JPS60262992A - Heat and corrosion resistant multiply coated steel material and formation of multilayered coat - Google Patents

Abstract

PURPOSE:To form a multilayered coat having superior heat and corrosion resistances by forming a Zn-Ni alloy layer on the surface of a steel member used in a heated atmosphere by plating and a black Ni layer on the Zn-Ni alloy layer by plating. CONSTITUTION:The surface 1' of a steel member 1 used in a heated atmosphere at <=250 deg.C is degreased and derusted. The surface 1' is electroplated with a Zn-Ni alloy contg. 1.5-7wt% Ni to form a Zn-Ni alloy layer 2, and an Ni-Zn layer 3 contg. 30-50wt% Zn and having black appearance is formed on the surface 2' of the layer 2 by electroplating. Since the two layers are similar in composition to each other, they have superior adhesion, and a steel member having a formed multilayered coated showing superior heat and corrosion resistances in a heated atmosphere at about 250 deg.C is obtd.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention is used as various parts or members around an internal combustion engine, for example, in a heated atmosphere of about 250°C or less. The present invention relates to a polymer coated steel material that is applied to the surface of a steel material such as a plate, a tube, a rod, a wire rod, etc., and which requires both heat resistance and corrosion resistance, and a method for forming the polymer coat.

[Problems with conventional technology]

Conventionally, steel materials with a heat-resistant and corrosion-resistant coating structure for various parts used around engines or these members are simply coated with a zinc plating layer on the surface of the steel material, which is generally formed by electroplating or dipping. In practical use, either a chromate coating is provided, or a black chromate coating is formed on the zinc plating layer on the surface of the steel material in connection with the requirement for quality value in terms of appearance.

However, in these conventional products, both the acid chromate coating and the black chromate coating generally discolor in a short period of time due to the continuous or intermittent heat effects from the engine during long-term running. However, there are still problems in which heat resistance is not fully satisfied, and corrosion resistance is also impaired due to deterioration of heat resistance. The current situation requires improvement.

[Purpose of the invention]

The present invention solves the above-mentioned conventional problems by significantly improving the adhesion of a zinc-nickel alloy plating layer and a black nickel electroplating layer on their mutually adhering surfaces, and We have developed a heat-resistant and corrosion-resistant material that can effectively solve the problem of corrosion resistance and these simple polymeric coating formation methods, and that can satisfy both heat resistance and corrosion resistance even when used in a heated atmosphere below the above-mentioned temperature. The purpose of this paper is to propose a corrosion-resistant polymer coated steel material and a method for forming the polymer coat.

[Structure of the invention]

The gist of the present invention is a heat-resistant and corrosion-resistant polymer-coated steel material made by coating a steel material with a zinc-nickel alloy plating layer as a lower layer, and then depositing and polymerizing a black nickel electroplating layer on the surface of the plating layer. Further, as a method for forming a polymer coating on the polymer coated steel material, a plating layer of a zinc-nickel alloy is formed by an electroplating method on the surface of the steel material which has been previously subjected to pretreatment such as degreasing and derusting. Furthermore, the gist of the present invention is a method for forming a polymerization coating in which a black nickel electroplating layer is formed on the surface of a zinc-nickel alloy plating layer by an electroplating method.The present invention will be explained as follows based on the drawings. It is.

Figures 1 and 2 show the main parts of heat-resistant and corrosion-resistant polymer-coated steel materials formed by the polymer coating forming method of the present invention on plate material (Figure 1) and pipe material (Figure 2), respectively. It is an enlarged cross-sectional view with a partial notch, and (1) is a steel material whose surface has been pretreated such as degreasing and derusting (one part has a plating layer (2) made of a zinc-nickel alloy formed by electroplating). , (3) is an electroplated layer of black nickel that is deposited and polymerized on the surface of the plating layer (2) made of zinc-nickel alloy (29 by electroplating method).The zinc-nickel plating layer is made of zinc chloride. , is applied with an electroplated layer containing nickel chloride and ammonium chloride at a pH of 5B to 6J3 as main components, and is formed with nickel contained in the range of 7% to 1.5% by weight, Naturally, the presence of these elements in nickel provides effective heat resistance and corrosion resistance.

On the other hand, when depositing and polymerizing the black nickel electroplating layer (3), it is possible to use an electroplating layer of p'15.6 to 5.9 consisting of nickel sulfate, zinc sulfate, nickel ammonium sulfate, and potassium thiocyanide. , and is formed with a black appearance consisting of a nickel-zinc alloy layer containing zinc in the range of 30% to 50% by weight, and is a similar metal similar to the zinc-nickel plating layer of the above-mentioned layer. Deposition polymerization with the composition 1. Therefore, the adhesion between the mutually adhered and polymerized surfaces is significantly improved.

At the same time, these processing operations can be made extremely simple without being restricted by the above-mentioned 1) rounding using an electroplated layer in the range of H5.6 to 5.9 and pretreatment in between, which are used during deposition polymerization. It is possible.

[Action of the invention]

Since the gist of the present invention is the above-mentioned polymerized coating structure and method for forming the same, the present invention provides a plating layer (2) made of a zinc-nickel alloy.
) and the black nickel electroplating layer (3) on the polymerized surface, the upper black nickel electroplating layer (3)
), the heat resistance under a heated atmosphere of 250℃ or less is improved, and the lower plating layer (2
) results in both heat resistance and corrosion resistance.
Since the process is carried out within the range of H value (pretreatment in the intermediate range is simple, productivity can be improved and formation can be made at low cost).

[Embodiments of the invention]

Example 1 - Steel material...Material: 8TPG3 & Outer diameter: 10. 〇-Thickness 0
．． 7%.

A pipe material having a length of 500x is pretreated by degreasing and denitration using conventional methods.

・Zinc-nickel alloy plating treatment Zinc chloride 452/mu Nickel chloride 75f/mu Ammonium chloride 250P/mu Boric acid 209/l P
A plating bath of H5.8 was used, the tube material was used as a cathode, and the nickel plate was used as an anode at a bath temperature of ℃ and a cathode current density of 2A.
/d- for 10 minutes, followed by washing with water to obtain a zinc-nickel alloy plating layer having a layer thickness of 5 μm.

・Intermediate pretreatment: After immersing in a 10% sulfuric acid aqueous solution for 5 seconds, washing with water is performed.

・Black nickel electroplated nickel sulfate 75f/4 zinc sulfate 38 F/4 nickel ammonium sulfate 452/potassium muthiocyanide 15
Using an electroplated layer with a pH of 5.6 and a composition of f/l,
The tube material having the zinc-nickel alloy plating layer was used as a cathode, and the nickel plate was used as an anode, and after applying current for 5 minutes at a bath temperature of 50°C and a cathode current density of I A/d-, the plating layer was washed with water. An electroplated layer of black nickel having a thickness of 4 μm was deposited and polymerized on the layer.

Example 2 ・Steel material: Same as Example 1.

・Zinc-nickel alloy plating treatment Zinc chloride 60f/mu Nickel chloride 902/mu ammonium chloride 200f/muammonia water 50m Using the plate as an anode, the plate was energized for 8 minutes at a bath temperature of 35° C. and a cathode current density of 25 A/d−, and then washed with water to obtain a zinc-nickel alloy plating layer having a layer thickness of 5 μm.

- Intermediate pretreatment - Same as Example 1.

・Black nickel electroplated nickel sulfate 60v/zinc sulfate 45f/nickel ammonium sulfate 502/potassium muthiocyanide 18t
An electrolytic plated layer with a pH of 5.9 and a composition of 1/1 was used, the tube material having the zinc-nickel alloy plated layer was used as a cathode, and the nickel plate was used as an anode at a bath temperature of 45°C and a cathode current density of KO, After applying electricity for 7 minutes at 71 Jdw/, washing with water was performed, and as a result, a black nickel electrolytic plating layer having a layer thickness of 4 μm was deposited and polymerized on the plating layer.

Comparative Example For the same steel material as in Example 1, a plating bath consisting of zinc oxide (9) f/mu, soda cyanide 50 f/mu, caustic soda 609/l was used, and the tube material was used as the cathode, while the zinc plate was used as the anode. 15 at cathode current density 3A/dry/at room temperature
After applying electricity for a minute, it was washed with water to obtain a zinc plating layer having a layer thickness of 9 μm, and then immersed in a black chromate bath for 20 seconds at room temperature, washed with water, and dried to obtain a black chromate coating.

The above-mentioned products of the present invention (Examples 1 and 2) and conventional products (comparative example)
The comparative characteristics results regarding heat resistance and corrosion resistance tests are as follows:
1 and Table 2.

・Heat resistance test results After continuous constant heating at 200℃ for 24 hours in a heated atmosphere, cooling in the atmosphere, the atmospheric temperature was already 1, and then the temperature was 2.
The specimens were heated continuously for 24 hours in an atmosphere at a temperature of 50° C., and the external appearance of each specimen was visually observed.

- Corrosion Resistance Test Results A sample after 24 hours of 200'CA and a sample after 24 hours of 250α of the heat resistance test were each tested according to the salt spray test method specified in JIS Z-2371.

Table 2 In the table, W is white rust spots, R is red rust spots, WW is flowing white rust,
RR indicates flowing red rust, and the numbers attached to the above-mentioned occurrences indicate the average number of occurrences up to the time of completion and the surface area of the occurrence area. BaW.

Only R was recorded regardless of whether WW occurred, and if RR occurred, only RR was recorded regardless of whether R occurred.

〔Effect of the invention〕

As described above, the heat-resistant and corrosion-resistant polymer coated steel material and the method for forming the polymer coat according to the present invention include the mutual zinc-nickel alloy plating layer (2) and the black nickel electroplating layer (3), each of which is heated by the heating process. It is possible to simultaneously satisfy heat resistance and corrosion resistance under atmospheric conditions, and the adhesion of these mutually adhered polymerized surfaces is significantly improved.
Furthermore, when depositing and polymerizing the black nickel electroplating layer (3), it is possible to improve productivity and make it relatively inexpensive by simplifying the intermediate pretreatment related to the range of pI (value of use) of the electroplating layer. This is an extremely useful heat-resistant and corrosion-resistant polymer coated steel material and a method for forming the polymer coat, which have many features such as:

[Brief explanation of the drawing]

Figure 1s1 is an enlarged sectional view with a partial cutout of part 11 in which a heat-resistant and corrosion-resistant polymeric coating according to an embodiment of the present invention is applied to a plate material, and Figure IIXz is an enlarged sectional view with a partial cutout of the main part similarly applied to a pipe material. It is. (1)...Steel material, (one...surface, (2)...
Plating layer of zinc-nickel alloy, (2') ... surface, (
3)...Black nickel electroplated layer. Sugar 1 JtS21NQ Voluntary Procedure Amendment July 1980] 7th Patent Office Commissioner Manabu Shiga 1981 Patent Application No. 117284 2 Title of Invention Heat and Corrosion Resistant Polymer Coating Material and Polymer Coating Forming Method 4 Agent [Example of the invention] Example 1 - Steel material...Material S'l'PG3 & outer diameter 10Ω nominal wall thickness 0.7 - length 500% pipe material was degreased and derusted using the usual method. Perform processing.・Zinc-nickel alloy plating treatment A plating bath with a pH of 5.8 consisting of a composition of zinc chloride 45f/mu nickel chloride 75f/mu ammonium chloride 250 S'/4 ml 12 ot/l was used, and the tube material was used as the cathode, while After applying electricity for 10 minutes at a cathode current density of 2 A/dn/ at the bath temperature side of °C using a nickel plate as an anode, washing with water was carried out.
A zinc-nickel alloy plating layer having a layer thickness of 5 μm was obtained.・Intermediate pretreatment: After immersing in a 10% sulfuric acid aqueous solution for 5 seconds, washing with water is performed.・Black nickel electroplated nickel sulfate 75F/4 zinc sulfate 38F/nickel ammonium sulfate 452/potassium muthiocyanide 15
An electroplated layer having a pH of 5.6 and a composition of f/l was used, the tube material having the zinc-nickel alloy plating layer was used as a cathode, and the nickel plate was used as an anode at a bath temperature of 50°C and a cathode current density of I A/L. After applying electricity for 5 minutes at d- and washing with water, a black nickel electrolytic plating layer having a layer thickness of 4 μm was deposited and polymerized on the plating layer. Example 2 Steel material: Same as Example 1.・Zinc-nickel alloy plating treatment Zinc chloride 60? /muammonium chloride 90t/muammonium chloride 200f/muammonya water 50TRVII:)
p consisting of group 151) Using a plating bath of 16.5,
The tube material was used as a cathode, and the nickel plate was used as an anode to conduct electricity for 8 minutes at a bath temperature of 35° C. and a cathode current density of 25 A/d−, followed by washing with water to obtain a zinc-nickel alloy plating layer having a layer thickness of 5 μm. . - Intermediate pretreatment - Same as Example 1.・Black nickel electroplated nickel sulfate 60v/zinc sulfate 45f/nickel ammonium sulfate 50? /potassium muthiocyanide 18
Using an electroplated layer with a pH of 5.9 and a composition of r/L,
The tubular material having the zinc-nickel alloy plating layer was used as a cathode, and the nickel plate was used as an anode, and the bath temperature was 45° C., the cathode current density If G, and 7 A/dw/ were energized for 7 minutes, and then washed with water. As a result, An electrolytic plated layer of black nickel having a thickness of 4 μm was deposited and polymerized on the plated layer. Comparative Example For the same steel material as in Example 1, a plating bath having a composition of zinc oxide f/mu, cyanide soda 502/mu caustic soda 60 t/l was used, and the tube material was used as the cathode, while the zinc plate was used as the anode. After applying electricity for 15 minutes at room temperature at a cathode current density of 3A/d-, washing with water to obtain a zinc plating layer with a layer thickness of 9μ, immersion in a black chromate bath for 20 seconds at room temperature, and then washing with water. After drying, a black chromate film was obtained. The above-mentioned products of the present invention (Examples 1 and 2) and conventional products (comparative example)
The comparative characteristics results regarding heat resistance and corrosion resistance tests are shown in the table below.
1 and Table 2.・Heat resistance test results After continuous constant heating in a heated atmosphere of 200℃ for 24 hours, cooling in the atmosphere and cooling down at atmospheric temperature 1, then heating again at 2
The specimens were heated continuously for 24 hours in an atmosphere at a temperature of 50 C, and the external appearance of each specimen was visually observed. - Corrosion Resistance Test Results The heat resistance test samples after 24 hours at 200'C and samples after 24 hours at 250'C were tested according to the salt spray test method according to JIS Z-2371.

Claims (1)

[Claims] 1) The surface of a steel material (1) with a plating layer (2) made of a zinc-nickel alloy as the lower layer, and the surface of the plating layer (
A heat-resistant and corrosion-resistant polymer coated steel material, characterized in that it is formed by depositing and polymerizing a black nickel electroplating layer (3) on 2). 2) A plating layer (2) of a zinc-nickel alloy is formed by electroplating on the surface (1) of a steel material (1) that has been pretreated with degreasing, denitrification, etc. A method for forming a heat-resistant and corrosion-resistant polymeric coating, which comprises forming an electroplated layer (3) of black nickel on the surface (2') of the electroplated layer (2) by adhesion and polymerization.