JPS6191392A - Corrosion-resistant double-coated steel material and formation of double coating - Google Patents

Abstract

PURPOSE:To improve the corrosion resistance and workability of a steel material by forming the plated layer of Zn on the surface of the steel material and the electroplated layer of Ni on the plated layer. CONSTITUTION:The surface 1' of the steel material 1 having optionally the plated film 5 of Cu is pretreated, and the plated layer 2 of Zn or a Zn alloy contg. Ni is formed on the surface 1' by electroplating. The electroplated layer 3 of Ni is then formed on the surface 2' of the plated layer 2 in an alkaline Ni electroplating bath having 7.5-10.0pH contg. org. carboxylic acid as a complexing agent. The steel material having the superior corrosion resistance even under severe changing temp. conditions is obtd.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Application Field] The present invention is applicable to various parts around the internal combustion engine of an automobile or the like, or as an Fi member, especially for heating. e
Boards and pipes used under ambient conditions.

The present invention relates to corrosion-resistant polymer coated steel materials related to the corrosion resistance of the surface of steel materials such as rods or wire rods, and to improvements in methods for forming the polymer coat.

[Conventional technology]

Conventionally, this type of coated steel material is generally a steel material α formed by the m method or the dipping method as shown in Fig. 3.
A chromic acid coating (1&) was applied to the zinc alloy 1i'HI2 on the surface (1?') of B by a conventional chromate coating treatment and used for its removal.

[Advantages that the invention seeks to solve]

However, with such a corrosion-resistant interlayer material, it is possible to sufficiently resist corrosion under conditions of severe temperature changes such as cold winters and long-term continuous running during winter.
Therefore, as a countermeasure to this problem, it is necessary to make the zinc plating 1 to 02 extremely thick, for example, about 15μ to 5μ, which naturally leads to a decrease in processability and a high price for the product. During the molding process, there was a problem that the plating layer 02 often peeled off, which generally impeded the processability.

In addition, in connection with this problem, in recent years, in order to suppress the activity of the zinc plating layer, it has been proposed to precipitate an alloy with a metal more noble than zinc in terms of potential, such as iron or nickel metal '5-zinc, thereby preventing corrosion of the plating layer. A plated layer consisting of a single layer of zinc-based alloy has been developed, and some of it has been put into practical use, but the current situation is that it is still able to sufficiently achieve the A eclipse effect, and further improvement is desired. It is in.

[Means to solve the problem]

The present invention has been made to solve the above-mentioned conventional problems, and includes a corrosion-resistant coating formed on the surface of an iron material, with a plating layer made of a lead-based or zinc-based nickel alloy as an underlying layer, and furthermore, By forming a composite N4 structure by depositing and polymerizing a nickel electroplated layer formed in an alkaline (pH 7.5 to 10.0) electrolytic bath containing carboxylic acid as an upper layer, zinc or f,% base-nickel Of alloy? It has a structure in which mutual adhesion on the surface of the gold layer is significantly improved, and a chromic acid coating is formed on the outer surface, and M can be effectively determined in relation to these polymerization coating formation methods relatively easily at time and date. The object of the present invention is to develop a corrosion-resistant polymer coated steel material and a method for forming a polymer coat that can satisfactorily cope with the above-mentioned conditions.

Hereinafter, the present invention will be explained in detail based on the drawings.
Both Figures 2 and 2 are enlarged cross-sectional views of the main parts of the kojishita in a plate material (Fig. 1) and a pipe material (Fig. 2) as corrosion-resistant polymer coated steel materials constructed by the polymer coating forming method of the present invention. (1) is a steel material made of a plate, tube, rod, wire, etc. with or without a copper plating film, and its surface (1 A plating 1 (2) made of dizinc or a zinc-based nickel alloy is formed by electroplating, and then a plating 1 (2) made of dizinc or a zinc-based nickel alloy is formed on the nuclear nickel layer (2').
), in particular an alkaline (pH 7.5 to 10.0) bath containing an organic carboxylic acid as a complexing agent. (
4) is a chromic acid J film applied to the outer surface (3) of the alternating nickel layers (3), and (5) is a copper gilt film. During the electro-1 treatment of the nickel on the upper tooth layer, Especially alkaline containing organic carboxylic acids (pH 7.5 to 10.0)
)'s electroplating bath f'r1'1! There are various reasons for using it! i! As a result, citric acid, 1 as an organic carboxylic acid
Manli acid, malic acid, lactic acid, uccinic acid, glybonic acid, or their salts are used, and these all form nickel and steel acid in alkali ff, ajt to prevent nickel precipitation. , At the same time, due to the above-mentioned range of values, a polymeric coating with extremely poor adhesion between the two layers can be formed on the plating layer (2). In a sleeping bath with a pH of less than 7.5, the J1i (2) of the lower part of the 1st Symphony will be eroded, and nickel will be deposited by substitution on the layer (sufficient adhesion between the two cannot be obtained, or -10
, 0, nickel tends to precipitate and it becomes difficult to maintain a uniform nickel concentration.
It is in the range of o to 9.5.

In addition to the above-mentioned carboxylic acid, the key layer also contains nickel sulfate as a main component, conduction aids such as sodium sulfate, ammonium sulfate, and ammonium chloride, caustic soda and ammonia as pH regulators, and boric acid as a buffer agent. A similar nickel electrode ##f3 is used, which does not cause zinc erosion during electromagnetic treatment and has excellent uniform deposition ability.
I can get 1, so I drop it.

[Action of the invention]

Since the gist of the present invention is the above-mentioned polymerized rim material and method for forming the polymerized coating, one key 1f5 of the upper layer of nickel (
3) is a more noble metal than the lower zinc or zinc-based-nickel alloy plating layer (2), so it is difficult to soak even under the harsh conditions of the 5M surrounding atmosphere, and at the same time the upper layer Corrosion generated by reaction with zinc or zinc-based-nickel alloy may also occur when moisture or corrosive media enters from the outside into these areas due to dents, damage, or pinholes in the nickel key layer (3). As a result, the subsequent corrosion progress is significantly suppressed, and as long as zinc is present in the reaction system, the surface of the steel material (1) (one corrosion As a result, corrosion resistance can be sufficiently exhibited.

Regarding the chromic acid coating (4) applied to the lock as desired,
Inert treatment with chromate solution can further improve corrosion resistance.

〔Example〕

Example 1, Steel material...Material 5TP () 38, Outer diameter 8.01,
A pipe material with a wall thickness of 0.7% and a length of 30 oz is pretreated to degrease and remove rust using conventional methods.

・Zinc plating treatment...zinc oxide 301/l, cyanide 501/l, caustic soda 601! Using a plating film with a composition of /l, the entire tube material was used as a cathode, and a -1 zinc plate was used as an anode. After applying current for 15 minutes at room temperature at a cathode current density of 3A/dm, the layer was washed with water, and the layer thickness was from 9μ. A gold layer of zinc was obtained.

, Intermediate treatment: After immersing in a 5% sulfuric acid aqueous solution for 5 seconds, washing with water is performed.

・Nickel electroplating treatment...nickel sulfate 120Fl/l
, ammonium sulfate 509/l, citric acid 75g/1.
Succinic acid 15 g/l, caustic soda 8C 1g/1%
'Kg of pH 9.0 consisting of boric acid 201/l! !
, using a bath with the tube material as a cathode and a nickel plate as an anode at room temperature with a cathode current density of 2 A / am 10
After energizing for a minute and washing with water, a nickel electrolytic plated layer having a thickness of 6.5 μm was deposited and polymerized on the zinc plated layer.

, Chromate treatment: The polymer-coated pipe material was immersed for 40 seconds in an aqueous solution of anhydrous chromium 9259/l, sulfuric acid 2rttt/l, and nitric acid 2wt1/l, washed with water, and then dried at ω°C to remove the chromic acid coating. Formed.

Example 2 Steel material: 5TR material with copper plating film (3μ)
()38, outer diameter 8.0%, wall thickness 0.7%, length 300X
The pipe material is pre-treated to degrease and remove rust using conventional methods.

・Zinc plating treatment...zinc sulfate 36011/l, aluminum chloride 12.511/l, sodium sulfate 75.9/l
A plating film having a composition of 1 is used, the tube material is used as a cathode, and a -1 zinc plate is used as an anode to maintain a cathode current density of 1 at a bath temperature of °C.
After applying current at 2 A/dm for 3 minutes, washing was performed with water to obtain a zinc gold layer having a layer thickness of 9 μm.

, Intermediate treatment... Same as Example 1 Nickel electroplating treatment... Nickel sulfate 10011/l
, ammonium chloride 40 p/l, ammonium citrate cIOE/l, rift4 acid 10 FI/l
, caustic soda 70E/1. Using a 8.5-t broken membrane having a composition of boric acid 2DFl/l, using the tube material as a cathode and a nickel plate as an anode, the cathode current density was 2A at room temperature.
/ As a result of energizing at am2 for 10 minutes and washing with water,
An electroplated layer of nickel having a thickness of 6 μm was deposited and polymerized on the zinc-rich gold layer.

・Chromate treatment: Same as Example 1 Example 3 ・Steel material: Same as Example 1 ・Zinc-based-nickel alloy plating treatment: Zinc chloride 15
g/1% nickel chloride 75 F/l - ammonium chloride 2509/1% TqI! A metal bath having a composition of 209/1 was used, the tube material was used as a cathode, and the nickel plate was used as an anode, and the bath temperature was 0°C and current was applied at a cathode current density of 2 A/d for 15 minutes, followed by washing with water to determine the layer thickness. A metal layer of zinc-based nickel alloy having a thickness of 7.5 μm was obtained.

・Intermediate treatment: Same as Example IK, Nickel To the base liquid, 1
It was immersed at M50°C for (4) seconds, washed with water, and then dried at ω°C to form a chromic acid film.

Comparative Example: After subjecting the steel material of the same sample as in Example 1 to a conventional galvanizing treatment to obtain a zinc oxide of 115μ, the same intermediate treatment as in Example IHI 1 was carried out, and then, As a post-treatment, chromate solution (Dipsol Z-4!
'! 3) was soaked for 20 minutes at room temperature, washed with hot water and dried to form a chromic acid film.

The results of comparative characteristics of the above-mentioned product of the present invention (Example 1.2.3) and the conventional product (comparative example) in a regular meeting test are shown in Table 1 below.

, Corrosion resistance test results (according to the provisions of the salt spray test method according to JISZ-2371) Table 1 [Effects of the invention] As described above, the regularly polymerized coated steel material and the method for forming the polymerized coat according to the present invention are It has an i-layer structure in which a plating layer (2) made of a zinc-based-nickel alloy and an electrolytic plating layer (3) of nickel are adhered and polymerized, and the adhesion is particularly good at the mutually adhered and polymerized surfaces. This makes it possible to sufficiently improve processability, and at the same time, zinc or zinc-based
The corrosion products generated by the reaction with the nickel alloy promote the sealing of dents, damage, pinholes, etc. in the nickel electroplated layer (3),
Furthermore, the chromic acid coating (4) applied to the outer surface (3) suppresses the occurrence of white rust, and the synergistic effect of stabilizing the formation of passive mIIIX on the surface further improves corrosion resistance. Even under the severe usage conditions of the mold enclosure, it is not soaked in, and as long as zinc is present in the reaction system, it can fully exhibit its corrosion-resistant effect as shown in the corrosion-inhibiting effect 1c. A very useful regular polymeric coated steel material and a polymerized '41 coating method are provided.

[Brief explanation of drawings]

FIG. 1 is an enlarged cross-sectional view with a partial cutout of the main part of a plate material as an example of corrosion-resistant lightning-coated steel material showing one embodiment of the present invention, and FIG. FIG. 3 is an enlarged sectional view showing a conventional embodiment. (1)...Steel material, (one...surface, (2)...
Plating layer, (2... layer on, (31... on plating layer, (3
')...outer surface, (4)...chromic acid coating. Patent Applicant: Usui Kokusai Sangyo Co., Ltd. Agent: 1) Yoshihisa 1゛-”1P Figure 1 Figure 2 Figure 5

Claims (1)

[Claims] 1) A plating layer (2) made of zinc or a zinc-based-nickel alloy is formed as a lower layer on the surface (1') of a steel material (1) with or without a copper plating film. , on the plating layer (2')
A corrosion-resistant polymer coated steel material characterized in that it is constructed by depositing and polymerizing a nickel electroplating layer (3) as an upper layer. 2) The corrosion-resistant polymer coated steel material according to claim 1, characterized in that the outer surface (3') of the nickel electroplating layer (3) is further coated with a chromic acid coating (4). Corrosion-resistant polymer coated steel. 3) Plating the surface (1') of the steel material (1) with or without a copper plating film, which has been pretreated by degreasing, degreasing, etc., with zinc or a zinc-based-nickel alloy by electroplating. on the layer (2') of the plating layer (2) thus formed.
Then, a nickel electroplating layer (3) is applied and polymerized using an alkaline (pH 7.5 to 10.0) electroplating bath containing an organic carboxylic acid, and then a chromate coating is applied to the outer surface. A method for forming a corrosion-resistant polymeric coating, comprising forming a chromic acid coating (4) on a surface (3').