JPS61183491A - Corrosion resistant double coated steel material - Google Patents

Abstract

PURPOSE:To obtain a double coated steel material having excellent sacrificial corrosion preventiveness, adhesiveness and corrosion resistance by depositing a lower layer consisting of a Zn-base Ni alloy and an upper layer of a Zn-base Ni alloy contg. Ni at a lower ratio on the surface of the steel material and coating further a resin layer thereon via a chromic acid film. CONSTITUTION:The lower layer which is a plating layer 2 consisting of the Zn-base Ni alloy contg. 10-15wt% Ni is provided on the surface 1' of the iron or steel materials 1 on which a copper plating film 6 is formed according to need. A plating film 3 consisting of the Zn-base Ni alloy contg. >=5% Ni or Zn simple substance is deposited and superposed as the upper layer on the surface 2' of the lower layer. The resin layer 5 consisting of a PE resin, etc., is formed on the surface 3' thereof via the chromic acid film 4. The corrosion- resistant double coated steel material having the improved adhesiveness between the alloy layers and between the film 4 and the resin layer 5 is obtd. by the above-mentioned method.

Description

Detailed Description of the Invention [Industrial Field of Application] In view of the need for corrosion resistance on narrow surfaces of steel materials such as plates, tubes, rods or wire rods, the present invention has been developed to improve the corrosion resistance of the resin layer covering the outer surface. Form 1c relates to improvements in corrosion-resistant polymer coated steel.

[Conventional technology]

Conventionally, this type of corrosion-resistant polymer-coated steel material has been produced by applying either an electroplating film of simple zinc or a hot-dip plating layer consisting of a tin-lead alloy to the surface of a steel material with or without a copper plating film. , by coating the surface with a resin layer, or recently, instead of the electroplating film of zinc alone or the hot-dip plating layer of tin-lead alloy, a single plating layer of zinc-nickel alloy is applied, and chromium is coated with a single plating layer of zinc-nickel alloy. A product in which an acid film is applied and a resin layer is formed on the surface has been developed and put into practical use.

[Problem that the invention seeks to solve]

However, in such conventional products, when the former is used as a component of an automobile, etc.
Corrosion resistance is generally poor in environments where salts are sprayed to prevent freezing on roads at beaches or in cold regions, and further improvements in corrosion resistance have been desired. In addition, in the case of the latter, due to its single-plated layer structure and alloy composition that is made up of zinc and contains a relatively large amount of nickel, the adhesion resistance of the chromic acid film is incomplete and the surface is coated. This has problems such as inhibiting adhesion with the resin layer to be formed, making it easy to peel off during post-processing as a product, and even damaging the resin layer and causing deterioration in corrosion resistance.

This invention solves these conventional problems by using a zinc-nickel alloy that adheres to the surface of a steel material, especially when the lower layer is coated with nickel.
A plating layer of a zinc-based nickel alloy consisting of 0% to 15% by weight, and further a plating film consisting of a zinc-based nickel alloy consisting of 5% by weight or less of the same type of nickel or zinc alone as an upper layer on the surface of the plating layer. By depositing and polymerizing it to form a multilayer structure, interposing a chromic acid film on the surface of the metal-depleted film, and coating the outer surface with a resin layer, sufficient corrosion resistance can be achieved even under the above environment. The purpose is to demonstrate.

[Means to solve the problem]

This invention provides a method for forming a plating layer of a zinc-based nickel alloy containing 10% by weight to 15% by weight of nickel on the surface of a steel material with or without a copper plating film, and further providing a different aspect of the plating layer. Then, a zinc-based nickel alloy containing 5% by weight or less of nickel or an I gold film made of zinc alone is deposited and polymerized as an upper layer, and a chromic acid film is interposed on the surface of the plating film, and a resin layer is formed on the outer surface. The gist is a corrosion-resistant polymer-coated steel material coated with.

An embodiment of the present invention will be described below with reference to the drawings. Fig. 1 is an enlarged partially cutaway sectional view of a pipe material as a corrosion-resistant polymer coated steel material of the present invention, and Fig. 2 is a partially cutaway enlarged sectional view of a pipe material as a corrosion-resistant polymer coated steel material of the present invention. It is an enlarged sectional view with a partial notch. (1) is a steel material made of plates, tubes, rods, wires, etc.
6) or not (1), a plating layer (2) of a zinc-based-nickel alloy consisting of 10% to 15% by weight of nickel is the lower layer, and the surface of the plating layer (2)
Zinc base consisting of 5% by weight or less of nickel as an upper layer.
It is formed by depositing and polymerizing a plating film (3) of nickel alloy or zinc alone. (5) is a resin layer made of polyethylene resin, vinyl chloride resin, fluororesin, etc., which is coated on the outer surface of the plating film (3) with a chromic acid film (4) interposed therebetween.

[For production]

Since the present invention has the above-mentioned configuration, the sacrificial corrosion protection provided by the slow anodic dissolution rate of the zinc-based-nickel alloy plating layer (2) consisting of 10% to 15% by weight of nickel as the lower layer can improve the sacrificial corrosion resistance of the steel material. (1) It forms an excellent protective property against the surface (1). Regarding the range of nickel content mentioned above, if the content of nickel is less than 10% by weight, it is not enough to simply rely on zinc. On the other hand, if the content exceeds 15% by weight, the corrosion potential approaches the steel material, degrading the sacrificial corrosion protection and increasing the hardness of the plating layer (2). This is due to the fact that the post-processability is deteriorated under these conditions.Furthermore, under these conditions, the zinc base consisting of less than 5% by weight of nickel deposited and polymerized on the upper layer.
A nickel alloy plating film (3) improves adhesion with the lower layer, and a chromic acid film (4) is then applied to the top surface.
), and at the same time prevents the sacrificial corrosion resistance from deteriorating due to the proximity of the corrosion potential with the underlying zinc-based-nickel alloy plating # (2+). Furthermore, due to the good adhesion resistance of the chromic acid coating (4), the adhesion with the resin layer (5) on the outer surface is significantly improved.

〔Example〕

Example 1 - Steel material...Pipe material, material 5TP038, outer diameter 8.01, wall thickness 0.7%, length 500% 14011/1% calm cl 2501/l, Hβ033D
i/l,...value 5.8...Plating conditions: bath temperature ω℃, cathode current density 2A/dm,
Time: 10 minutes...Plating layer: nickel 11% by weight, balance zinc, layer thickness 5
μ NaCN 1001/l, NaOH65J7/
1... Plating conditions: bath temperature 6°C, cathode current density 2A/d
mj time 8 minutes...Plating film; nickel double layer, residual zinc, film thickness 4μ, chromic acid coating...Liquid composition; Crys 151 /
l, Ha 80a 4ml/1...coating conditions;
Liquid temperature: 5°C, time: Resin layer: Vinylidene fluoride resin, baking temperature: 250°C, layer thickness: μ Example 2: Steel material: Same as Example IK, but surface I/
It has a copper plating film made of c3μ.

1001! /l, NH4 (J 25011/l, H3
B0゜20g/11-value 6.5 ... Plating conditions: Same as Example 1 ... Plating layer: nickel 14% by weight, balance zinc, layer thickness 5
μ ・Zinc alone (upper layer)...Bath composition; Zn30.9 /
l, NaCN 10011/l, NaOH70#
/1...Plating conditions; Same as Example 1...Plating film; Film thickness 4μ Chromic acid coating...Both liquid composition and coating conditions are the same as Example 1.Resin layer...Example Comparative Example Same as Example 1 After forming an electroplating layer with a layer thickness of 9μ on the same steel pipe material as Example 1, further coating with the same chromic acid coating as Example 1 and a resin layer with a layer thickness of 5 μm. I got it.

The above-mentioned products of the present invention (Examples 1 and 2) and conventional products (comparative example)
Comparative property results related to the corrosion resistance test (JI8Z-2371) are shown in Table 1 below.

〔Effect of the invention〕

As explained above, the corrosion-resistant polymer-coated steel material according to the present invention can be produced using a homogeneous zinc-nickel alloy with different nickel contents, or a zinc-based alloy with a specified nickel content range as the lower layer. - Due to the polymerized structure of the upper layer of zinc applied to the nickel alloy, it is possible to exhibit excellent protection due to slow sacrificial corrosion resistance, and at the same time, the alloy has sufficient corrosion resistance and mutual adhesion. In addition, the adhesion with the resin layer can be significantly improved by perfecting the adhesion resistance of the chromic acid coating, and the protection provided by the resin layer formed on the outer surface provides excellent corrosion resistance. This is an extremely useful corrosion-resistant polymer coated steel material.

[Brief explanation of the drawing]

FIG. 1 is an enlarged cross-sectional view with a partial cutout of a main part formed on a pipe material as a corrosion-resistant polymer coated steel material according to an embodiment of the present invention;
FIG. 2 is an enlarged cross-sectional view of the main part formed in the plate material with a portion cut away. (1)...Steel material, (one...surface, (2)...
Plating layer, (2... surface, (3)... plating film, (3
U...Surface, (4)...Chromium coating, (5)...
-Resin layer, (6)...copper plating film. Patent applicant: Shirai Kokusai Sangyo Co., Ltd. Agent: 1) Yoshihisa 1-21;
r=] - Doto Figure 1 Figure 2

Claims (1)

[Claims] On the surface (1') of a steel material (1) with or without a copper plating film (6), a plating layer (2) of a zinc-based nickel alloy consisting of 10% to 15% by weight of nickel is formed as a lower layer. Further, on the surface (2') of the plating layer, a plating film (3) of a zinc-based nickel alloy or zinc alone containing 5% by weight or less of nickel is deposited and polymerized as an upper layer. A corrosion-resistant polymer coated steel material characterized in that 3') is coated with a resin layer (5) on the outer surface with a chromic acid coating (4) interposed therebetween.