Contact materials

Abstract

The present invention provides a contact material that can sufficiently suppress short circuits at contacts caused by the detachment of conductive particles, and that also possesses sufficient wear resistance and conductivity. [Solution] A contact material comprising a silver-containing film, wherein the silver-containing film comprises a silver-containing layer containing 50% by mass or more of silver and particles made of a plurality of nonconductive organic compounds, at least a portion of each particle being embedded in the silver-containing layer, and the nonconductive organic compounds having a fluoro group (-F), a methyl group (-CH3), a carbonyl group (-C(=O)-), and an amino group (-NR) in their unit molecular structure. 1 R 2 And R 1 and R 2 R is a hydrogen or hydrocarbon group, 1 and R 2 A contact material comprising one or more selected from the group consisting of a hydroxyl group (-OH), an ether bond (-O-), and an ester bond (-C(=O)-O-).

Description

Technical Field

[0001] This disclosure relates to a contact material.

Background Art

[0002] With the strengthening of CO2 emission regulations, an increase in electric vehicles (EVs) and plug-in hybrid vehicles (PHEVs) with low dependence on fossil fuels is expected. Since these vehicles need to be charged with a battery daily, the contact material connecting the external power source and the vehicle can have a significantly increased number of insertions and removals compared to the contact material of conventional vehicles. For the contact material of vehicles, a silver (Ag) plating film with high conductivity (low contact resistance) is often applied. However, generally, the hardness of the Ag plating film is low, and "seizure" easily occurs when Ag slides against each other. Therefore, when repeated insertions and removals (sliding) are performed, the wear of the Ag plating film can easily progress.

[0003] Conventionally, in order to improve the wear resistance of the Ag plating film, (1) Hardening of Ag plating by refining crystal grains (2) Hardening by alloying Ag with Se (selenium) or Sb (antimony), etc. etc. have been studied. However, the improvement of wear resistance was insufficient by either of the above methods (1) and (2). In addition, Se and Sb are toxic elements, which require attention in management, and there is also a problem that the conductivity decreases with alloying.

[0004] In addition, improvement of wear resistance other than hardening of the Ag plating film has also been studied. Mainly, as disclosed in Non-Patent Documents 1 and 2, (3) Eutectic (dispersion plating) of carbon-based particles into the Ag plating film has been studied. In these studies, mainly graphite, carbon black (CB) or carbon nanotubes (CNT) have been used. The reasons are as follows: (i) Carbon-based particles such as graphite act as solid lubricants, so wear resistance improvement can be expected, and (ii) Since carbon-based particles have conductivity, when eutectic (dispersed) in the Ag plating film, it is considered that there is little risk of deteriorating the contact resistance. In fact, in Non-Patent Document 1, it has been shown that an Ag-graphite composite plating film obtained by suspending graphite particles in an Ag plating solution and performing plating treatment can achieve good wear resistance not only compared to an Ag plating film but also compared to a hard Ag-Sb alloy plating film.

Prior Art Documents

Non-Patent Documents

[0005]

Non-Patent Document 1

Non-Patent Document 2

Summary of the Invention

Problems to be Solved by the Invention

[0006] Regarding the above (3), it has been studied since long ago as in Non-Patent Document 2, and it can be said to be general as a method for improving the wear resistance of silver-containing films. However, despite the increasing demand for contact materials that achieve both wear resistance and conductivity with the predicted increase in EVs and PHEVs, the utilization of the above (3) has not advanced. This reason is considered to be due to the concern that when carbon particle dispersion plating is applied to a contact material and sliding (insertion / extraction) is repeated, the carbon particles held in the Ag plating film will fall off due to wear. If the carbon-based particles fall off and accumulate around the contact, there is a risk of causing a short circuit in the contact, and particularly in the terminals for EVs and PHEVs that require energization at high voltages and large currents, problems with safety can occur.

[0007] The present invention has been made in view of such a situation, and one of its objects is to provide a contact material that can sufficiently suppress short - circuiting of contacts due to the dropout of conductive particles and has sufficient wear resistance and conductivity.

Means for Solving the Problems

[0008] Aspect 1 of the present invention is a contact material including a silver - containing film, wherein the silver - containing film includes a silver - containing layer containing 50 mass% or more of silver and particles composed of a plurality of non - conductive organic compounds, and at least a part of each particle is buried in the silver - containing layer, the non - conductive organic compound includes at least one selected from the group consisting of a fluoro group (-F), a methyl group (-CH3), a carbonyl group (-C(=O)-), an amino group (-NR 1 R 2 where R 1 and R 2 are hydrogen or a hydrocarbon group, and R 1 and R 2 may be the same or different), a hydroxy group (-OH), an ether bond (-O-), and an ester bond (-C(=O)-O-), and satisfies the following formula (1): 0.50≦A p / (A p +A Ag )×100≦12.10 ···(1) In formula (1), A p is the area of the portion of the particles composed of the plurality of non - conductive organic compounds buried in the silver - containing layer in a cross - section parallel to the film - thickness direction of the silver - containing film, and A Ag is the area of the silver - containing layer in a cross - section parallel to the film - thickness direction of the silver - containing film.

[0009] Aspect 2 of the present invention is The contact material according to Embodiment 1 is characterized in that, when the non-conductive organic compound is subjected to thermogravimetric differential thermal analysis from room temperature to a maximum of 1000°C at a heating rate of 10°C / min, its melting point is greater than 140°C or it does not exhibit a melting point.

[0010] A third aspect of the present invention is: The contact material according to embodiment 1 or 2, wherein when the non-conductive organic compound is subjected to thermogravimetric differential thermal analysis from room temperature to a maximum of 1000°C at a heating rate of 10°C / min, the decomposition point is 500°C or lower when it shows a decomposition point, and the melting point is 500°C or lower when it does not show a decomposition point but shows a melting point.

[0011] Aspect 4 of the present invention is The aforementioned nonconductive organic compound has a carbonyl group (-C(=O)-) and an amino group (-NR) within its unit molecular structure. 1 R 2 And R 1 and R 2 R is a hydrogen or hydrocarbon group, 1 and R 2 The contact material according to any one of embodiments 1 to 3, comprising one or more selected from the group consisting of (which may be the same or different) and a hydroxyl group (-OH). [Effects of the Invention]

[0012] According to embodiments of the present invention, it is possible to provide a contact material that can sufficiently suppress short circuits at contacts due to the detachment of conductive particles, and that has sufficient wear resistance and conductivity. [Brief explanation of the drawing]

[0013] [Figure 1] Figure 1 is a schematic cross-sectional view of an example of a contact material according to an embodiment of the present invention. [Figure 2] Figure 2 is a schematic cross-sectional view of another example of a contact material according to an embodiment of the present invention. [Figure 3A] Figure 3A is a cross-sectional SEM image of the contact material No. 2 of Example 1, parallel to the film thickness direction of the silver-containing film. [Figure 3B]Figure 3B is an image obtained by cropping only the silver-containing film from Figure 3A. [Figure 3C] Figure 3C is a binarized image of Figure 3B. [Figure 4] Figure 4 shows the heat resistance evaluation results for contact material No. 10 in Example 2. [Figure 5] Figure 5 shows the heat resistance evaluation results for contact material No. 11 in Example 2. [Figure 6] Figure 6 shows the heat resistance evaluation results for contact material No. 12 in Example 2. [Figure 7] Figure 7 shows the wear resistance evaluation results for the contact material of reference example No. 13. [Figure 8] Figure 8 shows the wear resistance evaluation results for the contact material of reference example No. 14. [Figure 9] Figure 9 shows the wear resistance evaluation results for the contact material of reference example No. 15. [Figure 10] Figure 10 shows the wear resistance evaluation results for the contact material of reference example No. 16. [Figure 11] Figure 11 shows the wear resistance evaluation results for the contact material of reference example No. 17. [Figure 12] Figure 12 shows the wear resistance evaluation results for the contact material of reference example No. 18. [Figure 13] Figure 13 shows the wear resistance evaluation results for the contact material of reference example No. 19. [Figure 14] Figure 14 shows the wear resistance evaluation results for the contact material of reference example No. 20. [Figure 15] Figure 15 shows the wear resistance evaluation results for the contact material of reference example No. 21. [Figure 16] Figure 16 shows the wear resistance evaluation results for the contact material of reference example No. 22. [Figure 17] Figure 17 shows the wear resistance evaluation results for the contact material of reference example No. 23. [Figure 18] Figure 18 shows the wear resistance evaluation results for the contact material of reference example No. 24. [Figure 19] Figure 19 shows the wear resistance evaluation results for the contact material of reference example No. 25. [Figure 20] Figure 20 shows the wear resistance evaluation results for the contact material of reference example No. 26. [Figure 21] Figure 21 shows the wear resistance evaluation results for the contact material of reference example No. 27. [Figure 22] Figure 22 shows the wear resistance evaluation results for the contact material of reference example No. 28. [Modes for carrying out the invention]

[0014] The inventors of the present invention have investigated from various angles to realize a contact material that can sufficiently suppress short circuits at contacts due to the detachment of conductive particles, and that has sufficient wear resistance and conductivity. In the study of conventional co-deposition plating technology, such as that described in Non-Patent Literature 1, carbon-based particles have been used as a solid lubricant (and that has good conductivity). However, as a result of the inventors' investigations, it was found that sufficient wear resistance and conductivity can be obtained by having a silver-containing film in which a predetermined amount of particles made of a specific non-conductive organic compound, which does not necessarily have a solid lubricating effect, are co-deposited (embedded) in a silver-containing layer. This is thought to be because, when the silver-containing film slides, for example, some of the non-conductive organic compound decomposes and diffuses to the vicinity of the contact material surface, and / or some of the non-conductive organic compound reacts with the silver-containing layer near the contact material surface, thereby lowering the coefficient of friction near the contact material surface and improving the wear resistance of the contact material. Furthermore, since the amount of decomposition products and reactants is small, and the proportion of particles made of the specific non-conductive organic compound in the silver-containing film is controlled to be below a predetermined value, it is thought that sufficient conductivity can be ensured. As a result, we have been able to realize a contact material that sufficiently suppresses the risk of short circuits at the contacts due to the detachment of conductive particles, while also possessing sufficient wear resistance and conductivity. It should be noted that the above mechanism does not limit the technical scope of the embodiments of the present invention.

[0015] The details of each requirement defined in the embodiments of the present invention are shown below.

[0016] The contact material according to an embodiment of the present invention includes a silver-containing film, the silver-containing film comprising a silver-containing layer containing 50% by mass or more of silver and particles made of a plurality of nonconductive organic compounds, at least a portion of each particle being embedded in the silver-containing layer, the nonconductive organic compounds having a fluoro group (-F), a methyl group (-CH3), a carbonyl group (-C(=O)-), and an amino group (-NR) in their unit molecular structure. 1 R 2 And R 1 and R 2 R is a hydrogen or hydrocarbon group, 1 and R 2 It contains one or more selected from the group consisting of (the same or different), a hydroxyl group (-OH), an ether bond (-O-), and an ester bond (-C(=O)-O-), and satisfies the following formula (1). 0.50 ≤ A p / ( A p +A Ag ) × 100 ≤ 12.10 ···(1) In equation (1), A p A is the area of ​​the portion of the particles made of the plurality of nonconductive organic compounds that are embedded in the silver-containing layer, in a cross-section parallel to the film thickness direction of the silver-containing film. Ag This is the area of ​​the silver-containing layer in a cross-section parallel to the film thickness direction of the silver-containing film. As a result, the risk of short circuits at the contacts due to the detachment of conductive particles can be sufficiently suppressed, and sufficient wear resistance and conductivity can be provided.

[0017] Figure 1 shows a schematic cross-sectional view of an example of a contact material according to an embodiment of the present invention. In Figure 1, the contact material 1 includes a silver-containing film 2, and the silver-containing film 2 includes a silver-containing layer 2a and a plurality of particles 2b (hereinafter sometimes simply referred to as "particles 2b") made of a non-conductive organic compound containing the above-mentioned specific functional group in its unit molecular structure. Note that Figure 1 is a cross-section parallel to the film thickness direction of the silver-containing film 2 (and silver-containing layer 2a). At least a portion of each particle 2b is embedded in the silver-containing layer 2a. In other words, for each particle 2b, either it is completely embedded in the silver-containing layer 2a, or a portion is embedded in the silver-containing layer 2a and the rest is exposed on the surface of the silver-containing layer 2a. Furthermore, the area A of the portion of the multiple particles 2b embedded in the silver-containing layer 2a satisfies equation (1) above. p , and the area A of the silver-containing layer 2a Ag It is under control.

[0018] The silver-containing layer 2a is a layer containing 50% by mass or more of silver. In addition to soft Ag plating, hard Ag plating, bright Ag plating, and semi-bright Ag plating, which are commonly used in terminal surface treatments, alloy plating may be used as the silver-containing layer 2a for purposes such as improving the corrosion resistance (sulfidation resistance, etc.) and wear resistance of the matrix. However, since wear resistance can be mainly provided by particles 2b, it is preferable to use a pure Ag plating layer with excellent conductivity unless there is another purpose such as improving corrosion resistance. For example, it is preferable to contain 90% by mass or more of silver, more preferably 95% by mass or more, and even more preferably 99% by mass or more.

[0019] The average thickness of the silver-containing layer 2a (for example, the average thickness of the silver-containing layer 2a obtained from any two or more locations on the contact material 1) is not particularly limited and can be adjusted as appropriate depending on the application, but it may be, for example, 100 μm or less, or even 50 μm or less.

[0020] Regarding particle 2b, "non-conductive" means that it does not exhibit conductivity, for example, the volume resistivity measured according to ASTM D257 is approximately 10. 3 This refers to values ​​greater than or equal to [Ω·cm].

[0021] With respect to particle 2b, "organic compound" refers to a compound containing carbon, excluding compounds with simple structures such as carbon monoxide, carbon dioxide, carbonates, hydrogen cyanide, cyanates, thiocyanates, B4C, and SiC. For example, a silicone resin with a siloxane bond (-Si-O-Si-) as the main chain and organic groups in the side chains is included in "organic compound" as defined herein.

[0022] The nonconductive organic compounds that make up particle 2b are a fluoro group (-F), a methyl group (-CH3), a carbonyl group (-C(=O)-), and an amino group (-NR). 1 R 2 And R 1 and R 2 R is a hydrogen or hydrocarbon group, 1 and R 2 The particles contain one or more selected from the group consisting of carbonyl groups (-C(=O)-), amino groups (-NR-), and ester groups (-C(=O)-O-). By including these predetermined functional groups, wear resistance can be improved. More preferably, the nonconductive organic compound constituting particle 2b contains carbonyl groups (-C(=O)-), amino groups (-NR-) within its unit molecular structure. 1 R 2 And R 1 and R 2 R is a hydrogen or hydrocarbon group, 1 and R 2 It must contain one or more selected from the group consisting of (which may be the same or different) and a hydroxyl group (-OH). Here, "unit molecular structure" means one repeating unit in the case of a polymer, and an individual molecule in the case of a nonpolymer.

[0023] The non-conductive organic compound constituting particle 2b preferably has a melting point of 140°C or higher, or does not exhibit a melting point (i.e., decomposes without melting). This suppresses deterioration of wear resistance caused by the melting of the organic compound when the contact material 1 (and the contact material 11 described later) is heated to 140°C. More preferably, the melting point of the non-conductive organic compound constituting particle 2b is 160°C or higher. Here, "melting point" refers to the melting point obtained by performing thermogravimetric differential thermal analysis (TG-DTA) from room temperature to a maximum of 1000°C at a heating rate of 10°C / min under atmospheric conditions. Specifically, the melting point can be defined as the temperature at the intersection of a straight line extrapolated up to the first inflection point where the heat flow rate begins to decrease with increasing temperature in the DTA curve, and a straight line after the second inflection point where the heat flow rate begins to decrease with a constant slope (i.e., the straight line with the constant slope). Furthermore, if the non-conductive organic compound constituting particle 2b does not exhibit a melting point (i.e., a compound that decomposes without melting), the decomposition point is preferably 140°C or higher, more preferably 160°C or higher, 200°C or higher, 250°C or higher, or 300°C or higher. Here, the "decomposition point" is the decomposition point obtained by performing thermogravimetric differential thermal analysis (TG-DTA) from room temperature to a maximum of 1000°C at a heating rate of 10°C / min under atmospheric conditions. Specifically, the decomposition point can be defined as the temperature at the intersection of a straight line extrapolated up to the first inflection point where the heat flow rate begins to decrease with increasing temperature in the DTA curve, and a straight line from the second inflection point onward where the heat flow rate begins to decrease with a constant slope (i.e., the straight line with the constant slope).

[0024] From the viewpoint of improving the wear resistance of the contact material 1 (and the contact material 11 described later), the nonconductive organic compound constituting particle 2b preferably has a decomposition point of 500°C or lower. More preferably, the decomposition point is 450°C or lower, and even more preferably 400°C or lower. When the compound does not show a decomposition point but shows a melting point (in the case of a compound that melts but does not decompose), the melting point is preferably 500°C or lower, more preferably 450°C or lower, and even more preferably 400°C or lower.

[0025] The combustion point of the nonconductive organic compound constituting particle 2b is not particularly limited, but it may be, for example, 180°C or higher. Here, the "combustion point" is the combustion point determined by performing thermogravimetric differential thermal analysis (TG-DTA) from room temperature to a maximum of 1000°C at a heating rate of 10°C / min, for example, under atmospheric conditions. Specifically, the combustion point can be defined as the temperature at the intersection of a straight line extrapolated up to the first inflection point where the heat flow rate begins to increase with increasing temperature in the DTA curve, and a straight line from the second inflection point onward where the heat flow rate begins to increase with a constant slope (i.e., the straight line with the constant slope).

[0026] Regarding particle 2b, "particle" refers to a relatively small substance with an equivalent circular diameter of 50 μm or less, and its shape may be anything. In one embodiment of the present invention, from the viewpoint of conductivity, the average particle size (average equivalent circular diameter) of particle 2b may be 10 μm or less. Also, in one embodiment of the present invention, from the viewpoint of wear resistance, the average particle size of particle 2b may be 0.1 μm or more.

[0027] The area ratio [A p / ( A p +A Ag The upper limit of [A] × 100 (%) is set to 12.10%. This improves conductivity. Preferably, this upper limit is 10.00%. On the other hand, the area ratio [A] of the above formula (1) p / ( A p +A AgThe lower limit of [) × 100 (%)] is 0.50%. This can improve wear resistance. Preferably, the lower limit is 1.50%.

[0028] Area A of silver-containing layer 2a Ag This can be determined by binarizing a cross-sectional SEM image parallel to the film thickness direction of the silver-containing film 2 using image processing software (e.g., "ImageJ"). Specifically, in a cross-sectional SEM image, the silver-containing layer 2a may appear relatively bright (i.e., white), while the protective layer of the sample for cross-sectional SEM may appear relatively dark (i.e., black). For example, the area of ​​the bright portion after binarization using a brightness intermediate between the silver-containing layer 2a and the protective layer as a threshold is the area A of the silver-containing layer 2a. Ag This can be done. Furthermore, if there are irregularities on the upper surface of the silver-containing layer 2a in the cross-sectional SEM image, the area of ​​the silver-containing layer 2a may be determined by using the average line of these irregularities as the boundary line between the silver-containing layer 2a and the upper layer (for example, the protective layer of the sample for cross-sectional SEM). The same applies to the lower surface of the silver-containing layer 2a. On the other hand, the area A of the portion of the multiple particles 2b that is embedded in the silver-containing layer 2a. p This can be the area of ​​the dark portion (corresponding to the non-conductive organic compound) after binarization, which is embedded in the silver-containing layer 2a. In the cross-sectional SEM image, if there are irregularities on the upper surface of the silver-containing layer 2a, the average line of these irregularities is used as the boundary line between the silver-containing layer 2a and the upper layer (for example, the protective layer of the sample for cross-sectional SEM), and the portion below this average line is considered to be the portion embedded in the silver-containing layer 2a. The same applies to the lower surface of the silver-containing layer 2a.

[0029] Figure 2 shows a schematic cross-sectional view of another example of a contact material according to an embodiment of the present invention, in which each particle 2b is completely embedded in the silver-containing layer 2a of the contact material 11. In the case of Figure 2, the particles 2b may be of a size that allows them to be completely embedded in the silver-containing layer 2a, that is, the average particle size of the particles 2b may be less than the average thickness of the silver-containing layer 2a. Note that Figure 2 is a cross-section parallel to the film thickness direction of the silver-containing film 2 (and silver-containing layer 2a).

[0030] From the viewpoint of further improving conductivity (further reducing contact resistance), a configuration in which each particle 2b is completely embedded in the silver-containing layer 2a, as shown in Figure 2, is preferred. On the other hand, from the viewpoint of further improving wear resistance, a configuration including particles 2b in which a portion is embedded in the silver-containing layer 2a and the remaining portion is exposed on the surface of the silver-containing layer 2a, as shown in Figure 1, is preferred.

[0031] Without departing from the objective of the embodiments of the present invention, the contact materials 1 and 11 may contain particles other than particles 2b. For example, the contact materials 1 and 11 may contain particles made of nonconductive organic compounds that do not contain the specific functional groups described above, or they may contain inorganic particles, or they may contain particles that are not embedded in the silver-containing layer 2a. The contact materials 1 and 11 may also contain conductive particles, but the less conductive particles there are, the more preferable it is to suppress short circuits at the contacts due to the shedding of conductive particles. For example, it is preferable that 50 volume% or more of the particles contained in the contact materials 1 and 11 are nonconductive particles 2b, more preferably 60 volume% or more, 70 volume% or more, 80 volume% or more, 90 volume% or more, and even more preferably all (100 volume%) are nonconductive particles 2b. Furthermore, the ratio of particles 2b, at least partially embedded in the silver-containing layer 2a, to the total number of particles contained in the contact materials 1 and 11 is preferably 50 area % or more, more preferably 60 area % or more, 70 area % or more, 80 area % or more, 90 area % or more, and even more preferably 100 area %.

[0032] The contact materials 1 and 11 according to the embodiment of the present invention may include other layers (e.g., a conductive substrate, a strike plating layer, etc.) in order to achieve the objectives of the present invention. For example, in the contact materials 1 and 11, a silver-containing film 2 may be formed on a conductive substrate (e.g., a substrate made of copper or a copper alloy).

[0033] In an embodiment of the present invention, the contact material 1 is obtained by, for example, dispersing a predetermined amount of particles 2b in a silver (or silver alloy) plating solution on a substrate and applying an electric current while stirring to perform a silver plating treatment, thereby obtaining a contact material in which a predetermined amount of particles 2b are embedded (co-deposited) in the silver-containing layer 2a. In some cases, a strike silver plating treatment may be performed before the silver plating treatment.

[0034] In the process of electroplating by dispersing particle 2b in a plating solution, the following reactions (A) and (B) proceed simultaneously. (A) A reaction in which liquid-dispersed particles are electrostatically or physically adsorbed (in contact) onto the surface of the substrate. (B) A reaction in which the silver-containing layer 2a is deposited (grown) on the surface of the substrate. "Eutectoid formation" occurs when particles 2b adsorbed in (A) are incorporated into the silver-containing layer 2a of (B). Under conditions where eutectoid plating proceeds steadily, the particles 2b adsorbed in the initial stages of the reaction are incorporated into the silver-containing layer 2a, and at the same time, new particles 2b are adsorbed. For this reason, even when the plating process is stopped, in most cases, the particles 2b are exposed on the outermost surface, and in a normal eutectoid plating process, contact material 1 containing particles 2b, some of which are embedded in the silver-containing layer 2a and the rest of which are exposed on the surface of the silver-containing layer 2a, can be easily manufactured. Here, the amount of particles 2b co-deposited into the silver-containing layer 2a (for example, the area ratio of particles 2b) is determined by the balance between the adsorption frequency of (A) and the plating film growth rate of (B). Therefore, it is possible to change the amount of co-deposited particles by changing the plating conditions, such as the amount of particles 2b dispersed in the plating solution. For example, by performing the plating process using a plating solution that does not contain particles 2b dispersed in the plating solution at the end of the plating process, or by changing the stirring speed of the plating solution to reduce the adsorption frequency of (A), it is possible to create a layer on the outermost surface of the plating in which particles 2b do not co-deposit, thereby producing a contact material 11 in which all particles 2b are embedded in the silver-containing layer 2a.

[0035] The contact materials 1 and 11 according to the embodiment of the present invention possess not only sufficient conductivity but also sufficient wear resistance (i.e., a sufficiently low coefficient of friction). Specifically, the contact materials 1 and 11 according to the embodiment of the present invention can achieve an initial contact resistance of 0.5 mΩ or less, and a coefficient of friction of 0.5 or less after 20 cycles of the sliding test described below. <Sliding Test> After forming a hard Ag plating layer (Vickers hardness HV: 160 or higher) of 40 μm or more on the substrate, a mating material is prepared by forming hemispherical protrusions with a radius of curvature R = 1.8 mm using a hand press. This mating material is then slid against the contact material 1 or 11 (silver-containing film 2) to be tested for a predetermined number of cycles with a vertical load of 3 N, a sliding distance of 10 mm, and a sliding speed of 80 mm / min. For example, a horizontal load testing machine manufactured by Aiko Engineering can be used as the sliding test machine.

[0036] Furthermore, it is preferable that the contact materials 1 and 11 according to the embodiment of the present invention have high heat resistance. Specifically, it is preferable that the friction coefficient increase rate calculated by the following formula (2) is 200% or less when heated at a predetermined temperature and time, and more preferably 120% or less. It is preferable that the above friction coefficient increase rate is satisfied even at high heating temperatures, with a heating temperature of 140°C or higher, more preferably 160°C or higher, and even more preferably 180°C or higher. It is also preferable that the above friction coefficient increase rate is satisfied even at long heating times, with a heating time of 100 hours or more, more preferably 200 hours or more, and even more preferably 500 hours or more. Increase in coefficient of friction (%) = 100 × [Coefficient of friction after heating and then performing the above sliding test for another 500 cycles] / [Coefficient of friction after performing the above sliding test for another 500 cycles without heating] ... (2) [Examples]

[0037] The embodiments of the present invention will be described in more detail below with reference to examples. The embodiments of the present invention are not limited by the following examples, and can be implemented with appropriate modifications within the scope that is consistent with the spirit described above and below, and all such modifications are included within the technical scope of the embodiments of the present invention. [Examples]

[0038] A 0.3mm thick pure copper plate was used as the plating substrate. After degreasing the surface with acetone cleaning, a commercially available Strike Ag plating solution (Dain Silver GPE-ST, manufactured by Yamato Kasei Co., Ltd.) was used as the base for the plating process, with the pure Ag plate as the counter electrode at 5 A / dm². 2 A current density of 3 A / dm was applied for 1 minute, and a strike Ag plating treatment with a thickness of approximately 0.1 μm was performed on the substrate. Subsequently, using a commercially available non-cyanide semi-bright Ag plating solution (Dain Silver GPE-SB, manufactured by Yamato Kasei Co., Ltd.), various particles shown in Table 1 and a surfactant were dispersed in the plating solution, and while stirring, a pure Ag plate was used as the counter electrode at 3 A / dm 2 By applying current at the specified current density for 5 minutes, contact materials No. 1 to 9 were obtained, each containing a silver-containing film in which individual particles were co-deposited (embedded) within an Ag plating layer (silver content of 99% by mass or more) with a thickness of approximately 10 μm. For Nos. 1 to 9, Surflon S231 (manufactured by AGX Seimi Chemical) was used as the surfactant, with an additive amount of 50 g / L.

[0039] [Table 1]

[0040] For contact materials No. 1 to 9, (a) the area ratio [A p / ( A p +A Ag (b) Contact resistance and (c) Abrasion resistance were evaluated using the following method: (b) Contact resistance and (c) Abrasion resistance.

[0041] <(a) Area ratio of equation (1) [A p / ( A p +A Ag ) × 100 (%)> Using a scanning electron microscope (SEM, Hitachi S-3500N), under conditions of an acceleration voltage of 20kV and a work distance of 15mm, cross-sectional SEM images (secondary electron images) parallel to the film thickness direction of the silver-containing film (and silver-containing layer) were acquired for samples of contact materials No. 1 to 9 coated with a protective layer for cross-sectional SEM. Area A of the silver-containing layer Ag A was defined as the area of ​​the bright portion after the cross-sectional SEM image was binarized using the image processing software "ImageJ" as described above. In the cross-sectional SEM image, the average line of the irregularities on the upper surface of the silver-containing layer was used as the boundary line between the silver-containing layer and the protective layer of the cross-sectional SEM sample. Area A represents the portion of multiple particles embedded in the silver-containing layer. p This refers to the area of ​​the dark portion (corresponding to the non-conductive organic compound) after binarization as described above, which is the area of ​​the portion embedded in the silver-containing layer. In the cross-sectional SEM image, the average line of the irregularities on the upper surface of the silver-containing layer was used as the boundary line between the silver-containing layer and the protective layer of the cross-sectional SEM sample, and the portion below this average line was considered to be the portion embedded in the silver-containing layer. Figures 3A and 3C show examples of how to calculate the area ratio of particles. Figure 3A is a cross-sectional SEM image of the silver-containing film (and silver-containing layer) of contact material No. 2, parallel to the film thickness direction. Figure 3B is an image cropped from Figure 3A showing only the silver-containing layer (and particles embedded in the silver-containing layer). Figure 3C is a binarized image of Figure 3B. When the area of ​​the black part in Figure 3C was divided by the area in Figure 3B, the area ratio was 2.51%.

[0042] <(b) Contact resistance evaluation> The contact resistance of the silver-containing films of contact materials No. 1 to 9 was measured using an electrical contact simulator (manufactured by Yamazaki Seiki Kenkyusho). The applied load was 5N, and the average value of measurements taken at three locations was used as the contact resistance of contact materials No. 1 to 9. Contact materials with a contact resistance of 0.50 [mΩ] or less were considered to have sufficient conductivity (○).

[0043] <(c) Abrasion resistance evaluation> A sample prepared by forming a hard Ag plating (Vickers hardness Hv: approximately 165) layer of approximately 50 μm on a 0.25 mm thick pure copper plate, and then forming a hemispherical protrusion with a radius of curvature R=1.8 mm by hand pressing, was used as the mating material for contact materials No. 1 to 9. A sliding test was conducted using a sliding test machine (Aiko Engineering horizontal load test machine) with an applied vertical load of 3 N, a sliding distance of 10 mm, and a sliding speed of 80 mm / min. The sliding cycle was 20 cycles. A friction coefficient of 0.50 [mΩ] or less after sliding was considered to have sufficient wear resistance (〇).

[0044] The results are summarized in Table 2. In the "Short-circuit prevention" column, if 50% or more of the particles in the contact material are non-conductive particles, short-circuits at the contacts due to particle detachment can be sufficiently suppressed (○). Values ​​marked with an asterisk (*) indicate that they fall outside the scope of the embodiments of the present invention.

[0045] [Table 2]

[0046] Based on the results in Table 2, the following conclusions can be drawn: Contact materials No. 2-4 and 6-9 all satisfy the requirements specified in the embodiments of the present invention, and are able to sufficiently suppress short circuits at the contacts due to the shedding of conductive particles, while also possessing sufficient wear resistance and conductivity. On the other hand, the contact materials No. 1 and 5 in Table 2 both failed to meet the area ratio range (0.50 to 12.10) of formula (1), which is a requirement specified in the embodiments of the present invention, and therefore had insufficient wear resistance or conductivity. [Examples]

[0047] From Example 1, contact materials No. 10 to 12 were obtained by changing the type of particles to be embedded and the amount added, as shown in Table 3. For Nos. 10 to 12, Surflon S231 (manufactured by AGX Seimi Chemical) was used as the surfactant, with an amount of 50 g / L for No. 10 and 10 g / L for Nos. 11 and 12.

[0048] [Table 3]

[0049] For contact materials No. 10 to 12, (d) thermogravimetric differential thermal analysis (TG-DTA) and (e) heat resistance evaluation were performed.

[0050] <(d) Thermogravimetric differential thermal analysis (TG-DTA)> For the organic compound particles used as contact materials No. 10 to No. 12, thermogravimetric differential thermal analysis was performed on them under air conditions at a heating rate of 10°C / min, from room temperature to a maximum of 1000°C, using a differential thermal balance (Rigaku, Thermo plus EVOII), to determine the melting point, decomposition point, and combustion point of each compound particle.

[0051] <(e) Heat resistance evaluation> Contact materials No. 10 to No. 12 were heated in a constant temperature chamber (Yamato Scientific, DN-43) set to 140 to 180°C in an atmospheric environment for 100 to 500 hours, after which the sliding test described in (c) Abrasion Resistance Evaluation above was performed. The sliding cycle was set to 500 cycles. Figures 4 to 6 show the heat resistance evaluation results for contact materials No. 10 to No. 12, respectively.

[0052] The results are summarized in Table 4. A "-" in the "TG-DTA Results" column indicates that the temperature was not indicated. In the "Heat Resistance Evaluation Results" column, a friction coefficient increase rate calculated using formula (2) above after 500 hours of heating at each temperature was marked as particularly good (◎) if it was 120% or less, good (〇) if it was 200% or less, and × otherwise. A "-" in the "Heat Resistance Evaluation Results" column indicates that the evaluation was not performed.

[0053] [Table 4]

[0054] The results in Table 4 show a correlation between the melting point of non-conductive organic compounds and their heat resistance evaluation. Contact materials No. 11 and 12, which had a melting point of 140°C or higher, or did not show a melting point, exhibited good heat resistance.

[0055] [Reference example] The following examples illustrate the requirements of the embodiments of the present invention, which state that "a nonconductive organic compound contains a fluoro group (-F), a methyl group (-CH3), a carbonyl group (-C(=O)-), and an amino group (-NR) within its unit molecular structure." 1 R 2 And R 1 and R 2 R is a hydrogen or hydrocarbon group, 1 and R 2 It is explained that a good effect is achieved by including one or more selected from the group consisting of a hydroxyl group (-OH), an ether bond (-O-), and an ester bond (-C(=O)-O-).

[0056] [Reference example 1] A 0.3mm thick pure copper plate was used as the plating substrate. After degreasing the surface with acetone cleaning, a commercially available Strike Ag plating solution (Dain Silver GPE-ST, manufactured by Yamato Kasei Co., Ltd.) was used as the base for the plating process, with the pure Ag plate as the counter electrode at 5 A / dm². 2 A current density of approximately 0.1 μm was applied for 1 minute, and a strike Ag plating treatment was performed on the substrate. Subsequently, a commercially available non-cyanide semi-bright Ag plating solution (Dain Silver GPE-SB, manufactured by Yamato Kasei Co., Ltd.) was used, with a pure Ag plate as the counter electrode, and a current density of 3 A / dm was applied. 2 A current density was applied for 5 minutes to form a semi-gloss Ag plating layer (silver content 99% by mass or more) with a thickness of approximately 10 μm. Subsequently, 0.2 ml / cm³ of a solution prepared by suspending various particles (or dispersions of particles) shown in Table 5 in alcohol at a ratio of 20 mg / ml was applied to the surface of the Ag plating layer. 2 Contact materials No. 13 to No. 24 were prepared by dropping and drying, each containing a silver-containing film in which various particles came into contact with the surface of the Ag plating layer.

[0057] [Table 5]

[0058] (f1) Abrasion resistance evaluation was performed on contact materials No. 13 to No. 24.

[0059] <(f1) Abrasion resistance evaluation> The sliding test described in (c) Wear Resistance Evaluation of Example 1 above was performed. The maximum number of sliding cycles was 500. The results are shown in Figures 7 to 18. Figures 7 to 18 show the results of the sliding test performed on the contact materials of Test No. 13 to 24, respectively. The maximum value of the friction coefficient (ratio of horizontal load to vertical load) was measured for each sliding cycle. A friction coefficient greater than 0.50 after 500 cycles was considered insufficient (×), a friction coefficient of 0.50 or less after 500 cycles was considered slightly insufficient (△), a friction coefficient of 0.50 or less after 300 cycles was considered sufficient (〇), and a friction coefficient of 0.30 or less after 100 cycles was considered good (◎). For measurements taken multiple times, the average value was used for the judgment.

[0060] The results are summarized in Table 6. In the "Short-circuit prevention" column, if 50% or more of the particles in the contact material are non-conductive particles, short circuits at the contacts due to particle detachment can be sufficiently suppressed (○). If less than 50% of the particles in the contact material are non-conductive particles (i.e., if more than 50% of the particles in the contact material are conductive particles), there is a risk of short circuits at the contacts due to particle detachment (×).

[0061] [Table 6]

[0062] Based on the results in Table 6, the following conclusions can be drawn. All of the contact materials No. 13 to 18 in Table 6 contained at least one non-conductive organic compound selected from the group consisting of fluoro groups, methyl groups, carbonyl groups, amino groups, hydroxyl groups, ether bonds (-O-), and ester bonds (-C(=O)-O-) within their unit molecular structure, resulting in a friction coefficient of 0.50 or less after 300 cycles. Furthermore, all of the contact materials No. 13 to 16 in Table 6 met the desirable requirement of containing at least one non-conductive organic compound selected from the group consisting of carbonyl groups, amino groups, and hydroxyl groups within their unit molecular structure, resulting in a friction coefficient of 0.30 or less after 100 cycles, which was a favorable result.

[0063] [Reference example 2] A 0.3mm thick pure copper plate was used as the plating substrate. After degreasing the surface with acetone cleaning, a commercially available Strike Ag plating solution (Dain Silver GPE-ST, manufactured by Yamato Kasei Co., Ltd.) was used as the base for the plating process, with the pure Ag plate as the counter electrode at 5 A / dm². 2 A current density of approximately 0.1 μm was applied for 1 minute, and a strike Ag plating treatment was performed on the substrate. Subsequently, a commercially available non-cyanide semi-bright Ag plating solution (Dain Silver GPE-SB, manufactured by Yamato Kasei Co., Ltd.) was used, with a pure Ag plate as the counter electrode, and a current density of 3 A / dm was applied. 2 A current density was applied for 5 minutes to form a semi-gloss Ag plating layer (silver content 99% by mass or more) with a thickness of approximately 10 μm. Subsequently, 0.2 ml / cm³ of a solution prepared by suspending various particles (or dispersions of particles) shown in Table 7 in alcohol at a ratio of 20 mg / ml was applied to the surface of the Ag plating layer. 2 Contact materials No. 25 to No. 28 were prepared by dropping and drying, and each contained a silver-containing film in which various particles came into contact with the surface of the Ag plating layer.

[0064] [Table 7]

[0065] (f2) Abrasion resistance evaluation was performed on contact materials No. 25 to No. 28.

[0066] <(f2) Abrasion resistance evaluation> Using a ball-on-disk testing apparatus (CSM, Tribometer), a φ6mm high-carbon chromium bearing steel (SUJ2) ball was used as the mating material for a 100-cycle reciprocating sliding test against contact materials No. 25 to 28. The applied vertical load was 1N, the sliding width (sliding stroke) per cycle was 10mm, and the average sliding speed was 30mm / second. The results are shown in Figures 19 to 22. Figures 19 to 22 show the results of the abrasion resistance evaluation performed on the contact materials for Test Nos. 25 to 28, respectively. The maximum value of the friction coefficient (ratio of horizontal load to vertical load) was measured in each sliding cycle. A friction coefficient greater than 1.0 after 100 cycles was deemed insufficient (×), a friction coefficient between 0.20 and 1.0 after 100 cycles was deemed sufficient (〇), and a friction coefficient less than 0.20 after 100 cycles was deemed good (◎). For measurements taken multiple times, the average value was used for the judgment.

[0067] The results are summarized in Table 8. In the "Short-circuit prevention" column, if 50% or more of the particles in the contact material are non-conductive particles, short circuits at the contacts due to particle detachment can be sufficiently suppressed (○). If less than 50% of the particles in the contact material are non-conductive particles (i.e., if more than 50% of the particles in the contact material are conductive particles), there is a risk of short circuits at the contacts due to particle detachment (×).

[0068] [Table 8]

[0069] Based on the results in Table 8, the following conclusions can be drawn. All of the contact materials No. 25 to 27 in Table 8 contained at least one non-conductive organic compound selected from the group consisting of fluoro groups, methyl groups, carbonyl groups, amino groups, hydroxyl groups, ether bonds (-O-), and ester bonds (-C(=O)-O-) within their unit molecular structure, resulting in a friction coefficient of 1.0 or less after 100 cycles. Furthermore, the contact material No. 27 in Table 8 met the desirable requirement of containing at least one non-conductive organic compound selected from the group consisting of carbonyl groups, amino groups, and hydroxyl groups within its unit molecular structure, resulting in a friction coefficient of less than 0.20 after 100 cycles, which was a favorable result. [Explanation of symbols]

[0070] 1 Contact material 2 Silver-containing film 2a Silver-containing layer 2b Particles made of non-conductive organic compounds 11 Contact materials

Claims

1. A contact material containing a silver-containing film, The silver-containing film comprises a silver-containing layer containing 50% by mass or more of silver, and a plurality of particles consisting solely of non-conductive organic compounds (except in cases where the average particle size of the plurality of particles consisting solely of non-conductive organic compounds is 500 nm or less), wherein at least a portion of each particle is embedded in the silver-containing layer. The aforementioned nonconductive organic compound has, within its unit molecular structure, Fluorine group (-F), methyl group (-CH ３ ), carbonyl group (-C(=O)-), amino group (-NR １ R ２ And R １ and R ２ R is a hydrogen or hydrocarbon group, １ and R ２ (These may be the same or different) and include one or more selected from the group consisting of a hydroxyl group (-OH), an ether bond (-O-), and an ester bond (-C(=O)-O-), When the non-conductive organic compound is subjected to thermogravimetric differential thermal analysis at a heating rate of 10°C / min from room temperature to a maximum of 1000°C, it is determined whether the melting point is 140°C or higher, or whether it does not exhibit a melting point. A contact material that satisfies the following equation (1). 0.50≦Ap / (A ｐ +A Ａｇ )×100≦12.10 ・・・(1) In equation (1), A ｐ A is the area of ​​the portion of the plurality of particles consisting solely of the non-conductive organic compound that is embedded in the silver-containing layer, in a cross-section parallel to the film thickness direction of the silver-containing film. Ａｇ This is the area of ​​the silver-containing layer in a cross-section parallel to the film thickness direction of the silver-containing film.

2. The nonconductive organic compound has a carbonyl group (-C(=O)-) and an amino group (-NR) within its unit molecular structure. １ R ２ And R １ and R ２ R is a hydrogen or hydrocarbon group, １ and R ２ The contact material according to claim 1, comprising one or more selected from the group consisting of (which may be the same or different) and a hydroxyl group (-OH).

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