JP2007042391A - Electric contact material manufacturing method and electric contact material - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an electric contact material manufacturing method and an electric contact material capable of enlarging a rugged shape on the surface of a metal plating. <P>SOLUTION: In applying electric plating on a parent material 2, overcurrent is made to flow at an initial stage of the electric plating, and afterwards, normal current is made to flow to form a silver plating on the parent material 2. For this treatment, first, an amount of the parent material 2 necessary for plating is rolled for leading it into a first plating tub 3a as a tub in which overcurrent is circulated. As the parent material 2 is set in the first plating tub 3a, overcurrent is made to flow between the parent material 2 dipped in plating liquid 4 and electrodes to form silver plating on the parent material 2 dipped in the plating liquid 4. Further, a part where the silver plating is formed in the first plating tub 3a is set in a second plating tub 3b, a normal-value current is made to flow between the parent material and the electrodes, and a silver component is piled on the above silver plating to form a silver plating with a necessary thickness. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to an electrical contact material manufacturing method and electrical contact material used for, for example, a switching contact of an electrical circuit.

  Conventionally, as an electrical contact material used for a switching contact of an electrical circuit, for example, a sintered silver-graphite alloy as disclosed in Patent Documents 1 to 3 has been widely used. Graphite originally has little weldability, is extremely chemically stable, and has a very high lubricating action. Therefore, since the silver-graphite alloy containing graphite becomes a material having high slidability, if the silver-graphite alloy is used as an electrical contact material, it is not necessary to use a lubricant such as grease or oil. Silver-graphite alloys are used as greaseless sliding contact materials.

  Here, when a sintered material is used, there is no limit to the amount of graphite that can be contained in silver, but as the graphite content relative to silver increases, the strength of the electrical contact material decreases and becomes brittle with respect to strength. There is a problem. Therefore, when considering the strength of the electrical contact material, a method of manufacturing a graphite-containing electrical contact material by plating a base metal with a metal containing graphite may be taken.

Generally, as a procedure for manufacturing a plating-type electrical contact material, first, graphite powder is mixed in a plating basket containing a silver-containing liquid, and a base material such as copper is immersed in the plating solution. In this state, when a voltage is applied between the base material and the electrode, silver will be attached to the base material. At this time, since silver takes in graphite and adheres to the base material, the surface of the base material contains graphite. The silver plating is formed. In this graphite-containing silver plating, the degree of lubrication effect is determined by the amount of graphite exposed on the plating surface.
JP 2002-53919 A JP-A-1996-13065 JP 63-7345 A

  By the way, in this type of graphite-containing silver plating, graphite adheres to the plating in a state of being taken in by the silver, and therefore enters and attaches to the irregularities on the plating surface. Therefore, if the surface unevenness of the silver plating is small, the amount of graphite to be attached decreases accordingly, and a sufficient surface graphite area ratio (graphite area with respect to the plating surface) cannot be obtained, so that sufficient wear resistance cannot be ensured. there were. In addition, graphite is attached by being caught by silver plating, so if the uneven shape on the plating surface is small, the degree of catching will be weak, so graphite will easily drop off from the plating surface, which also causes a problem in reducing wear resistance. It was coming.

  The objective of this invention is providing the electrical contact material manufacturing method and electrical contact material which can enlarge the uneven | corrugated shape of the surface of metal plating.

  In order to solve the above-described problems, in the invention according to claim 1, electroplating is performed by applying a voltage between a base material immersed in a plating solution and an electrode, and metal ions in the plating solution are removed. In the electrical contact material manufacturing method in which a graphite-containing metal plating is formed on the surface of the base material by being attached to the base material, when a voltage is applied between the base material and the electrode, excessive voltage is applied during the voltage application process. The gist is to pass an electric current.

  According to the present invention, when an overcurrent is passed between the base material and the electrode during electroplating, the plating speed is increased during the overcurrent application period, and when the metal ions adhere to the base material, the adhesion is biased. Therefore, the uneven shape on the surface of the metal plating becomes large, and the surface shape of the metal plating becomes rough. By the way, for example, when graphite particles are mixed in the plating solution, when the metal ions adhere to the base material, the graphite particles adhere to the base material in a state of being taken in by the metal ions and enter into the unevenness of the metal plating. Attach to metal plating. Therefore, if the irregular shape on the surface of the metal plating is increased, the amount of graphite on the metal plating is increased, so that the surface graphite area ratio of the metal plating is increased and high wear resistance is ensured.

The invention according to claim 2 is characterized in that, in the invention according to claim 1, the period in which the overcurrent flows is an initial stage within a certain period after the electroplating is started.
According to the present invention, in addition to the operation of the first aspect of the invention, when an overcurrent is passed in the initial stage of electroplating, the surface layer (for example, the first layer) of the base material is formed of a metal plating having a large uneven shape. A layer is formed. Accordingly, since the metal plating having a large unevenness is formed at an early stage of electroplating, it is possible to form the metal plating having a large surface unevenness without increasing the thickness of the metal plating so much.

  In the invention of claim 3, the surface of the base material is processed and roughened in advance, and then a voltage is applied between the base material and the electrode immersed in the plating solution in the subsequent process step. The gist is that electroplating is performed, and metal ions in the plating solution are adhered to the base material to form metal plating on the surface of the base material.

  According to this invention, the surface of the base material is processed to roughen the surface of the base material in advance, so that when the base material is electroplated, the metal plating is formed along the surface shape of the base material. Therefore, the uneven shape on the surface of the metal plating becomes large, and the surface shape of the metal plating becomes rough. By the way, for example, when graphite particles are mixed in the plating solution, when the metal ions adhere to the base material, the graphite particles adhere to the base material in a state of being taken in by the metal ions and enter into the unevenness of the metal plating. Attach to metal plating. Therefore, if the irregular shape on the surface of the metal plating is increased, the amount of graphite on the metal plating is increased, so that the surface graphite area ratio of the metal plating is increased and high wear resistance is ensured.

  According to a fourth aspect of the present invention, a voltage is applied between a base material immersed in a plating solution and an electrode to perform electroplating, and metal ions in the plating solution are attached to the base material to thereby form the base material. Forming a metal plating on the surface of the material, etching the base material on which the metal plating is formed to dissolve the surface of the metal plating, re-applying the electroplating on the base material after the etching, The gist is to form the metal plating again on the surface of the base material after the etching.

  According to the present invention, when etching is performed after the first electroplating, the surface of the metal plating is dissolved and the plated surface shape becomes rough. Then, when electroplating is again applied to the base material after etching, metal ions are attached to the roughened plating surface shape, so that metal plating is formed. Is formed in a large state. By the way, for example, when graphite particles are mixed in the plating solution, when the metal ions adhere to the base material, the graphite particles adhere to the base material in a state of being taken in by the metal ions and enter into the unevenness of the metal plating. Attach to metal plating. Therefore, if the irregular shape on the surface of the metal plating is increased, the amount of graphite on the metal plating is increased, so that the surface graphite area ratio of the metal plating is increased and high wear resistance is ensured.

  The invention according to claim 5 is the invention according to any one of claims 1 to 4, wherein graphite particles are mixed in the plating solution, and the electroplating is performed on the base material. The gist is that the metal plating is formed on the surface of the base material in a state containing the graphite particles.

  According to the present invention, in addition to the action of the invention according to any one of claims 1 to 4, the metal plating contains graphite particles having a solid lubricating action. The electrical contact material provided with can be used as a greaseless sliding contact material.

  In the invention according to claim 6, electroplating is performed by applying a voltage between a base material immersed in a plating solution and an electrode, and metal ions in the plating solution are adhered to the base material to thereby form the base material. The gist of the invention is an electrical contact material produced by forming a metal plating on the surface of the material and applying an overcurrent during the voltage application process when a voltage is applied between the base material and the electrode. According to the present invention, an effect similar to that of the first aspect can be obtained.

  According to the seventh aspect of the present invention, the surface of the base material is processed and roughened in advance, and then a voltage is applied between the base material immersed in the plating solution and the electrode in the subsequent process step. The gist of the present invention is an electrical contact material in which electroplating is performed and metal ions in the plating solution are adhered to the base material to form a metal plating on the surface of the base material. According to the present invention, an effect similar to that of the third aspect can be obtained.

  According to the eighth aspect of the present invention, a voltage is applied between a base material immersed in a plating solution and an electrode to perform electroplating, and metal ions in the plating solution are attached to the base material to thereby form the base material. Forming a metal plating on the surface of the material, etching the base material on which the metal plating is formed to dissolve the surface of the metal plating, re-applying the electroplating on the base material after the etching, The gist of the invention is an electrical contact material in which the metal plating is formed again on the surface of the base material after etching. According to the present invention, an effect similar to that of the fourth aspect can be obtained.

  According to the present invention, the uneven shape on the surface of the metal plating can be increased.

  Hereinafter, an embodiment of an electrical contact material manufacturing method and an electrical contact material embodying the present invention will be described with reference to FIGS.

(Overcurrent application processing)
FIG. 1 is a schematic configuration diagram showing a schematic configuration of the electroplating apparatus 1. The electroplating apparatus 1, while the base material 2 to be plated is immersed in the plating solution 4 in the plating bowl 3, applies a DC voltage between the electrode (not shown) and the base material 2 that are also immersed in the plating solution 4. This is a device for applying a direct current to the base material 2 by applying it and forming metal plating on the surface of the base material 2. At this time, the base material 2 becomes a cathode (minus), the electrode becomes an anode (plus), and metal ions in the plating solution are attracted to the base material 2, whereby metal plating is formed on the base material 2.

  In the electroplating apparatus 1 of this example, a plating rod 3 is divided into two regions by an intermediate partition wall 5, and at the time of electroplating, the base material 2 is a plating solution in each cage in the order of the first plating rod 3a and the second plating rod 3b. 4 respectively. In the electroplating apparatus 1 of this example, an overcurrent is passed through the base material 2 by the first plating rod 3a in which the base material 2 is first hidden, and the base material 2 is applied by the second plating rod 3b in which the base material 2 is subsequently hidden. A process of forming a metal plating on the surface of the base material 2 is performed by passing a normal current.

  The base material 2 is wound around a roll and installed outside the plating basket 3. The partition wall 5 and the pair of side walls 6 and 7 of the plating basket 3 are provided with through holes 5a, 6a and 7a in the lower part thereof, and the base material 2 is provided with one through hole 6a (on the right side in FIG. 1) during plating. Is introduced into the first plating rod 3a and led out of the second plating rod 3b from the other (left side in FIG. 1) through the through hole 5a of the partition wall 5. The plating solution 4 leaking from the through holes 6 a and 7 a is temporarily stored in the storage portion 8 below the plating basket 3, and the plating solution 4 is pumped up to the plating basket 3 by the pump device 9.

  Since the electroplating apparatus 1 of this example uses a molten solution of silver cyanide as the plating solution 4, a silver plating 10 (see FIG. 2) is formed as a metal plating on the surface of a base material 2 such as copper. When the silver plating 10 is formed on the base material 2 by the electroplating apparatus 1, the plating solution 4 is mixed with powder of graphite particles 11 having a particle size of about 1 to 20 μm (hereinafter referred to as graphite particles). Therefore, when the silver component adheres to the base material 2 during the plating process, powder graphite particles 11 are also taken together with the silver, and the graphite particles 11 are dispersed in the silver plating 10 as shown in FIGS. It becomes the state contained in the state. The silver plating 10 corresponds to metal plating.

  When the silver plating 10 containing graphite is formed on the base material 2 by the electroplating apparatus 1, the silver plating 10 is formed by flowing an overcurrent within a certain period from the initial stage of electroplating, that is, from the start of electroplating. In this process, first, the base material 2 of an amount necessary for plating is introduced into the first plating rod 3a through the through hole 6a while being wound up in order. When a necessary amount of the base material 2 is set on the first plating rod 3a, the state is maintained, and an overcurrent flows between an electrode (not shown) immersed in the first plating rod 3a and the base material 2. . At this time, the current value of the overcurrent that flows through the base material 2 is set to a value that is, for example, 3 to 5 times the normal current value (that is, the current value that flows through the base material 2 by the second plating rod 3b). Has been.

  When an overcurrent is applied to the base material 2 by electroplating, the plating speed increases during the overcurrent application period, so that when the silver component adheres to the base material 2, it adheres to the base material 2 in a biased state. As shown in FIG. 2A, the silver plating 10 is formed on the base material 2 in a state where the surface 10a has a large uneven shape (the surface 10a is rough). At this time, silver adheres to the base material 2 due to electrical coupling, but the graphite particles 11 in the plating solution 4 are attached to the silver plating 10 in a state where the silver particles are taken into the silver when the silver adheres to the base material 2. The silver plating 10 is dispersed in the silver plating 10 in a state of being surrounded by surface irregularities.

  After passing the overcurrent for a predetermined time, the process of passing the overcurrent to the base material 2 is stopped, and the portion plated with the first plating rod 3a is subsequently introduced into the second plating rod 3b through the through hole 5a. Is done. When the portion plated with the first plating rod 3a is set on the second plating rod 3b, the state is maintained, and between the electrode (not shown) immersed in the second plating rod 3b and the base material 2 A normal value current is passed through. When a current having a normal value is passed through the base material 2 for a predetermined time, a silver component is newly stacked on the layer of the silver plating 10 formed by passing an overcurrent, and finally, as shown in FIG. Thus, a silver plating 10 having a required layer thickness is formed on the base material 2.

  When the silver plating 10 having the required layer thickness is formed, the process of supplying a normal current to the base material 2 is stopped, and the portion plated with the second plating rod 3b is then passed through the through hole 7a. It leads out to the exterior of 2 plating cage | basket 3b. Then, electroplating in which normal current is passed after passing an overcurrent is repeatedly performed until the silver plating 10 is formed in all locations of the base material 2 wound in a roll shape, and manufactured by the above processing. The base material 2 is handled as the electrical contact material 12.

  By the way, when the silver plating 10 is formed with a normal current value in the electroplating, the silver plating 10 with the surface unevenness not so large is formed. However, in this example, an overcurrent is passed in the initial stage of electroplating, and a silver plating 10 having large surface irregularities is previously formed on the base material 2 and a silver component is attached thereto at a normal current. Therefore, even when electroplating is performed at a normal low current value, since the silver component is previously stacked on the silver plating 10 having large unevenness, the surface of the finally formed silver plating 10 has a large uneven shape. It becomes a state.

  Further, since the graphite particles 11 contained in the silver plating 10 are attached to the silver plating 10 in a state of being wrapped in the surface unevenness of the silver plating 10, if the uneven shape of the silver plating 10 is large, the silver plating 10 has a large amount. It can be said that the graphite particles are attached. Therefore, in this example, the surface unevenness of the silver plating 10 is formed by performing the process of applying an overcurrent to the base material 2 in the initial stage of electroplating, and therefore the graphite particles 11 are attached by that much. It becomes a state. Therefore, the surface graphite area ratio of the silver plating 10 is increased, and the wear resistance of the silver plating 10 can be increased.

(Base material surface treatment)
FIG. 3 is a perspective view when performing the process of roughening the surface 2 a of the base material 2. The method of enlarging the surface unevenness of the silver plating 10 is replaced with a method of flowing an overcurrent at the initial stage of electroplating, and a base material in which the surface 2a of the base material 2 is roughened in advance, and the base material 2 is roughened. There is also a method of enlarging the surface unevenness of the silver plating 10 by electroplating 2 as a post-process. In order to roughen the surface 2a of the base material 2 in advance, for example, a file or shot blasting may be used. However, the method is not particularly limited as long as the surface unevenness of the base material 2 can be roughened.

  When electroplating is performed on the base material 2 having a rough surface 2 a, the silver component in the plating solution 4 is sequentially stacked on the surface 2 a of the base material 2 to form a layer of silver plating 10. It is formed in a shape along the shape. Therefore, if the unevenness of the surface 2a of the base material 2 is large, the silver plating 10 formed on the surface 2a of the base material 2 is also formed with a large surface unevenness. Therefore, if the surface unevenness of the silver plating 10 is large, a large amount of graphite particles 11 are attached to the silver plating 10, the surface graphite area ratio is increased, and the wear resistance of the silver plating 10 is increased.

(Etching-re-plating process)
FIG. 4 is an explanatory diagram when the electrical contact material 12 subjected to the silver plating 10 is etched. The method of enlarging the surface unevenness of the silver plating 10 is not limited to a method of flowing an overcurrent in the initial stage of electroplating or a method of roughening the surface 2a of the base material 2 in advance, but an electrical contact provided with the silver plating 10 Alternatively, the material 12 may be etched and re-plated. Note that the silver plating 10 formed on the base material 2 by the first electroplating does not necessarily need to contain the graphite particles 11, and may be plating of only the silver component.

  In this process, first, the silver plating 10 is formed on the base material 2 by, for example, electroplating in which a current having a normal value is passed, and the electrical contact material 12 having the silver plating 10 on the surface layer is prepared. Subsequently, the electrical contact material 12 is subjected to an etching process. As this etching process, first, as shown in FIG. 4, the electrical contact material 12 is immersed in an etching solution 14 in an etching bowl 13 to melt its surface, and then a patterning process using a mask is performed to make the surface of the silver plating 10 uneven. Form. Thereby, the surface 10a of the silver plating 10 is changed from the state shown in FIG. 5A where the surface unevenness is not so large to the state shown in FIG. 5B where the surface unevenness is increased.

  After the etching process, the electric contact material 12 is subjected to electroplating again. That is, the electrical contact material 12 subjected to the etching process is set again in the electroplating apparatus 1, and a DC voltage is applied between the electrical contact material 12 and the electrode in the plating solution 4 to A silver component is laminated on the surface to re-form the silver plating 10. The re-plating plating conditions (for example, the current value applied during plating) may be the same as or different from the initial electroplating.

  When the electroplating is again applied to the silver plating 10 having a large surface irregularity, the silver component in the plating solution 4 is sequentially stacked on the surface 10a of the silver plating 10 to form a laminated state. It is formed in a shape along the surface shape of the later silver plating 10. Therefore, in this example, since the silver plating 10 is re-plated on the surface of the silver plating 10 whose surface unevenness is roughened by etching, the surface layer of the final silver plating 10 has a large surface unevenness as shown in FIG. It becomes a state. Therefore, if the surface unevenness of the silver plating 10 is large, a large amount of graphite particles 11 are attached to the silver plating 10, the surface graphite area ratio is increased, and the wear resistance of the silver plating 10 is increased.

(Laser processing)
FIG. 6 is a schematic configuration diagram showing a schematic configuration of the laser device 15. Incidentally, the electrical contact material 12 having the silver plating 10 may be subjected to a high temperature treatment (reflow treatment) to improve the fixability of the graphite particles 11 contained in the silver plating 10. The laser device 15 is a device that melts a workpiece by irradiating the workpiece with a laser as a high-temperature treatment. The laser device 15 includes a processing chamber 16 that accommodates the electrical contact material 12 in a sealed state, a laser irradiation unit 17 attached in the processing chamber 16, and a vacuum pump 18 that decompresses the processing chamber 16 to a vacuum (non-oxidizing atmosphere). And. The laser device 15 includes a drive mechanism 19 that reciprocates the laser irradiation unit 17 in a predetermined direction, and a conveyance mechanism 20 that conveys a workpiece in a direction orthogonal to the reciprocation direction of the laser irradiation unit 17.

  Next, a procedure for melting the electrical contact material 12 with the laser device 15 will be described. When performing the laser processing, the electrical contact material 12 cut into a flat plate of a predetermined area after the plating processing is processed in the processing chamber 16 of the laser device 15. Then, the inside of the processing chamber 16 is decompressed to a vacuum state by the vacuum pump 18. Note that the processing chamber 16 is not necessarily in a vacuum state, and a non-oxidizing atmosphere is sufficient.

  After the inside of the processing chamber 16 is in a vacuum state, the laser irradiation unit 17 starts the forward movement by the drive mechanism 19, and the electric contact material 12 set in the processing chamber 16 is irradiated with the laser in the course of the forward movement. Then, the first line is melted on the surface 10 a of the silver plating 10. Here, since the melting point of silver is about 962 ° C. and the melting point of the graphite particles 11 is about 3550 ° C., the melting temperature by the laser irradiation unit 17 is lower than the melting point of the base material 2 and only the silver plating 10 is melted. Therefore, it is set to about 1000 ° C to 1500 ° C.

  When the laser irradiation unit 17 finishes one forward movement, the transport mechanism 20 transports the electrical contact material 12 by a predetermined amount. Subsequently, the laser irradiation unit 17 starts to move backward, and in the process of moving backward, the silver plating 10 is irradiated with a laser to melt the second line on the surface 10 a of the silver plating 10. When the laser irradiation unit 17 completes one backward movement, the transport mechanism 20 transports the electrical contact material 12 again by a predetermined amount. Thereafter, the laser irradiation by the laser irradiation unit 17 and the electrical contact material 12 are performed in the same manner as described above. The conveyance is repeated until laser irradiation is performed on all the lines of the silver plating 10.

  Accordingly, since the surface 10a of the silver plating 10 is melted, the melted silver component flows into the gaps between the graphite particles 11, and the melted silver component is uneven in the silver plating 10 as shown in FIG. The graphite particles 11 are filled with a silver component. Therefore, the melted silver component strongly fixes the graphite particles 11 in the silver plating 10 around, and the fixability of the graphite particles 11 is enhanced. Thereby, it becomes difficult for the graphite particles 11 to fall off from the silver plating 10, and the wear resistance of the silver plating 10 (electrical contact material 12) is improved.

(Heat treatment by furnace)
FIG. 7 is a schematic configuration diagram showing a schematic configuration of the furnace device 21. The method for melting the surface 10a of the silver plating 10 is not limited to the laser processing described above, and for example, heat treatment using the furnace device 21 may be used. The furnace apparatus 21 is an apparatus that puts a workpiece into the furnace 22 and raises the temperature inside the furnace 22 to melt the workpiece. The furnace device 21 includes a processing chamber 23 that houses the electrical contact material 12 in a sealed state, a heat source 24 that raises the temperature in the processing chamber 23, and a vacuum pump 25 that places the processing chamber 23 in a vacuum (non-oxidizing atmosphere) state. And.

  Next, the procedure for melting the electrical contact material 12 in the furnace apparatus 21 will be described. When performing the heat treatment by the furnace 22, the electrical contact material 12 cut into a flat plate having a predetermined area after the plating process is processed in the furnace 22. Then, the inside of the processing chamber 23 is decompressed to a vacuum state by the vacuum pump 25. Note that, as in the case of laser processing, the processing chamber 23 is not necessarily in a vacuum state, and may be a non-oxidizing atmosphere. Various heat sources 24 such as a high-frequency heating heat source are used.

  After the inside of the processing chamber 23 is in a vacuum state, when the power is turned on to the heat source 24 and the temperature of the processing chamber 23 is increased, the surface 10a of the silver plating 10 is melted. Here, the melting temperature of the heat treatment in the furnace 22 is set to about 1000 ° C. to 1500 ° C. for the same reason in the case of the laser treatment. Therefore, even when the furnace 22 is used, the surface 10a of the silver plating 10 is melted, whereby the fixability of the graphite particles 11 is increased, and the wear resistance of the silver plating 10 is improved as in the case of laser processing.

(Pressure treatment)
FIG. 8 is a schematic configuration diagram showing a schematic configuration of the pressure treatment device 26. Here, the method of fixing the graphite particles 11 in the silver plating 10 to the silver plating 10 is not limited to the high temperature processing, and may be a pressurizing process for fixing by pressure. The pressure treatment device 26 is a device that plastically deforms the surface of the workpiece by pressurizing the workpiece with a roller or the like. The pressure treatment device 26 includes a support base 27 on which the electrical contact material 12 is placed, a roller 28 capable of rotating, and the roller 28 pressed against the electrical contact material 12 with a predetermined pressure in a predetermined direction. And a drive mechanism 29 that moves in the direction of arrow A in FIG.

  Next, the procedure for pressurizing the electrical contact material 12 with the pressure treatment device 26 to plastically deform the surface of the electrical contact material 12 will be described. When performing the pressure treatment, the plate is cut into a flat plate having a predetermined area after the plating treatment. The made electrical contact material 12 is set on the support base 27. Then, the drive mechanism 29 presses the roller 28 against the electrical contact material 12 with a predetermined pressure. In this state, the drive mechanism 29 moves the roller 28 in the direction of the arrow A1 in FIG. Pressure. At this time, the pressure value (predetermined pressure) that the roller 28 applies to the surface 10a of the silver plating 10 is set to a value at which the surface 10a of the silver plating 10 is plastically deformed.

  Therefore, since the surface 10a of the silver plating 10 is plastically deformed by the pressurizing process, the plastically deformed silver component is buried around the graphite particles 11 as shown in FIG. Therefore, the plastically deformed silver component strongly fixes the graphite particles 11 in the silver plating 10 around, and the fixability of the graphite particles 11 is enhanced. Thereby, it becomes difficult for the graphite particles 11 to fall off from the silver plating 10, and the wear resistance of the silver plating 10 (electrical contact material 12) is improved. Further, when the graphite particles 11 in the silver plating 10 are fixed by the pressure treatment, the surface hardness of the silver plating 10 is increased by the pressure treatment, so that the graphite particles 11 are firmly fixed on the silver plating 10. Thus, the wear resistance of the silver plating 10 is further increased.

  Here, the surface graphite area ratio S is appropriately determined depending on the amount of graphite on the plating surface table. FIG. 9 is a graph showing the relationship between the surface graphite area ratio S and the number of times of durability N. The endurance number N of the contact material 12 is determined. Accordingly, the durability number N differs depending on the target product specifications. However, in order to ensure sufficient wear resistance, the durability number N is secured 1 million times as can be seen from the graph of FIG. It is desirable to set the surface graphite area ratio S to .45 or more.

According to the configuration of the present embodiment, the following effects can be obtained.
(1) When electroplating the base material 2, an overcurrent flows at the initial stage, so that the plating speed increases during the overcurrent application, and the silver component adhering to the base material 2 is biased. The uneven shape of the plating surface can be increased. Therefore, if the irregular shape of the silver plating 10 is increased, a large number of graphite particles 11 are attached accordingly, so that the surface graphite area ratio S of the silver plating 10 is increased, and the wear resistance of the silver plating 10 can be improved. . Further, when the surface 2a of the base material 2 is roughened in advance and electroplating is performed on the base material 2, etching is performed after the silver plating 10 is formed on the base material 2 by electroplating, and the electroplating is performed after the etching. Similarly, when the material 2 is re-plated, the surface unevenness of the silver plating 10 can be increased, and the wear resistance of the silver plating 10 can be improved.

  (2) When the silver plating 10 is formed by flowing an overcurrent during electroplating, the overcurrent flows in the initial stage of electroplating. It is formed on the surface layer. Accordingly, since the silver plating 10 having a large concavo-convex shape is formed at an early stage of electroplating, the silver plating 10 having a large surface concavo-convex shape can be formed without increasing the layer thickness of the silver plating 10 so much.

  (3) When the surface 2a of the base material 2 is roughened in advance and electroplating is performed on the base material 2, the surface 2a of the base material 2 needs only a simple work of shaving with a file or the like. Thus, the silver plating 10 having large surface irregularities can be formed without performing laborious work.

  (4) Since the silver plating 10 contains graphite particles 11 having a solid lubricating action, the electrical contact material 12 of this example to which the graphite-containing silver plating 10 is applied is used as a greaseless sliding contact material. can do. Therefore, it is not necessary to use a lubricant such as grease or oil, the cost for the lubricant can be eliminated, and grease and oil are hardened at low temperatures. Can also respond.

In addition, embodiment is not limited to the said structure, You may change into the following aspects.
-The silver plating 10 may be either glossy plating or matte plating, but the matte plating has the property that the surface unevenness increases, so if the matte plating is adopted, the surface unevenness of the silver plating 10 is further increased. be able to.

  When the silver plating 10 is formed by flowing an overcurrent at the time of electroplating, the timing of flowing the overcurrent is not limited to the initial stage of electroplating, for example, by performing electroplating for a while (for example, about 10 seconds) at a normal current value From the above, a procedure for passing an overcurrent to the base material 2 may be performed.

  When the silver plating 10 is formed by flowing an overcurrent during electroplating, the plating rod 3 is divided into two parts, a first plating rod 3a for overcurrent and a second plating rod 3b for normal current. The present invention is not limited to this, and the plating cage 3 may be used as a single cage for both overcurrent use and normal current use.

  -When etching the silver plating 10 and re-plating it, the etching solution used at that time is not limited to a solution using various components such as copper, hydrochloric acid, iron, hydrogen peroxide or sulfuric acid. The component is not particularly limited as long as it can dissolve 10 surfaces.

  -When metal plating is formed by electroplating, the metal plating is not limited to silver plating 10, but for example, gold plating, electroless nickel plating, chromium plating, nickel plating, solder plating, tin plating, zinc plating, etc. may be adopted. Good.

  When the surface 2a of the base material 2 is roughened and plated, or when the silver plating 10 is etched and re-plated, the method of plating the base material 2 is not limited to electroplating, for example, chemical plating, Hot dipping, physical vapor deposition, chemical vapor deposition, penetration plating, or the like may be employed.

Next, technical ideas that can be grasped from the above-described embodiment and other examples will be described below together with their effects.
(1) An electrical contact material characterized in that the surface of the base material is processed to be roughened in advance, and the base material having a rough surface is plated to form a metal plating on the surface of the base material. Production method. Also in this case, the surface unevenness of the metal plating can be increased.

  (2) Plating the base material to form a metal plating on the surface of the base material, etching the base material on which the metal plating is formed to dissolve the surface of the metal plating, A method for producing an electrical contact material, wherein the base material is plated again and the metal plating is formed on the surface of the base material after etching. Also in this case, the surface unevenness of the metal plating can be increased.

The schematic block diagram which shows schematic structure of an electroplating apparatus. (A) is a cross-sectional view of the electrical contact material when an overcurrent is applied by electroplating, (b) is a cross-sectional view of the electrical contact material when the plating process of silver plating is completed, and (c) is after electroplating Sectional drawing of the electrical contact material at the time of giving high temperature processing (pressurization process) to the electrical contact material of. The perspective view which shows the working state at the time of roughening the surface of a base material. Explanatory drawing at the time of etching the electrical contact material which gave silver plating. (A) is a cross-sectional view of an electrical contact material formed with silver plating by the first electroplating, (b) is a cross-sectional view of the electrical contact material after etching is performed after the first electroplating, (c) ) Is a cross-sectional view of an electrical contact material in which silver plating is formed by re-plating of electroplating after etching. The schematic block diagram which shows schematic structure of a laser apparatus. The schematic block diagram which shows schematic structure of a furnace apparatus. The schematic block diagram which shows schematic structure of a pressurization processing apparatus. The graph which shows the relationship between the surface graphite area ratio and its durability.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 2 ... Base material, 2a ... Surface, 4 ... Plating liquid, 10 ... Silver plating as metal plating, 11 ... Graphite particle, 12 ... Electrical contact material.

Claims (8)

Electroplating is performed by applying a voltage between a base material immersed in a plating solution and an electrode, and metal ions contained in the plating solution are attached to the base material so that the surface of the base material is plated with graphite. In the electrical contact material manufacturing method for forming
When applying a voltage between the said base material and the said electrode, an overcurrent is sent in the voltage application process, The electrical contact material manufacturing method characterized by the above-mentioned.   The electrical contact material manufacturing method according to claim 1, wherein the period for supplying the overcurrent is an initial stage within a predetermined period after the electroplating is started.   The surface of the base material is processed and roughened in advance, and then electroplating is performed by applying a voltage between the base material and the electrode immersed in the plating solution in the subsequent process step, in the plating solution A metal ion is formed on the surface of the base material by attaching the metal ions to the base material.   Electroplating is performed by applying a voltage between a base material immersed in a plating solution and an electrode, and metal ions in the plating solution are attached to the base material to form a metal plating on the surface of the base material. The base material on which the metal plating is formed is etched to dissolve the surface of the metal plating, the electroplating is again applied to the base material after the etching, and the surface of the base material after the etching is applied. The method of manufacturing an electrical contact material, wherein the metal plating is formed again.   Graphite particles are mixed in the plating solution, and when the electroplating is performed on the base material, the metal plating is formed on the surface of the base material in a state containing the graphite particles. The electrical contact material manufacturing method according to any one of claims 1 to 4, wherein the electrical contact material is produced.   Electroplating is performed by applying a voltage between a base material immersed in a plating solution and an electrode, and metal ions in the plating solution are attached to the base material to form a metal plating on the surface of the base material. An electrical contact material manufactured by applying an overcurrent during the voltage application process when applying a voltage between the base material and the electrode.   The surface of the base material is processed and roughened in advance, and then electroplating is performed by applying a voltage between the base material and the electrode immersed in the plating solution in the subsequent process step, in the plating solution An electrical contact material characterized in that a metal plating is formed on the surface of the base material by adhering metal ions to the base material.   Electroplating is performed by applying a voltage between a base material immersed in a plating solution and an electrode, and metal ions in the plating solution are attached to the base material to form a metal plating on the surface of the base material. The base material on which the metal plating is formed is etched to dissolve the surface of the metal plating, the electroplating is again applied to the base material after the etching, and the surface of the base material after the etching is applied. An electrical contact material wherein the metal plating is formed again.

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