JP6892638B1 - Plating member and manufacturing method of plating member - Google Patents

Abstract

PROBLEM TO BE SOLVED: To improve the adhesion of zinc-nickel alloy plating to a member to be plated even when the surface of the member to be plated has minute pores or irregularities, thereby improving the corrosion resistance of the member to be plated and preventing plating defects. Provided are a plating member and a method for manufacturing the plating member, which can be reduced. SOLUTION: A galvanized member 10 having at least a surface made of zinc is formed, a galvanized layer 20 is formed on the member 10 to be plated, and a galvanized nickel alloy plated layer 30 is formed on the galvanized layer 20. The plated member to be done. [Selection diagram] Fig. 1

Description

The present invention relates to a plated member subjected to zinc-nickel alloy plating treatment and a method for manufacturing the plated member.

Conventionally, a technique of performing a zinc-nickel alloy plating treatment in order to impart high corrosion resistance to a plated member has been known (for example, Patent Document 1).

JP-A-2018-003040

However, if there are minute vacancies or irregularities on the surface of the member to be plated, the adhesion of the zinc-nickel alloy plating will decrease around the vacancies or irregularities, and with the passage of time, so-called "humps" or "humps" It was a cause of plating defects called "swelling".

The present invention provides a plating member and a method for manufacturing a plating member, which can reduce plating defects by suppressing a decrease in corrosion resistance due to minute pores and irregularities existing on the surface of the member to be plated. The purpose is to do.

The plating member according to the present invention has at least a member to be plated whose surface is made of die-cast zinc, a zinc plating layer is formed on the member to be plated, and a zinc-nickel alloy plating layer is formed on the zinc plating layer. Is formed.
In the plating member, the zinc plating layer can be configured to be a layer formed by performing a zinc plating treatment by an electroplating method.
In the plating member, the member to be plated can be configured to have holes or irregularities having a depth or height of 5 μm or more on the surface.
The method for manufacturing a plating member according to the present invention includes a zinc plating step of forming a zinc plating layer on the member to be plated by subjecting the member to be plated having at least a surface made of zinc die cast to a zinc plating treatment. It has a zinc-nickel alloy plating step of forming a zinc-nickel alloy plating layer on the zinc plating layer by subjecting a member to be plated on which a zinc plating layer is formed to a zinc-nickel alloy plating treatment.
In the method for manufacturing a plated member, the member to be plated can be configured to have holes or irregularities having a depth or height of 5 μm or more on the surface.
In the method for manufacturing a plating member, the zinc plating treatment can be performed so that the concentration of zinc in the zinc plating solution is less than 8 g / L in the galvanizing step.

According to the present invention, even if the surface of the member to be plated has minute pores or irregularities, the adhesion of the zinc-nickel alloy plating can be improved, thereby improving the corrosion resistance of the plated member and reducing plating defects. It is possible to provide a plating member and a method for manufacturing the plating member.

It is sectional drawing which shows the outline of the plating member which concerns on this embodiment. It is a flowchart which shows the manufacturing method of the plating member which concerns on this embodiment. It is a cross-sectional photograph of Comparative Example 1 in which copper plating and zinc nickel plating were laminated in order on zinc die casting. It is a cross-sectional photograph of Comparative Example 2 in which zinc nickel plating was directly laminated on zinc die casting. It is a cross-sectional photograph of an Example in which zinc plating and zinc nickel plating were laminated in order on a zinc die cast. It is a photograph which shows the result of having tested the corrosion resistance of the plating member which concerns on this embodiment by a salt spray test.

Hereinafter, the plating member according to the present invention will be described with reference to the drawings. The plating member according to the present invention is not particularly limited, and can be used, for example, as a member for electronic devices, automobiles, gas appliances, and the like.

FIG. 1 is a cross-sectional view showing an outline of the plating member 1 according to the present embodiment. As shown in FIG. 1, the plating member 1 according to the present embodiment uses the member 10 to be plated as a base material, and the zinc plating layer 20 and the zinc nickel alloy plating layer 30 are laminated in this order on the member 10 to be plated. It is composed of.

The member 10 to be plated is not particularly limited as long as it is a member whose surface is made of zinc at least, but in the present embodiment, zinc die casting cast by a die casting method is used as the member 10 to be plated. The surface of the member 10 to be plated, particularly the surface of the member 10 to be plated cast by die casting, has fine pores and irregularities (for example, pores and protrusions of about 5 to 100 μm). The plating is easily peeled off around such holes and irregularities, which causes plating defects called "humps" and "swelling". However, in the plating member 1 according to the present embodiment, even if such a member 10 to be plated can be used by the plating method described later, plating defects can be reduced, so that fine pores and irregularities are present on the surface. It is especially useful for die-casting members that are easy to use. Further, in the present embodiment, using zinc die casting as the member to be plated 10 is useful in the following points. That is, since zinc is not as hard as steel, it is easier to process and can be mass-produced than steel members. Further, zinc die casting is easier to process into a complicated shape than a steel member, requires relatively little post-treatment such as deburring and polishing, and can be manufactured at a low cost.

In the plating member 1 according to the present embodiment, as shown in FIG. 1, the zinc plating layer 20 is formed on the zinc die casting which is the member to be plated 10. The thickness of the galvanized layer 20 is not particularly limited, but is preferably 1 to 10 μm, and more preferably 3 to 6 μm. Normally, the thicker the galvanized layer 20, the higher the corrosion resistance. However, in the plating member 1 according to the present embodiment, since the surface of the member 1 to be plated and the galvanized layer 20 are mainly composed of zinc, the member to be plated The adhesion between the surface of 1 and the galvanized layer 20 is high, and the corrosion potential between the surface of the member 1 to be plated and the galvanized layer 20 is low. Therefore, sufficient corrosion resistance can be obtained even if the thickness of the galvanized layer 20 is made thinner than usual. Further, in the plating member 1 according to the present embodiment, as will be described later, the thickness of the galvanized layer 20 is increased by performing the plating process using a galvanized solution having a low zinc concentration (for example, 5 g / L). Even when the thickness is thinned, the galvanized layer 20 can be appropriately formed even in the vicinity of pores and irregularities on the surface where non-plated portions are likely to occur, and the occurrence of non-plated portions can be prevented.

Further, in the plating member 1 according to the present embodiment, in order to obtain higher corrosion resistance, as shown in FIG. 1, a zinc-nickel alloy plating layer 30 containing zinc is further formed on the zinc plating layer 20. The composition of the zinc-nickel alloy plating layer 30 may include at least Ni and Zn, but may further contain other elements such as Sn, Cr, and Co. The thickness of the zinc-nickel alloy plating layer 30 is not particularly limited, but in the present embodiment, it is preferably 5 to 20 μm, and more preferably 8 to 15 μm. The Zn / Ni ratio of the zinc-nickel alloy plating layer 30 is also not particularly limited, but can be 2 to 10 in terms of mass ratio, preferably 4 to 8, and more preferably 5 to 7. Also, the zinc-nickel alloy plating layer 30 can be a so-called "high nickel" plating layer.

Further, in the plating member 1 according to the present embodiment, as shown in FIG. 1, a trivalent chromate layer 40 is formed on the zinc-nickel alloy plating layer 30. The trivalent chromate layer 40 was formed on the zinc-based alloy plating layer 30 by immersing the member 10 to be plated in which the zinc-based alloy plating layer 30 was laminated in a mixed acid containing chromium hydroxide as a main component. It is a trivalent chromium chemical conversion film. The amount of the trivalent chromate layer 40 adhered is not particularly limited, but can be set to 5 to ^{200 mg / m 2 per side in terms of metallic chromium in order to enhance corrosion resistance.} After the trivalent chromate treatment, the plating member 1 is subjected to a drying step such as hot air drying to form a trivalent chromate layer 40.

Next, a method of manufacturing the plating member 1 according to the present embodiment will be described with reference to FIG. FIG. 2 is a flowchart showing a manufacturing method of the plating member 1 according to the present embodiment. In the method of manufacturing the plating member 1 described below, it is assumed that the member 10 to be plated which has already been manufactured by the die casting method is used as the member 10 to be plated which is the base material of the plating member 1.

In step S101, the member 10 to be plated is cleaned in order to remove impurities adhering to the surface of the member 10 to be plated. For example, as a cleaning treatment, a cleaning treatment with water can be performed. Further, as a pretreatment, an alkali treatment for degreasing the surface of the member 10 to be plated with an alkali such as caustic soda, an acid treatment for activating the surface of the member 10 to be plated with an acid such as sulfuric acid, or the like may be performed. Good.

In step S102, a zinc plating process is performed. For example, the galvanized layer 20 can be formed on the member 10 to be plated by subjecting the member 10 to be plated in step S101 to a zinc plating treatment by an electroplating method. Further, in the normal zinc plating treatment, the zinc metal concentration is set to 10 g / L, the caustic soda concentration is set to 120 / L, etc. as the zinc plating solution. Further, in order to form the zinc plating layer 20 even on minute pores and irregularities on the surface (that is, to improve uniform electrodeposition), the zinc metal concentration is less than 8 g / L, more preferably 4 g / L or more. And the zinc plating treatment is performed using a zinc plating solution having a concentration of less than 6 g / L and a concentration of conductive caustic soda of 100 g / L. As a result, the plating deposition rate in the galvanizing step can be slowed down, and the uniform electrodeposition property can be improved even when the current density varies in the member 10 to be plated. According to this method, in the present embodiment, even when the surface of the member 10 to be plated has minute pores or irregularities, the zinc plating layer 20 is appropriately formed (there is an uncoated portion of the zinc plating layer 20). Uniform electrodeposition can be improved to the extent that it does not occur. Then, after washing the member 10 to be plated on which the zinc plating layer 20 is formed with water, the process proceeds to step S103.

In step S103, a zinc-nickel alloy plating process is performed. The zinc-nickel alloy plating treatment method may be an acidic bath method or an alkaline bath method. By performing a zinc-nickel alloy plating treatment on the member 10 to be plated on which the zinc plating layer 20 formed in step S102 is formed, the zinc nickel alloy plating layer 30 can be formed on the zinc plating layer 20. Then, after washing the member 10 to be plated on which the zinc-nickel alloy plating layer 30 is formed with water, the process proceeds to step S104.

In step S104, trivalent chromate treatment is performed. For example, the member 10 to be plated on which the zinc-based alloy plating layer 30 is formed is immersed in a trivalent chromium chemical conversion treatment solution at a liquid temperature of, for example, 10 to 80 ° C. for 5 to 600 seconds to obtain a trivalent chromium chemical conversion film of 0.1. It is formed on the zinc-based alloy plating layer 30 with a thickness of about 0.3 μm. In addition, in order to increase the gloss of the trivalent chromium chemical conversion film, the member 10 to be plated may be immersed in a dilute nitric acid solution before the trivalent chromium chemical conversion treatment. Further, when the trivalent chromium chemical conversion film formed in this manner is to be finished, the trivalent chromium chemical conversion film of the member 10 to be plated having the trivalent chromium chemical conversion film is washed with water or without washing with water. Is brought into contact with the finishing agent in the form of an aqueous solution (preferably immersed in the finishing agent aqueous solution), the finishing agent is attached, and dehydration drying is performed without washing with water to form a layer of the finishing agent on the trivalent chromium chemical conversion film. .. The contact temperature (preferably immersion temperature) of the finishing treatment is usually 10 to 80 ° C., the contact time (preferably immersion time) is 3 to 30 seconds, the drying temperature is 50 ° C. to 200 ° C., and the drying time is 5 minutes to 60 ° C. Minutes. The thickness of the finishing layer can be arbitrary, but is preferably about 0.05 to 0.3 μm.

Next, an example of the plating member 1 according to the present embodiment will be described. In this embodiment, first, the cross-sectional structure of the plating member 1 according to the present embodiment was observed, and the corrosion resistance and the adhesion were tested. Further, in order to examine the uniform electrodeposition property of the plating member 1 according to the present embodiment, a Hull cell test was conducted. Each test will be described below.

(Observation of the cross section of the plating member 1)
First, as Example 1, a plating member in which a zinc plating layer was formed on a zinc die casting member and a zinc nickel alloy layer was formed on the zinc die casting member was manufactured based on the above-mentioned manufacturing method of the plating member 1. Further, as a comparative example, a plating member (Comparative Example 1) in which a copper plating layer was formed on a zinc die-cast member and a zinc-nickel alloy layer was formed on the copper plating layer, and a zinc-nickel alloy plating layer was directly formed on the zinc die-cast member. A plated member (Comparative Example 2) was manufactured.

Then, using a focused ion beam-scanning ion microscope (FIB-SIM), the cross sections of the plating members of Example 1 and Comparative Examples 1 and 2 were observed. FIG. 3 is a SIM image of a cross section of a plating member of Comparative Example 1 in which a copper plating layer is formed on a zinc die cast member and a zinc nickel alloy layer is formed on the copper plating layer. FIG. 4 is a zinc nickel directly on the zinc die cast member. 6 is a SIM image of a cross section of a plating member of Comparative Example 2 in which an alloy plating layer is formed. Further, FIG. 5 is a SIM image of a cross section of the plating member of Example 1 in which a zinc plating layer is formed and a zinc nickel alloy layer is formed on the zinc plating layer. In Example 1 and Comparative Examples 1 and 2, a protective layer made of carbon is formed on the surface of the plating member 1 in order to protect the plating member from damage caused by cutting. Further, in FIGS. 3 to 5, (A) is an image magnified 4000 times, and (B) is an image magnified 10000 times. As shown in FIG. 5, in Example 1, by forming a zinc plating layer between the zinc die cast and the zinc nickel alloy plating layer, the zinc die cast and the zinc plating layer, and the zinc plating layer and the zinc nickel alloy layer are formed. It can be seen that and are formed in close contact with each other. Similarly, in Comparative Example 1 shown in FIG. 3, by forming a copper plating layer between the zinc die casting and the zinc nickel alloy plating layer, the zinc die casting and the copper plating layer and the copper plating layer and the zinc nickel alloy layer are formed. It can be seen that and are formed in close contact with each other. On the other hand, as shown in FIG. 4, in Comparative Example 2, an intermediate layer was formed even though the zinc-nickel alloy plating layer was formed on the zinc die casting. It is considered that this intermediate layer is due to a smut or the like. When the zinc-nickel alloy plating layer is directly laminated on the zinc die casting, such an intermediate layer (smut) is considered to be a factor of lowering the adhesion of the plating.

(Corrosion resistance test)
Next, the corrosion resistance of the plating member 1 according to the present embodiment was tested by a salt spray test method (JIS Z 2371). Further, in this test, in addition to the plating members of Examples 1 and Comparative Examples 1 and 2 described above, a copper plating layer and a nickel layer were sequentially formed on the zinc die-cast member, and then trivalent chromate treatment was further performed. The test was carried out using the member (Comparative Example 3). Specifically, the plated members of Examples 1 and Comparative Examples 1 to 3 were exposed to an atmosphere in which salt water having a concentration of 50 g / L and pH 7 was continuously sprayed for 240 hours, and the occurrence of white rust was visually confirmed. FIG. 6 shows the test results of the salt spray test.

As shown in FIG. 6, in the plated member of Example 1, no white rust was observed even after 240 hours had passed. On the other hand, in Comparative Example 1, the occurrence of white rust was confirmed after 200 hours had passed. Further, in Comparative Example 2, the occurrence of white rust was confirmed after 72 hours, and in Comparative Example 3, the occurrence of white rust was confirmed from 200 hours. From this, in the plating member of Example 1 in which the galvanized layer and the zinc-nickel alloy layer were formed on the zinc die-cast member, white rust was generated even under the condition that white rust was generated in the plated members of Comparative Examples 1 to 3. It was found that the corrosion resistance was superior to that of the plated members of Comparative Examples 1 to 3.

(Adhesion test)
Further, the adhesion resistance of the plating of the plating member 1 according to the present embodiment was tested by a cross-cut method (JIS K 5600-5-6). In this test, as in the corrosion resistance test, the test was performed using the plated members of Examples 1 and Comparative Examples 1 to 3. Further, in this test, (1) the plating members of Examples 1 and Comparative Examples 1 to 3 which have not been subjected to the salt spray test after the plating treatment, and (2) the salt spray test for 240 hours after the plating treatment are performed. Cross-cutting was performed on the plated members of Examples 1 and Comparative Examples 1 to 3 after each of the above.

Table 1 below shows the test results by the cross-cut method. In Table 1 below, the case where the plating did not peel off was described as "none", and the case where the plating peeled off was described as "yes".

As shown in Table 1, in the state after the plating treatment and not performing the salt spray test, no peeling of the plating could be confirmed for all the plating members of Example 1 and Comparative Examples 1 to 3. On the other hand, among the plating members after the above-mentioned salt spray test, the plating member of Comparative Example 2 in which the zinc-nickel alloy plating layer was formed directly on the zinc die-cast member had peeling of the plating. From this, in the plating member of Example 1 in which the zinc plating layer and the zinc nickel alloy layer were sequentially formed on the zinc die casting member, at least the plating member of Comparative Example 2 in which the zinc nickel alloy plating layer was formed directly on the zinc die casting member. It was found that the adhesion of the plating was better than that of the plating.

(Uniform electrodeposition test)
Further, in order to examine the uniform electrodeposition property of the plating member 1 according to the present embodiment, a Hull cell test was conducted. In this test, the current density was 5A / dm ² , 4A / dm ² , 3A / dm ² , 2A / dm ² , 1A / dm ² , 0.5A / dm ² , 0.2A / dm ² , 0.1A / dm ^2, the nine lanes and 0.05 a / dm ^2, was carried out and the zinc plated and zinc-nickel alloy plated five minutes. The test results are shown in Table 2 below.

As shown in Table 2, the film thickness of the zinc-plated layer is less dependent on the current density than the zinc-nickel alloy layer, and the film thickness can be made relatively thick even when the current density is low. For example, in the example shown in Table 2, the ratio of the film thickness when the ^{current densities are 5 A / dm 2} and 0.05 A / dm ^{2 ((the film thickness at 0.05 A / dm 2} ) / (5 A / dm ²⁾ The film thickness)) is 0.15 / 6.57 = 0.02 in the galvanized alloy plating layer, whereas 0.68 / 0.87 = 0.78 in the galvanized layer. It becomes. Since the galvanized layer is less affected by the current density and can form a film having a constant thickness even when the current density is low (or when the current density varies widely), it can be formed on the surface of the zinc die casting. Even if there are vacancies and irregularities and the current density inside the vacancies and dents is low, plating can be applied appropriately to the inside of the vacancies and dents, effectively solving the problem of forming non-plated parts. Can be prevented.

As described above, the plating member 1 according to the present embodiment has at least a member 10 to be plated whose surface is made of zinc, a zinc plating layer 20 is formed on the member 10 to be plated, and further, zinc plating is performed. A galvanized zinc alloy plating layer 30 is formed on the layer 20. In this way, at least the surface of the member 10 to be plated is made of zinc, and the galvanized layer 20 containing the same zinc is laminated on the zinc-plated layer 20 to improve the adhesion between the member 10 to be plated and the galvanized layer 20. And the corrosion potential difference can be reduced. Similarly, by laminating the zinc-based alloy plating layer 30 containing the same zinc on the zinc-plated layer 20, the adhesion between the zinc-plated layer 20 and the zinc-nickel alloy plating layer 30 can be improved, and the adhesion can be improved. The corrosion potential difference can be reduced. In particular, as compared with the case where the zinc-nickel alloy plating layer 30 is directly laminated on the member 10 to be plated, zinc is formed by forming the zinc plating layer 20 between the member 10 to be plated and the zinc-nickel alloy plating layer 30. Zinc plating, which has higher uniform electrodeposition than nickel alloy plating, covers minute pores and irregularities formed on the surface of the member 10 to be plated, and the adhesion of the zinc nickel alloy plating layer 30 to the member 10 to be plated. As a result, plating defects called "humps" and "swelling" can be reduced, and corrosion resistance can be improved. For example, in the plating member 1 according to the present embodiment, the plating defect is reduced to about 1/5 as compared with the conventional member in which the copper cyanide strike and nickel chrome plating are applied to the member to be plated. Can be done. Further, since the plating member 1 according to the present embodiment has the zinc-nickel alloy plating layer 30, it is strong against chloride ions and can exhibit high corrosion resistance even in salt-damaged areas.

Further, the member 10 to be plated can be a metal member cast by the die casting method. Since a metal member cast by the die casting method usually has a complicated structure and shape, when the zinc-based alloy plating process is directly performed on the member 10 to be plated, the current density varies and the current density becomes high. The corrosion resistance may be lowered due to a relatively low non-plated portion that has not been plated. On the other hand, in the present embodiment, by performing zinc plating having high uniform electrodeposition property with respect to zinc-nickel alloy plating as a base, even a die-cast member having a complicated structure and shape is plated relatively uniformly. It can be treated and corrosion resistance can be enhanced. As described above, the plating method according to the present embodiment is particularly useful when the zinc die casting is used as the member 10 to be plated.

Further, conventionally, it is conceivable to use a stainless steel material as a member to be plated for rust prevention, but in the plating member 1 according to the present embodiment, the cost is reduced by using metallic zinc which is cheaper than stainless steel. However, it is possible to provide a plating member 1 having high corrosion resistance. Further, conventionally, in order to improve the adhesion of plating to the member to be plated, nickel plating or chrome plating is performed after plating using copper cyanide, but cyan has a high environmental load. There is also the problem. On the other hand, in the plating member 1 according to the present embodiment, high adhesion can be realized without using cyan, and the plating member 1 which is also excellent for the environment can be provided.

Although the preferred embodiment of the present invention has been described above, the technical scope of the present invention is not limited to the description of the above embodiment. Various changes / improvements can be made to the above-described embodiment, and those in which such changes / improvements have been made are also included in the technical scope of the present invention.

1 ... Plating member 10 ... Member to be plated 20 ... Zinc plating layer 30 ... Zinc-nickel alloy plating layer 40 ... Trivalent chromate layer

Claims (6)

It has at least a member to be plated whose surface is made of zinc die-cast.
A zinc plating layer is formed on the member to be plated, and a zinc plating layer is formed.
A plating member in which a zinc-nickel alloy plating layer is formed on the zinc plating layer. The plating member according to claim 1, wherein the zinc plating layer is a layer formed by performing a zinc plating treatment by an electroplating method. The plating member according to claim 1 or 2, wherein the member to be plated has holes or irregularities having a depth or height of 5 μm or more on the surface. A zinc plating step of forming a zinc plating layer on the member to be plated by subjecting a member to be plated having at least a surface made of zinc die casting to a zinc plating process.
A method for manufacturing a plating member, which comprises a zinc-nickel alloy plating step of forming a zinc-nickel alloy plating layer on the zinc plating layer by subjecting the member to be plated on which the zinc plating layer is formed to a zinc-nickel alloy plating treatment. .. The method for manufacturing a plated member according to claim 4, wherein the member to be plated has holes or irregularities having a depth or height of 5 μm or more on the surface. The method for producing a plating member according to claim 4 or 5, wherein in the galvanizing step, the zinc plating treatment is performed with the concentration of zinc in the zinc plating solution set to less than 8 g / L.

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