JPS6252036B2 - - Google Patents

Description

[Detailed description of the invention]

[Industrial Field of Application] The present invention relates to plates, tubes, rods, or wires that are used in a heated atmosphere of about 250°C or less, for example, as various parts around an internal combustion engine or these members. The present invention relates to a polymer coated steel material that is applied to the surface of a steel material such as steel materials that requires heat resistance and corrosion resistance at the same time, and to improvements in a method for forming the polymer coat. [Problems with the prior art] Conventionally, various parts used around engines or steel materials with heat-resistant and corrosion-resistant coating structures have generally been coated with zinc on the surface of steel materials formed by electroplating or dipping. Either a regular chromate film is simply formed on the zinc plating layer on the surface of the steel material, or a black chromate film is formed on the zinc plating layer on the surface of the steel material in relation to the requirements for quality value in appearance. and put it into practical use. However, in the case of these conventional products, both the chromate coating and the black chromate coating generally discolor in a short period of time and eventually disappear due to the heat effect caused by continuous or intermittent repetition from the engine during long-term running. It is still not possible to fully satisfy the requirements for heat resistance, such as peeling, peeling, etc. At the same time, there is a problem that corrosion resistance is also deteriorated due to deterioration of heat resistance. The current situation requires it. [Object of the Invention] The present invention solves the above-mentioned conventional problems by significantly improving the adhesion of the alternately deposited and polymerized surfaces of the zinc-nickel alloy plating layer and the black nickel electrolytic plating layer, and
Furthermore, the corrosion resistance of each of the above-mentioned plating layers and electroplating layers and the simple polymer coating formation method are effectively solved, and the heat resistance and corrosion resistance are maintained even when used in a heated atmosphere below the above-mentioned temperature. The purpose of the present invention is to propose a heat-resistant and corrosion-resistant polymer coated steel material and a method for forming the polymer coat, which can satisfy both of the above requirements. [Structure of the Invention] The present invention provides a heat-resistant and corrosion-resistant material obtained by coating a steel material with a zinc-nickel alloy plating layer as a lower layer, and then depositing and polymerizing a black nickel electrolytic plating layer on the surface of the plating layer. The gist is polymerized coated steel, and the method for forming the polymerized coating of the polymerized coated steel includes plating a zinc-nickel alloy by electroplating on the surface of steel that has been pretreated by degreasing, derusting, etc. The present invention is described below with reference to the drawings. Then, it is as follows. FIGS. 1 and 2 both show a plate material (FIG. 1) and a pipe material (FIG.
Figure 1 is an enlarged cross-sectional view with a partial cutaway of the main parts applied to each of the above, and 1 is a plated surface 1' made of zinc-nickel alloy by electroplating, which has been pretreated by degreasing, derusting, etc. The steel material on which layer 2 was formed, 3 is the surface 2' of the plating layer 2 made of zinc-nickel alloy.
This is an electroplated layer of black nickel that is deposited and polymerized using the electroplating method. The zinc-nickel plating layer is applied using an electroplating bath containing zinc chloride, nickel chloride, and ammonium chloride as main components at a pH of 5.8 to 6.8, and also contains nickel in an amount of 7% to 15% by weight. It is formed in a state in which the content of nickel is within a range of 1.5%, and naturally the heat resistance and corrosion resistance are effectively achieved by the content of these elements in nickel. On the other hand, when depositing and polymerizing the black nickel electroplating layer 3, it is possible to use an electroplating bath containing nickel sulfate, zinc sulfate, ammonium nickel sulfate, and potassium thiocyanide with a pH of 5.6 to 5.9, and containing 30% by weight of zinc. It is formed with a black appearance and is made of a nickel-zinc alloy layer containing in the range of 50% by weight, and is deposited and polymerized with a composition of the same metal similar to the lower zinc-nickel plating layer. As a result, the adhesion between the mutually adhered and polymerized surfaces is significantly improved. At the same time, the above-mentioned PH5.6 to 5.9 used during deposition polymerization.
Since an electroplating bath within this range is used, these processing operations can be extremely simplified without being restricted by intermediate pre-treatments. [Function 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 excellent coating and polymerization of the plating layer 2 made of zinc-nickel alloy and the electroplated layer 3 made of black nickel. In addition to adhesion, the upper black nickel electroplated layer 3 provides heat resistance in a heated atmosphere of 250℃ or less, and the lower layer 2 made of zinc-nickel alloy provides heat resistance. At the same time, corrosion resistance is exhibited, and on the other hand, in order to treat within the PH value range of the electroplating bath during deposition polymerization, the intermediate pretreatment is simplified,
Therefore, productivity can be improved and formation can be made at low cost. [Embodiments of the invention] Example 1 ● Steel material...Material STPG38, outer diameter 10.0 m/m, wall thickness 0.7 m/m, length 500 m/m pipe material was degreased and pretreated to remove rust by conventional methods. conduct. ●Zinc-nickel alloy plating treatment Using a plating bath with a pH of 5.8 consisting of 45 g of zinc chloride, 75 g of nickel chloride, 250 g of ammonium chloride, and 20 g of boric acid, the tube material is used as the cathode, while the nickel plate is used as the anode. After applying current for 10 minutes at a bath temperature of 38° C. and a cathode current density of 2 A/dm ² , washing was performed with water to obtain a zinc-nickel alloy plating layer having a layer thickness of 5 μm. ●Intermediate pretreatment...Immerse in 10% sulfuric acid aqueous solution for 5 seconds, then rinse with water. ●Black nickel electroplating treatment A PH5.6 electroplating bath consisting of nickel sulfate 75g/, zinc sulfate 38g/, nickel ammonium sulfate 45g/, and potassium thiocyanide 15g/ was used, and the above-mentioned zinc-nickel alloy plating layer was formed. Using the tube as a cathode and the nickel plate as an anode, electricity was applied for 5 minutes at a bath temperature of 50°C and a cathode current density of 1A/ ^dm2 , followed by washing with water. As a result, a black nickel electroplating with a layer thickness of 4μ was formed on the plating layer. The layers were obtained by deposition polymerization. Example 2 ●Steel material...Same as Example 1. ●Zinc-nickel alloy plating treatment Zinc chloride 60g/, Nickel chloride 90g/, Ammonium chloride 200g/, Ammonia water 50ml/
Using a plating bath with a pH of 6.5 having the composition, the tube material was used as a cathode, and the nickel plate was used as an anode, and current was applied at a bath temperature of 35°C and a cathode current density of 2.5 A/dm ² for 8 minutes, followed by washing with water. A zinc-nickel alloy plating layer having a layer thickness of 5 μm was obtained. ●Intermediate pretreatment...Same as Example 1. ●Black nickel electroplating treatment A PH5.9 electroplating bath consisting of nickel sulfate 60g/, zinc sulfate 45g/, nickel ammonium sulfate 50g/, and potassium thiocyanide 18g/ was used, and the above-mentioned zinc-nickel alloy plating layer was used. Using the tube as a cathode and the nickel plate as an anode, electricity was applied for 7 minutes at a bath temperature of 45°C and a cathode current density of 0.7A/ ^dm2 , followed by water washing. As a result, a black nickel layer with a thickness of 4μ was deposited on the plating layer. An electroplated layer was formed by deposition polymerization. Comparative example: 30g/zinc oxide for the same steel material as Example 1
Using a plating bath with a composition of 50 g of soda cyanide and 60 g of caustic soda, the tube was used as a cathode and the zinc plate was used as an anode, and the current was applied at room temperature for 15 minutes at a cathode current density of 3 A/dm ² , followed by washing with water. After doing this to obtain a zinc plating layer having a layer thickness of 9 μm, it was immersed in a black chromate bath for 20 seconds at room temperature, and then washed with water and dried to obtain a black chromate coating. The comparative characteristic results of the heat resistance and corrosion resistance tests between the products of the present invention (Examples 1 and 2) and the conventional product (comparative example) are shown in Tables 1 and 2 below. ●Heat resistance test results: After constant constant heating for 24 hours in a heated atmosphere of 200℃, the temperature is lowered to atmospheric temperature by being left to cool in the atmosphere.
Thereafter, the specimens were heated again for 24 hours at a constant temperature at 250° C., and the appearance of each specimen was visually observed.

[Table] ●Corrosion Resistance Test Results The above 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 JISZ-2371.

〔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 have the above-mentioned mutual zinc-nickel alloy plating layer 2 and black nickel electroplating layer 3, respectively, and the heating atmosphere condition. It is possible to simultaneously satisfy heat resistance and corrosion resistance at the bottom, and to significantly improve the adhesion between these mutual adhesion and polymerization surfaces. PH of
Extremely useful heat- and corrosion-resistant polymer-coated steel and polymer-coated steel materials with many features, including the ability to increase productivity and be relatively inexpensive due to the simplification of intermediate pretreatments related to the range of use of values. It is a method of formation.

[Brief explanation of the drawing]

Fig. 1 is an enlarged cross-sectional view with a partial notch showing a main part of a plate material coated with a heat-resistant and corrosion-resistant polymer coating according to an embodiment of the present invention, and Fig. 2 is an enlarged view with a partial cutout showing a main part similarly applied to a pipe material. FIG. 1...Steel material, 1'...Surface, 2...Zinc-nickel alloy plating layer, 2'...Surface, 3...Black nickel electrolytic plating layer.

Claims (1)

[Scope of Claims] 1 A plating layer 2 made of a zinc-nickel alloy is formed as a lower layer on the surface 1' of a steel material 1, and an electrolytic plating layer 3 of black nickel is further applied and polymerized on the surface 2' of the plating layer as an upper layer. A heat-resistant and corrosion-resistant polymer coated steel material. 2 Steel material 1 that has been pretreated such as degreasing and derusting
A plating layer 2 of zinc-nickel alloy is formed on the surface 1' of the zinc-nickel alloy by electroplating, and an electroplating layer 3 of black nickel is deposited and polymerized on the surface 2' of the zinc-nickel alloy plating layer 2 by electroplating. A method for forming a heat-resistant and corrosion-resistant polymer coating.