Method for manufacturing electroless nickel-plated component and electroless nickel-plated component manufactured thereby

Abstract

A method for manufacturing an electroless nickel-plated component is provided. According to this, an electroless nickel-plated layer formed on a component surface can prevent elements in the alloy of various components exposed to high-temperature environments of 600 °C or higher from becoming volatile, and due to the plated layer stably maintaining adhesiveness for a long period of time and having high hardness, abrasion resistance, and corrosion resistance, can also protect the component surface under various physical / chemical environments, and can therefore be widely applied to components in various devices, such as SOFCs, used in high-temperature conditions.

Description

Method for manufacturing electroless nickel-plated parts and electroless nickel-plated parts manufactured thereby

[0001] The present invention relates to a method for manufacturing an electroless nickel-plated part, and more specifically, to a method for manufacturing an electroless nickel-plated part and an electroless nickel-plated part manufactured thereby.

[0002] Electroless plating is a method in which a metal plating layer is formed on a target object through a metal oxidation-reduction reaction. Since plating is possible regardless of the shape of the product, it is used in various industrial fields.

[0003] Meanwhile, with growing concerns about the depletion of existing energy resources like oil and natural gas, and increasing demand for environmentally friendly resources, research into fuel cells is actively underway as a new alternative energy source. Fuel cells are known as an environmentally friendly energy source that utilizes the reverse reaction of water electrolysis. Various types of fuel cells are currently being developed, including phosphate fuel cells, molten carbonate fuel cells, and solid oxide fuel cells (SOFCs).

[0004] Among these, the solid oxide fuel cell (SOFC) is a fuel cell that uses a solid oxide that can transmit oxygen or hydrogen ions as an electrolyte, and operates at the highest temperature (600 to 1000℃) of the existing fuel cells. Since all components are made of solids, it has a simpler structure than other fuel cells, and there are no problems with electrolyte loss, replenishment, or corrosion. In addition, since it operates at high temperatures, it does not require a precious metal catalyst, and it is easy to supply fuel through direct internal reforming. Since it emits high-temperature gas, it is possible to generate combined heat and power using waste heat. Therefore, research and development is actively being conducted in advanced countries such as the United States and Japan.

[0005] Because solid oxide fuel cells operate at high temperatures, various components that make up the fuel cell are made of heat-resistant metals. In addition, some components are being replaced with corrosion-resistant stainless steel to prevent corrosion from the high-temperature steam generated during fuel cell operation.

[0006] Meanwhile, stainless steel contains alloying elements such as chromium to prevent surface corrosion. At high SOFC operating temperatures, chromium migrates to the surface of components and forms a chromium oxide film, thereby protecting the stainless steel surface. However, the chromium oxide film reacts with oxygen and water vapor in the high-temperature SOFC operating temperature range to form a chromium gas phase. The volatilized chromium gas phase migrates into the cathode due to the partial pressure difference that occurs during operation, ultimately poisoning the cathode and causing serious degradation of SOFC performance.

[0007] To solve these problems, research is being conducted to form an electroless nickel plating layer on the stainless steel surface to prevent poisoning by chromium volatilization on the stainless steel surface. However, the formed electroless nickel plating layer has good adhesion and bonding with the surface of the part at room temperature or relatively low temperature, but there is a problem that the adhesion and bonding rapidly decrease at the high operating temperature at which SOFC operates.

[0008] Accordingly, there is an urgent need for research on an electroless nickel plating method that can prevent elements in the alloy forming parts of various devices used under high-temperature conditions, such as SOFCs, from volatilizing under high-temperature conditions, while allowing the formed plating layer to maintain excellent adhesion for a long time and have high hardness, thereby protecting the surface of the parts under various physical / chemical environments.

[0009] The present invention has been devised in consideration of the above points, and the purpose of the present invention is to provide a method for manufacturing an electroless nickel-plated part, which can prevent elements in an alloy forming parts of various devices operating under high-temperature conditions, such as SOFCs, from volatilizing under high-temperature conditions, while allowing the formed plating layer to maintain stable adhesion for a long time and have high hardness, corrosion resistance, and wear resistance, thereby protecting the surface of the part under various physical / chemical environments, and an electroless nickel-plated part manufactured thereby.

[0010] In order to solve the above-described problem, the present invention provides a method for manufacturing an electroless nickel-plated part with improved high-temperature adhesion, comprising the steps of: (1) performing a pretreatment process including a sandblasting process and a nickel strike plating process on a plated part; (2) forming an electroless nickel plating layer on the plated part; and (3) performing a high-temperature heat treatment on the electroless nickel-plated part at a temperature of 550°C or higher.

[0011] According to one embodiment of the present invention, the pretreatment process may further include a degreasing process performed between the sandblasting process and the nickel strike plating process, in which the degreasing solution is immersed in a 10 to 15 wt% degreasing solution at 40 to 60°C for 1 to 10 minutes and then electrolytic degreasing is performed for 1 to 5 minutes under a current density of 1 to 2 A / d㎡; an acid etching process performed by immersing in an etching solution mixed with a 1 to 7 wt% nitric acid aqueous solution, a 1 to 6 wt% hydrofluoric acid aqueous solution, and a 1 to 15 wt% hydrochloric acid aqueous solution for 1 to 10 minutes; and an activation process performed by immersing in a 15 to 25 wt% hydrochloric acid aqueous solution for 2 to 15 minutes.

[0012] In addition, the sandblasting process is performed so that the centerline average roughness (Ra) of the plating area is 0.8 ㎛ or more, and the nickel strike process can be performed for 5 to 10 minutes at a current density of 1.5 to 5.0 A / d㎡ after immersing the surface-activated plating part in a nickel strike plating solution.

[0013] Additionally, the center line surface roughness can be performed to be 0.8 to 5.0 μm.

[0014] Additionally, step (2) can be performed by immersing the plated part in an electroless nickel plating solution having a pH of 4 to 5 at a temperature of 80 to 90°C for 20 to 120 minutes.

[0015] In addition, step (3) can be performed by performing high-temperature heat treatment at 550°C or higher for 3 to 7 hours on the cooled part after low-temperature heat treatment performed at 190 to 410°C for 1 to 9 hours, and more preferably, high-temperature heat treatment can be performed at a temperature of 600 to 700°C for 4 to 5 hours in a vacuum atmosphere.

[0016] In addition, the present invention provides an electroless nickel plated part manufactured according to the present invention.

[0017] The method for manufacturing an electroless nickel-plated part according to the present invention prevents elements in an alloy forming various parts that are exposed to a high-temperature environment of 600°C or higher from volatilizing in the high-temperature environment by forming an electroless nickel-plated layer on the surface of the part, and the formed plating layer stably maintains adhesion for a long time and has high hardness, wear resistance, and corrosion resistance, thereby protecting the surface of the part under various physical / chemical environments, and thus can be widely applied to parts in various devices used under high-temperature conditions such as SOFC.

[0018] FIG. 1 and FIG. 2 are graphs showing a photograph of the surface of a plated part and a measured surface roughness, respectively, after completing the sandblasting process as a pretreatment process of step (1) in a method for manufacturing an electroless nickel plated part according to one embodiment of the present invention.

[0019] FIGS. 3A to 3C are photographs of components manufactured according to a method for manufacturing an electroless nickel plated component according to one embodiment of the present invention, wherein FIG. 3A is a photograph of the surface of an electroless nickel plated component, FIG. 3B is a photograph after a cross-cut evaluation of the surface of an electroless nickel plated component, and FIG. 3C is a photograph after a 90° and 180° mandrel bending experiment.

[0020] Figure 4 is a photograph of the surface of an electroless nickel-plated part according to Comparative Example 1 of the method for manufacturing an electroless nickel-plated part of the present invention.

[0021] Figure 5 is a photograph of the surface of an electroless nickel-plated part according to Comparative Example 2 of the method for manufacturing an electroless nickel-plated part of the present invention.

[0022] FIGS. 6A and 6B are cross-sectional H / X SEM-EDS photographs of an electroless nickel plating part manufactured by an electroless nickel plating manufacturing method according to one embodiment of the present invention, wherein FIG. 6A is a 5000x cross-sectional SEM, and FIG. 6B is an element-specific EDS mapping photograph and its analysis results.

[0023] FIG. 7a and FIG. 7b are cross-sectional H / X SEM-EDS photographs of electroless nickel-plated parts according to Comparative Example 3 for a method for manufacturing electroless nickel-plated parts. FIG. 7a is a 5000x magnification cross-sectional SEM, and FIG. 7b is an element-specific EDS mapping photograph and its analysis results.

[0024] FIG. 8a and FIG. 8b are cross-sectional H / X SEM-EDS photographs of electroless nickel-plated parts according to Comparative Example 5 for a method for manufacturing electroless nickel-plated parts, wherein FIG. 7a is a 5000x cross-sectional SEM, and FIG. 7b is an element-specific EDS mapping photograph and its analysis results.

[0025] Hereinafter, embodiments of the present invention will be described in detail so that those skilled in the art can easily implement the invention. The present invention may be implemented in various different forms and is not limited to the embodiments described herein.

[0026]

[0027] An electroless nickel plated part according to one embodiment of the present invention can be manufactured by including: (1) a step of pretreating a plated part; (2) a step of forming an electroless nickel plating layer on the plated part; and (3) a step of high-temperature heat treating the electroless nickel plated part at a temperature of 550°C or higher.

[0028]

[0029] First, as step (1) according to the present invention, a step of preprocessing the plated part is performed.

[0030] The plated component may be a component within a known device that requires electroless nickel plating, and the present invention is not particularly limited thereto. For example, the plated component may be various components such as pipes, pins, plates, and covers. In addition, the device on which the plated component is mounted may be, for example, a device that is exposed to a high temperature environment, for example, an environment of 600°C or higher, or an operating temperature of 600°C or higher. As a specific example, the device may be a solid oxide fuel cell, and the plated component may be various components constituting a heat exchanger provided within the solid oxide fuel cell, and there are no limitations in size, type, shape, etc.

[0031] In addition, the material of the above-mentioned plated part may be a known material capable of electroless nickel plating, for example, a stainless steel alloy, and the present invention is not particularly limited with respect to the detailed composition thereof, and for example, there is no limitation such as SS310, SS304, etc.

[0032]

[0033] The pretreatment process for the plated part includes a sandblasting process and a nickel strike plating process, and may further include known pretreatment sub-processes performed before electroless nickel plating, such as a degreasing process, an acid etching process, and an activation process, between the sandblasting process and the nickel strike plating process.

[0034]

[0035] The sandblasting process and the nickel strike plating process performed as pretreatment processes can be combined with the high-temperature heat treatment of step (3) described below to enable the electroless nickel plating layer to maintain excellent adhesion at high temperatures. The electroless nickel plating layer formed in step (2) described below can have its hardness reduced when heat treated at a high temperature exceeding 400°C, so the heat treatment is not usually performed at a high temperature of 500 to 600°C or higher. Although the reduced hardness does not directly cause a reduction in adhesion, the reduced hardness may be undesirable as it increases the probability of causing a reduction in adhesion. However, the present invention performs electroless nickel plating on the surface on which the sandblasting process and the nickel strike plating process performed as pretreatment processes have been performed even when the high-temperature heat treatment of step (3) is performed, so that the electroless nickel plating layer formed under high-temperature usage conditions can maintain excellent adhesion for a long time. If neither the sandblasting process nor the nickel strike plating process is performed during the pretreatment process, or if both the sandblasting process and the nickel strike plating process are performed as pretreatment processes but step (3) described below is not performed, or if the heat treatment is performed but the heat treatment is performed at a temperature lower than 550°C, there is a concern that partial peeling may occur after the high-temperature heat treatment in step (3), or even if there is no abnormality in appearance after the high-temperature heat treatment, the time for maintaining adhesion during use in a high-temperature environment may be shortened.

[0036]

[0037] The above sandblasting process can be performed using equipment, methods, and conditions conventional in the art. Preferably, the surface of the plated part that has undergone the sandblasting process may have a centerline average roughness (Ra) of 0.8 ㎛ or more, more preferably 0.8 to 5.0 ㎛, and even more preferably 0.8 to 2.2 ㎛. If the centerline average roughness is less than 0.8 ㎛, it may be difficult to achieve the desired level of high-temperature adhesion, etc. In addition, if the centerline average roughness exceeds 5.0 ㎛, uniform treatment may not be applied to the entire surface area during the nickel strike plating process pretreatment, and as a result, there is a concern that the adhesion may deteriorate after the high-temperature heat treatment in step (3) or the time for stably maintaining adhesion during use at high temperatures may be shortened.

[0038]

[0039] In addition, the nickel strike plating process as a pretreatment process is performed later to increase the adhesion of the electroless nickel plating layer formed on the surface, and by combining it with the sandblasting process performed previously, the electroless nickel plating layer can have excellent adhesion to the surface of the plated part even at high temperatures. The nickel strike plating process can be performed through methods and conditions known in the art. However, it is preferable that the plated part is immersed in the nickel strike plating solution for 10 to 20 minutes and then performed at a current density of 1.5 to 5.0 A / d㎡ for 5 to 10 minutes, thereby advantageously achieving the purpose of the present invention. However, if the current density and / or performance time during nickel strike plating is exceeded, it may be difficult to ensure high-temperature adhesion. The above nickel strike solution can be used without limitation as long as it is a nickel strike solution known to be suitable for the material of the plated part, for example, stainless steel, and specifically, it can be a mixed solution of a 120 to 240 g / l nickel chloride aqueous solution and a 65 to 125 g / l hydrochloric acid aqueous solution, or a mixed solution of 110 to 120 g / l nickel sulfate, 110 to 120 g / l nickel chloride, 10 to 20 g / l boric acid, and 10% hydrochloric acid, but is not limited thereto.

[0040]

[0041] Meanwhile, the above-described nickel strike plating process can be more preferably performed on surface-activated plated parts, and for this purpose, an activation process can be further performed between the above-described sandblasting process and the nickel strike plating process. In addition, before performing the activation process, a degreasing process and an acid etching process can be further performed to remove surface contamination, rust, and other foreign substances from the plated parts that have undergone the sandblasting process.

[0042] The above degreasing process is a process for removing foreign substances and oil components present on the surface of a plated alloy part, and this can be carried out in the same manner as a conventional method. The degreasing process can be carried out, for example, by immersing the plated part in a degreasing solution or by an electrolytic degreasing method in which a voltage is applied after immersion. At this time, the degreasing solution used for immersion degreasing or electrolytic degreasing is preferably to contain at least one selected from sodium carbonate, sodium hydroxide (NaOH), and a surfactant. In addition, the degreasing solution is preferably a solution containing an anionic surfactant such as ethoxylated nonylphenol. Anionic surfactants are effective in removing oil components. For example, the degreasing solution can be composed of an aqueous solution containing 80 to 150 g / L of sodium carbonate (Na2CO3), 80 to 150 g / L of sulfuric acid (H2SO4), and 2 to 7 ml / L of an anionic surfactant based on 1 liter (L) of the total degreasing solution.

[0043] In addition, during electrolytic degreasing, the plated part may be immersed in a 10 to 15 wt% degreasing solution at 40 to 60°C for 1 to 10 minutes and then electrolytic degreasing may be performed for 1 to 5 minutes under a current density of 1 to 2 A / d㎡, more preferably, immersed in a 12 to 15 wt% degreasing solution at 50 to 55°C for 3 to 5 minutes and then electrolytic degreasing may be performed for 1 to 3 minutes under a current density of 1 to 2 A / d㎡, and additionally, washing may be performed after electrolytic degreasing.

[0044] Next, the acid etching process is a process for removing oxide films or smut, which is a reducing metal, formed on the surface of the plated part, and this can be performed using a conventional acid etching method. For example, the acid etching process can be performed through cleaning with an etching solution, which is an acid solution. Specifically, the etching solution may be a 1 to 7 wt% nitric acid aqueous solution, a 1 to 6 wt% hydrofluoric acid aqueous solution, a 1 to 15 wt% hydrochloric acid aqueous solution, and more preferably a 3 to 7 wt% nitric acid aqueous solution, a 3 to 6 wt% hydrofluoric acid aqueous solution, and a 10 to 15 wt% hydrochloric acid mixed in a volume ratio of 1: 0.1 to 3: 0.1 to 3.

[0045] Additionally, the acid etching process can be performed by immersing the plated part in such an etching solution for 1 to 10 minutes, more preferably 5 to 10 minutes, and, if necessary, a further washing process can be performed after immersion.

[0046] Additionally, the acid etching process can be performed at room temperature, for example, at a temperature of 20 to 25°C, but is not limited thereto.

[0047]

[0048] Next, the activation process activates the surface so that the plated part process formed on the plated surface and the electroless electrolytic nickel plating described later can be smoothly performed. An activation method known to be suitable for a specific plated part and type of plating can be used. For example, the activation process can be performed by immersing in a 15 to 30 wt% hydrochloric acid aqueous solution for 2 to 15 minutes, more preferably in a 15 to 25 wt% hydrochloric acid aqueous solution for 2 to 15 minutes, and this can advantageously achieve the purpose of the present invention. In addition, a washing process can be further performed after surface activation, if necessary. In addition, the activation process can be performed at room temperature, for example, 20 to 25°C.

[0049]

[0050] Next, as step (2) according to the present invention, a step of forming an electroless nickel plating layer is performed. The electroless nickel plating layer can prevent volatilization of components that can volatilize at high temperatures among the elements forming the plated part, and can improve the corrosion resistance, wear resistance, etc. of the plated part.

[0051] (2) Electroless nickel plating in step 2 can be performed by immersing the plated part joint in a nickel-phosphorus containing plating solution having a pH of 4 to 5 and then performing the process at a temperature of 80 to 90°C for 20 to 120 minutes, thereby advantageously forming an electroless nickel plating layer having a uniform thickness and excellent surface quality to the desired thickness.

[0052] The electroless nickel plating solution may be a plating solution used in conventional electroless nickel plating containing a nickel precursor, and the present invention is not particularly limited thereto. For example, the electroless nickel plating solution includes a solvent, a nickel metal salt as a nickel precursor, and a reducing agent, and may further include other known complexing agents, stabilizers, metal stabilizers, and pH adjusters.

[0053] The above solvent is a common one used in electroless nickel plating solutions, and may be water, for example.

[0054] In addition, the nickel metal salt, which is a nickel precursor, may include, for example, nickel hydrochloride, and as a specific example, may include at least one of nickel sulfamate, nickel sulfate, nickel chloride, nickel nitrate, nickel oxide, and nickel carbonate. In addition, the nickel metal salt may be included in an amount ranging from 4 g to 7 g per 1 liter of the electroless nickel plating solution.

[0055] In addition, the reducing agent can reduce nickel ions dissociated from the nickel metal salt. The reducing agent may include, for example, at least one of hypophosphite, boron hydride, dimethylamine borane, and hydrazine, and preferably, hypophosphite, and may include at least one of sodium hypophosphite, potassium hypophosphite, and ammonium hypophosphite as the hypophosphite. In addition, the electroless nickel plating layer formed due to the inclusion of such a phosphorus reducing agent may contain a phosphorus component.

[0056] Additionally, the reducing agent may be included in an amount ranging from 20 g to 50 g per 1 liter of the electroless nickel plating solution, but is not limited thereto.

[0057] In addition, since known additives can be used in the electroless nickel plating solution, a detailed description thereof is omitted in the present invention.

[0058]

[0059] (2) The thickness of the electroless nickel plating layer formed through the step may be 6.5 to 20㎛, which may be more advantageous in preventing not only corrosion resistance and wear resistance of the plated part but also volatilization of alloy elements constituting the plated part. If the thickness of the electroless nickel plating layer is less than 6.5㎛, it may be difficult to prevent volatilization of alloy elements or its long-term durability may be weakened. In addition, if the thickness of the electroless nickel plating layer exceeds 20㎛, the density of the electroless nickel plating layer is reduced, which is not good in long-term durability such as reduced adhesion under high-temperature environments, and may also not be good economically.

[0060]

[0061] Next, as step (3) according to the present invention, a step of high-temperature heat treatment of the electroless nickel-plated part at a temperature of 550°C or higher is performed.

[0062] (3) The high-temperature heat treatment in step (3) is performed to prevent the deterioration of the adhesion of the electroless nickel plating layer that occurs when the part on which the electroless nickel plating layer has been formed is placed in a high-temperature environment. The high-temperature heat treatment can be performed at a temperature of 550°C or higher for 3 to 7 hours, and preferably, it can be performed at a temperature of 600 to 700°C for 3 to 5 hours. If the high-temperature heat treatment is performed at a temperature lower than 550°C, even though the heat treatment is performed, for example, peeling of the electroless nickel plating layer may occur on the surface of the electroless nickel plating part during high-temperature use. In addition, when the heat treatment is performed at a temperature exceeding 700°C, the level of improvement in high-temperature adhesion may be minimal, and there is a concern that the electroless nickel plating layer may melt.

[0063] In addition, the high-temperature heat treatment can preferably be performed under a vacuum atmosphere, which can be advantageous in further improving high-temperature adhesion while eliminating concerns about hardness reduction due to high-temperature heat treatment.

[0064] In addition, the high-temperature heat treatment may be conducted at a rate of 10 to 16°C / min until the desired heat treatment temperature is reached, which may be advantageous in achieving the purpose of the present invention. If the rate of heating is less than 10°C / min, there is a risk that the process time may be delayed, and if it exceeds 16°C / min, it may be difficult to maintain continuous adhesion when exposed to a high-temperature environment during use.

[0065]

[0066] Meanwhile, according to a preferred embodiment of the present invention, step (3) may further include performing a low-temperature heat treatment at 190 to 410°C for 1 to 9 hours prior to the high-temperature heat treatment, thereby further improving the adhesion and hardness of the electroless nickel plating layer under high-temperature conditions. In addition, the low-temperature heat treatment may additionally eliminate hydrogen embrittlement occurring during acid etching, activation processes, etc. performed prior to step (2).

[0067] In addition, the high-temperature heat treatment after the low-temperature heat treatment is preferably performed through different heat treatment processes, and in particular, a cooling process may be performed between the low-temperature heat treatment and the high-temperature heat treatment, which may be more advantageous in maintaining the adhesion of the electroless nickel plating layer and improving the hardness under high-temperature environments. If the high-temperature heat treatment is performed continuously without cooling after the low-temperature heat treatment, the high-temperature adhesion of the electroless nickel plating layer may actually deteriorate.

[0068]

[0069] The present invention will be described in more detail through the following examples, but the following examples do not limit the scope of the present invention, and should be interpreted as helping to understand the present invention.

[0070]

[0071] <Example 1>

[0072] A 0.5 mm thick stainless steel (STS310) part was prepared as a plated part and then a pretreatment process was performed. First, a sandblasting process was performed on the surface, and the average centerline roughness of the surface after the sandblasting process was 0.839 μm. Afterwards, the part was immersed in a 12.5 wt% degreasing solution (Clean-L20) at 55°C for 5 minutes, and then electrolytic degreasing was performed for 2 minutes at a current density of 2 A / d㎡. Afterwards, an etching process was performed at 23°C for 5 minutes in an etching solution containing a mixture of 5 wt% nitric acid solution, 4 wt% hydrofluoric acid solution, and 12.5 wt% hydrochloric acid solution. Afterwards, the surface was activated by immersing in a 22 wt% hydrochloric acid solution at 23°C for 2 minutes, and then washed with water. Afterwards, the sample was immersed in a nickel strike solution containing 250 g / L of nickel chloride and 100 ml / L of hydrochloric acid solution at 23°C for 15 minutes, and nickel strike plating was performed for 10 minutes under a current density of 2 A / d㎡, and then washed with water.

[0073] For stainless steel parts that had completed the pretreatment process, an electroless nickel plating layer was formed by immersing them in an electroless nickel plating solution (Nichem® MP 1189) at pH 4.7 and 83°C for 30 minutes.

[0074] Afterwards, the parts on which the electroless nickel plating layer was formed were mounted on a furnace, heated at a heating rate of 15°C / min in an air atmosphere, and subjected to low-temperature heat treatment at 350°C for 1.5 hours, followed by natural cooling. Afterwards, the parts on which the low-temperature heat treatment was performed were remounted on the furnace, heated at a heating rate of 15°C / min in a vacuum atmosphere, and subjected to high-temperature heat treatment at 620°C for 4 hours, followed by natural cooling, thereby manufacturing parts on which the electroless nickel plating layer was formed.

[0075]

[0076] <Examples 2 to 4>

[0077] A part was manufactured in the same manner as Example 1, but the surface roughness was changed after the sandblasting process as shown in Table 1 below, or the temperature was changed during high-temperature heat treatment to manufacture a part having an electroless nickel plating layer as shown in Table 1 below.

[0078]

[0079] Comparative Examples 1 to 5

[0080] A part was manufactured in the same manner as in Example 1, but the sandblasting process or the nickel strike plating process was omitted as a pretreatment process as in Table 1 below, or the high-temperature heat treatment or the low-temperature heat treatment and the high-temperature heat treatment were omitted to manufacture a part having an electroless nickel plating layer formed as in Table 1 below.

[0081]

[0082] Experimental Example 1

[0083] The following physical properties were evaluated for parts formed with an electroless nickel plating layer manufactured through examples and comparative examples, and the results are shown in Table 1 below.

[0084]

[0085] 1. Surface roughness measurement

[0086] In Examples 1 and 2, the surface roughness of the plated part surface after the sandblasting process was measured using a confocal microscope, and the related photographs are shown in FIGS. 1 and 2, respectively.

[0087]

[0088] 2. Evaluation of the appearance of the electroless nickel plating layer

[0089] For each example and comparative example, 10 specimens were evaluated for appearance abnormality, and the number of specimens in which peeling occurred was counted. If the number of specimens in which peeling occurred was 0, it was evaluated as ×, if peeling occurred in 1 to 3 specimens, it was evaluated as △, and if peeling occurred in 4 or more specimens, it was evaluated as ○.

[0090]

[0091] 3. Evaluation of the adhesion of the electroless nickel plating layer after exposure to a high-temperature environment

[0092] Parts with no apparent abnormalities were exposed to a temperature of 650°C for 50 hours.

[0093] Afterwards, mandrel bending tests were performed at 90° and 180°, respectively, and the presence or absence of poor plating adhesion was visually evaluated. The evaluation results were indicated as ○ if lifting or peeling occurred, △ if cracks occurred, and × if there were no abnormalities.

[0094] In addition, after performing a 10×10 cross-cut evaluation at 1 cm intervals, the number of cells with even a small amount of peeling out of a total of 100 cells was counted. At this time, the cross-cut evaluation was evaluated according to the ASTM D3359 Standard Test Method for Rating Adgesion by Tape Test.

[0095]

[0096] Example 1 Example 2 Example 3 Example 4 Comparative Example 1 Comparative Example 2 Comparative Example 3 Comparative Example 4 Comparative Example 5 Pretreatment process Sandblasting presence / Surface roughness (Ra, ㎛) ○ / 0.839 ○ / 0.775 ○ / 0.839 ○ / 0.839 Not performed ○ / 0.839 ○ / 0.839 ○ / 0.839 ○ / 0.839 Nickel strike plating ○○○○○ Not performed ○○○ Low temperature heat treatment Temperature (℃) / Time / Atmosphere 350 / 1.5h / Standby 350 / 1.5h / Standby Not performed 350 / 1.5h / Standby 350 / 1.5h / Standby 400 / 1h / Standby 350 / 1.5h / Standby Not performed High temperature Heat treatment temperature (℃) / time / atmosphere 620 / 4h / vacuum 620 / 4h / vacuum 620 / 4h / vacuum 560 / 6h / vacuum 620 / 4h / vacuum 620 / 4h / vacuum not performed 500 / 8h / vacuum not performed Electroless nickel plating layer appearance evaluation × × × × ○ △ × × × Adhesion evaluation after high temperature exposure 90 ° bending / 180 ° bending / number of peeled sections after crosscut evaluation × / × / 0 × / ○ / 20 ○ / ○ / 15 × / × / 10 Not evaluated ○ / ○ / 41 ○ / ○ / 100 ○ / ○ / 54 ○ / ○ / 100

[0097] As can be seen in Table 1,

[0098] In Comparative Examples 1 and 2, in which neither the sandblasting process nor the nickel strike plating process was performed as a pretreatment process, it can be seen that the frequency of appearance abnormalities occurring after high-temperature heat treatment is higher compared to the examples.

[0099] In addition, it can be seen that in Comparative Examples 3 and 5, which did not perform high-temperature heat treatment, or Comparative Example 4, in which the high-temperature heat treatment temperature was outside the range of the present invention, the adhesion of the electroless nickel plating layer was significantly reduced or lost after the parts were exposed to high temperatures for a long period of time, compared to the examples.

[0100]

[0101] Experimental Example 2

[0102] Cross-sectional H / X SEM-EDS analysis was performed on the parts according to Example 1, Comparative Example 3, and Comparative Example 5, and the results are shown in FIGS. 6a to 6b for Example 1, FIGS. 7a to 7b for Comparative Example 3, and FIGS. 8a to 8b for Comparative Example 5, respectively.

[0103]

[0104] As can be seen from the results in Table 1 and from FIGS. 6a to 6b, 7a to 7b, and 8a to 8b,

[0105] In all of Example 1, Comparative Example 3, and Comparative Example 5, it can be confirmed that an electroless nickel plating layer with a predetermined thickness is formed on the surface of the part.

[0106] However, as can be seen from Fig. 8a, the electroless nickel plating layer of Comparative Example 5, which did not undergo a heat treatment process, has no problem with adhesion to the surface of the plated part, but it cannot maintain adhesion when exposed to a high-temperature environment, as can be seen from the results in Table 1.

[0107] In addition, as can be seen from Table 1 and Fig. 7a, in the case of Comparative Example 3, which performed low-temperature heat treatment, although there was no abnormality in the visual inspection of the appearance, fine lifting occurred continuously between the electroless nickel plating layer and the surface of the plated part, and even though heat treatment was performed, high-temperature heat treatment was not performed, and as a result, it can be confirmed from the results in Table 1 that the adhesion of the plating layer could not be maintained in a high-temperature environment.

[0108] In contrast, in the case of Example 1, as confirmed through Table 1 and Fig. 6a, it can be confirmed that no lifting occurred between the electroless nickel plating layer and the surface of the plated part compared to Comparative Example 3 due to high-temperature heat treatment, and it can be seen that excellent adhesion of the plating layer can be secured even in a high-temperature environment due to high-temperature heat treatment.

[0109]

[0110] Although one embodiment of the present invention has been described above, the spirit of the present invention is not limited to the embodiment presented in this specification, and a person skilled in the art who understands the spirit of the present invention will be able to easily propose other embodiments by adding, changing, deleting, or adding components within the scope of the same spirit, but this will also be considered to fall within the spirit of the present invention.

Claims

1. (1) A step of performing a pretreatment process including a sandblasting process and a nickel strike plating process on a plated part; (2) a step of forming an electroless nickel plating layer on the plated part; and (3) A method for manufacturing an electroless nickel-plated part with improved high-temperature adhesion, comprising the step of performing high-temperature heat treatment on an electroless nickel-plated part at a temperature of 550°C or higher.

2. In paragraph 1, The above pretreatment process is between the sandblasting process and the nickel strike plating process. A degreasing process performed by immersing in a 10 to 15 wt% degreasing solution at 40 to 60°C for 1 to 10 minutes and then electrolytic degreasing for 1 to 5 minutes under a current density of 1 to 2 A / d㎡. An acid etching process performed by immersing in an etching solution containing a mixture of 1 to 7 wt% nitric acid aqueous solution, 1 to 6 wt% hydrofluoric acid aqueous solution, and 1 to 15 wt% hydrochloric acid aqueous solution for 1 to 10 minutes, and A method for manufacturing an electroless nickel plated part, further comprising an activation process performed by immersing in a 15 to 25 wt% hydrochloric acid aqueous solution for 2 to 15 minutes.

3. In paragraph 1, A method for manufacturing an electroless nickel-plated part, wherein the above sandblasting process is performed so that the center line average roughness (Ra) of the plated area is 0.8 ㎛ or more.

4. In paragraph 1, The above nickel strike plating process is a method for manufacturing an electroless nickel plated part, which is performed by immersing a surface-activated plated part in a nickel strike plating solution and then applying a current density of 1.5 to 5.0 A / d㎡ for 5 to 10 minutes.

5. In paragraph 3, A method for manufacturing an electroless nickel plating part, wherein the center line surface roughness is performed to be 0.8 to 5 ㎛.

6. In paragraph 1, (2) A method for manufacturing electroless nickel-plated parts, which is performed by immersing the plated parts in an electroless nickel plating solution having a pH of 4 to 5 at a temperature of 80 to 90°C for 20 to 120 minutes.

7. In paragraph 1, (3) A method for manufacturing an electroless nickel-plated part, characterized in that the step comprises performing a high-temperature heat treatment at 550°C or higher for 3 to 7 hours on a part cooled after a low-temperature heat treatment performed at 190 to 410°C for 1 to 9 hours.

8. In paragraph 7, A method for manufacturing electroless nickel plating parts in which high-temperature heat treatment is performed at a temperature of 600 to 700°C for 4 to 5 hours in a vacuum atmosphere.

9. An electroless nickel plated part manufactured according to any one of clauses 1 to 8.

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