Composite material, method for producing composite material, terminal, and method for producing terminal

Abstract

Provided is a composite material in which a composite film comprising a silver layer containing metal sulfide particles is formed on a blank, and the value (X) obtained by dividing the arithmetic average roughness (Ra) of the composite film by the thickness ([mu] m) of the composite film is 0.14 or less.

Description

Technical Field

[0001] The present invention relates to a composite material formed by forming a predetermined composite film on a blank and a method for producing the same, and in particular to a composite material used as a material for sliding contact parts such as switches and connectors and a method for producing the same. Background Art

[0002] Conventionally, silver (Ag)-plated materials, which are made of copper (Cu) or Cu alloys, have been used as materials for sliding electrical contact components such as switches and connectors to prevent oxidation of the conductor material caused by heat during sliding.

[0003] However, silver plating is soft and easily wears away, and generally has a high coefficient of friction, making it prone to peeling due to sliding. To address this issue, a method has been proposed for improving wear resistance by forming a composite material coating on a conductor blank using electroplating. The composite material coating is formed by dispersing graphite particles, such as carbon particles such as graphite and carbon black, which have excellent wear resistance and lubricity, in a silver matrix (see, for example, Patent Documents 1 to 3). It should be noted that Patent Document 3 generally states that, in addition to carbon particles, particles composed of molybdenum disulfide, tungsten disulfide, boron nitride, or graphite fluoride can also effectively improve wear resistance.

[0004] In addition, as another composite material with excellent wear resistance, Patent Document 4 discloses a terminal material for a connector, which has the following characteristics: it is a terminal material formed by forming an antimony-containing silver plating layer on a substrate at least the surface of which is composed of copper or a copper alloy, and the average crystal grain size of the aforementioned silver plating layer is greater than 0.1 μm and less than 2.0 μm.

[0005] As a material having better wear resistance than the composite materials described above, Patent Document 5 discloses a composite material in which a composite coating composed of a silver layer containing carbon particles is formed on a blank, wherein the silver crystallite size of the composite coating is 40 nm or less.

[0006] Prior art literature

[0007] Patent Literature

[0008] Patent Document 1: Japanese Patent Application Laid-Open No. 9-7445

[0009] Patent Document 2: Japanese Patent Application Laid-Open No. 2007-16250

[0010] Patent Document 3: Japanese Patent No. 2018-1023347

[0011] Patent Document 4: Japanese Patent No. 2020-105551

[0012] Patent Document 5: International Publication No. 2021 / 261066 Summary of the Invention

[0013] Problems to be solved by the invention

[0014] However, the composite material disclosed in Patent Document 5 has numerous nodular electrodeposited structures, believed to be composed of silver, on the surface of the composite coating. These nodules are weakly bonded to the surrounding tissue (the silver matrix constituting the composite coating) and are easily detached by external stress. Therefore, when users use the composite material (e.g., during bending), these nodules could become contaminants and contaminate equipment.

[0015] The present invention has been made under the above circumstances, and an object of the present invention is to provide a composite material having practically sufficient wear resistance and suppressing the shedding of silver from the composite coating during bending, and a method for producing the same.

[0016] Solutions for solving problems

[0017] The present inventors conducted intensive research to solve the above-mentioned problems and found that if a blank is electroplated using a silver plating solution containing metal sulfide particles, a composite coating with fewer protrusions and suppressed nodule formation can be formed. The present invention was completed by discovering that a composite material having this composite coating can solve the above-mentioned problems.

[0018] That is, the present invention is as follows.

[0019] [1] A composite material comprising a composite coating comprising a silver layer containing metal sulfide particles formed on a blank, wherein the value X obtained by dividing the arithmetic mean roughness Ra (μm) of the composite coating by the thickness (μm) of the composite coating is not more than 0.14.

[0020] [2] The composite material according to [1], wherein the metal sulfide constituting the metal sulfide particles is at least one selected from the group consisting of molybdenum sulfide, tungsten sulfide, and tin sulfide.

[0021] [3] The composite material according to [1] or [2], wherein the silver crystallite size of the composite coating is 62 nm or less.

[0022] [4] The composite material according to any one of [1] to [3], wherein the mass ratio of the metal sulfide particles on the surface of the composite coating, as determined by energy dispersive X-ray analysis of the surface of the composite coating, is 1.0 to 50% by mass.

[0023] [5] The composite material according to any one of [1] to [4], wherein the blank is made of copper or a copper alloy.

[0024] [6] The composite material according to any one of [1] to [5], wherein the metal sulfide constituting the metal sulfide particles is at least one selected from the group consisting of MoS2 and WS2.

[0025] [7] The composite material according to any one of [1] to [6], wherein the thickness of the composite film is 0.5 to 45 μm.

[0026] [8] The composite material according to any one of [1] to [7], wherein the content of the metal sulfide particles in the composite film is 0.5 to 30% by mass.

[0027] [9] The composite material according to any one of [1] to [8], wherein the silver crystallite size of the composite coating is 62 nm or less, and the value X is 0.088 or less.

[0028]

[10] The composite material according to any one of [1] to [9], wherein the content of the metal sulfide particles in the composite film is 2.5 to 10% by mass, and the metal sulfide constituting the metal sulfide particles is molybdenum sulfide.

[0029]

[11] A method for producing a composite material, wherein electroplating is performed in a silver plating solution containing metal sulfide particles, thereby forming a composite coating composed of a silver layer containing the metal sulfide particles on a blank.

[0030]

[12] The method for producing a composite material according to

[11] , wherein the blank is made of copper or a copper alloy.

[0031]

[13] The method for producing a composite material according to

[11] or

[12] , wherein the silver plating solution contains a compound A represented by the following general formula (I):

[0032]

[0033] (In formula (I), m is an integer from 1 to 5, R 1 is carboxyl, R 2 is aldehyde, carboxyl, amino, hydroxyl or sulfonic acid, R 3 is hydrogen or any substituent, when m is 2 or more, multiple R 2 When m is 3 or less, the presence of multiple R 3 are optionally the same as or different from each other, R 1 and R 2 Each of the two groups is optionally independently bonded to the benzene ring via a divalent group, wherein the divalent group is composed of at least one selected from the group consisting of -O- and -CH2-.

[0034]

[14] The method for producing a composite material according to any one of

[11] to

[13] , wherein the metal sulfide constituting the metal sulfide particles is at least one selected from the group consisting of molybdenum sulfide, tungsten sulfide, and tin sulfide.

[0035]

[15] The method for producing a composite material according to any one of

[11] to

[14] , wherein the volume-based cumulative 50% particle size (D50) of the metal sulfide particles measured using a laser diffraction / scattering particle size distribution analyzer is 0.5 to 15 μm.

[0036]

[16] The method for producing a composite material according to any one of

[11] to

[15] , wherein the metal sulfide constituting the metal sulfide particles is at least one selected from the group consisting of MoS2 and WS2.

[0037]

[17] A terminal using the composite material described in any one of [1] to

[10] as its constituent material.

[0038]

[18] A method for manufacturing a terminal, comprising processing the composite material according to any one of [1] to

[10] into the shape of a terminal.

[0039] Effects of the Invention

[0040] According to the present invention, there are provided a composite material having practically sufficient wear resistance and suppressing the loss of silver from a composite coating during bending, a method for producing the composite material, and related technologies. BRIEF DESCRIPTION OF THE DRAWINGS

[0041] Figure 1 This is a schematic cross-sectional view for explaining a silver shedding evaluation test during bending in Examples. DETAILED DESCRIPTION

[0042] Hereinafter, embodiments of the present invention will be described.

[0043] [Method for producing composite materials]

[0044] An embodiment of the present invention's method for producing a composite material involves forming a composite coating comprising metal sulfide particles in a silver layer on a blank by electroplating in a silver plating solution containing metal sulfide particles. The various components of this composite material production method are described below.

[0045] <<Blank>>

[0046] The constituent material of the blank on which the composite coating is formed is preferably a material that can be silver-plated and has the conductivity required for materials of sliding contact components such as switches and connectors. Furthermore, from a cost perspective, Cu (copper) and Cu alloys are preferred. The aforementioned Cu alloy, from the perspective of balancing conductivity and wear resistance, is preferably an alloy composed of the following components: Cu; at least one selected from the group consisting of Si (silicon), Fe (iron), Mg (magnesium), P (phosphorus), Ni (nickel), Sn (tin), Co (cobalt), Zn (zinc), Be (beryllium), Pb (lead), Te (tellurium), Ag (silver), Zr (zirconium), Cr (chromium), Al (aluminum), Ti (titanium), B (boron), Li (lithium), and Bi (bismuth); and unavoidable impurities. The amount of Cu in the Cu alloy is preferably 85% by mass or more, more preferably 92% by mass or more (the amount of Cu is preferably 99.95% by mass or less).

[0047] As described later, the blank is preferably used for a terminal (as a composite material with a composite coating formed thereon), but sometimes the blank itself has a shape suitable for such a purpose, and sometimes the blank is still in a flat shape (such as a flat plate shape) and is then formed into the shape of the intended purpose after forming the composite material. From the perspective of achieving the effects of the present invention, the blank is preferably in a flat shape such as a flat plate shape.

[0048] <<Formation of the basal layer>>

[0049] In the manufacturing method of the composite material of the present invention, a base layer can be formed on the blank, and the base layer is subjected to the electroplating described later. The base layer is formed for the purpose of preventing the copper of the blank from diffusing to the surface of the coating and oxidizing to deteriorate the conductivity of the composite material, and for the purpose of improving the adhesion of the composite coating. As the constituent metal of the base layer, there can be mentioned: at least one metal or alloy selected from the group consisting of Cu, Ni, Sn and Ag. It should be noted that the base layer can be a single layer composed of Cu, Ni, Sn, Ag or their alloys; the layer (laminated structure) formed by combining them, for the formation of the base layer, according to the use of the composite material to be manufactured, can be the entire surface layer of the blank, or a part thereof.

[0050] The method for forming the base layer is not particularly limited, and the base layer may be formed by electroplating using a plating solution containing ions of the aforementioned constituent metals using a known method, or by sequentially stacking layers composed of the metals constituting the target alloy layer and then performing reflow (heat treatment).

[0051] <<Ag flash plating>>

[0052] Before forming the composite coating on the blank, a very thin intermediate layer is preferably formed by silver flash plating to improve the adhesion between the blank and the composite coating. It should be noted that when a base layer is formed on the blank, Ag flash plating is performed on the base layer. The Ag flash plating method can be any conventional method without particular limitation, as long as it does not impair the effects of the present invention.

[0053] <<Electroplating>>

[0054] In the method for producing a composite material of the present invention, the above-described blank is electroplated in a specific silver plating solution to form a composite coating containing metal sulfide particles in a silver layer on the blank.

[0055] Silver plating solution

[0056] The silver plating solution contains silver ions and metal sulfide particles, and preferably contains a specific compound A.

[0057] (Silver Ion)

[0058] The silver plating solution contains silver ions. From the perspective of the formation speed of the composite coating and the suppression of uneven appearance of the composite coating, the silver concentration in the silver plating solution is preferably 5 to 150 g / L, more preferably 10 to 120 g / L, and most preferably 20 to 100 g / L.

[0059] (Metal sulfide particles)

[0060] Secondly, the silver plating solution contains metal sulfide particles. If the silver plating solution contains metal sulfide particles, these particles are incorporated into the silver matrix when the composite coating (silver plating) is formed on the blank by electroplating. These metal sulfide particles are substances that exfoliate in layers. If the composite coating contains metal sulfide particles, the wear resistance of the composite material is improved. It should be noted that the amount of metal sulfide exfoliated in layers is very small and does not cause contamination.

[0061] Furthermore, when silver plating is performed using carbon particles and a specific plating solution, as in Patent Document 5, nodular electrodeposited structures are formed as described above. However, when silver plating is performed using metal sulfide particles, as in the present invention, certain changes may occur during the formation of the silver matrix in the plated layer, suppressing the formation of nodular electrodeposited structures. This results in a composite coating with a small arithmetic mean roughness Ra and a value X, obtained by dividing the arithmetic mean roughness Ra by the thickness of the composite coating. This composite coating is extremely resistant to silver shedding during bending. It should be noted that the mechanism for the formation of nodular electrodeposited structures is believed to be that electricity is applied to a portion of the carbon particles, causing silver to precipitate on these particles, which then grows and forms nodules. Metal sulfide particles have a higher electrical resistance than carbon particles, making it less likely that electricity is applied to the metal sulfide particles. As a result, it is believed that the formation of nodular electrodeposited structures is less likely to occur.

[0062] From the perspective of wear resistance, the metal sulfide constituting the metal sulfide particles is preferably at least one selected from the group consisting of molybdenum sulfide, tungsten sulfide, and tin sulfide. Furthermore, from the perspective of ease of incorporation into a silver matrix by electroplating, the metal sulfide particles are particularly preferably at least one selected from the group consisting of MoS and WS.

[0063] The volume-based cumulative 50% particle size (D50) of the metal sulfide particles, as measured using a laser diffraction / scattering particle size distribution analyzer, is preferably 0.5 to 15 μm, more preferably 1 to 10 μm, and particularly preferably 3.5 to 10 μm from the perspective of wear resistance. The shape of the metal sulfide particles is not particularly limited to approximately spherical, scaly, or irregular shapes, but is preferably scaly from the perspective of improving the wear resistance of the composite material by smoothing the surface of the composite coating.

[0064] Furthermore, oxidation or alkalization of the metal sulfide particles can remove lipophilic organic matter adsorbed on the particle surfaces. Examples of such lipophilic organic matter include aliphatic hydrocarbons such as alkanes and alkenes, and aromatic hydrocarbons such as alkylbenzenes. Oxidation or alkalization of the metal sulfide particles removes lipophilic organic matter such as aliphatic hydrocarbons and aromatic hydrocarbons from the particle surfaces, thereby enabling a more uniform dispersion of the particles in the silver plating solution used in the present invention and increasing the amount of metal sulfide particles incorporated into the silver plating. Furthermore, it is believed that the compound A, described later, in the silver plating solution can function appropriately. As a result, a composite coating with high hardness and a low coefficient of friction can be formed. Furthermore, by subjecting molybdenum sulfide particles with a D50 of 3.5 to 10 μm to oxidation or alkalization, preferably alkalization, before silver plating, a composite coating with particularly excellent wear resistance can be formed.

[0065] Examples of the oxidation treatment method include wet oxidation. Examples of wet oxidation methods include suspending metal sulfide particles in water and then adding an appropriate amount of an oxidizing agent. Examples of the oxidizing agent include nitric acid, hydrogen peroxide, potassium permanganate, potassium persulfate, and sodium perchlorate.

[0066] Examples of the aforementioned alkalization treatment method include wet alkalization. Examples of wet alkalization methods include methods in which the metal sulfide particles are brought into contact with an alkaline aqueous solution. Specifically, methods include suspending the metal sulfide particles in water and then adding an appropriate amount of an alkaline substance. Examples of alkaline substances include potassium hydroxide, sodium hydroxide, calcium hydroxide, and lithium hydroxide. From the perspective of forming a composite coating with excellent wear resistance, the alkalization treatment is preferably carried out by adding an alkaline substance so that the pH of the water in which the metal sulfide particles are suspended reaches 12 or higher. It is believed that the introduction of hydrophilic groups (e.g., hydroxyl groups) onto the surface of the metal sulfide particles by the alkalization treatment also contributes to dispersibility in the silver plating solution.

[0067] Furthermore, from the viewpoint of the wear resistance of the composite material obtained by forming a composite coating on a blank using a silver plating solution and from the viewpoint that there is a limit to the amount of particles that can be introduced into the composite coating, the amount of metal sulfide particles in the silver plating solution is preferably 10 to 200 g / L, more preferably 25 to 150 g / L, and most preferably 50 to 120 g / L.

[0068] (Compound A)

[0069] Next, the silver plating solution used in the method for producing a composite material of the present invention preferably contains a compound (A) represented by the following general formula (I).

[0070]

[0071] In formula (I), m is an integer of 1 to 5, R 1 is carboxyl, R 2 is aldehyde, carboxyl, amino, hydroxyl or sulfonic acid, R 3 is hydrogen or any substituent, R 1 and R 2 Optionally, each independently bonded to the benzene ring via a divalent group, wherein the divalent group is composed of at least one selected from the group consisting of -O- and -CH2-. Examples of the divalent group include: -CH2-CH2-O-, -CH2-CH2-CH2-O-, (-CH2-CH2-O-) n (n is an integer greater than or equal to 2).

[0072] It is believed that Compound A, by adsorbing on the surface of the deposited silver, inhibits silver crystal growth, thereby reducing the size of silver crystallites in the composite coating formed by electroplating. This results in a composite material with high hardness and excellent wear resistance.

[0073] In the above general formula (I), when m is 2 or more, the presence of multiple R 2 When m is 3 or less, the presence of multiple R 3 are optionally the same as or different from each other. 3 Examples of the aforementioned "optional substituent" include an alkyl group having 1 to 10 carbon atoms, an alkylaryl group, an acetyl group, a nitro group, a halogen group, and an alkoxy group having 1 to 10 carbon atoms.

[0074] From the viewpoint of suppressing uneven appearance of the composite coating and appropriately controlling the size of silver crystallites in the formed composite coating, the concentration of Compound A in the silver plating solution is preferably 2 to 250 g / L, more preferably 3 to 200 g / L.

[0075] (Complexing agent)

[0076] The silver plating solution used in the present invention preferably contains a complexing agent. The complexing agent complexes the silver ions in the silver plating solution, thereby improving their stability as ions. Through this action, the solubility of silver in the solvent constituting the plating solution is increased.

[0077] Conventionally known complexing agents can be used without particular limitation as the complexing agent. However, from the perspective of the stability of the resulting complex, compounds having a sulfonic acid group are preferred. Examples of compounds having a sulfonic acid group include alkylsulfonic acids having 1 to 12 carbon atoms, alkanolsulfonic acids having 1 to 12 carbon atoms, and hydroxyarylsulfonic acids. Specific examples of these compounds include methanesulfonic acid, 2-propanolsulfonic acid, and phenolsulfonic acid.

[0078] From the viewpoint of stabilizing silver ions, the amount of the complexing agent in the silver plating solution is preferably 30 to 200 g / L, more preferably 50 to 120 g / L.

[0079] (Other additives)

[0080] As other additives, for example, the silver plating solution used in the present invention may contain a brightener, a curing agent, and a conductive salt.

[0081] (Solvent)

[0082] The solvent constituting the silver plating solution is mainly water. Water is preferred from the viewpoint of the solubility of the (complexed) silver ions, the solubility of other components contained in the plating solution, and the low environmental load. In addition, a mixed solvent of water and alcohol may also be used as the solvent.

[0083] <Plating Conditions>

[0084] Next, the various conditions for electroplating using the silver plating solution described above will be described. For example, through the electroplating described below, metallic silver is deposited on the blank, and the metal sulfide particles described above are incorporated into the silver matrix to form a composite coating. It should be noted that when a base layer is formed on the blank, the composite coating is formed thereon, while when silver flash plating is performed, the composite coating is formed on the flash-plated layer.

[0085] (cathode and anode)

[0086] The blank to be electroplated is the cathode, and a silver electrode plate, for example, which dissolves and provides silver ions, is the anode.

[0087] (Current density)

[0088] The cathode and anode are immersed in a silver plating solution (plating bath) and current is passed to perform silver plating. From the perspective of the formation speed of the composite film and the perspective of suppressing the uneven appearance of the composite film, the current density here is preferably 0.3 to 10 A / dm 2 , more preferably 0.5 to 8 A / dm 2 , more preferably 0.8 to 6 A / dm 2 .

[0089] (Temperature / Stirring / Plating Time / Plating Target Part)

[0090] From the viewpoint of production efficiency of plating and preventing excessive evaporation of liquid, the temperature (plating temperature) of the plating bath (silver plating solution) during electroplating is preferably 15 to 50° C., more preferably 20 to 45° C. From the viewpoint of implementing uniform plating, the stirring of the plating bath at this time is preferably 200 to 550 rpm, more preferably 350 to 500 rpm. The silver plating time (the time of applying current) can be appropriately adjusted according to the thickness of the target composite film, and a representative range is 25 to 4500 seconds. In addition, depending on the purpose of the composite material manufactured, the object part to be plated can be the entire surface layer of the blank or a part of the surface layer of the blank.

[0091] Note that, from the viewpoint of wear resistance and suppression of silver from the composite coating during bending, in order to form an excellent composite coating, the silver plating time is preferably set to 2000 seconds or less.

[0092] Partial Removal of Metal Sulfide Particles from the Composite Coating Surface

[0093] By the electroplating described above, a composite coating is formed on the blank. On the surface of the composite coating, there will be: metal sulfide particles that are incorporated (buried) into the silver matrix and are not easy to fall off; and metal sulfide particles that are attached to the surface rather than incorporated and are easy to fall off. The latter may contaminate the equipment when the composite material is bent, etc. Therefore, it is preferred to clean and remove such metal sulfide particles. One of the cleaning methods is to perform ultrasonic cleaning on the surface of the composite coating. Ultrasonic cleaning is preferably performed at 20 to 100 kHz for 1 to 300 seconds. In addition, as another cleaning method, electrolytic cleaning can be cited. In this case, electrolytic cleaning is preferably performed at 1 to 30 A / dm 2 Perform for 10 to 300 seconds.

[0094] [Composite Materials]

[0095] The following describes an embodiment of the composite material of the present invention. This composite material is formed by forming a composite coating containing metal sulfide particles in a silver layer on a blank. This composite material can be produced, for example, using the composite material production method of the present invention. The various components of this composite material are described below.

[0096] <<Blank>>

[0097] The aforementioned blank is the same as the blank described above for the method for producing the composite material of the present invention. Specifically, the blank is preferably made of Cu (copper) or a Cu alloy. The Cu alloy is preferably an alloy composed of the following components, from the perspective of achieving both electrical conductivity and wear resistance: Cu; at least one selected from the group consisting of Si (silicon), Fe (iron), Mg (magnesium), P (phosphorus), Ni (nickel), Sn (tin), Co (cobalt), Zn (zinc), Be (beryllium), Pb (lead), Te (tellurium), Ag (silver), Zr (zirconium), Cr (chromium), Al (aluminum), Ti (titanium), B (boron), Li (lithium), and Bi (bismuth); and unavoidable impurities.

[0098] <<Composite coating>>

[0099] The composite coating formed on the blank is composed of a silver layer containing metal sulfide particles. In this silver layer, the metal sulfide particles are (preferably substantially uniformly) dispersed in a silver matrix. It should be noted that when Ag flash plating is performed before forming the composite coating, an intermediate layer resulting from this flash plating exists between the blank (or the base layer described later) and the composite coating. However, in many cases, this intermediate layer is so thin that it cannot be distinguished from the composite coating. Furthermore, the composite coating can be formed on the entire surface of the blank or on a portion of the surface.

[0100] <Metal sulfide particles>

[0101] The metal sulfide particles are the same as those described above for the method for producing the composite material of the present invention. Specifically, the metal sulfide constituting the particles is preferably at least one selected from the group consisting of molybdenum sulfide, tungsten sulfide, and tin sulfide, with MoS and WS being particularly preferred. The shape of the metal sulfide particles is not particularly limited to approximately spherical, scaly, or irregular shapes, but a scaly shape is preferred from the perspective of improving the wear resistance of the composite material by smoothing the surface of the composite coating.

[0102] From the perspective of the wear resistance of the composite material, the average primary particle size of the metal sulfide particles is preferably 0.5 to 15 μm, more preferably 3 to 10 μm. The average primary particle size refers to the average value of the major diameter of the particles, where the major diameter refers to the length of the longest line segment that can be drawn within the particles in an image (plane) obtained by observing the metal sulfide particles in the composite film of the composite material at an appropriate magnification. The major diameter is the value obtained for 50 or more particles.

[0103] Furthermore, X-ray diffraction (XRD) analysis can identify the presence of metal sulfide particles in the composite coating. More specifically, X-ray diffraction measurements are performed on the surface of the composite coating using an X-ray diffraction apparatus in accordance with JIS H7805:2005. Using X-ray analysis software (e.g., PDXL manufactured by Rigaku Corporation), the measured peaks are compared with the X-ray diffraction patterns recorded on JCPDS cards for metal sulfides such as MoS2 (which record information such as the diffraction peaks, lattice spacing, and lattice number of each crystal). In addition to peaks for Ag, peaks identified as those for metal sulfides such as MoS2 are also confirmed. This confirms the presence of metal sulfide particles in the composite coating.

[0104] <Arithmetic mean roughness Ra of composite coating and thickness of composite coating>

[0105] The composite coating of the present invention presents a surface morphology with few nodules, and the value X obtained by dividing the arithmetic mean roughness Ra (μm) by the thickness (μm) of the composite coating is 0.14 or less. Through research by the present inventors, it was found that the greater the thickness of the composite coating, the easier it is to form the aforementioned nodules and the larger their size will be. It was also found that the aforementioned value X is a more effective indicator of the ease of silver falling off from the composite coating during bending than Ra itself, which represents the surface morphology. From the viewpoint of suppressing the falling off of silver from the composite coating during bending, and from the viewpoint of the difficulty in producing a composite material having a composite coating with a very small value X, the aforementioned value X is preferably 0.01 to 0.12, and more preferably 0.02 to 0.11.

[0106] From the viewpoint of wear resistance, the composite film of the composite material of the present invention preferably has an arithmetic mean roughness Ra of 0.1 to 3.0 μm, more preferably 0.1 to 2.1 μm. The method for measuring Ra will be described in detail in the Examples.

[0107] There is no particular restriction on the thickness of the composite coating of the composite material of the present invention, but from the viewpoint of wear resistance and conductivity, it is preferred to have a minimum thickness. In addition, even if the thickness is too large, the effect of the composite coating is saturated, and the cost of raw materials will increase. From the above viewpoints, the thickness of the composite coating is preferably 0.5 to 45 μm, more preferably 0.5 to 35 μm, and further preferably 1 to 25 μm. If we also consider the suppression of silver shedding during bending, it is most preferably 1 to 10 μm. The details of the method for measuring the thickness of the composite coating will be described in the examples. It should be noted that, when Ag flash plating is performed as described above, an intermediate layer obtained based on the flash plating will exist between the blank (or the base layer described later) and the composite coating. When it cannot be distinguished from the composite coating, the thickness of the intermediate layer is also included in the thickness of the composite coating.

[0108] <Crystalline size and Vickers hardness>

[0109] The crystallite size of silver in the composite coating in the embodiment of the composite material of the present invention is preferably 62 nm or less. Thus, due to the small crystallite size, based on the Hall-Petch relationship (generally speaking, the smaller the grains of the metal material, the greater the strength), the hardness of the composite coating is high, and there is a tendency that the composite coating is not easily ground due to the high hardness, and the wear resistance of the composite material becomes higher. In addition, there is a limit to the miniaturization of the crystallite size. From these viewpoints, the crystallite size is more preferably 6 to 60 nm, and particularly preferably 10 to 60 nm. The crystallite size can be managed to be 35 to 58 nm. From the viewpoint of taking into account both wear resistance and suppression of silver shedding during bending, it is particularly preferred that the crystallite size of silver is less than 62 nm and the value X is less than 0.088.

[0110] It should be noted that in the present invention, the crystallite size of silver is the crystallite size of the crystal plane with the highest intensity in XRD analysis. A more detailed method for measuring the crystallite size is described in the Examples.

[0111] As described above, the composite coating preferably has a small crystallite size and therefore high hardness, and specifically, its Vickers hardness Hv is preferably 100 or higher, more preferably 110 to 230. The method of measuring the Vickers hardness Hv will be described in detail in the Examples.

[0112] <Mass ratio of metal sulfide particles on the surface of the composite coating and content in the composite coating>

[0113] As described above, the composite film in an embodiment of the composite material of the present invention contains metal sulfide particles. From the perspective of the wear resistance and electrical conductivity of the composite material, the mass ratio of these particles on the surface of the composite film is preferably 1-50 mass%, more preferably 2-35 mass%, and even more preferably 3-25 mass%. As described in the description of the composite material production method of the present invention, metal sulfide particles may be present on the surface of the composite film, but they are only attached and easily fall off. In such cases, ultrasonic cleaning similar to that described in the section "Partial Removal of Metal Sulfide Particles from the Composite Film Surface" is first performed, and then the mass ratio of the metal sulfide particles on the surface of the composite film is determined. The mass ratio of the metal sulfide particles on the surface of the composite film is determined by energy dispersive X-ray analysis, and details of this measurement method are described in the Examples.

[0114] From the perspective of maintaining a balance between wear resistance and electrical conductivity, the content of metal sulfide particles in a composite coating containing metal sulfide particles is preferably 0.5 to 30 mass%, more preferably 0.8 to 30 mass%, even more preferably 1 to 20 mass%, and particularly preferably 1.5 to 10 mass%. Furthermore, from the perspective of wear resistance, it is particularly preferred that the metal sulfide be molybdenum sulfide and that the content in the composite coating be 2.5 to 10 mass%. Details of the method for determining this content will be described in the Examples.

[0115] <Total content of silver and metal sulfide>

[0116] The elemental composition of the composite film in the embodiment of the composite material of the present invention is typically substantially composed of silver and metal sulfide (metal and sulfur). Specifically, the total content of these elements in the composite film is 99% by mass or more, more preferably 99.5% by mass or more.

[0117] <<Basal layer>>

[0118] For various purposes, a base layer can be formed between the blank and the composite coating. As the constituent metal of the base layer, at least one metal or alloy selected from the group consisting of Cu, Ni, Sn and Ag can be cited. For example, in order to prevent the copper in the blank from diffusing to the surface of the composite coating and causing deterioration of conductivity, it is preferred to form a base layer composed of Ni. When the blank is a zinc-containing copper alloy such as brass, in order to prevent the zinc in the blank from diffusing to the surface of the composite coating, it is preferred to form a base layer composed of Cu. In order to improve the adhesion of the composite coating to the blank, it is preferred to form a base layer composed of Ag. The thickness of the base layer is not particularly limited. From the perspective of its function and cost, it is preferably 0.1 to 2 μm, more preferably 0.2 to 1.5 μm. In addition, the terminals of electrical / electronic components mostly use materials that are Sn-plated or reflow-plated (a stacked structure of Cu, Ni and Sn bases from the blank side). In the present invention, a base layer of such a stacked structure can also be formed. Therefore, in the present invention, the base of the composite coating can be a single layer composed of Cu, Ni, Sn, Ag or their alloys; it can also be a layer composed of a combination of them (laminated structure). Moreover, for example, the composite coating defined in the present invention can be formed on the electrical contact part of the blank (the base layer may or may not be formed), and a reflow-plated Sn base layer can be formed on the wire seam part (no composite coating is formed), etc., and different layers can be formed according to different locations.

[0119] <<Abrasion resistance>>

[0120] The composite material of the present invention has excellent wear resistance. Specifically, when the wear resistance is evaluated using the method of using a flat test piece and a test piece with an indentation in the examples described below, no blank is exposed in the flat test piece when 1000 reciprocating sliding operations are performed; preferably, no blank is exposed in the flat test piece when 2500 reciprocating sliding operations are performed; and particularly preferably, no blank is exposed in the flat test piece when 10,000 reciprocating sliding operations are performed. In addition, the number of reciprocating sliding operations required to reduce the thickness of the composite film by 1 μm obtained by this test is preferably 300 times or more, more preferably 600 times or more, and particularly preferably 900 times or more (usually 3000 times or less).

[0121] <<Silver peeling from the composite coating during bending>>

[0122] As described above, in embodiments of the composite material of the present invention, the value X (Ra / composite coating thickness) is as low as 0.14 or less, thereby suppressing the shedding of silver from the composite coating during bending. Specifically, in the silver shedding evaluation test using bending described in the Examples below, the peeled carbon ribbon was subjected to EDS analysis using an energy-dispersive X-ray analyzer. When the sum of the detected elements (Ag, elements constituting metal sulfides (Mo, S, etc.), and C, etc.) was taken as 100 mass%, the proportion of Ag was preferably 15 mass% or less, more preferably 10 mass% or less, even more preferably 5 mass% or less, particularly preferably 3 mass% or less, and most preferably 1.2 mass% or less. It should be noted that it is difficult to achieve a zero Ag proportion, and it is typically 0.1 mass% or more.

[0123] [Terminal]

[0124] The composite material of the present invention has practically sufficient wear resistance and suppresses the shedding of silver from the composite coating during bending. Therefore, it is preferably used as a constituent material for terminals, particularly electrical contact components such as switches and connectors that slide during use.

[0125] The composite material of the present invention, which has no terminal formed therein, such as a flat plate shape, can be processed into the shape of a terminal by shearing such as punching or bending, thereby producing a terminal.

[0126] Example

[0127] Hereinafter, embodiments of the composite material and the method for producing the same of the present invention will be described in detail.

[0128] <Preparation of Metal Sulfide Particles>

[0129] Flake-shaped MoS2 particles (Moly Powder PA, manufactured by SUMICO LUBRICANT CO., LTD.) having a volume-based cumulative 50% particle size (D50) of 5 μm as measured by a laser diffraction / scattering particle size distribution analyzer were prepared. Note that D50 is the manufacturer's nominal value for MoS2 particles.

[0130] [Example 1] <Ag flash plating>

[0131] A test piece measuring 1.0 cm wide by 4.0 cm long was cut from a 0.2 mm thick Cu-Ni-Sn-P alloy plate (a copper alloy plate containing 1.0 mass% Ni, 0.9 mass% Sn, and 0.05 mass% P, with the balance being Cu and unavoidable impurities) (NB109EH manufactured by DOWA METALTECH CO., LTD.). This test piece was used as a blank, and this blank was used as a cathode. A titanium mesh electrode plate (a titanium mesh blank coated with iridium oxide) was used as an anode. The plating was carried out at a current density of 5 A / dm in a sulfonic acid-based Ag flash plating solution containing methanesulfonic acid as a complexing agent (DAIN SILVER GPE-ST manufactured by DAIWA CHEMICAL CO., LTD., silver concentration 3 g / L, methanesulfonic acid concentration 42 g / L, temperature 25°C). 2 Electroplating (Ag flash plating) was performed for 90 seconds. Note that Ag flash plating was performed on the entire surface layer of the blank.

[0132] Ag-MoS2 plating

[0133] The above-mentioned MoS particles as metal sulfide particles were added to a sulfonic acid-based silver plating solution (DAIN SILVER GPE-HB manufactured by DAIWA CHEMICAL CO., LTD. (containing compound A belonging to general formula (I) and mainly water as the solvent)) containing methanesulfonic acid as a complexing agent, having a silver concentration of 30 g / L and a methanesulfonic acid concentration of 60 g / L, thereby preparing a sulfonic acid-based silver plating solution containing metal sulfide particles having a concentration of 100 g / L, silver having a concentration of 30 g / L, methanesulfonic acid having a concentration of 60 g / L, and compound A having a concentration of 4.2 g / L.

[0134] Next, the Ag flash-plated blank was used as the cathode and the silver electrode plate as the anode. The silver plating solution containing the metal sulfide particles was stirred at 400 rpm by a stirrer at a temperature of 25°C and a current density of 1 A / dm 2 Electroplating was performed for 855 seconds, resulting in a composite material consisting of a silver layer containing metal sulfide particles (Ag-MoS2 coating) formed on the blank. It should be noted that the composite coating was formed over the entire surface of the blank. This composite coating was essentially composed of silver and metal sulfide particles.

[0135] Ultrasonic cleaning

[0136] The composite film surface of the obtained composite material was ultrasonically cleaned at 28 kHz for 4 minutes using an ultrasonic cleaner (VS-100III manufactured by AS ONE, output power 100 W, tank dimensions: length 140 mm × width 240 mm × depth 100 mm, pure water used as liquid, water temperature 20°C).

[0137] The production conditions and the like of the composite material described above are summarized in Table 1 described below, along with the production conditions and the like of Examples 2 to 7 and Comparative Examples 1 and 2 described below.

[0138] The following evaluations were performed on the obtained composite material (material after ultrasonic cleaning treatment).

[0139] <Composite film thickness>

[0140] The thickness of the composite film (a 0.2 mm diameter circular area in the center of a 1 cm × 4 cm area) was measured using a fluorescent X-ray film thickness meter (FT110A, manufactured by Hitachi High-Tech Science Corporation) and was found to be 5.1 μm. The composite film thickness was determined based on the intensity of the detected Ag fluorescent X-rays, assuming the composite film was a Ag film.

[0141] <Arithmetic mean roughness Ra of composite coating>

[0142] The surface of the composite film was imaged at 1000x magnification using a laser microscope (VKX-110 manufactured by KEYENCE CORPORATION). The arithmetic mean roughness Ra, a parameter indicating surface roughness (of the entire observed surface of the composite film), was calculated using an analysis application (VK-HIXA version 3.8.0.0 manufactured by KEYENCE CORPORATION) in accordance with JIS B0601 (2001). The result was 0.3 μm. Therefore, the value X, obtained by dividing the arithmetic mean roughness Ra of the composite film by the thickness (μm) of the composite film, was 0.059.

[0143] <Content of Metal Sulfide Particles or Carbon Particles in the Composite Film>

[0144] In accordance with JIS H7805:2005, an X-ray diffraction apparatus (D2Phaser2ndGeneration manufactured by BRUKER JAPAN KK) was used to perform X-ray diffraction measurement on the surface of the composite film (Cu Kα-ray tube, tube voltage: 30 kV, tube current: 10 mA, step width: 0.02°, scanning range: 2θ=10° to 155°, scanning speed: 5° / min, and measurement time: approximately 30 minutes). X-ray analysis software (PDXL manufactured by Rigaku Corporation) was used to compare the measured peaks with the X-ray diffraction pattern recorded on the JCPDS card of MoS2 (which records information such as the diffraction peaks, lattice spacing, and lattice number of each crystal). As a result, in addition to the peak of Ag, a peak identified as MoS2 was also confirmed. It should be noted that in Example 5 described later, the X-ray diffraction pattern of the JCPDS card of WS2 was compared instead of MoS2, and in addition to the peak of Ag, a peak identified as WS2 was also confirmed.

[0145] Then, the contents (mass %) of Ag and Mo (W in Example 5) in the composite film were determined using ICP-OES (Agilent Technologies Japan, Ltd., Agilent 5800 ICP-OES spectrometer) (plasma spectrometry).

[0146] Weigh 0.5g of a composite material (the raw material and the plated film have different constituent elements), add 5mL of nitric acid, and heat and dissolve at 150-200°C for 10-20 minutes. Cool the solution to room temperature, filter through an MCE membrane filter (0.45μm mesh, filter diameter 47mm), and dilute the filtrate to 100mL with pure water (Test Solution A). Separately, add 5mL of nitric acid and 4mL of a mixture of sulfuric acid and water (1:1 by volume) to the filtration residue and dissolve it by heating at 200-250°C. Cool the solution to room temperature and dilute to 100mL with pure water (Test Solution B).

[0147] ICP-OES was performed on the test solutions A and B obtained above to determine the amount of each element contained in the composite material sample. Among the detected elements, Ag and Mo were focused on, and the MoS2 content (in Example 5, the WS2 content) was calculated based on the Mo content in the total. Specifically, when the Ag content in the composite film is X (mass %) and the MoS2 content is Y (mass %), the MoS2 content in the composite film is calculated using the formula Y / (X+Y) (mass %).

[0148] In Comparative Examples 1 and 2 described below, the C content (Z mass %) constituting the carbon particles was determined using a microcarbon / sulfur analyzer (EMIA-810W, manufactured by Kuba Ltd.) (infrared absorption method). The Ag content (X mass %) was then used to calculate the carbon particle content in the composite film as Z / (X + Z) (mass %).

[0149] <Amount of Metal Sulfide Particles or Carbon Particles on the Composite Film Surface>

[0150] The surface of the composite film was observed using a desktop electron microscope (TM4000 Plus, manufactured by Hitachi High-Tech Science Corporation) at a magnification of 1000x at an accelerating voltage of 15 kV. Within this observation area (one field of view), EDS analysis was performed using an energy dispersive X-ray analyzer (AztecOne, manufactured by Oxford Instruments KK) attached to the desktop electron microscope. The amounts of Ag and Mo (W in Example 5, described later, and C in Comparative Examples 1 and 2) in the composite film were determined using this method.

[0151] Subsequently, the amount of MoS2 was calculated based on the amount of Mo (the WS2 content was calculated in Example 5). Furthermore, when the amount of Ag on the surface of the composite film is set to S (mass %) and the amount of MoS2 is set to T (mass %), the amount of MoS2 on the surface of the composite film is calculated using the formula T / (S+T) (mass %).

[0152] <Silver crystallite size of composite coating>

[0153] The surface of the composite coating was subjected to X-ray diffraction measurement in accordance with JIS H 7805: 2005 using an X-ray diffractometer (D2 Phaser 2nd Generation, manufactured by BRUKER JAPAN KK) (Cu Kα-ray tube, tube voltage: 30 kV, tube current: 10 mA, step width: 0.02°, scanning range: 2θ = 10° to 155°, scanning speed: 5° / min, measurement time: approximately 30 minutes, peak of the 111 plane: 2θ = 37.9 to 38.7°, peak of the 220 plane: 2θ = 64.5 to 65.8°). The full width at half maximum (FWHM) was determined from the strongest line peak with the highest detected silver peak intensity using X-ray analysis software (PDXL, manufactured by Rigaku Corporation), and the crystallite size of the plane corresponding to the strongest silver line was calculated based on the Scherrer equation. In Example 1, the strongest line peak is the peak of the 220 plane, and the crystallite size is 51.6 nm.

[0154] It should be noted that the Scherrer formula is as follows.

[0155] D=K·λ / (β·cosθ)

[0156] D: Crystallite size

[0157] K: Scherrer constant, take 0.9

[0158] λ: X-ray wavelength, CuKα rays are

[0159] β: Full width at half maximum (FWHM) (rad)

[0160] θ: Measurement angle (deg)

[0161] <Vickers hardness Hv of composite coating surface>

[0162] The Vickers hardness (Hv) of the composite coating surface was measured using a microhardness tester (HM221 manufactured by Mitutoyo Corporation) with a load of 0.01 N applied to the flat portion of the composite material for 10 seconds in accordance with JIS Z2244. The average of three measurements was used. The result was a Vickers hardness (Hv) of 146.

[0163] <Evaluation of wear resistance and friction coefficient>

[0164] The same Cu-Ni-Sn-P alloy sheet used in Example 1 was subjected to the same plating treatment (AgSb plating) as in Comparative Example 1 described below. A test piece measuring 1.0 cm wide by 4.0 cm long was cut from the resulting plated material and subjected to an indentation (extrusion into a hemispherical shape) with an inner diameter of 1.0 mm. The thickness of the composite coating (AgSb plating) on ​​the indented test piece was 40 to 60 μm.

[0165] Using a sliding wear tester (CRS-G2050-DWA manufactured by Yamazaki Seiki Laboratories, Ltd.), on the composite material (flat test piece) obtained in Example 1 above, the convex part of the test piece with the indentation (indenter) was in contact with the flat test piece, and the indenter was pressed against the test piece with a constant load (5N) while continuously performing a reciprocating sliding motion (sliding distance 10 mm (i.e., 1 reciprocating stroke is 20 mm), sliding speed 10 mm / s).

[0166] The coefficient of friction was determined by measuring the sliding load from the start of sliding to a sliding distance of 5 mm. The sliding load data for a sliding distance of 2 to 3 mm were averaged to determine the coefficient of friction (average sliding load F / 5 N). The coefficient of friction was 0.21.

[0167] For wear resistance, the above-described reciprocating sliding operation was continued, and the wear state of the flat test piece was confirmed after 1000 and 2500 reciprocating sliding cycles. Specifically, the center of the sliding mark of the flat test piece was observed at 200x magnification using a microscope (VHX-1000 manufactured by KEYENCE CORPORATION) to confirm whether the blank (brown alloy plate) was exposed through the sliding mark.

[0168] Furthermore, the reduction in thickness of the composite coating at the time of 1000 reciprocating sliding operations was calculated, and the number of times required for the composite coating thickness to decrease by 1 μm due to the reciprocating sliding operations was thus calculated. Note that in Comparative Example 2, described later, the blank was exposed before the 1000th reciprocating sliding operation, so the number of times required for the thickness to decrease by 1 μm was calculated based on the number of times at that point (550).

[0169] Silver loss due to bending

[0170] A bending test piece with a width of 10 mm and a length of 30 mm was cut from the obtained composite material with the length direction being TD (direction perpendicular to the rolling direction) and the width direction being LD (rolling direction). The bending test piece was subjected to a 90° W bending test in accordance with JIS H3130 with a bending radius of R = 0.2 mm using LD as the bending axis (BadWay bending (BW bending)).

[0171] Edge Reference Figure 1 The 90° W-bending test will be described. Figure 1 This is a schematic cross-sectional view showing the peaks and valleys of a test piece sandwiched between an upper jig and a lower jig. It should be noted that when the test piece is clamped and bent between the upper and lower jigs, the load applied to the upper and lower jigs is monitored to prevent further load from being applied to the bent test piece.

[0172] A carbon tape (Nisshin-EM Co., Ltd. carbon double-sided tape for SEM 7322: width 12 mm) was applied to the surface of the test piece in contact with the upper jig, and then peeled off by manually pulling the tape vertically upward.

[0173] The carbon tape was attached so that 1 mm was exposed on both sides in the width direction of the test piece.

[0174] On the surface of the test piece of the peeled carbon ribbon that contacts the upper mold jig, observation was performed using a desktop electron microscope (TM4000 Plus, manufactured by Hitachi High-Tech Science Corporation) at an accelerating voltage of 15 kV, starting from the center of the width direction of the position corresponding to the bent portion of the test piece, which is the valley, and moving 1 mm in the longitudinal direction toward the center of the width direction of the position corresponding to the bent portion, which is the peak. Observation was performed at a magnification of 100 times.

[0175] EDS analysis was then performed on the observation area (one field of view) of the carbon ribbon using an energy dispersive X-ray analyzer (AztecOne, manufactured by Oxford Instruments KK) attached to the aforementioned desktop microscope. The results revealed the presence of C, O, Ag, Mo, and S, with the amount of Ag being 0.87% by mass relative to the total of 100% by mass.

[0176] In this specification, this numerical value is used as an indicator of silver shedding during bending.

[0177] The above evaluation results are summarized in Table 2 below together with the evaluation results of Examples 2 to 7 and Comparative Examples 1 and 2 below.

[0178] [Example 2]

[0179] A composite material was prepared in the same manner as in Example 1, except that the plating time in the "Ag-MoS2 Plating" section was changed to 510 seconds. The resulting composite material was evaluated in the same manner as in Example 1 for surface roughness Ra, composite coating thickness, crystallite size, metal sulfide particle content and surface mass, Vickers hardness, friction coefficient, wear resistance, and silver shedding during bending. The results are summarized in Table 2 below. Furthermore, in XRD analysis, the strongest line peak was the peak at the 220° plane.

[0180] [Example 3]

[0181] A composite material was prepared in the same manner as in Example 1, except that the plating time in the "Ag-MoS2 Plating" step was changed to 3600 seconds. The resulting composite material was evaluated in the same manner as in Example 1 for surface roughness Ra, composite coating thickness, crystallite size, metal sulfide particle content and surface area, Vickers hardness, friction coefficient, wear resistance, and silver shedding during bending. The results are summarized in Table 2 below. Furthermore, in XRD analysis, the strongest line peak was the peak at the 220° plane.

[0182] [Example 4]

[0183] Change the current density in <Ag-MoS2 plating> to 3A / dm 2 A composite material was prepared in the same manner as in Example 1, except that the plating time was changed to 270 seconds. The resulting composite material was evaluated in the same manner as in Example 1 for surface roughness Ra, composite coating thickness, crystallite size, metal sulfide particle content and surface area, Vickers hardness, friction coefficient, wear resistance, and silver shedding during bending. The results are summarized in Table 2 below. Furthermore, in XRD analysis, the strongest line peak was the peak at the 220° plane.

[0184] [Example 5]

[0185] A composite material was prepared in the same manner as in Example 1, except that WS2 particles (WS2 Powder, average particle size (D50) 5.9 μm (nominal value), manufactured by Kojundo Chemical Laboratory Co., Ltd.) were used as metal sulfide particles. The resulting composite material was evaluated in the same manner as in Example 1 for surface roughness Ra, composite coating thickness, crystallite size, metal sulfide particle content and surface area, Vickers hardness, friction coefficient and wear resistance, and silver shedding due to bending. The results of these evaluations are summarized in Table 2 below. Furthermore, in XRD analysis, the strongest line peak was the peak at the 220° plane.

[0186] [Example 6]

[0187] A composite material was produced in the same manner as in Example 1 except that a sulfonic acid-based silver plating solution having a silver concentration of 30 g / L and containing methanesulfonic acid as a complexing agent at a concentration of 60 g / L (DAIN SILVER GPE-PL manufactured by DAIWA CHEMICAL CO., LTD. (does not contain a compound belonging to the general formula (I) and the solvent is water)) was used instead of the sulfonic acid-based silver plating solution of Example 1, and the same MoS2 particles as in Example 1 were added thereto. The resulting sulfonic acid-based silver plating solution containing metal sulfide particles was used.

[0188] The resulting composite material was evaluated in the same manner as in Example 1 for surface roughness Ra, composite coating thickness, crystallite size, metal sulfide particle content and surface area, Vickers hardness, friction coefficient, wear resistance, and silver shedding during bending. The evaluation results are summarized in Table 2 below. Furthermore, in XRD analysis, the strongest line peak was that of the 111 plane.

[0189] [Example 7]

[0190] A composite material was produced in the same manner as in Example 4 except that the MoS 2 particles used in Example 4 were obtained by subjecting the MoS 2 particles used in Example 4 to an alkalization treatment as described below.

[0191] <Alkalinization treatment>

[0192] The MoS2 particles are subjected to an alkalization treatment before being immersed in the sulfonic acid silver plating solution. For the alkalization treatment method, a hot stirrer and a strong stirring device are used to stir a liquid containing 100g of MoS2 particles in 1.75L of pure water at 400rpm, and the temperature is raised until it reaches about 50°C. Then, an aqueous solution containing 5g of KOH is added to the pure water containing the above-mentioned MoS2 particles to make the volume reach 2L, and stirring is maintained for 5 minutes. The pH of the resulting mixed solution is less than 12. An aqueous solution containing 1g of KOH dissolved in 0.05L of pure water is added to the mixed solution, and the mixture is stirred for 5 minutes in the same manner as above and the pH is measured. The above operation is repeated until the pH of the mixed solution reaches 12 or above. When the pH reaches 12 or above, the mixed solution is filtered using a suction filter, pure water is added to the residue, and it is stirred and filtered. This operation is repeated until the conductivity of the filtrate reaches 10μS / cm or below. Then, when the conductivity of the filtrate reaches 10 μS / cm or less, the MoS2 residue after filtration is added to the sulfonic acid silver plating solution.

[0193] The composite material obtained in Example 7 was evaluated in the same manner as in Example 1 for surface roughness Ra, composite coating thickness, crystallite size, metal sulfide particle content and surface area, Vickers hardness, friction coefficient, wear resistance, and silver shedding during bending. Wear resistance was also confirmed by checking for substrate exposure after 10,000 sliding cycles. These evaluation results are summarized in Table 2 below. Furthermore, the strongest line peak in XRD analysis was the peak at the 220° plane.

[0194] [Comparative Example 1]

[0195] In addition to the metal sulfide particles, flake-shaped graphite particles (PAG-3000, manufactured by Nippon Graphite Industry Co., Ltd.) having an average particle size of 5.0 μm were used, which were obtained by oxidation treatment. These graphite particles were added to the sulfonic acid silver plating solution (DAIN SILVERGPE-HB, manufactured by DAIWA CHEMICAL CO., LTD.) used in Example 1 in an amount to give a concentration of 50 g / L. The sulfonic acid silver plating solution containing the carbon particles obtained above was used in <Ag-MoS2 plating>, and the current density was changed to 3 A / dm 2 , and the plating time was changed to 1000 seconds, a composite material was prepared in the same manner as in Example 1. It should be noted that the average particle size is the particle size at which the cumulative value on a volume basis is 50%, as measured using a laser diffraction / scattering particle size distribution analyzer (MT3300 (LOW-WET MT3000II Mode, manufactured by Microtrac BEL Corp.).

[0196] The oxidation treatment was performed as follows: 80 g of the scaly graphite particles were added to 1.4 L of pure water, and the mixture was heated to 50° C. while stirring. Subsequently, 0.6 L of a 0.1 mol / L aqueous potassium persulfate solution was slowly added dropwise to the mixture as an oxidizing agent. The mixture was stirred for 2 hours for oxidation treatment, and then filtered and separated using filter paper. The resulting solid was washed with water.

[0197] The resulting composite material was evaluated in the same manner as in Example 1 for surface roughness Ra, composite coating thickness, crystallite size, carbon particle content and surface area, Vickers hardness, friction coefficient, wear resistance, and silver shedding during bending. The evaluation results are summarized in Table 2 below. Furthermore, in XRD analysis, the strongest line peak was that of the 111 plane.

[0198] [Comparative Example 2]

[0199] A sulfonic acid silver plating solution having a silver concentration of 30 g / L and containing methanesulfonic acid as a complexing agent at a concentration of 60 g / L (DAIN SILVER GPE-PL manufactured by DAIWA CHEMICAL CO., LTD. (does not contain a compound belonging to general formula (I), and the solvent is water)) was used instead of the sulfonic acid silver plating solution of Example 1. Graphite particles having a particle size of 1.8 μm (UTC-48J manufactured by Nippon Graphite Industries, Ltd.) having an oxidation treatment performed in the same manner as in Comparative Example 1 were added thereto so as to give a concentration of 50 g / L so that the cumulative value on a volume basis was 50%. The composite material was produced in the same manner as in Comparative Example 1, except that the obtained sulfonic acid silver plating solution containing carbon particles was used in <Ag-MoS2 plating> and the plating time was set to 270 seconds.

[0200] The resulting composite material was evaluated in the same manner as in Example 1 for surface roughness Ra, composite coating thickness, crystallite size, carbon particle content and surface area, Vickers hardness, friction coefficient, wear resistance, and silver shedding during bending. The evaluation results are summarized in Table 2 below. Furthermore, in XRD analysis, the strongest line peak was that of the 111 plane.

[0201] The production conditions and the like of the composite materials of Examples 1 to 7 and Comparative Examples 1 and 2 are summarized in Table 1 below, and the evaluation results are summarized in Table 2 below.

[0202] [Table 1]

[0203]

[0204] [Table 2]

[0205]

Claims

1. A composite material comprising a composite coating comprising a silver layer containing metal sulfide particles formed on a blank, wherein a value X obtained by dividing the arithmetic mean roughness Ra (μm) of the composite coating by the thickness (μm) of the composite coating is 0.14 or less.

2. The composite material according to claim 1, wherein The metal sulfide constituting the metal sulfide particles is at least one selected from the group consisting of molybdenum sulfide, tungsten sulfide, and tin sulfide.

3. The composite material according to claim 1 or 2, wherein The silver crystallite size of the composite coating is less than 62 nm.

4. The composite material according to claim 1 or 2, wherein The mass ratio of the metal sulfide particles in the surface of the composite coating, determined by measuring the surface of the composite coating by energy dispersive X-ray analysis, is 1 to 50 mass %.

5. The composite material according to claim 1 or 2, wherein The blank is composed of copper or a copper alloy.

6. The composite material according to claim 1 or 2, wherein The metal sulfide constituting the metal sulfide particles is at least one selected from the group consisting of MoS2 and WS2.

7. The composite material according to claim 1 or 2, wherein The thickness of the composite film is 0.5-45 μm.

8. The composite material according to claim 1 or 2, wherein The content of the metal sulfide particles in the composite film is 0.5 to 30% by mass.

9. The composite material according to claim 1 or 2, wherein The silver crystallite size of the composite coating is 62 nm or less, and the value X is 0.088 or less.

10. The composite material according to claim 1 or 2, wherein The content of the metal sulfide particles in the composite film is 2.5 to 10% by mass, and the metal sulfide constituting the metal sulfide particles is molybdenum sulfide.

11. A method for producing a composite material, comprising forming a composite coating composed of a silver layer containing metal sulfide particles on a blank by electroplating in a silver plating solution containing the metal sulfide particles.

12. The method for producing a composite material according to claim 11, wherein: The blank is composed of copper or a copper alloy.

13. The method for producing a composite material according to claim 11 or 12, wherein: The silver plating solution contains a compound A represented by the following general formula (I): In formula (I), m is an integer of 1 to 5, R 1 is carboxyl, R 2 is aldehyde, carboxyl, amino, hydroxyl or sulfonic acid, R 3 is hydrogen or any substituent, when m is 2 or more, multiple R 2 When m is 3 or less, the presence of multiple R 3 are optionally the same as or different from each other, R 1 and R 2 Optionally, each independently bonds to the benzene ring via a divalent group consisting of at least one selected from the group consisting of -O- and -CH2-.

14. The method for producing a composite material according to claim 11 or 12, wherein: The metal sulfide constituting the metal sulfide particles is at least one selected from the group consisting of molybdenum sulfide, tungsten sulfide, and tin sulfide.

15. The method for producing a composite material according to claim 11 or 12, wherein: The metal sulfide particles have a volume-based cumulative 50% particle size (D50) of 0.5 to 15 μm as measured by a laser diffraction / scattering particle size distribution analyzer.

16. The method for producing a composite material according to claim 11 or 12, wherein: The metal sulfide constituting the metal sulfide particles is at least one selected from the group consisting of MoS2 and WS2.

17. A terminal using the composite material according to claim 1 or 2 as its constituent material.

18. A method for manufacturing a terminal, comprising processing the composite material according to claim 1 or 2 into the shape of a terminal.

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