentose, saccharin, sugar, protein such as glue, etc. is added to the plating bath to harden the plating film. However, it has been difficult to control the bath concentration of organic matter at a minute level and within a narrow range. (The additive decomposes and is consumed as the electrolysis progresses, and if it is too concentrated, it causes a decrease in mold reading efficiency and deterioration in chemical conversion processability.) (Objective of the Invention) The present invention solves the problems of the prior art as described above. It is an object of the present invention to provide an electrolytic Zn-plated steel sheet that is improved, has stable quality, is inexpensive, and has particularly excellent sliding resistance.

(Structure of the Invention) The gist of the present invention is that a thin layer of a single-layer Zn alloy or a Zn-Fe alloy is attached as a surface layer on an electrolytic Zn plating layer applied to a steel plate.

The electrolytic Zn plating layer may be plated on one side, equally thick on both sides, or differential pressure plated on both sides. The thickness of the plating layer is not particularly limited as long as it is necessary for corrosion resistance. Usually, it is 10 to 100 g/m' per side.

As the Zn-based intermetallic compound applied as the surface layer, Zn-
Ni alloy plating (Ni5-20wt%), Zn-Fe
Alloy plating (Fe5-4wt) coating is excellent in terms of corrosion resistance and is optimal. Although these intermetallic compounds have hardness and excellent adhesion, they are brittle and are susceptible to high plastic deformation, so it is desirable to make the plating thickness as thin as possible. These Zn-based alloy platings are coated with a small amount of cy)Ni, Fe, Cr, Mn, No
, Pb, Cu, Sn, Ti, Go, P,
One or more types of S, B, etc. can be added.

Furthermore, the surface layer of the present invention may be subjected to a known chromate treatment to improve white rust resistance, or an organic resin coating with a thickness of several microns may be applied to improve fingerprint resistance. can.

The Ni content in the Zn-Ni alloy is set to 5 to 20 wt$,
In addition, the Fe content in the Zn-Fe alloy is 5 to 40 Wt.
The reason why it is limited to $ is because alloys in this range have suitable corrosion resistance as a surface layer. A more preferable range is N
i1O~I13wtX, Fe1O~20wt%.

The reason why the amount of plating on the surface layer was limited to 0.1 to 5 g/rn' is that if it is less than 0.1 g/m', the effect of improving sliding properties is insufficient, and if it exceeds 5 g/m', the plasticity This is because it is weak against deformation, and cracks tend to enter the surface layer and become a starting point for crack propagation to the inner layer, and making it thicker than that is ineffective and uneconomical. A more preferable amount of adhesion is 0.
5-4 g/m', the most preferred range is 1-3 g/m'
It is.

Next, the present invention will be further explained by examples.

(Example 1) A Zn plating layer with a plating amount of 100 g/rrl' was applied as an inner layer to a cold-rolled steel sheet base (thickness 0.8+am, guild m) by a known electroplating method (ZnCl2200 g/l).
, NH4Cltoog/length, pt(2, eiQoC
coated with constant current density electrolysis (eoA/am') in a plating bath, and further coated with a Zn-Ni alloy plating layer of Ni12wtX with various thicknesses as a surface layer,
A sample was produced.

(Known plating bath, Ni/Zn molar ratio 1.5-3.0
The amount of plating deposited was varied by varying the temperature 40-70°C, pH 1.5-2.5, current density 20-40 A/dm', and current application time. ) This sample was subjected to the following sliding resistance evaluation test. The test results are shown in Figure 1.

(Sliding resistance evaluation test) @50mm taken from each sample, length 600m+o
The test piece is supported between two upper and lower chucks, and nylon pads (pressing area 50 mm x 50 m
m) with hydraulic pressure of 25 kg/cm'
I pressed it with Next, the test piece supported by the chuck was
Ten scraping tests were carried out at a rising rate of 11 ffl/sec. Sliding resistance was evaluated using a 5-point method based on the appearance of the scratched surface of the test piece and the occurrence of scratches. (Example 2) As is clear from each example, the steel plate of the present invention has excellent sliding resistance and workability.

[Brief explanation of the drawing]

FIG. 1 is a graph showing the test results of Example 1, and FIG. 2 is a graph showing the test results of Example 2. Agent Patent Attorney Shuntetsu Sasaki 1st illustration

Claims (1)

[Claims] At least one side of the steel plate has 0 coatings of paint as a surface layer.
．． 1~5g/m'0) Zn-Ni alloy (N
i 5~20wt%) or Zn-Fe alloy (Fe5~20wt%) or Zn-Fe alloy (Fe5~20wt%)
40wt ivy) has a plating film, and the inner layer is electric Zn.
A multilayer electroplated steel sheet characterized by having plating.