KR20230126454A - High corrosion resistance surface treatment coating method of bracket for electric vehicle thermal management system device - Google Patents

Abstract

The present invention relates to a high-corrosion-resistance surface treatment coating method of a bracket for a thermal management system device of an electric vehicle, and more specifically, to a high-corrosion-resistance surface treatment coating method comprising: a degreasing and acid treatment step of removing impurities from an object to be plated; a plating step of forming a plating layer using a zinc-nickel alloy plating solution; a chromate treatment step of forming a chromate layer on the surface of the plating layer to protect the plating layer; a top coating step of forming a coating layer on the surface of the chromate layer to improve corrosion resistance; and a drying step of drying the plated object having the coating layer formed thereon. The present invention relates to a high-corrosion-resistance surface treatment coating method of a bracket for a thermal management system device of an electric vehicle, wherein surface treatment is performed so that a plating layer, a chromate layer and a coating layer can be sequentially formed, thereby enhancing corrosion resistance and heat resistance when the coating method is applied to a bracket for a thermal management system device of an electric vehicle.

Description

High corrosion resistance surface treatment coating method for brackets for electric vehicle thermal management system

The present invention relates to a coating method for highly corrosion-resistant surface treatment of a bracket for an electric vehicle thermal management system device, and more specifically, a degreasing and acid treatment step of removing impurities from an object to be plated, and a plating layer using a zinc-nickel alloy plating solution. A plating step to form a plating layer, a chromate treatment step to form a chromate layer on the surface of the plating layer to protect the plating layer, a top coating step to form a coating layer on the surface of the chromate layer to improve corrosion resistance, and a drying step to dry the plating body on which the coating layer is formed. It relates to a high corrosion resistance surface treatment coating method for a bracket for an electric vehicle thermal management system device, characterized in that.

Unlike vehicles with internal combustion engines, eco-friendly vehicles such as electric vehicles do not have an available heat source, so a separate heat management device that goes beyond waste heat recovery and utilization is essential. In other words, in order to maximize the efficiency and performance of each part by maintaining the temperature of the main parts necessary for driving the inside of the car at an appropriate level all year round, a device that manages the heat of the driving device and electric component battery is essential. It is mounted on a vehicle using a bracket to which the device can be connected.

Brackets for electric vehicle thermal management system devices were surface-treated by electrodeposition plating in the early stage of development, but in the case of electrodeposition plating, heat resistance is weak and corrosion easily occurs, and the risk of fire is high. problem occurred.

That is, conventional automobile parts have been progressing in the form of plating zinc (Zn) on parts to improve rust prevention performance. However, zinc (Zn) plating has a problem in that peeling of the plating layer occurs because the thickness of the plating layer must be increased to improve corrosion resistance. These problems act as a factor that reduces corrosion resistance.

Accordingly, for the purpose of solving the above problems, zinc alloy plating technology is attracting attention. Zinc alloy plating technology is a technology for each process to achieve high-speed and high-efficiency production processes while further improving the appearance, corrosion resistance, rust resistance, paintability, or impact resistance peelability required by steel sheets used for automobiles and home appliances. this is developing

Recently, automobile parts require adhesion and high corrosion resistance, so it is necessary to develop a technology that can replace the existing zinc (Zn) plating. Accordingly, zinc (Zn)-nickel (Ni) alloy plating is emerging as an alternative technology to conventional zinc (Zn) plating.

Zinc (Zn)-nickel (Ni) alloy plating is reported to have 5 to 7 times higher corrosion resistance than zinc (Zn) plating with the same plating thickness when the nickel (Ni) content is 12 to 18 wt%. Such excellent corrosion resistance is because only γ single phase is generated within the nickel (Ni) range, and various technologies are being developed to improve the corrosion resistance of a zinc (Zn)-nickel (Ni) plated body.

Republic of Korea Patent Registration No. 10-1839233 discloses a zinc-nickel alloy electroplating solution that can secure good anode reactivity and electrodeposition reactivity, resulting in excellent adhesion, glossiness, surface appearance, and improved surface quality such as surface roughness. A composition and a technique for manufacturing a zinc-nickel alloy electro-galvanized steel sheet are disclosed. In addition, Korean Patent Registration No. 10-1130821 discloses that the surface gloss can be improved by adding an appropriate additive in a certain ratio to a basic solution in which chloride ions are adjusted to potassium chloride based on zinc chloride and nickel chloride, and the current is applied to the edge of the steel sheet. Disclosed is a technology for manufacturing a plating solution capable of suppressing overplating by reducing the concentration of.

Accordingly, although many technologies are known for plating solutions and plating technologies for improving corrosion resistance, development of highly corrosion-resistant surface treatment technologies that can be applied to specific parts such as brackets for electric vehicle thermal management system devices among automobile parts is insufficient. The situation is.

Therefore, the present invention solves the above problems and can be applied to a bracket for an electric vehicle thermal management system device, and by surface treatment so that a plating layer, a chromate layer, and a coating layer are sequentially formed, corrosion resistance and corrosion resistance when applied to a bracket for an electric vehicle thermal management system device A highly corrosion-resistant surface treatment coating method for a bracket for an electric vehicle thermal management system device, which has the advantage of enhancing heat resistance, was developed.

Republic of Korea Patent Registration No. 10-1839233 (2018.03.09. Registration) Republic of Korea Patent Registration No. 10-1130821 (registered on March 20, 2012)

The present invention has been made to solve the problems described above and provide necessary technology,

The present invention includes a degreasing and acid treatment step of removing impurities from the object to be plated, a plating step of forming a plating layer using a zinc-nickel alloy plating solution, a chromate treatment step of forming a chromate layer on the surface of the plating layer to protect the plating layer, To provide a high corrosion resistance surface treatment coating method for a bracket for an electric vehicle thermal management system device, comprising a top coating step of forming a coating layer on the surface of the chromate layer to improve corrosion resistance and a drying step of drying the plating body on which the coating layer is formed. There is a purpose.

In addition, the present invention has the advantage of enhancing corrosion resistance and heat resistance when applied to a bracket for an electric vehicle thermal management system device by surface treatment of a bracket for an electric vehicle thermal management system device, but surface treatment such that a plating layer, a chromate layer, and a coating layer are sequentially formed. Another object is to provide a high corrosion resistance surface treatment coating method for a bracket for an electric vehicle thermal management system device having.

As one embodiment of the present invention for achieving the above object,

One embodiment of the present invention is a coating method for highly corrosion-resistant surface treatment of a bracket for an electric vehicle thermal management system device, wherein the surface of the object to be plated is immersed in a degreasing solution maintained at a temperature of 40 to 50 ° C for 8 to 10 minutes. A first degreasing step of removing oil from; An acid treatment step of removing metal corrosion on the surface of the object to be plated by immersing the object to be plated from which oil is removed in the first degreasing step in a hydrochloric acid solution maintained at a temperature of 25 to 30 ° C. for 8 to 10 minutes; a second degreasing step of removing oil from the surface of the to-be-plated body by immersing the to-be-plated body from which metal corrosives have been removed in the acid treatment step in a degreasing solution maintained at a temperature of 40 to 50° C. for 8 to 10 minutes; Plating to form a plating layer on the surface of the object to be plated by electrolytically plating the object to be plated from which oil is removed in the second degreasing step at a temperature of 25 to 31 ° C. at a current value of 0.5 to 1 A / dm ² using an alloy plating solution step; A chromate treatment step of forming a chromate layer on the surface of the plating layer by immersing the plating body on which the plating layer is formed in the plating step in a chromate solution having a pH of 1.5 to 2.5 and a temperature maintained at 22 to 28 ° C for 54 to 66 seconds; A top coating step of forming a coating layer on the surface of the chromate layer by immersing the plating body on which the chromate layer is formed in the chromate treatment step in a top coating solution having a pH of 10 to 14 and a temperature maintained at 22 to 28 ° C for 15 to 25 seconds; and a drying step of drying the plated body on which the coating layer is formed in the top coating step at a temperature of 40 to 50° C. for 8 to 10 minutes. provides

In the present invention, the alloy plating solution used in the plating step is 54 to 66 mL/L of diethylene triamine and 1.2 to 1.6 g/L of nickel sulfate based on the total 1 L of the alloy plating solution. , Methyl pyridine 1.8 to 2.2 mL/L, Ethylene diamine 36 to 44 mL/L, Sodium tellurite 1.8 to 2.2 mL/L, Zinc 7.2 to 8.8 g/L and 108 to 132 g/L of sodium hydroxide.

In the present invention, the chromate solution used in the chromate treatment step includes 108 to 132 mL/L of chromic nitrate, 54 to 66 mL/L of cobalt nitrate, and 54 to 66 mL/L of nitric acid based on the total 1 L of the chromate solution. acid) is characterized in that it contains 4.5 to 5.5mL / L.

In the present invention, the top coating liquid used in the top coating step is 270 to 330 mL/L of silicon dioxide, 45 to 55 mL/L of carbon black and alcohol based on the total 1L of the top coating liquid. ) characterized in that 9 to 11mL / L is included.

In the present invention, a first washing step is performed after the first degreasing step, a second washing step is performed after the acid treatment step, and a third washing step is performed after the second degreasing step. A fourth washing step is performed after the plating step, and a fifth washing step is performed after the chromate treatment step, wherein the first washing step, the second washing step, the third washing step, and the fourth washing step are performed. And in the fifth washing step, the object to be plated or the plated object is washed with water having a pH of 10 or less for 10 to 20 seconds.

According to an embodiment of the present invention, a high corrosion resistance surface treatment coating method for a bracket for an electric vehicle thermal management system device includes a first degreasing step, an acid treatment step, a second degreasing step, a plating step, a chromate treatment step, a top coating step, and a drying step. The surface treatment is performed sequentially, but a chromate layer is formed on the surface of the plating layer formed using a zinc-nickel alloy plating solution, and the surface treatment is performed so that a coating layer is formed on the surface of the chromate layer, so that it is applied to a bracket for an electric vehicle thermal management system device It has the advantage of enhancing corrosion resistance and heat resistance.

1 is a flow chart illustrating a method for coating a high corrosion resistance surface treatment of a bracket for an apparatus for a thermal management system of an electric vehicle according to an embodiment of the present invention step by step.
FIG. 2 is a photograph showing a bracket for an electric vehicle thermal management system device surface-treated using the highly corrosion-resistant surface treatment coating method of the bracket for an electric vehicle thermal management system device according to the present invention.

Hereinafter, embodiments of the present invention will be described in detail so that those skilled in the art can easily practice the present invention. Embodiments of the present invention are provided to more completely explain the present invention to those skilled in the art. Accordingly, the embodiments of the present invention can be modified in many different forms, and the scope of the present invention is not limited to the embodiments described below.

Throughout the specification of the present invention, when a part "includes" a certain component, it means that it may further include other components without excluding other components unless otherwise stated.

Throughout the specification of the present invention, when a step is said to be located “on” or “before” another step, this is not only the case where a step is in a direct time-series relationship with another step, but also the mixing step after each step As such, the order of the two steps may include the same rights as in the case of an indirect time-series relationship in which the time-series order may change.

The terms "about," "substantially," and the like used throughout the specification of the present invention are used at or close to that value when manufacturing and material tolerances inherent in the stated meaning are given, and the present invention Accurate or absolute figures are used to prevent unfair use by unscrupulous infringers of the disclosed disclosures mentioned for the sake of understanding. The term “step of (doing)” or “step of” used throughout the present specification does not mean “step for”.

Terms used in the present invention are only used to describe specific embodiments, and are not intended to limit the present invention. Singular expressions include plural expressions unless the context clearly dictates otherwise. In the present invention, terms such as “comprise” or “having” are intended to designate the presence of features, numbers, steps, operations, components, parts, or combinations thereof described in the specification, but with one or more other features. It should be understood that the presence or addition of numbers, steps, operations, components, parts, or combinations thereof is not precluded.

The present invention relates to a high corrosion resistance surface treatment coating method for a bracket for an electric vehicle thermal management system device, and more specifically, a first degreasing step (S ₁₀₀ ), an acid treatment step (S ₂₀₀ ), and a second degreasing step (S ₃₀₀ ) , a plating step (S ₄₀₀ ), a chromate treatment step (S ₅₀₀ ), a top coating step (S ₆₀₀ ) and a drying step (S ₇₀₀ ).

Hereinafter, a high corrosion resistance surface treatment coating method (hereinafter, also referred to as a 'surface treatment coating method' or a 'coating method') of a bracket for an electric vehicle thermal management system device according to an embodiment of the present invention will be described in detail. A high corrosion resistance surface treatment coating method of a bracket for an electric vehicle thermal management system device according to an embodiment of the present invention can be more clearly understood by the following description.

1 is a flowchart illustrating a method for coating a high corrosion resistance surface treatment of a bracket for an apparatus for a thermal management system of an electric vehicle according to an exemplary embodiment of the present invention, step by step.

First, a first degreasing step (S ₁₀₀ ) may be performed.

A first degreasing step (S ₁₀₀ ) of removing oil from the surface of the object to be plated by immersing the object to be plated in a degreasing solution maintained at a temperature of 40 to 50 ° C. for 8 to 10 minutes is performed.

The first degreasing step (S ₁₀₀ ) of the present invention is a process performed to remove oleaginous contaminants such as cutting oil and processing oil present on the surface of the object to be plated so that the plating layer can be properly formed during subsequent plating, and is a general plating preparation work. can be said It can be said that degreasing is an important process in the plating process, and insufficient degreasing can cause defects such as poor adhesion, poor gloss, rough plating and swelling.

In addition, in the first degreasing step ( _S100 ) of the present invention, it is preferable to perform the degreasing process while circulating the degreasing liquid in the tank in order to prevent the oil components that have fallen from the surface of the object to be plated from adhering to the object to be plated again during product dipping. .

Although not limited thereto, the degreasing solution used in the first degreasing step (S ₁₀₀ ) is preferably one containing 50 to 70 mL/L of a degreasing agent based on the total 1L of the degreasing solution, and the degreasing agent is used in the plating process. Any type of degreasing agent that does not contain phenol and does not contain prohibited harmful substances or harmful substances requiring permission can be used.

According to one embodiment of the present invention, after the first degreasing step (S ₁₀₀ ), the to-be-plated body from which the oil is removed in the first degreasing step (S ₁₀₀ ) is washed with water having a pH of 10 or less. A first washing step (S ₁₁₀ ) of washing with water for 20 seconds may be characterized in that it is further included. This is a preparation process to improve the efficiency of the subsequent process, and is intended to remove foreign substances such as degreaser and alkaline liquid from the surface of the object to be plated through a water washing process after the first degreasing process.

Therefore, in the first degreasing step (S ₁₀₀ ), the degreasing process is performed while circulating the degreasing liquid in the tank, and the object to be plated is immersed in the degreasing liquid maintained at a temperature of 40 to 50 ° C. for 8 to 10 minutes. It is preferable to degrease by removing oil from the surface of the body, and at this time, it is preferable to use a degreasing solution containing 50 to 70 mL/L of a degreasing agent based on the total 1L of the degreasing solution. In addition, after the first degreasing step (S ₁₀₀ ), a first washing step (S ₁₁₀ ) of washing the object to be plated from which oil is removed with washing water maintaining a pH of 10 or less for 10 to 20 seconds is additionally performed. it is desirable to be

Next, an acid treatment step (S ₂₀₀ ) may be performed.

An acid treatment step of removing metal corrosion on the surface of the object to be plated by immersing the object to be plated from which oil is removed in the first degreasing step (S ₁₀₀ ) in a hydrochloric acid solution maintained at a temperature of 25 to 30 ° C for 8 to 10 minutes. (S ₂₀₀ ) is performed.

The acid treatment step (S ₂₀₀ ) of the present invention is a process performed to remove metal corrosive substances, such as metal oxides, that are not removed in the first degreasing step (S ₁₀₀ ).

In the acid treatment step (S ₂₀₀ ), it is preferable to remove metal corrosion on the surface of the object to be plated for 8 to 10 minutes in a hydrochloric acid solution maintained at a temperature of 25 to 30 ° C. This is because acid treatment in a hydrochloric acid solution maintained at a temperature exceeding 10 minutes for a time exceeding 10 minutes improves acid treatment ability but may cause corrosion of the surface of the object to be plated.

Although not limited thereto, the hydrochloric acid solution used in the acid treatment step (S ₂₀₀ ) is preferably used containing 220 to 250 mL/L of hydrochloric acid (35%) based on the total 1 L of the hydrochloric acid solution. do.

According to one embodiment of the present invention, after the acid treatment step (S ₂₀₀ ), the plated body from which metal corrosives are removed in the acid treatment step (S ₂₀₀ ) is washed with water having a pH of 10 or less. A second washing step ( _S210 ) of washing with water for 20 seconds may be further included, and most preferably, a process of washing the object to be plated with water maintaining a pH of 7 or less for 10 to 20 seconds. Do it. This is a preparatory process to improve the efficiency of subsequent processes, and is intended to remove foreign substances such as hydrochloric acid solution such as acid treatment liquid and metal corrosives from the surface of the object to be plated after the acid treatment process through a water washing process.

Therefore, in the acid treatment step ( _S200 ), the object to be plated from which oil is removed is immersed in a hydrochloric acid solution maintained at a temperature of 25 to 30 ° C. for 8 to 10 minutes to remove metal corrosion on the surface of the object to be plated. Acid treatment is preferable, and at this time, it is preferable to use a hydrochloric acid solution containing 220 to 250 mL/L of hydrochloric acid (35%) based on the total 1L of the hydrochloric acid solution. In addition, after the acid treatment step (S ₂₀₀ ), a second washing step (S ₂₁₀ ) of washing the object to be plated from which metal corrosives have been removed with washing water maintaining a pH of 7 or less for 10 to 20 seconds is additionally performed. it is desirable to be

Next, a second degreasing step (S ₃₀₀ ) may be performed.

A second degreasing step of removing oil from the surface of the to-be-plated body by immersing the to-be-plated body from which metal corrosives have been removed in the acid treatment step (S ₂₀₀ ) in a degreasing solution maintained at a temperature of 40 to 50 ° C for 8 to 10 minutes. (S ₃₀₀ ) is performed.

The second degreasing step ( _S300 ) of the present invention, like the first degreasing step ( _S100 ), cleans the object to be plated by removing oily contaminants such as cutting oil and processing oil present on the surface of the object to be plated, especially metal corrosion This is an additional process to effectively remove the oily contaminants remaining below.

In addition, in the second degreasing step ( _S300 ) of the present invention, it is preferable to perform the degreasing process while circulating the degreasing liquid in the tank in order to prevent the oil components that have fallen from the surface of the object to be plated from adhering to the object to be plated again during product dipping. do.

Although not limited thereto, the degreasing solution used in the secondary degreasing step (S ₃₀₀ ) is preferably one containing 50 to 70 mL/L of a degreasing agent based on the total 1L of the degreasing solution, and the degreasing agent is used in the plating process. Any type of degreasing agent that does not contain phenol and does not contain prohibited harmful substances or harmful substances requiring permission can be used.

According to one embodiment of the present invention, after the second degreasing step (S ₃₀₀ ), the to-be-plated body from which oil is removed in the second degreasing step (S ₃₀₀ ) is washed with water having a pH of 10 or less. It may be characterized in that a third washing step (S ₃₁₀ ) of washing with water for 20 seconds is further included. This is a preparatory process to improve the efficiency of the subsequent process, and is intended to effectively remove foreign substances such as degreaser, hydrochloric acid solution, and metal by-products on the surface of the object to be plated after the second degreasing process by additionally performing a water washing process.

Therefore, in the second degreasing step ( _S300 ), the degreasing process is performed while circulating the degreasing liquid in the tank, and the object to be plated is immersed in the degreasing liquid maintained at a temperature of 40 to 50 ° C. for 8 to 10 minutes. It is preferable to degrease by removing oil from the surface of the body, and at this time, it is preferable to use a degreasing solution containing 50 to 70 mL/L of a degreasing agent based on the total 1L of the degreasing solution. In addition, after the second degreasing step (S ₃₀₀ ), a third washing step (S ₃₁₀ ) of washing the object to be plated from which oil is removed with washing water maintaining a pH of 10 or less for 10 to 20 seconds is additionally performed. it is desirable to be

Next, a plating step (S ₄₀₀ ) may be performed.

In the second degreasing step (S ₃₀₀ ), the plated object from which the oil content is removed is electrolytically plated at a temperature of 25 to 31° C. at a current value of 0.5 to 1A/dm ² using an alloy plating solution to form a plating layer on the surface of the object to be plated. Performs a plating step (S ₄₀₀ ) to form.

The zinc-nickel alloy plating method is plating for high corrosion resistance and can be referred to as a method of simultaneously attaching zinc and nickel to the surface of an object to be plated using electricity.

In the plating step (S ₄₀₀ ) of the present invention, it is preferable to perform electroplating at a current value of 0.5 to 1 A/dm ² at a temperature of 25 to 31 ° C. to prevent non-plating and burning from occurring after the plating process is performed. .

According to one embodiment of the present invention, the alloy plating solution used in the plating step (S ₄₀₀ ), based on the total 1L of the alloy plating solution, diethylene triamine (Diethylene triamine) 54 to 66mL / L, nickel sulfate (Nickel sulfate) 1.2 to 1.6 g/L, methyl pyridine 1.8 to 2.2 mL/L, ethylene diamine 36 to 44 mL/L, sodium tellurite 1.8 to 2.2 mL/L, zinc ( Zinc) 7.2 to 8.8 g/L and sodium hydroxide 108 to 132 g/L.

Diethylenetriamine included in the alloy plating solution is used as a Ni additive, methylpyridine is used as a brightener, ethylenediamine is used as a high current improver, and sodium tellurate is used as a low current improver.

Preferably, the alloy plating solution contains 1.2 to 1.6 g/L of nickel sulfate and 7.2 to 8.8 g/L of zinc based on 1 L of the alloy plating solution. This is because, when nickel sulfate and zinc are contained in an amount less than the above range, continuous operation becomes impossible due to the formation of a surface film, and a problem in that a large amount of sludge of the solution is generated due to instantaneous film peeling may occur, and zinc salt And when the content of the nickel salt is excessively included than the above content range, the adhesion of the plating layer is deteriorated and the plating cost is excessively increased, resulting in a decrease in production efficiency.

Although not limited thereto, the alloy plating solution used in the plating step (S ₄₀₀ ) may be characterized in that the concentration of nickel [Ni] in the alloy plating solution satisfies the following condition.

13w% ≤ [Ni]/([Ni]+[Zn])×100(w%) ≤ 17w%

The concentration of nickel [Ni] in the alloy plating solution of the present invention is preferably 13w% or more and 17w% or less. This is because there is a concern that corrosion resistance may be deteriorated and peeling may occur during processing. Therefore, the concentration of nickel [Ni] in the alloy plating solution of the present invention preferably satisfies the above conditions.

Diethylenetriamine included in the alloy plating solution is used as a Ni additive, and diethylenetriamine is preferably included in an amount of 54 to 66mL/L based on the total 1L of the alloy plating solution. This is because if the content of the Ni additive is less than the above content range, the overall gloss of the plating layer is non-uniform and gloss is generated only in the high current density region, so there is a concern that the plating efficiency may not be improved. This is because if the content exceeds the range, the concentration of nickel [Ni] in the alloy plating solution may decrease, which may cause a problem in that the plating speed is lowered.

An object of the present invention is to provide a high corrosion resistance surface treatment coating method for a bracket for an electric vehicle thermal management system device having the advantage of maintaining high corrosion resistance specifications while being applicable to the bracket for an electric vehicle thermal management system device. For this, it is also important to appropriately dissolve zinc, nickel sulfate, and diethylenetriamine, which is a Ni additive, to maintain the nickel content attached to the product to be within 13 to 17w%. Therefore, in order to maintain the nickel content during plating to impart high corrosion resistance, it is preferable to maintain the contents of nickel sulfate, zinc, and diethylenetriamine, which is a Ni additive, within the set values defined above.

Methylpyridine contained in the alloy plating solution is used as a brightener, and it is preferable that methylpyridine is included in an amount of 1.8 to 2.2 mL/L based on the total 1L of the alloy plating solution. This is because if the content of the brightening agent is less than the above content range, the glossiness of the plating layer may deteriorate and the quality of the plated product itself may deteriorate. This is because, while the degree increases, the concentration of nickel [Ni] in the alloy plating solution decreases, which may cause a problem in that the plating speed is lowered.

In the present invention, ethylenediamine, a high-current improver, is added to prevent burning, and the plating layer is maintained in the part where the current is low, and at the same time, the resistance is relatively high, so the current is low, and the foreign matter contained in the alloy plating solution adheres to the inner part of the product. In order to prevent this phenomenon, it is characterized in that sodium tellurate, a low current improving agent, is added.

The alloy plating solution preferably contains 108 to 132 g/L of sodium hydroxide based on the total 1L of the alloy plating solution. This is because there is a concern that plating adhesion may be deteriorated, and when the content of sodium hydroxide is more than the above content range, the excessive concentration may cause a problem in that the appearance of the plating layer is blurred and the gloss is reduced.

Although not limited thereto, in the plating step (S ₄₀₀ ), it is preferable to perform the plating process for 45 minutes or longer to maintain the thickness of the formed plating layer at 5 μm or more.

According to one embodiment of the present invention, after the plating step (S ₄₀₀ ), the plating body on which the plating layer is formed in the plating step (S ₄₀₀ ) is washed with water with a pH of 10 or less for 10 to 20 seconds. A fourth washing step (S ₄₁₀ ) may be characterized in that it is further included. This is to remove foreign substances such as alkaline components, amine components, carbonates, and other by-products remaining after plating on the exterior of the plated product after the plating process through a water washing process. Since the water washing process after the plating process is related to product appearance and corrosion resistance, it is preferable to perform it repeatedly at least three times.

Therefore, in the plating step (S ₄₀₀ ), it is preferable to electroplat the object to be plated from which oil is removed using an alloy plating solution at a temperature of 25 to 31 ° C. at a current value of 0.5 to 1 A / dm ² for 45 minutes or more, , At this time, as the alloy plating solution, 54 to 66 mL/L of diethylenetriamine, 1.2 to 1.6 g/L of nickel sulfate, 1.8 to 2.2 mL/L of methylpyridine, and 36 to 44 mL/L of ethylenediamine based on the total 1L of the alloy plating solution , It is preferable to use one containing 1.8 to 2.2 mL/L of sodium tellurate, 7.2 to 8.8 g/L of zinc and 108 to 132 g/L of sodium hydroxide, and the concentration of nickel [Ni] in the alloy plating solution is 13w% ≤ It is preferable to satisfy the condition of [Ni]/([Ni]+[Zn])×100 (w%) ≤ 17w%. In addition, after the plating step ( _S400 ), a fourth washing step (S410) of repeatedly performing a process of washing the plated body on which the plating layer is formed for 10 to 20 seconds with washing water maintained at a pH of 10 or less three times or more ( _S410) . ) is preferably performed additionally.

Next, a chromate treatment step ( _S500 ) may be performed.

Chromate treatment step of forming a chromate layer on the surface of the plating layer by immersing the plating body on which the plating layer is formed in the plating step (S ₄₀₀ ) in a chromate solution having a pH of 1.5 to 2.5 and a temperature maintained at 22 to 28 ° C for 54 to 66 seconds. (S ₅₀₀ ) is performed.

Chromate treatment, also called chromate treatment, involves immersing a plated body coated with zinc or the like in a chromate solution containing chromium to form a chromate layer (chromate film, chromium layer, chromate film) on the surface of the plated body. It can mean, and has the advantage of improving corrosion resistance. That is, the chromate treatment step ( _S500 ) can be said to be a process of treating the plated body (product) on which the plating layer is formed to enhance color and corrosion resistance (white rust and red rust).

According to one embodiment of the present invention, the chromate solution used in the chromate treatment step ( _S500 ) contains 108 to 132 mL/L of chromic nitrate and 54 cobalt nitrate based on the total 1L of the chromate solution. to 66 mL/L and 4.5 to 5.5 mL/L of nitric acid.

Chromate treatment step ( _S500 ) of the present invention is a process performed to form a chromate layer on the surface of the plating layer by chromate treatment using a chromate solution containing chromium nitrate and cobalt nitrate and to treat the color to black. In the case of chromate treatment, when cobalt nitrate is used together, the corrosion resistance effect can be increased by thickening the chromate layer compared to the case of using the chromate solution to which only chromium nitrate is added alone.

In addition, since there is a concern that a chromate layer cannot be effectively formed on the surface of the plating layer only with chromium nitrate and cobalt nitrate contained in the chromate solution, the chromate layer can be rapidly formed by adding nitric acid. That is, by using a chromate solution to which nitric acid is added together with chromium nitrate and cobalt nitrate during the chromate solution treatment, the chromate treatment time can be shortened, and black color can be effectively treated even at low current parts.

In the chromate treatment step ( _S500 ) of the present invention, it is preferable to maintain the temperature of the chromate solution at 22 to 28 ° C. so that the chromium nitrate and cobalt nitrate contained in the chromate solution react well, and the chromate treatment time is also 54 to 66 It is preferable to set it in seconds, but if it is out of the above temperature range, there is a concern that the chromate treatment time will be prolonged and a uniform color may not appear, and if the temperature is high, there is a possibility that a brown color rather than black may occur. Therefore, the chromate treatment process is preferably performed at a temperature of 22 to 28 °C. In addition, it is preferable to maintain the pH of the chromate solution at 1.5 to 2.5. If the pH is less than 1.5, there is a risk of blackening of the plated body (product), and if the pH exceeds 2.5, the color is brown. This is because problems such as color expression not being performed properly may occur.

According to one embodiment of the present invention, after the chromate treatment step ( _S500 ), the plating body on which the chromate layer is formed in the chromate treatment step ( _S500 ) is washed with water having a pH of 10 or less for 10 to 20 seconds. It may be characterized by further comprising a 5th washing step (S ₅₁₀ ) of washing with water during washing, and most preferably, a process of washing the plated body with washing water maintaining a pH of 7 or less for 10 to 20 seconds is performed . This is because chromate residues may remain on the surface of the plating product after the chromate treatment process, and since chromate residues are acidic, corrosion may continue to occur and corrosion resistance may deteriorate if the water washing process is not performed. , It is to remove foreign substances such as chromate residue or residue remaining on the surface of the plated body (product) through a water washing process. Since the water washing process after chromate treatment is related to product appearance and corrosion resistance, it is preferable to perform it repeatedly at least twice or more.

Therefore, in the chromate treatment step ( _S500 ), the plated body on which the plated layer is formed is immersed in a chromate solution having a pH of 1.5 to 2.5 and a temperature maintained at 22 to 28 ° C for 54 to 66 seconds to form a chromate layer on the surface of the plated layer. In this case, it is preferable to use a chromate solution containing 108 to 132 mL/L of chromium nitrate, 54 to 66 mL/L of cobalt nitrate, and 4.5 to 5.5 mL/L of nitric acid based on the total 1 L of the chromate solution. In addition, after the chromate treatment step ( _S500 ), a fifth washing step of repeatedly performing a process of washing the plating body on which the chromate layer is formed with washing water maintaining a pH of 7 or less for 10 to 20 seconds twice or more ( S ₅₁₀ ) is preferably performed additionally.

Next, a top coating step ( _S600 ) may be performed.

In the chromate treatment step (S ₅₀₀ ), the plating body on which the chromate layer is formed is immersed in a top coating solution having a pH of 10 to 14 and a temperature maintained at 22 to 28 ° C for 15 to 25 seconds to form a coating layer on the surface of the chromate layer. A coating step (S ₆₀₀ ) is performed.

The top coating process of the present invention may be referred to as a process performed to enhance corrosion resistance and heat resistance by additionally forming a coating layer on the plating layer and the chromate layer.

According to one embodiment of the present invention, the top coating liquid used in the top coating step (S ₆₀₀ ) contains 270 to 330 mL/L of silicon dioxide and 45 carbon black based on the total 1L of the top coating liquid. to 55 mL/L and 9 to 11 mL/L of alcohol.

Silicon dioxide, which is the main component included in the top coating liquid, plays a role in enhancing corrosion resistance, but white stains and the like may occur on the exterior of the plated body (product) only with silicon dioxide. Accordingly, it is preferable to use a black top coating liquid by including silicon dioxide and carbon black in the top coating liquid. In addition, by adding alcohol to the top coating solution, the viscosity of the top coating solution can be lowered, thereby maximally preventing formation of the top coating solution.

That is, when a top coating solution containing silicon dioxide, carbon black, and alcohol is used, white stains can be prevented from occurring on the exterior of the plated body (product) on which the coating layer is formed, and corrosion resistance can also be improved.

It is preferable that the top coating solution contains 270 to 330 mL/L of silicon dioxide based on the total 1L of the top coating solution. This is because silicon dioxide has a strong viscosity, so when a high concentration is used, the top coating solution is formed on the product, resulting in product It is preferable to satisfy the above content range because a problem of deteriorating marketability may occur.

In the top coating step (S ₆₀₀ ) of the present invention, it is preferable to maintain the temperature of the top coating solution at 22 to 28 ° C. in order to effectively form the coating layer on the chromate layer, and the top coating treatment time will also ensure that the top coating solution is evenly smeared on the product surface. It is preferable to give a sufficient dipping time so that it is possible, and it is preferable to specifically set it to 15 to 25 seconds. In particular, it is important to maintain the temperature of the top coating liquid at 22 to 28 ° C. If the temperature is lower than 22 ° C. This is because there is a risk of hardening in the top coating solution at a temperature exceeding 28 ° C. In addition, it is preferable to maintain the pH of the top coating liquid at 10 to 14, because when the pH is less than 10, a neutralization reaction may occur in the top coating liquid.

Therefore, in the top coating step ( _S600 ), the plating body on which the chromate layer is formed is immersed in a top coating solution having a pH of 10 to 14 and a temperature maintained at 22 to 28 ° C for 15 to 25 seconds to form a coating layer on the surface of the chromate layer. In this case, it is preferable to use a top coating solution containing 270 to 330 mL/L of silicon dioxide, 45 to 55 mL/L of carbon black, and 9 to 11 mL/L of alcohol based on the total 1 L of the top coating solution.

Next, a drying step (S ₇₀₀ ) may be performed.

A drying step (S ₇₀₀ ) of drying the plated body on which the coating layer is formed in the top coating step (S ₆₀₀ ) at a temperature of 40 to 50 ° C. for 8 to 10 minutes is performed.

Since the surface of the plating body after the top coating step (S ₆₀₀ ) has been completed is in a state in which the top coating liquid is smeared on the surface, if the top coating liquid is left at room temperature as it is, the top coating liquid does not settle on the surface of the plating body and is smeared. As a result, stains may be generated on the exterior or corrosion resistance may be deteriorated. Therefore, the drying step ( _S700 ) of the present invention can be said to be a process performed to completely remove the top coating liquid including moisture from the surface of the plated body after the plating, chromate treatment, and top coating process have been completed.

In the drying step (S ₇₀₀ ) of the present invention, if the plated body is simply dried with air to remove the top coating solution containing moisture, the top coating solution containing moisture is removed, but the chromate layer and the coating layer may not be properly cured. Therefore, it is preferable to dry for 8 to 10 minutes at a temperature of 40 to 50 ° C. During drying, scratches may occur due to collision between plating bodies due to air. it is desirable

Hereinafter, a highly corrosion-resistant surface treatment coating method of a bracket for an electric vehicle thermal management system device according to the present invention will be described in detail by way of example so that those skilled in the art can easily perform the present invention. A high corrosion resistance surface treatment coating method of a bracket for an electric vehicle thermal management system device according to an embodiment of the present invention can be more clearly understood by referring to the following examples. However, the present invention may be implemented in many different forms and is not limited to the embodiments described herein.

Bracket for electric vehicle thermal management system device surface treated with the high corrosion resistance surface treatment coating method of the present invention

The bracket for the electric vehicle thermal management system device was surface treated using the high corrosion resistance surface treatment coating method of the present invention, and the bracket for the electric vehicle thermal management system device surface treated using the high corrosion resistance surface treatment coating method of the present invention is shown in FIG. 2 below. same as the picture of

1. 1st degreasing step (S ₁₀₀ ): The object to be plated is immersed in a degreasing solution maintained at a temperature of 45° C. for 9 minutes to remove oil from the surface of the object to be plated. At this time, as the degreasing solution, one containing 60 mL/L of the degreasing agent based on the total 1L of the degreasing solution is used.

2. First washing step (S ₁₁₀ ): Wash the object to be plated from which oil is removed with washing water maintaining a pH of 10 or less for 15 seconds.

3. Acid treatment step ( _S200 ): The to-be-plated object from which oil is removed is immersed in a hydrochloric acid solution maintained at a temperature of 28°C for 9 minutes to remove metal corrosion on the surface of the to-be-plated object. At this time, as the hydrochloric acid solution, one containing 225 mL/L of hydrochloric acid (35%) based on the total 1 L of the hydrochloric acid solution is used.

4. 2nd washing step ( _S210 ): Wash the object to be plated from which metal corrosives have been removed with washing water maintaining a pH of 7 or less for 15 seconds.

5. 2nd degreasing step (S ₃₀₀ ): The to-be-plated object from which metal corrosives are removed is immersed in a degreasing solution maintained at a temperature of 45°C for 9 minutes to remove oil from the surface of the to-be-plated object. At this time, as the degreasing solution, one containing 60 mL/L of the degreasing agent based on the total 1L of the degreasing solution is used.

6. Third washing step (S ₃₁₀ ): The object to be plated, from which oil is removed, is washed with washing water maintaining a pH of 10 or less for 15 seconds.

7. Plating step (S ₄₀₀ ): Electrolytic plating is performed on the object to be plated from which oil is removed using an alloy plating solution at a temperature of 28° C. at a current value of 0.7 A/dm ² to form a plating layer on the surface of the object to be plated. At this time, as the alloy plating solution, diethylenetriamine 60mL/L, nickel sulfate 1.4g/L, methylpyridine 2mL/L, ethylenediamine 40mL/L, sodium tellurate 2mL/L, zinc based on the total 1L of the alloy plating solution 8g/L and 120g/L of sodium hydroxide are used, but the concentration of nickel [Ni] in the alloy plating solution is 13w% ≤ [Ni]/([Ni]+[Zn])×100(w%) ≤ The condition of 17w% is satisfied. At this time, the plating process is performed for 45 minutes or more to maintain the plating thickness of 5 μm or more.

8. Fourth washing step (S ₄₁₀ ): A process of washing the plated body on which the plating layer is formed with washing water maintaining a pH of 10 or less for 15 seconds is performed 4 times.

9. Chromate treatment step ( _S500 ): The plated body having the plated layer is immersed in a chromate solution having a pH of 2 and a temperature maintained at 25° C. for 60 seconds to form a chromate layer on the surface of the plated layer. At this time, as the chromate solution, one containing 120 mL/L of chromium nitrate, 60 mL/L of cobalt nitrate, and 5 mL/L of nitric acid based on the total 1 L of the chromate solution is used.

10. Fifth washing step ( _S510 ): A process of washing the plated body on which the chromate layer is formed with washing water maintained at 7 or less for 15 seconds is performed three times.

11. Top coating step ( _S600 ): A coating layer is formed on the surface of the chromate layer by immersing the plating body on which the chromate layer is formed in a top coating solution having a pH of 12 and a temperature maintained at 25° C. for 20 seconds. At this time, as the top coating solution, one containing 300 mL/L of silicon dioxide, 50 mL/L of carbon black, and 10 mL/L of alcohol based on the total 1 L of the top coating solution is used.

12. Drying step (S ₇₀₀ ): The plated body on which the coating layer is formed is dried at a temperature of 45 ° C. for 9 minutes.

Corrosion resistance test

Bracket for electric vehicle thermal management system device (experimental group) of Example 1 surface-treated using the highly corrosion-resistant surface treatment coating method according to an embodiment of the present invention and the top coating step (S) of the surface treatment method of Example 1 A test was conducted to compare and confirm the corrosion resistance of the bracket (control group) for the electric vehicle thermal management system device surface-treated by omitting _{the 600} ) process.

For the experimental group and the control group, three samples of the experimental groups 1 to 3 and three samples of the control group 1 to 3 were prepared in the same way, and the corrosion resistance of the experimental groups 1 to 3 and the control group 1 to 3 was tested for white rust and redness using a salt spray tester. It was confirmed by checking the time at which rust started to occur.

The test conditions of the salt spray experiment (KSD9502) for the experimental groups 1 to 3 and the control group 1 to 3 are shown in Table 1, and the test results of the salt spray experiment (KSD9502) are shown in Table 2 below.

Test conditions (KSD9502 salt spray test method) NO. Test Items test standard Exam conditions One Salt water concentration (%) 5±0.5% 5.00% 2 pH concentration 6.5-7.2 7.1 3 Test bath temperature (℃) 35℃±2℃ 33.1℃ 4 Atomization pressure (Mpa) 0.1±0.01MPa 0.1Mpa

Test result (KSD9502 salt spray test method) white rust generation time Red-green occurrence time experimental group 1 210 hours 1005 hours experimental group 2 205 hours 1012 hours experimental group 3 207 hours 1007 hours Control 1 185 hours 820 hours Control 2 179 hours 795 hours Control 3 183 hours 828 hours

As shown in Table 2, the bracket for the electric vehicle thermal management system device (test group) of Example 1 surface-treated using the highly corrosion-resistant surface treatment coating method according to an embodiment of the present invention exhibits corrosion resistance (salt spray test) As it was confirmed in the confirmation test that the white rust generation time was more than 200 hours and the red rust generation time was more than 1000 hours, the bracket for the electric vehicle thermal management system device surface-treated by relatively omitting the top coating step (S ₆₀₀ ) process ( It was confirmed that the corrosion resistance was very good compared to the control group).

In conclusion, through the above Examples 1 and 2, the high corrosion resistance surface treatment coating method of the bracket for an electric vehicle thermal management system device according to an embodiment of the present invention is electrically It was confirmed that there is an advantage of enhancing corrosion resistance and heat resistance when applied to a bracket for a vehicle thermal management system device.

Above, the present invention has been described in detail with examples, but the present invention is not limited to the above embodiments, and can be modified in various forms, and conventional knowledge in the art within the technical spirit of the present invention It is clear that many variations are possible by those who have it. In addition, various forms of substitution, modification and change will be possible by those skilled in the art within the scope of the technical spirit of the present invention described in the claims, which also falls within the scope of the present invention. will do it

Claims (5)

A high corrosion resistance surface treatment coating method for a bracket for an electric vehicle thermal management system device,
A first degreasing step of immersing the object to be plated in a degreasing solution maintained at a temperature of 40 to 50° C. for 8 to 10 minutes to remove oil from the surface of the object to be plated;
An acid treatment step of removing metal corrosion on the surface of the object to be plated by immersing the object to be plated from which oil is removed in the first degreasing step in a hydrochloric acid solution maintained at a temperature of 25 to 30 ° C. for 8 to 10 minutes;
a second degreasing step of removing oil from the surface of the to-be-plated body by immersing the to-be-plated body from which metal corrosives have been removed in the acid treatment step in a degreasing solution maintained at a temperature of 40 to 50° C. for 8 to 10 minutes;
Plating to form a plating layer on the surface of the object to be plated by electrolytically plating the object to be plated from which oil is removed in the second degreasing step at a temperature of 25 to 31 ° C. at a current value of 0.5 to 1 A / dm ² using an alloy plating solution step;
A chromate treatment step of forming a chromate layer on the surface of the plating layer by immersing the plating body on which the plating layer is formed in the plating step in a chromate solution having a pH of 1.5 to 2.5 and a temperature maintained at 22 to 28 ° C for 54 to 66 seconds;
A top coating step of forming a coating layer on the surface of the chromate layer by immersing the plating body on which the chromate layer is formed in the chromate treatment step in a top coating solution having a pH of 10 to 14 and a temperature maintained at 22 to 28 ° C for 15 to 25 seconds; and
A drying step of drying the plating body on which the coating layer is formed in the top coating step at a temperature of 40 to 50 ° C. for 8 to 10 minutes. The method of claim 1,
The alloy plating solution used in the plating step is
54 to 66 mL/L of diethylene triamine, 1.2 to 1.6 g/L of nickel sulfate, 1.8 to 2.2 mL/L of methyl pyridine, and ethylenediamine based on 1 L of the total alloy plating solution (Ethylene diamine) 36 to 44mL/L, sodium tellurite 1.8 to 2.2mL/L, zinc 7.2 to 8.8g/L, and sodium hydroxide 108 to 132g/L High corrosion resistance surface treatment coating method of a bracket for an electric vehicle thermal management system device. The method of claim 1,
The chromate solution used in the chromate treatment step,
Based on the total 1L of the chromate solution, 108 to 132 mL/L of chromic nitrate, 54 to 66 mL/L of cobalt nitrate, and 4.5 to 5.5 mL/L of nitric acid are included. High corrosion resistance surface treatment coating method for brackets for automotive thermal management system devices. The method of claim 1,
The top coating liquid used in the top coating step is
Based on the total 1L of the top coating solution, 270 to 330 mL/L of silicon dioxide, 45 to 55 mL/L of carbon black, and 9 to 11 mL/L of alcohol are included for thermal management of electric vehicles. High corrosion resistance surface treatment coating method for brackets for system devices. According to any one of claims 1 to 4,
After the first degreasing step, a first washing step is performed,
After the acid treatment step, a second washing step is performed,
After the second degreasing step, a third washing step is performed,
After the plating step, a fourth washing step is performed,
After the chromate treatment step, it is characterized in that a fifth washing step is performed,
In the first washing step, the second washing step, the third washing step, the fourth washing step, and the fifth washing step, washing the object to be plated or the plated object with washing water maintaining a pH of 10 or less for 10 to 20 seconds High corrosion resistance surface treatment coating method of a bracket for an electric vehicle thermal management system device, characterized in that.