JP2022170877A - METALLIC COMPONENT COMPRISING SUBSTRATE COATED WITH Ag-GRAPHENE COMPOSITE PLATING FILM, AND METHOD OF PRODUCING THE SAME - Google Patents

Abstract

To provide a component comprising a substrate coated with an Ag-graphene composite plating film improved in both electroconductivity and abrasion resistance relative to a silver-plating film.SOLUTION: A component 10 comprising a substrate 2 coated with an Ag-graphene composite plating film 1, is characterized in that the size of graphene 8 dispersed in the Ag-graphene composite plating film 1 is from 0.05 to 6 μm, the content of the graphene 8 is from 3.0 to 30 at%, and the arrangement direction of the graphene 8 in the Ag-graphene composite plating film 1 is vertical to, parallel to, or tilted to the substrate 2.SELECTED DRAWING: Figure 11

Description

The present invention relates to an Ag-graphene composite plating film metal part and a method for producing the same.

Against the background of consideration for the global environment, the spread of EV/PHV has progressed rapidly in place of fossil fuel vehicles, and precious metal pure silver (Ag) plated materials with the highest conductivity among all metals are used for power saving. demand is increasing. However, since Ag is soft and easily adheres, wear resistance is low. Graphene is more conductive than silver and has excellent lubricity and thermal stability.

Patent Document 1 describes a silver-plated material that achieves both high hardness and low electrical resistance by using graphene oxide in addition to a curing agent. Further, Patent Document 2 describes an electrical contact material containing 0.1% by mass or more and 6% by mass or less of silver or copper, graphite, calcium or the like, and having a relative density of 97% or more.

On the other hand, in Non-Patent Document 1, an ethanol solution containing graphene is dripped on a silver plate and dried, and an abrasion test is performed with a silver-plated material to reduce the friction coefficient of the silver plate to 1/10 using graphene as a lubricant. It is described that it can be greatly reduced. In Non-Patent Document 2, a commercial graphene sheet is added to a silver plating solution, and a silver-graphene plating having an uneven surface is formed by electroplating. It is described to exhibit a lower coefficient of friction and corrosion current than silver plating in wear tests.

The conventional technique is a method of improving wear resistance mainly by hardening Ag plating, but the conductivity is lowered and the effect of improving wear resistance is limited. Attempts have been made to form composites with solid lubricants such as MoS ₂ , graphite, and non-metallic materials such as Teflon (registered trademark) particles, but there has been the problem of eventually causing a decrease in conductivity. On the other hand, the inventor has already developed a hybrid plating technique to create Ag-graphene composite plating, and has greatly improved wear resistance while maintaining conductivity (Patent Document 3).

JP 2018-199839 A JP 2015-99839 A Japanese Patent Application No. 2019-196958

“Graphene as a lubricant on Ag for electrical contact applications”, Fang Mao, Urban Wiklund, Anna M. Andersson, Ulf Jansson. Journal of Materials Science, vol.50, pp.6518-6525,2015. “Performance studies of Ag, Ag-graphite, and Ag-graphene coatings on Cu substrate for high-voltage isolation switch”, Wang Yan Lv, Ke Qin Zheng, Zeng Guang Zhang, Materials and Corrosion,vol.69. pp.1847- 1853, 2019.

However, the conductivity of the Ag-graphene composite plating film has a problem that has not been improved compared to the pure silver plating, and there is room for further improvement in its wear resistance. In particular, there has been a problem that improvement in both conductivity and wear resistance has not yet been achieved.

(1) A metal part having a substrate coated with an Ag-graphene composite plating film, wherein the size of the graphene dispersed in the Ag-graphene composite plating film (graphene size) is 0.05 to 6 μm, The content of graphene (graphene content) is 3.0 to 30 at%, and the orientation of the graphene in the Ag-graphene composite plating film is at least selected from perpendicular, parallel, and oblique to the substrate. A metal part characterized in that there is only one
The balance of the Ag-graphene composite plating film is Ag and unavoidable impurities.
(2) The metal part according to (1), wherein the Ag-graphene composite plating film has an electrical contact resistance of 0.1 to 0.7 mΩ.
(3) The wear coefficient for the Ag-graphene composite plating film is 0.1 to 0.4, and the wear amount is reduced to 1/10 to 1/30 (1) or (2) It is a metal part described in.
(4) The metal part according to any one of (1) to (3), wherein the Ag-graphene composite plating film has a Vickers hardness of 80 HV or more.
(5) The metal part according to any one of (1) to (4), which is used as an on-vehicle terminal/charging connector or a power transmission part.
(6) A method for manufacturing a metal component having a substrate coated with an Ag-graphene composite plating film, wherein the plating solution containing Ag and graphene is supplied substantially perpendicularly to the surface of the substrate to be plated. The plating solution flows in a direction (so-called coaxial stirring), convects in a substantially horizontal direction on the plating target surface (so-called torsional stirring), or flows in a substantially horizontal direction on the plating target surface (so-called orthogonal shaft stirring). A method of manufacturing a metal component, comprising electroplating the substrate with a plating solution containing a plating solution.
(7) The method for manufacturing metal parts according to (6), wherein the electric field strength (current density) during the electroplating is 0.1 A/dm ² to 10 A/dm ² .

The present invention also provides improved conductivity not achieved in the prior art. In particular, it is possible to consciously control conductivity and wear resistance (lubricity) in a well-balanced manner, and it is possible to provide various plating specifications depending on the actual terminal mounting location, that is, metal parts with such plating specifications.

(a) Manufacturing method for coating a Cu substrate with an Ag-graphene composite plating film by electroplating, (b) Schematic diagram of four typical aspects of a Cu substrate coated with an Ag-graphene composite plating film by the manufacturing method , respectively. FIG. 2 is a diagram schematically showing electrode arrangement, liquid flow, and agitating methods such as coaxial agitation and torsional agitation during electroplating. When using a commercially available non-cyanide silver plating solution A (general Ag plating), factors affecting conductivity by electrical contact resistance measurement FIG. 3 shows the effect of density, (c) the effect of stirring method and current density (graphene size 3 to 5 μm), and (d) the effect of current density (graphene size 3 to 5 μm, coaxial stirring). When using a commercially available cyanide-free silver plating solution B solution, the influence of stirring intensity on the conductivity (electrical contact resistance) of the Ag-graphene composite plating film was investigated with graphene size and stirring method as influencing factors (a) graphene size with coaxial stirring is 1 to 3 μm, (b) the graphene size is 6 μm or less by coaxial stirring (mixing), (c) the graphene size is 1 to 3 μm by torsional stirring, and (d) the graphene size is 6 μm or less by torsional stirring (mixing). , respectively. Regarding the effect of graphene size on wearability by sliding wear test (a1), (a2) pure Ag plating film (plating solution B, hard Ag plating), (b1), (b2), Ag-graphene composite plating film ( Graphene size of 1 μm or less), (c1), and (c2) Ag-graphene composite plated films (graphene size of 3 to 5 mm). Regarding the results of the sliding friction test, the cases of (a1) to (a4) pure Ag (plating solution A) and (b1) to (b4) Ag-graphene (graphene size 1 to 3 μm, agitation strength of torsional agitation of 6) are shown. Fig. 3 shows. Regarding the effect of graphene size on hardness (Vickers hardness) by microhardness measurement (a) Schematic diagram of microhardness measurement, (b) graphene size 3 to 5 μm or 1 μm with torsional stirring, (c) graphene size 3 with coaxial stirring It is a figure showing the case of ~5 μm and 1 μm, respectively. As the Ag plating solution, A solution (general Ag plating solution) was used. Regarding the effect of graphene size on hardness (Vickers hardness) by microhardness measurement, using Ag plating solution B (hard Ag plating solution), when the graphene size is 1 to 3 μm, (a) coaxial stirring and (b) torsion 4A and 4B are diagrams each showing a case of plating by stirring; FIG. FIG. 4 is a diagram showing the influence of graphene size on the pinning effect in the case of (a) graphene size of 1 μm or less and (b) graphene size of 3 to 5 μm. FIG. 2 shows the effect of current density on the bonding state of carbon in an Ag-graphene composite plating film by (a) Raman spectroscopic measurement and (b) plating film composition by EDS analysis, respectively. (a) TEM image of graphene in an Ag-graphene composite plated film during torsional stirring, (b) a schematic diagram of (a), respectively.

BEST MODE FOR CARRYING OUT THE INVENTION Hereinafter, embodiments of the present invention will be described with reference to the drawings. The present invention is not limited to the following embodiments, and changes, modifications, and improvements can be made without departing from the scope of the invention.

FIG. 1(a) shows a manufacturing method for coating a Cu substrate with an Ag-graphene composite film by electroplating, and FIG. 1(b) shows four representative aspects of Ag-graphene composite film plating by the manufacturing method. are shown respectively. A Cu substrate is coated with an Ag-graphene composite plating film 1 . Therefore, a metal component having a Cu substrate has a substrate coated with the Ag-graphene composite plating film 1 .
Graphene flakes, or graphene, can be produced by electrolytic exfoliation. Note that electrolytic delamination is decomposing graphite in layers under a high electric field.

As shown in FIG. 1(b), depending on the dispersion state of graphene in the Ag matrix in the Ag-graphene composite plating film 1, the Ag-graphene composite plating film 1 can provide various performances to the metal terminals. can. Electricity flows easily along the graphene sheet, so when mating with a mating terminal on the top and bottom, a metal terminal coated with Ag-graphene composite plating film (Ag-graphene composite plating film coated metal terminal) has high conductivity. To achieve this, it is preferable to select a high-conductivity specification such as (2). On the other hand, in order to obtain a highly lubricated Ag-graphene composite plating film-coated metal terminal, it is preferable to select a high lubrication specification such as (3) so that the graphene easily slides on the copper substrate. Further, since graphene has high strength in the direction parallel to the sheet, it is preferable to arrange the graphene sheet obliquely on the Ag film in a zigzag manner to select high-strength specifications such as (4). In this case, both conductivity and lubricity can be improved.

The conditions for electrolytic stripping were as follows. Laminated graphene flakes were fabricated by immersing graphite in an aqueous solution and decomposing the graphite into layers by strong electric field action and electrochemical reaction. The decomposed layered graphene was divided into the following graphene sizes by classification. The graphene sizes were 1 μm or less, 1 to 3 μm, 3 to 5 μm, and a mixture of 6 μm or less. In addition, the graphene size was classified by the mesh of the filter paper used at the time of filtration.

A silver plating solution L to which a graphene dispersion is added is put into the plating tank 5 of the electroplating apparatus 20 shown in FIG. ) 3 was vertically immersed and energized to perform electroplating on the object to be plated. The silver plating solution L can be forced to flow by means of, for example, a stirrer, a propeller, or the like. If, for example, the stirrer causes the silver plating solution L to flow in the direction r1 at the bottom of the plating tank 5, the direction of flow is horizontal (parallel to the bottom of the plating tank 5). At this time, the silver plating solution L contains the silver plating solution L that contacts the plating target surface 4 of the Cu alloy substrate 2 from the horizontal direction. In this case, the flow axis x1, such as r1, is vertical and can be said to be "coaxial" with the vertical axes x3 and x4 of the Cu alloy substrate 2 and the counter electrode 3, respectively. In other words, the agitation method that causes such delamination (flow) is called coaxial agitation.

On the other hand, if forced convection in the directions of r2 and r2' is generated in the silver plating solution L on the side surface of the plating tank 5 by a stirrer, for example, the direction of the flow will be vertical. At this time, the silver plating solution L contains the silver plating solution L that contacts the plating target surface 4 of the Cu alloy substrate 2 from the vertical direction. In this case, the flow axis x2 such as r2, r2' is horizontal, and x2 can be said to be an "orthogonal axis" orthogonal to the vertical axes x3, x4 of the Cu alloy substrates 2, 3. . In other words, the method of stirring that causes such a flow (flow) can be said to be "(cross-axis stirring).
Further, the case where the direction of flow such as r2 and the direction of flow such as r2' are opposite to each other can be called a "torsion axis". In other words, a stirring method that causes such a flow (convection) is called torsion shaft stirring (sometimes referred to as “torsion stirring”).

A Cu alloy substrate (20×60×0.3 mm) was prepared as a starting sample for the copper shown in FIG. 1(b). Alkaline electrolytic degreasing and pickling for the purpose of removing an oxide film were performed on the Cu alloy substrate as pretreatments, and the substrates were thoroughly washed after each pretreatment. Two types of commercially available non-cyanide Ag plating solutions (Ag 30 g/L) were used for Ag plating. Graphene was prepared from graphite (graphite) by electrolytic exfoliation and dispersed ultrasonically using an organic dispersant. The prepared graphene dispersion was added to the Ag plating solution (graphene dispersion/Ag plating solution=20 mL/L) to obtain an Ag-graphene plating solution.
Tables 1 and 2 summarize the manufacturing conditions of the manufactured sample (Ag-graphene composite plating film-coated Cu substrate (Example)) and their respective measured values. Table 3 shows the manufactured samples (Ag-plated film-coated Cu substrate (comparative example), various Ag-plated materials for commercially available vehicle-mounted terminals and charging connectors, and thick Ag-plated materials for power transmission switches (comparative example), and their respective measurements. The values are summarized, and a description of those tables is also added below.

(Electrical contact resistance measurement)
By the electrical contact resistance measurement as shown in the schematic diagram shown in FIG. ) was investigated.
The conditions, etc. for the electrical contact resistance measurement were as follows. Conditions: Load variation type (0 to 0.5 to 0N, with sliding), sliding type (value at load 0.5N), measuring device: electric contact resistance measuring instrument (electric contact simulator CRS-1 type). The mating terminal was 24K gold wire and the fixed terminal was 18K gold plated.
Figures 3(b) to (d) show the electrical contact resistance measurement results of composite plating films obtained using the Ag plating solution A, and Figures 4(a) to (d) show the results of measuring the electrical contact resistance of the composite plating film using the Ag plating solution B. dynamic formula).

From FIG. 3(b), it was found that all of the Ag-graphene composite plating films (Examples 1 to 8) had lower electrical contact resistance than the pure Ag plating film (Comparative Example 1), that is, had better conductivity. In addition, the composite of graphene with a graphene size of 3 to 5 μm had better conductivity than the composite of graphene with a size of 1 μm or less.

From FIG. 3(c), it was found that all the Ag-graphene composite plating films (Examples 9 to 12) had lower electrical contact resistance than the pure Ag plating film (Comparative Example 1), that is, had better conductivity. In particular, coaxial stirring is more effective in improving electrical conductivity than torsional stirring.

From FIG. 3(d), all of the Ag-graphene composite plating films (Examples 13-17) have lower electrical contact resistance than the pure Ag plating film (Comparative Example 1), and the higher the current density, the more pronounced the contact resistance. It was found that the conductivity was greatly improved. Moreover, the resistance value was lowered by 59% at maximum compared to the pure Ag plating film (Example 17). Also, in any case, it was found that an increase in the current density has a large effect of improving the conductivity.

As shown in FIGS. 4A to 4D, even when the silver plating solution B solution was used, the conductivity was improved in the Ag-graphene composite plating films under all conditions (Examples 18 to 29). I was able to confirm. That is, the electrical contact resistance was 42 to 71% with respect to the pure Ag plating film of Comparative Example 2 by combining the stirring intensity, stirring method, and graphene size.

(Sliding wear test)
A pure Ag plating film (Comparative Example 1), Ag-graphene composite plating film (graphene size 1 μm or less), (Ag-graphene composite plating film (graphene size 3 to 5 μm) was investigated.
The conditions, etc. of the sliding wear test were as follows. Conditions: load 3 N, frequency 1 Hz, sliding distance 500 μm, measuring device: precision wear friction tester (CRS-B type), mating material (emboss):
R=3 mm, commercially available general Ag plating material (80HV), Ag plating film: 5 μm, with Ni plating base. Two measurements were made for each sample.
In addition, the wear marks were photographed using a white laser microscope to produce a three-dimensional image. Subsequently, using the digital data of the three-dimensional image, the unworn portion was used as a reference surface, and the amount of adhesive wear was calculated for the portion above the reference surface, and the amount of scraping wear was calculated for the portion below the reference surface. Furthermore, the wear amount of the entire sample was calculated by adding the adhesive wear amount and the shaving wear amount.

5(a1) to (c1) respectively show pure silver plating (Comparative Example 2), graphene size of 1 μm or less (Example 7) and Ag-graphene composite plating film of 3 to 5 μm (Example 11). The correlation between the number of times and the coefficient of friction was shown. The results of each duplicate measurement were graphed. The pure silver plating shown in (a1) has a high friction coefficient of 0.6 to 0.9 due to adhesion, but the Ag-graphene composite plating film of (c1) with a thickness of 3 to 5 μm has little adhesion in the initial stage of wear, and is in a stable region. The coefficient of friction was as low as 0.28 to 0.32, which was about 62% lower than that of pure Ag plating.

In addition, when viewed from the three-dimensional images of the laser microscope shown in FIG. 5 ((a2) to (c2), the pure Ag plating film has severe uneven wear marks, but the Ag-Graphene composite plating film has almost no wear marks. In particular, from the three-dimensional image described above, the amount of adhesive wear and scraping wear were calculated, the wear amount of the entire sample was calculated, and the two measured values were averaged. 2. The wear amounts of Examples 7 and 11 were 167×10 ⁴ μm ³ , 116.0×10 ⁴ μm ³ and 5.9×10 ⁴ μm ³ respectively. Comparing the wear amount of Example 11 with the wear amount of the pure Ag plating film, 116.0×10 ⁴ μm ³ /167×10 ⁴ μm ³ =1/1.42, and 5.9×10 ⁴ μm ³ . /167×10 ⁴ μm ³ =1/28.3, which is less than 1/28.It was found that combining graphene with a graphene size of 3 to 5 μm provides the best wear resistance.

(For charging connector)
Example 25 and the pure Ag plating film (Comparative Example 2) for charging connectors were subjected to the same sliding wear test as in FIG. measured and calculated the amount of wear).
FIG. 6(a1) shows a graph of the friction coefficient and the number of times of wear measured twice with respect to the pure Ag plating film (Comparative Example 2). (a2) is a laser microscope photograph of the plating state after the sliding wear test, (a3) is a three-dimensional laser microscope image, and (a4) is the surface 15 that is not rubbed in (a2). Levels of the surface to be plated 16 after the sliding wear test as a reference surface are shown respectively. Then, the wear amount of the entire sample was calculated for the wear marks in the same manner as described above.

FIG. 6(b1) shows a graph of the friction coefficient and the number of abrasions measured twice for the Ag-graphene composite plating film (Example 25). (b2) is a laser microscope photograph of the plating state after the sliding wear test, (b3) is a three-dimensional laser microscope image, (b4) is the surface that is not rubbed in (b2). The level of the surface to be plated 18 after the sliding wear test with reference surface 17 is shown. Then, the wear amount of the entire sample was calculated for the wear marks in the same manner as described above.

From the comparison between FIGS. 6(a1) and (b1), the pure Ag plating film (Comparative Example 2) is generally unstable and the frictional force is large, while the Ag-graphene composite plating film (Example 25) is sliding. There was a stable region for dynamics. The coefficient of friction in the stable region is as low as 0.26, which is about 61% lower than pure Ag plating.
From the comparison of FIGS. 6(a2) and (a4) with (b2) and (b4), it is clear that the Ag-graphene composite plating film (Example 25) is more damaged by abrasion than the pure Ag plating film (Comparative Example 2). The wear amount ratio was 13×10 ⁴ μm ³ /167×10 ⁴ μm ³ =1/10.5, which was 1/10 or less.

Also, (a4) and (b4) show the profile of surface roughness across the wear scar. The pure Ag plating film shown in (a4) is shaved by 6.49 μm from the reference plane of the dotted line of the unworn portion and is deeper than the thickness (5 μm) of the plating film, but the Ag-graphene composite plating shown in (b4) The film has a thickness of 2.51 μm even at the maximum portion, indicating that the Ag-graphene composite plating film is less likely to be worn.

(Microhardness measurement)
By microhardness measurement such as the schematic diagram shown in FIG. 1 μm was investigated.
The conditions for microhardness measurement (Vickers hardness) were as follows. Conditions: Load: 490.3 mN, Holding time: 20 sec, Measuring device: Vickers hardness tester (HMV-1 ADW J)

From FIGS. 7B and 7C, it was found that the graphene of 1 μm or less is at the same level as the pure Ag plating film, and the graphene of 3 to 5 μm is 1.2 times harder than the pure Ag plating film.
In FIG. 8, when using a commercially available hard Ag plating solution (solution B) and adding 1 to 3 μm graphene, (a) coaxial stirring, (b) torsional stirring, the stirring strength is the hardness of the composite plating film. This is the result of examining the influence on In any case, it was found that the Ag-graphene composite plating was about 1.2 times harder than the hard Ag plating film when the stirring intensity was set to a weak strength of 4 or higher. That is, it was found that the Ag plating film was hardened by compositing with graphene.
As shown in FIGS. 9(a) and 9(b), the size of graphene affects how the pinning effect works. It is considered that the pinning effect is higher than that of (a)) and the hardness is increased. Note that the pinning effect is an effect of hardening the Ag matrix by connecting a plurality of crystals of the Ag matrix with one graphene.

Examples 1 to 17 of general Ag plating system and Examples 18 to 29 of hard Ag plating system, Comparative Examples 3 to 6 (Ag plating materials for automotive terminals (Company C to Company D)) and Comparative Examples 7 to 9 ( When Ag-plated materials for power transmission switches (Company F to Company H) are compared, all contact resistances of the examples of the present invention are lower than those of Comparative Examples 1 to 9, and higher conductivity than current products can be realized. Also, the Vickers hardness of the composite plating film was about 1.2 times harder than the pure Ag plating of Comparative Examples 1 and 2 by optimizing the plating conditions, and it was found that both high conductivity and hardening were achieved.

(Raman spectrometry, EDS analysis)
FIG. 10 shows the results of examining the effect of current density on the chemical composition of the Ag-graphene composite plated film (graphene size 3 to 5 μm) by (a) Raman spectrometry and (b) EDS analysis. .
In (a), the D-band is derived from defects, the G-band indicates the presence of sp ² bonds of C atoms, and the 2D-band is derived from Graphene. 16 and Example 17, the presence of graphene was confirmed.
Regarding Raman spectroscopy, model name: laser Raman spectrophotometer (NRS-3300), measurement range: 254.896 cm ^-1 to 3899.87 cm ^-1 , center wave number: 2301.01 cm ^-1 , excitation wavelength: 532.08 nm, Laser intensity: 7.9 mW. The EDS analysis was as follows. Acceleration voltage: 15 kV, magnification of photograph: 2000 times Analysis was performed in the entire area.

From FIG. 10(b), it can be seen that there is no change in the composition of the plating film (atomic concentration of carbon: 11.6 to 13.7 at.%) for similar Examples 13 to 17 even at high current densities. - It is possible to produce graphene composite plating film at high speed. On the other hand, in general composite plating, metal deposition takes precedence at high current densities, and there is a problem that the amount of composite decreases.

The graphene size is preferably 6 μm or less so that it does not protrude on the plating surface from the viewpoint of not exceeding the thickness (5 μm) of the plating film for automobile terminals and connectors, and 1 μm from the viewpoint of improving both the hardness and conductivity of the plating film. ~6 μm is more preferred. The content of graphene dispersed in the Ag-graphene composite plating film is 3.0 at% to 30 at%, preferably 5 at% to 25 at%, more preferably 8 at% to 20 at%, from the viewpoint of wear resistance and conductivity. . The temperature of 40° C. of the silver plating solution during electroplating is an example, and can be appropriately changed depending on the type of plating solution (for example, cyanide bath and various non-cyanide baths).

The electrical contact resistance of the Ag-graphene composite plating film should be as low as possible from the viewpoint of reducing power consumption, but in consideration of wear resistance and mechanical strength (hardness), it is preferably 0.1 mΩ to 0.7 mΩ. 0.1 mΩ to 0.6 mΩ is more preferred, and 0.1 mΩ to 0.4 mΩ is even more preferred.
The wear coefficient for the Ag-graphene composite plating film should be as low as possible from the viewpoint of extending the life of the connector, preferably 0.4 or less, and the wear amount is reduced to 1/10 to 1/30 compared to the current product is preferred.
The Vickers hardness of the Ag-graphene composite plating film is preferably 80 HV or more, more preferably 100 HV or more, more preferably 120 HV or more, compared to the current general Ag plating, considering the conductivity of the plating film and the aggressiveness to the wear partner material. preferable. In the case of hard Ag plating (adding antimony Sb or bismuth Bi), it is preferable that the hard Ag plating is higher than the current hard Ag plating of 120 HV and up to 300 HV, more preferably from 140 HV to 200 HV.

FIGS. 11(a1) and (b1) show images observed with a transmission microscope after FIB processing in the direction perpendicular to the coaxial stirrer and torsion stirrer substrate, respectively. (a2) and (b2) show schematic diagrams thereof. When the stirring method was coaxial stirring (Example 3), the distribution of graphene in the Ag-graphene composite plating film included graphene arranged substantially parallel to and oblique to the Cu substrate. On the other hand, when the stirring method was torsional stirring (Example 11), the distribution of graphene in the Ag-graphene composite plating film included graphene that was substantially perpendicular to the Cu substrate and perpendicular to it. In the case of coaxial stirring, the graphene sheets were arranged parallel to and oblique to the substrate, so it was found to be more preferable from the results of the electrical contact resistance, friction coefficient, and hardness described above. On the other hand, it was found that the glossiness and uniformity of the plating film were superior in the case of torsional stirring.

In addition, a comparison with the electrical contact resistance of current commercially available Ag-plated materials for automobile terminals and connectors (Comparative Examples 3 to 6) revealed that the Ag-graphene composite plating film of the present invention had a conductivity of 2.0% higher than that of the commercially available products. It was found to be 5-fold (0.72/0.29) to 5.9-fold (1.7/0.29) higher.

Furthermore, when compared with the electrical contact resistance of the current Ag-plated materials for power transmission parts (Comparative Examples 7 to 9), the Ag-graphene composite plating film in the present invention has 2.9 times the conductivity (0 .83/0.29) to 4.8 times (1.40/0.29) higher.
From the above, it was confirmed that the Ag-graphene composite plating film of the present invention has significantly improved both conductivity and wear resistance for use in automobile terminals/connectors and power transmission parts. As a result, on the premise of ensuring product quality, the amount of Ag used can be significantly reduced compared to current products, and it is believed that the reduction in power consumption will have a large ripple effect on the construction of a clean society.

With the advancement of electronic control due to the progress of automated driving of automobiles, there is a demand for higher performance and higher durability of terminals for connecting wire harnesses and various electronic devices. In addition, further expansion of EV/PHV is expected, and it is believed that there is a strong need for high performance and high durability of connectors for charging devices. In addition, it can be used as a plated material with higher conductivity and higher abrasion resistance to reduce power loss in high-voltage/high-current power transmitter switches that supply electricity.

1, 11: Ag-graphene composite plating film 2: Cu alloy substrate (cathode)
3: counter electrode (anode, silver plate)
4: Plating target surface 5: Plating tanks 15, 17: Non-friction surfaces 16, 18: Surface to be plated after sliding wear test 20: Electroplating apparatus L: Silver plating solution r1: Horizontal direction of silver plating solution Direction of flow r2, r2′: direction of flow in the vertical direction of the silver plating solution x1: axis of flow x2 such as r1: axis of flow x3, x4 such as r2, r2′: axis of flow in the vertical direction of the Cu alloy substrate shaft

Claims (7)

A metal part having a substrate coated with an Ag-graphene composite plating film, wherein the size of the graphene dispersed in the Ag-graphene composite plating film (graphene size) is 0.05 to 6 μm, and the graphene content The amount (graphene content) is 3.0 to 30 at%, and the arrangement direction of the graphene in the Ag-graphene composite plating film is at least one selected from perpendicular, parallel, and oblique to the substrate. Metal parts characterized by being one. 2. The metal part according to claim 1, wherein the Ag-graphene composite plating film has an electrical contact resistance of 0.1 to 0.7 mΩ. The metal according to claim 1 or 2, wherein the friction coefficient of the Ag-graphene composite plating film is 0.1 to 0.4, and the wear amount is reduced to 1/10 to 1/30. parts. 4. The metal part according to claim 1, wherein the Ag-graphene composite plating film has a Vickers hardness of 80 HV or more. 5. The metal part according to any one of claims 1 to 4, which is used for automobile terminals, charging connectors or power transmitter switches. A method for manufacturing a metal component having a substrate coated with an Ag-graphene composite plating film, wherein the plating solution containing Ag and graphene is supplied in a direction substantially perpendicular to the surface of the substrate to be plated. Any plating solution that flows (so-called coaxial stirring), convects substantially horizontally on the surface to be plated (so-called torsional stirring), or flows substantially horizontally on the surface to be plated (so-called orthogonal axis stirring). and electroplating the substrate with the plating solution. 7. The method for manufacturing metal parts according to claim 6, wherein the electric field strength (current density) during the electroplating is 0.1 A/dm ² to 10 A/dm ² .

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