KR20180057583A

KR20180057583A - High Corrosion Resistant High Speed Acidic Zinc-Nickel Alloy Plating Composition and Process Technology

Info

Publication number: KR20180057583A
Application number: KR1020180052993A
Authority: KR
Inventors: 박해덕; 정재홍; 박성헌
Original assignee: (주) 지오화인켐
Priority date: 2018-05-09
Filing date: 2018-05-09
Publication date: 2018-05-30

Abstract

According to the present specification, disclosed is a method for plating a metal surface with acid zinc-nickel in multiple stages. According to the method of one aspect of the present invention, a zinc-nickel plated layer is formed on a zinc plated layer of a plated object so that corrosion resistance can be increased more than two times as in comparison to when only zinc plated layer is formed. The method is useful since the same can be widely used in plating steel components exposed to corrosion environments such as vehicle calipers. In terms of construction, the method can manufacture a plating body with improved corrosion resistance and high-speed plating by simply remodeling the construction for conventionally used zinc plating. Therefore, cost efficiency of the method can be secured.

Description

Technical Field [0001] The present invention relates to a high corrosion resistant high-speed acidic zinc-nickel alloy plating composition and a high-

This disclosure discloses its composition and process technology for high corrosion resistance and high-acidity zinc-nickel alloy plating.

The metal has a unique electrode potential. When a dissimilar metal is electrically connected and left under a corrosive environment, a metal having a low electrode potential (a metal having a high ionization tendency) acts as an anode and a metal having a high electrode potential (a metal having a low ionization tendency) acts as a cathode to generate an electromotive force . At this time, the metal corresponding to the anode is ionized into cations, and the metal corresponding to the cathode is not ionized or corroded by receiving electrons from the anode. The corrosion prevention method using this phenomenon is called sacrificial anode method.

A method of galvanizing a steel material using the above principle is well known in the industry. Since the electrode potential of zinc is lower than that of iron, when zinc is plated with iron, zinc acts as a sacrificial anode, so that corrosion firstly prevents corrosion of the steel material for a long time.

KR 10-2014-0063868 A

In one aspect, an object of the present invention is to provide a method for improving the corrosion resistance of a metal.

In one aspect, the present invention provides a method of plating a metal surface comprising forming a zinc nickel plating layer using an acidic zinc nickel plating solution, wherein the zinc nickel plating layer comprises 12 to 25 wt% nickel .

In one aspect, the plating method of the present invention can form a zinc nickel plating layer on a plated body to exhibit corrosion resistance that is more than two times improved as compared with the case where only a zinc plating layer is formed. The method is exposed to a corrosive environment such as an automobile caliper It is economical because it is possible to manufacture a plated body having improved corrosion resistance through simple remodeling of a facility for galvanizing used in the past in terms of facilities.

1 is a sectional view of a plated body to be plated.
Fig. 2 is a view showing the outer shape of the plated caliper and the area where the thickness is measured in the plated layer. Fig.
3 is a view showing the result of measuring the thickness of the plating layer.
4 is a view for confirming the occurrence of rust of the plated caliper with time.

The inventors of the present invention have completed the present invention by focusing on the fact that the acidic zinc-nickel plating is applied to the steel to protect the zinc-nickel alloy layer and the plated body of the steel material, and the corrosion resistance of the zinc nickel plating as the surface layer is dramatically increased .

Hereinafter, the present invention will be described in detail.

The present invention, in one aspect, comprises a zinc nickel plating layer formed using an acidic zinc nickel plating solution, wherein the zinc nickel plating layer comprises 12 to 25 wt% nickel and 75 to 88 wt% By weight of zinc.

In this specification, plating may mean, for example, the application of a thin layer of another material to the surface of a metal or base metal. In the present specification, the material to be plated may mean an object to be plated.

In the above aspect, the acidic zinc-nickel plated layer may include 12 to 25% by weight of nickel and 75 to 88% by weight of zinc based on the total weight of the zinc-nickel plated layer. In one embodiment, the acidic zinc-nickel plated layer may include, but is not limited to, 12-18 wt% nickel. At least 10, at least 11, at least 12, at least 13, at least 14, at least 15, at least 16, at least 17, at least 18, at least 19, Or less, 22 wt% or less, 21 wt% or less, 20 wt% or less, 19 wt% or less, 18 wt% or less, Up to 17 wt%, up to 16 wt%, up to 15 wt%, up to 14 wt%, up to 13 wt%, up to 12 wt% up to 11 wt% up to 10 wt% up to 9 wt% When 12 to 18% by weight is contained in the zinc nickel plating layer, the corrosion resistance of the multilayer plated coated body is the most excellent.

In the above aspect, the zinc plating solution may be an acidic zinc plating solution. The zinc plating solution may be classified into an acidic zinc plating solution and an alkaline zinc plating solution. The acidic zinc plating solution may be a plating solution containing zinc and an acidic substance and may be, for example, a plating solution containing zinc metal, potassium chloride, zinc chloride and boric acid.

In the method of plating a metal surface, which is an aspect of the present invention, the zinc nickel plating solution may be an acidic zinc nickel plating solution. The zinc nickel plating solution may mean a zinc plating solution containing nickel. In view of the above, the acid zinc nickel plating solution may mean an acidic zinc plating solution containing nickel.

In this respect, the acidic zinc nickel plating solution may have a pH of 4.5 to 6.0. For example, the pH of the zinc nickel plating solution may be at least 4.0, at least 4.1, at least 4.3, at least 4.4, at least 4.5, at least 4.6, at least 5.0, at least 5.3, at least 5.5, at least 5.7, at least 5.9 or at least 6.0, But is not limited to, 5.9 or less, 5.7 or less, 5.5 or less, 5.3 or less, 5.1 or less, 4.9 or less, 4.7 or less, 4.5 or less, 4.3 or less or 4.1 or less or 4.0 or less.

In the above aspect, the zinc nickel plating solution may contain zinc and nickel in a weight ratio of 5 to 15: 1 to 6. The weight ratio of zinc and nickel contained in the zinc nickel plating solution is not limited and may be 1 to 18: 1, 1 to 16: 1, 1 to 14: 1, 1 to 12: 1, 1 to 10: 1, 1 to 6: 1, 1 to 4: 1, 1 to 2: 1 or 1: 1 to 2.

In the above aspect, the zinc nickel plating solution may further include chlorine, and may contain zinc, nickel and chlorine in a weight ratio of 5: 15: 1 to 6: 45: 70, but is not limited thereto.

In this respect, the plating step can be carried out under the following conditions. Plating time, the current density of the blood plating current density, based on the surface area of the sieve 0.5 ~ 2.0 A / dm ^2, voltage of 1 to 17 volts, 15 ~ 40 ℃ plating liquid temperature and 1 to 30 minutes is 0.5 ~ 20 A / dm ² day, ^{but, 0.5 ~ 18 A / dm 2} , 1 ~ 1.8 A / dm 2, 3 ~ 15 A / dm 2, 4 ~ 12 A / dm 2, 0.5 ~ 5 A / dm 2, 0.5 ~ 4A / dm ² , 0.5 to 3 A / dm ^2, or 0.5 to 2 A / dm ² , but is not limited thereto. The voltage may be 1 to 17 volts, 2 to 10 volts, 2 to 9 volts, 1 to 9 volts, 1 to 8 volts, 2 to 8 volts, 3 to 15 volts, 3 to 15 volts, 4 to 17 volts, 16 volts, 5 to 16 volts, or 5 to 15 volts. The voltage can be adjusted by a person skilled in the art to a suitable range by a plating method. For example, the barrel type plating is 5 to 15 volts, A voltage of 8 volts may be appropriate. The temperature of the plating solution may be 15 to 40 DEG C, 15 to 35 DEG C, 15 to 30 DEG C, 20 to 40 DEG C, 20 to 35 DEG C or 20 to 30 DEG C, The plating time may be 1 to 30 minutes, but is not limited to, for example, 1 minute, 3 minutes, 5 minutes, 10 minutes, 15 minutes, 20 minutes, 25 minutes, 30 minutes 40 minutes or less, 35 minutes or less, 30 minutes or less, 25 minutes or less, 20 minutes or less, or more than 35 minutes, 40 minutes or more, Less than 15 minutes, less than 10 minutes, less than 5 minutes, or less than 3 minutes.

In the above aspect, the method may further include: a pre-treatment step of a plated body including at least one of degreasing, pickling, water washing and neutralization; Or post-treatment of the plated body including at least one of activation, chromate treatment, top coating and drying of a zinc nickel plated body.

In the present specification, degreasing may mean the removal of fecal contaminants or SMUTs present on the surface of the body to be cleaned. The degreasing may include immersion degreasing and electrolytic degreasing. Deposition degreasing can be carried out by immersing the plated bodies in an alkaline, acidic or neutral degreasing bath. For example, the alkaline degreasing solution may be heated to 30 to 80 占 폚, and the substrate to be plated may be immersed for 5 to 30 minutes to perform degreasing. The electrolytic degreasing may be carried out by subjecting the plated member to a positive electrode method, periodic reverse).

In this specification, the term "pickling" may mean treating an acid to be plated, in order to remove foreign matter such as an oxide film or rust existing on the plated body after the degreasing step. For example, the acid used for the pickling may be a diluted solution of 10 to 50% of strong acid, and specifically, the plated body may be immersed in a diluted solution of hydrochloric acid or sulfuric acid for 5 to 20 minutes. On the other hand, the solution used for pickling may contain a corrosion inhibitor, which may include 0.1 to 1% by weight of the corrosion inhibitor.

Washing means washing the surface of the object to be plated using water, and washing with water may be carried out after degreasing, after acid pickling, after neutralization, after the activating step, or after zinc or zinc nickel plating.

In the present specification, the chromate treatment is also referred to as a chromate treatment, which may mean dipping a plated material plated with zinc or the like into a chromate solution containing chromic acid to form a croupate coating on the surface of the plated body . The chromate treatment may include a hexavalent chromate treatment using hexavalent chromium or a trivalent chromate using trivalent chromium. For example, the plating treatment may be performed by immersing the zinc plated electroplated body in the chromate solution for 30 to 60 seconds have.

In the present specification, the term top coating means to form a coating film by immersing a plated body in a coating solution to reinforce the corrosion resistance of the plated body to be plated. The coating liquid may be, but is not limited to, an epoxy series coating liquid.

In one aspect, the average thickness of the zinc nickel plating layer may be 0.5 to 2.0 占 퐉. In the present specification, the average thickness may mean an average value of the thicknesses measured at any three points, except for the thinnest portion and the thickest portion of the thickness of the plating layer. The average thickness of the zinc nickel plating layer may be at least 0.1 μm, at least 0.5 μm, at least 1 μm, at least 2 μm, at least 3 μm, at least 4 μm, at least 5 μm, at least 6 μm, at least 7 μm, 4 μm or less, 3.5 μm or less, 3 μm or less, 2.5 μm or less, 2 μm or less, 1.5 μm or less, 1.0 μm or less, or Or less.

In another aspect, the present invention comprises a zinc-nickel plated layer located on a surface of a article to be plated, wherein the zinc-nickel plated layer comprises 12 to 25 wt% nickel and 75 to 88 wt%, based on the total weight of the zinc- % &Lt; / RTI > zinc.

In the above aspect, the average thickness of the zinc nickel plating layer may be 0.5 to 20 탆, but is not limited thereto.

Further, in the above aspect, the multilayer-plated article is characterized in that, when measured according to ISO9227, which is a standard method of corrosion resistance evaluation of the International Organization for Standardization under the following conditions, when rust occurs 300 hours or more, or 800 hours or more Layered product in which red rust occurs: salt water having a concentration of 5%, a pH of 70, and a specific gravity of 1032; 15 ml / hr of salt water spray amount; And a temperature of 35 DEG C. The corrosion resistance is 45 to 55% in salt concentration, 1029 to 1036 in salt water concentration, 65 to 72 in salt water pH, 33 to 37 DEG C in salt water and 1 to 2 ml / hr in salt water according to ISO9227 In the range of < / RTI >

In one embodiment, the article may be a brake caliper, and may be a brake caliper for a motor vehicle.

In the above aspect, the article may be an article including a plating layer by any one of the multi-layer plating methods.

In one embodiment, the multi-layer plating method may be carried out in the order of pre-treatment, activation, acidic zinc-nickel plating, post-treatment, dehydration and drying in this order. The plating method will be described step by step as follows.

(1) Pre-treatment step

First, the plated body is pretreated. The pretreatment may be carried out by a method usually carried out in the art, and the pretreatment may include, for example, evacuation, washing, pickling and neutralization for removing impurities.

The pretreatment preferably includes at least one of an immersion degreasing step of immersing and degreasing the object to be plated in a degreasing liquid and an electrolytic degreasing step of electrolytically degreasing the object to be plated. Such impregnation degreasing and electrolytic degreasing can remove impurities as well as oil components. The degreasing liquid may include at least one selected from sodium hydroxide (NaOH) and a surfactant. At this time, it is preferable that the degreasing liquid contains sodium hydroxide (NaOH) at a concentration (content) of 100 g / L or more based on 1 liter (L) of the whole degreasing solution. Specifically, it is preferable to include 100 to 150 g / L of sodium hydroxide (NaOH). Thus, when sodium hydroxide (NaOH) is contained in the degreasing liquid, the oil component of the plated body can be effectively removed. The degreasing liquid preferably contains 2 to 7 ml / L of a surfactant based on 1 liter (L) of the entire degreasing liquid. In this case, the surfactant is preferably ethoxylated nonylphenol Can be used. The degreasing process, that is, the immersion degreasing process and the electrolytic degreasing process are not particularly limited. For example, the immersion degreasing step may be carried out by immersing the plating solution in the degreasing solution as described above, and then maintaining the solution at a temperature of from room temperature to 50 ° C for 5 to 20 minutes. The electrolytic degreasing step may be performed by immersing the plating solution in the degreasing solution as described above, and then applying a voltage of 2 to 10 V for 1 to 5 minutes at a temperature of from room temperature to 50 ° C. The degreasing may be performed at least once.

The pickling process is a process for removing the oxide film or rust on the surface of the object to be plated, and can be carried out by immersing the object to be plated in a diluted liquid of a strong acid. For example, a plating treatment can be performed by immersing the plated body in a 10 to 50% diluted solution of hydrochloric acid or sulfuric acid for 5 to 20 minutes. At this time, an acid inhibitor is added to the acid solution to prevent the plating agent from being damaged. To 1% by weight. After the acid pickling, the electrolytic degreasing is performed, and then the neutralization step is performed. In the neutralization step, the surface of the plated body is matched with the pH of the plating liquid similarly to the pH of the plating liquid. The surface to be plated is treated with the same acidity as the plating liquid by immersing the plated body in a dilute acid solution. For example, a plating solution is applied to a 1 to 10% It can be immersed for several minutes to neutralize. The water can be used for 3 to 60 seconds at room temperature using water before the immersion degreasing, pickling, electrolytic degreasing and neutralization. The water washing treatment can be carried out twice or more.

(2) Plating step

The surface of the pre-treated plated body is plated. The plating is carried out in the order of acidic zinc-nickel plating.

If the current density is too low, it will be difficult to obtain plating with the target thickness and it is difficult to achieve the desired thickness. In the case of the lak process, the cathode is electrolyzed at a current density of 1 to 4 A / dm ² per area of the plated body and 0.5 to 1.5 A / dm ^{2 in} the case of the barrel process. Metal impurities which are not in contact with each other may be deposited in the plating and precipitate. When the amount is too high, excessive current may be generated in the high current density portion, so it is important to maintain the appropriate current density. The plating rate is determined by various variables such as the current density, the temperature and composition of the plating solution, and the type of rectifier. When the plating is performed at the above current density, the plating rate is 0.1 to 0.4 μm / min. dm ² and a plating solution temperature of 17 to 20 ° C for 30 minutes to obtain a zinc-nickel alloy plating having a thickness of 1 to 4 μm and a zinc: nickel ratio of 83 to 87: 13 to 17.

The above washing can be carried out once or more before and after the zinc plating, the activation step and the zinc nickel plating

(3) Post-processing step

The post-treatment step may include a post-treatment activation process, a chromate process, a topcoating process, and the like

The post-treatment activation process is to smooth the chromate reaction by removing the plating additive, the oxide film, and the like that can remain on the surface after zinc nickel plating. For example, activation treatment may be performed by immersing the plated body in 0.5 to 10% hydrochloric acid diluted solution for 5 to 60 seconds. If the activation purpose is achieved, the type of acid or the dilution ratio is not limited. If the chromate process is smooth, May be omitted.

After the post-treatment activation step, a chromate process can be performed. The chromate process can be carried out by immersing the plated substance in a chromate solution containing 0.05 to 0.5% dissolved chromium. The chromate solution can be classified into zinc plating and zinc nickel plating depending on the kind of plating, coloring according to color, blacking, and white coloring. When the top layer plating is zinc nickel, a chromate treatment solution for zinc nickel plating is used. For example, the chromate layer (coating) can be formed by immersing the object to be coated for 30 to 60 seconds while maintaining the chromate solution (concentration of dissolved chromium: 0.05 to 0.1%) at a concentration of 6 to 15% at 25 to 35 ° C.

After the chromate process, a topcoat process may be performed for corrosion resistance enhancement. A coating film having a thickness of several mu m to several tens of mu m can be formed on the surface by immersing the object to be treated in a water-soluble or oil-based coating liquid of 5 to 35%. A suitably treated coating film is applied to the object to be treated with a neutral salt spray test standard of 50 to 200 Time. For example, a top coating film can be formed by immersing a plated body for 15 to 30 seconds in a 15 to 20% diluted aqueous epoxy-based coating solution.

The water may be washed two or more times before and after the activation step, the chromate step, and the top coating step.

Lastly, dehydration and drying are carried out. Since the washing liquid or the coating liquid remains on the surface of the plated material, surface water stains and formation of a coating liquid may occur. Therefore, it is preferable to spray compressed air or dehydrate using a centrifugal dehydrator Desalination is performed. On the other hand, the formed chromate and top coating film must be heated under certain conditions before curing proceeds to form a complete protective film. The drying is preferably performed at a temperature of 70 to 110 DEG C for 10 to 30 minutes. If the drying temperature is low or the drying time is short, the dehydration of the coating layer is incomplete and the hardening is less so that problems such as color discoloration and corrosion resistance may occur, If the temperature is too high, the chromate film may be destroyed. Therefore, it is important to maintain proper drying conditions to improve the corrosion resistance.

Table 1 below summarizes the order and method of the multi-layer plating.

Remarks fair
number Process Name medicine Temperature time Remarks Pretreatment One Degreasing Degreasing agent, sodium hydroxide Room temperature ~ 60 ℃ 2 to 20 minutes More than once 2 Suesse Purified water or tap water Room temperature 3 to 60 seconds More than 2 times 3 Pickle Hydrochloric acid, inhibitor Room temperature 5 to 20 minutes More than once 4 Suesse Purified water or tap water Room temperature 3 to 60 seconds More than 2 times 5 Electrolytic degreasing Degreasing agent, sodium hydroxide Room temperature ~ 50 ℃ 1 to 5 minutes Voltage 4 ~ 10V 6 Suesse Purified water or tap water Room temperature 3 to 60 seconds More than 2 times 7 Neutralization Hydrochloric acid Room temperature 3 to 15 seconds pH 0.5 to 2 8 Suesse Purified water or tap water Room temperature 3 to 60 seconds More than 2 times Plated 9 Acid zinc Nickel plating Zinc, nickel, chlorine, additives Room temperature ~ 60 ℃ 5 to 20 minutes 10 Suesse Purified water or tap water Room temperature 3 to 60 seconds More than 2 times After treatment 11 Activation nitric acid Room temperature 5 to 15 seconds 12 Suesse Purified water or tap water Room temperature 3 to 60 seconds More than 2 times 13 Chromate Chromate drug Room temperature ~ 35 ℃ 30 to 90 seconds 14 Suesse Purified water or tap water Room temperature 3 to 60 seconds More than 2 times 15 Top Coating Top Coating Room temperature ~ 50 ℃ 10 to 30 seconds Dehydration drying 16 dehydration - Room temperature - 17 dry - 80 ~ 60 ℃ 15 to 30 minutes

DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, embodiments of the present invention will be described. The following embodiments are provided to help understand the present invention, and thus the technical scope of the present invention is not limited thereto.

[Example 1] Plating of a plated body

[Example 1-1] Pretreatment of plated body

The brake caliper is immersed in a degreasing solution containing 30 mL / L of JIO PL clean (containing 10 to 20% of potassium silicate and 10 to 20% of surfactant) and 30 g / L of thiohydroxide at about 50 ° C. for about 20 minutes to perform immersion degreasing Respectively. Thereafter, the caliper subjected to the immersion degreasing was washed with water, and the acid was immersed in a diluted hydrochloric acid solution of 35% hydrochloric acid to 30% in water for 10 minutes at room temperature. Thereafter, the caliper was washed with water, and a solution of 45 volts and 20A / min was prepared in a degreasing solution aqueous solution containing 70 mL / L of JIO EC clean (containing 10 to 20% potassium silicate and 2 to 10% EDTA) at about 40 ° C and 70 g / / dm < ² > was applied to perform electrolytic degreasing. The caliper was electrolytically degreased, washed with water, and then neutralized. Neutralization was carried out at room temperature for 30 seconds using 35% hydrochloric acid diluted with 50 g / L of hydrochloric acid diluted with water, neutralized and then rinsed again.

[Example 1-2] Plating and post-treatment of plated body

The pre-treated caliper was acidic zinc-nickel plated at 30 ° C in a zinc nickel plating solution (JIO ANZI-275: Benzoate = 0.1% to 1%, Phenol = 0.5% to 5%, Alcohol = 0.05% to 0.5%, Benzylideneacetone = 0.01% To 0.1% by weight) was used, and a current of 25 V and a current of 16 A / dm ² was applied for 5 minutes. Thereafter, the acidic zinc plated caliper was washed with water and then subjected to a chromate process. A chromate solution containing 75 mL / L of JIOFINISHI-5100 (containing Cr: 2 to 4%, Co: 0.5 to 2%) was used for the chromate process, and the process was performed at 30 캜 for 45 seconds and then washed with water. , And JIO FINISHI-105 (containing SiO2: 4.5 to 5.5%) at 200 g / L for 30 seconds at 25 DEG C, washed again with water and then dried at about 95 DEG C for 20 minutes. Finally, zinc- Nickel multi-layer plated calipers were prepared.

[Example 2] Measurement of the thickness of the plating layer and the content of zinc and nickel in the plating layer

[Example 2-1] XRF

The thickness of the plated layer formed on the caliper was measured by X-ray Flourescence Spectrometry (XRF) using SFT9200 of Seiko Instrument Inc. The thickness was measured at three locations of the caliper, and the average was obtained. The thickness of the zinc nickel plating layer was about 8.0 mu m (Fig. 2).

[Example 2-2] Plating layer analysis using FIB (focused ion beam) -EDS (energy dispersive x-ray spectroscopy) SEM (Scanning Electron Microscopy)

A hole was drilled in the plated caliper using a dual beam focussed ion beam (AURIGA, Carl Zeiss), and the thickness was observed with an electron microscope. As a result, it was found that the thickness of the acidic zinc-nickel plated layer was 5 to 8 탆 (Fig. 3A). It was also confirmed that about 22% of nickel was contained in the plating layer and about 78% of zinc was contained (FIG. 3B).

[Example 4] Measurement of corrosion resistance of a multi-layer plated caliper

The corrosion resistance of the multilayer plated caliper was measured through the neutral salt spray test. The measurement method was ISO9227, a corrosion resistance measurement method recognized by the International Organization for Standardization.

As a result, white rust occurred after 312 hours and red rust occurred after 864 hours (FIG. 4). This is a much better corrosion resistance than the automobile industry standard, which requires 12 hours of occurrence of white rust and 240 hours of red rust occurrence.

[Comparative Example 1] Corrosion resistance measurement of a galvanized caliper

Corrosion resistance was measured in the same manner as in Example 4 with respect to the zinc-plated caliper subjected to the same treatment as the acidic zinc-nickel plated caliper of the present invention except that only the zinc plated layer was formed. As a result, the caliper having a zinc plated layer thickness of 8 mu m showed a white rust production time of 72 hours and a white rust production time of 240 hours.

The results of Example 4 and Comparative Example 1 show that the acidic zinc-zinc nickel plated caliper of the present invention exhibits improved corrosion resistance compared to the zinc plated caliper.

[Example 5] Measurement of adhesion of plating

The plated caliper was heated to about 220 占 폚 for 30 minutes and immersed in water at about 26 占 폚 to peel off the plating. As a result, the plating layer was not peeled off. And the acidic zinc-nickel plating layer.

10: Plated body
20: zinc nickel plating layer
30: Chromate layer

Claims

Wherein the acidic zinc-nickel plated layer comprises 12 to 25 wt% nickel and 75 to 88 wt% zinc based on the total weight of the zinc-nickel plated layer, &Lt; / RTI >

The method according to claim 1,
A method of plating a metal surface which is an acidic zinc-nickel alloy plating solution.

3. The method of claim 2,
Wherein the acidic zinc-nickel alloy plating solution has a pH of 4.5 to 6.0.

3. The method of claim 2,
Wherein the zinc nickel plating solution contains zinc and chlorine in a weight ratio of 1: 3: 9-13.

The method according to claim 1,
Wherein the zinc nickel plating solution is an acidic zinc nickel plating solution.

3. The method of claim 2,
Wherein the acidic zinc nickel plating solution contains zinc and nickel in a weight ratio of 5 to 15: 1 to 6.

3. The method of claim 2,
Wherein the zinc nickel plating solution further contains chlorine and contains zinc, nickel and chlorine in a weight ratio of 5: 15: 1 to 6: 45: 70.

3. The method of claim 2,
Wherein the acidic zinc nickel plating solution comprises zinc at a concentration of 20 to 45 g / L based on the total volume of the zinc nickel plating solution; Nickel in a concentration of 4 to 30 g / L; And a chlorine concentration of 180 to 230 g / L.

The method according to claim 1,
Wherein the plating step is carried out under the following conditions:
i) a current density of 0.5 to 20 A / dm < ² > based on the surface area of the plated body;
ii) a voltage of 1 to 17 volts;
iii) a plating solution temperature of 15 to 40 占 폚; And a plating time of 1 to 30 minutes.

The method of claim 1, wherein
Wherein the acid is 0.5-10% (w / v) hydrochloric acid.

The method according to claim 1,
The method may further comprise: before the first plating step, a pretreatment step of the plated body including at least one of degreasing, pickling, water washing and neutralization; Or post-treatment of a plated body comprising at least one of activation, chromate treatment, top coating and drying of a zinc nickel plated body to be plated.

The method according to claim 1,
Wherein the average thickness of the acidic zinc-nickel plating layer is 5 to 8 占 퐉.

A plating layer positioned on the surface of the article to be plated;
Wherein the acidic zinc-nickel plated layer comprises 12 to 25 wt% nickel and 75 to 88 wt% zinc based on the total weight of the zinc-nickel plated layer.

14. The article of claim 13, wherein said article is a brake caliper, acidic zinc-nickel alloy plated article.