JPH07278879A - Plating method and device therefor - Google Patents

Abstract

PURPOSE:To form plating layers which are changed in eutectic density of a dispersant in the thickness direction of plating layers with one kind of a plating bath contg. the dispersant. CONSTITUTION:The plating liquid is supplied from a tank 15 in which the plating bath contg. the dispersant is stored to a treatment device main body 2. While this plating liquid is fluidized between a work 1 and electrodes 7, an electric current is passed therebetween, by which plating is executed. The flow velocity of the plating liquid between the work 1 and the electrodes 7 is made adjustable by an automatic valve 17 of a plating liquid supply pipe 22 and an automatic valve 20 of a bypass pipe 23. On the other hand, the density of the current to be supplied to the electrodes 7 is made regulatable by a rectifier 26. These valves are controlled by a controller 25. The flow velocity of the plating liquid between the work 1 and the electrodes 7 and the density of the current to be supplied to the electrodes 7 are fluctuated at prescribed time intervals.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method and an apparatus for plating by supplying an electric current while flowing a plating solution containing a dispersant between a surface to be plated of a work and an electrode. The present invention relates to a plating method and its apparatus for forming a plating layer in which the eutectoid density of a dispersant is changed in the thickness direction of the plating layer.

[0002]

2. Description of the Related Art Conventionally, so-called composite plating, in which a dispersant is co-deposited, is known as a type of plating that provides excellent properties such as lubricity and friction coefficient. For example, a cylinder of a cylinder block of an engine is known. It is effectively used as a plating on the inner peripheral surface.

In the case of performing the composite plating as described above, if the dispersant is co-deposited to such an extent that the requirements such as the above-mentioned lubricity and the like are satisfied only by the single-layer composite plating, the adhesion to the work is deteriorated. In some cases, it may not be possible to sufficiently satisfy various requirements for plating. Therefore, a technique for changing the eutectoid density of the dispersant in the plating layer in the thickness direction of the plating layer has been developed. For example, a single plating layer that does not eutectize the dispersant is formed on the work surface,
By forming a composite plating layer with a co-deposited dispersant on its surface, and indirectly improving the adhesion strength of the composite plating to the work, plating of multiple layers with different co-deposition densities of the dispersant is performed. A technique of multi-layer plating for applying is developed.

[0004]

When performing the above-mentioned multilayer plating, a plurality of types of plating solutions, for example, a plating solution containing no dispersant and a plating solution containing a dispersant are provided between the surface to be plated and the electrode. And need to intervene. Therefore, in reality, first, after forming a single plating layer on the surface of the work in the bath of the plating bath containing no dispersant, the work is moved to the bath of the plating bath containing the dispersant. The composite plating layer is formed on the surface of the single plating layer that has already been formed. However, performing plating while moving the work between a plurality of baths in this way is disadvantageous in terms of work efficiency, equipment, and cost.

By the way, as a method for plating a work, a method of immersing the work in a plating bath is generally used, but recently, as a high-speed plating method for enhancing the processing efficiency, a work surface to be plated and an electrode are treated. A technique has been developed in which a plating solution is made to flow between them to energize a work and an electrode, thereby increasing a plating rate. However, even in the case of this high-speed plating method, when performing multi-layer plating, a plurality of types of plating baths and corresponding plating treatments are provided, so that work efficiency, equipment, etc. are not sufficiently improved.

In view of the above circumstances, the present invention is a plating method capable of forming a plating layer in which the eutectoid density of the dispersant changes in the thickness direction of the plating layer with one type of plating bath containing the dispersant. And its device.

[0007]

The plating method of the present invention comprises:
In a method of performing plating by applying a current while flowing a plating solution of a plating bath containing a dispersant between a surface to be plated of a work and an electrode, the flow rate of the plating solution and the current density of the supplied current are The eutectoid density of the dispersant in the plating layer formed on the surface to be plated of the work is changed in the thickness direction of the plating layer by varying it with the passage of time during the plating process (claim 1). It should be noted that “changing according to the passage of time during the plating treatment” is meant to include both continuous cases and intermittent cases.

Further, in the plating method according to the first aspect of the present invention, after flowing a current having a high current density while flowing the plating solution at a high speed, the flow rate of the plating solution and the current density of the supply current are gradually reduced. (Claim 2).

Further, in the plating method according to claim 1, the flow rate of the plating solution and the current density of the supply current are varied at predetermined time intervals so that the plating layer has a different eutectoid density of a dispersant. A plurality of plating layers are laminated and formed (claim 3).

In addition, in the plating method according to the third aspect of the present invention, after flowing a current having a high current density while flowing the plating solution at a high speed, a current having a low current density is caused while flowing the plating solution at a low speed. Is energized (Claim 4).

Further, in the plating method according to any one of claims 1 to 4, a nickel bath is used as the plating bath,
Silicon carbide is used as the dispersant (claim 5).

The plating apparatus of the present invention is an apparatus for performing plating by applying a current while flowing a plating solution of a plating bath containing a dispersant between a surface to be plated of a work and an electrode. Flow velocity adjusting means for adjusting the flow velocity of the plating solution between the surface and the electrode, current density adjusting means for adjusting the current density of the energizing current, time measuring means for measuring the passage of time during the plating process, and passage of the above time. And a control means for controlling the flow velocity adjusting means and the current density adjusting means so as to change the flow rate of the plating solution and the current density of the applied current in accordance with the above (claim 6).

[0013]

According to the present invention, by changing the flow rate of the plating solution and the current density of the supplied current, the plating layer can be formed from one type of plating bath containing a dispersant according to the flow rate and the current density. A plating layer in which the eutectoid density of the dispersant changes in the thickness direction of is formed. That is, since the dispersant tends to be less likely to be co-deposited as the flow rate and the current density increase, the flow rate and the current density vary even if the amount of the dispersant in the plating solution is constant. As a result, the eutectoid amount of the dispersant during plating changes.

At this time, first, a current having a high current density is applied while the plating solution is flowing at a high speed, and then the flow rate of the plating solution and the current density of the supplied current are gradually reduced. In plating, a part where the dispersant is hardly codeposited is formed on the surface of the workpiece to be plated, and a plating layer is formed so that the co-deposition density of the dispersant increases toward the surface side. ).

If the flow rate of the plating solution and the current density of the supply current are varied at predetermined time intervals, a plurality of plating layers having different eutectoid densities of the dispersant are formed on the surface to be plated of the work. It is formed by stacking (claim 3).

At this time, first, a current having a high current density is passed while flowing the plating solution at a high speed, and then a current having a low current density is passed while flowing the plating solution at a low speed. First, a plating layer on which the dispersant is hardly codeposited is formed on the surface to be plated, and a plating layer on which the dispersant is codeposited is formed on the surface (claim 4).

Further, if a nickel bath is used as the plating bath and silicon carbide is used as the dispersant, the silicon carbide is almost the same in the time zone when the plating solution is made to flow at a high speed and a high current density current is passed. A nickel plating layer that is not deposited is obtained, and in the time zone in which a current of low current density is applied while the plating solution is flowing at a low speed, a Ni-SiC composite plating layer in which silicon carbide is sufficiently co-deposited is obtained (claim 5).

Further, according to the invention of claim 6, the flow velocity of the plating solution and the current density of the energizing current are adjusted by the control means based on a predetermined time, whereby the dispersant is contained. A plating layer in which the eutectoid density of the dispersant changes in the thickness direction is formed from various types of plating baths in accordance with the flow velocity and the current density.

[0019]

Embodiments of the present invention will be described with reference to the drawings.

First, an example of the plating apparatus according to the present invention will be described with reference to the drawings. FIG. 1 shows a processing apparatus main body of a plating processing section in the plating apparatus of the present invention.

As shown in the figure, a cylindrical work 1 such as a cylinder of a cylinder block of an automobile is supported by the processing apparatus main body 2 of the plating processing section. The inner peripheral surface of the work 1 is plated.

The work 1 is supported by the work supporting portion 3 formed on the upper surface side of the processing apparatus main body 2 in a state where the upper opening edge portion is sealed by the sealing jig 4. The sealing jig 4 is made of a conductive material and has a function as a connection terminal when energized.

A plating solution introducing passage 5 extending in the lateral direction is formed in the work supporting portion 3, and an opening 6 communicating with the plating solution introducing passage 5 is provided at a position corresponding to the lower opening of the work 1. Is provided. Then, when the work 1 is supported by the work supporting portion 3, the lower opening of the work 1 and the opening 6 are aligned with each other, and the peripheral edges of these openings are in close contact with each other. .

Further, the processing device main body 2 has a work 1
The electrode 7 is arranged at a position corresponding to the opening of the electrode.
The electrode 7 is formed in a cylindrical shape, is coupled to a holder 8 attached to the lower wall of the processing apparatus main body 2, penetrates through the plating solution introduction passage 5, and projects upward from the opening 6. Then, with the work 1 supported by the work support portion 3, the electrode 7 projects into the hollow portion of the work 1, and the upper end of the electrode 7 reaches near the upper end of the work 1. As a result, in the hollow portion of the work 1, the flow path 9 communicating with the outside and the inside of the electrode 7 at the upper part,
10 is formed, and the outer flow path 9 communicates with the plating solution introduction passage 5.

A plating solution outlet passage 11 communicating with the passage 10 inside the electrode 7 is formed across the holder 8 and the lower wall of the processing apparatus main body 2. The plating solution outlet passage 11 is connected to a plating solution recovery pipe 21 in a piping system described later via a connecting pipe 12.

The holder 8 is made of a conductive material and has a function as a connection terminal when energized.

FIG. 2 shows a piping system and a control system of the plating apparatus.

As shown in the figure, a plating solution supply pipe 22 and a plating solution recovery pipe 21 are provided between the tank 15 for storing the plating bath and the pump 16 connected thereto and the processing apparatus body 2. It is arranged. The plating solution supply pipe 2
2, the upstream end side thereof is connected to the pump 16 and the downstream end side thereof is the plating solution introduction passage 5 of the processing apparatus main body 2.
It is connected to the. Further, a bypass pipe 23 is connected to the plating solution supply pipe 22 at a position immediately downstream of the pump 16, and the downstream end side of the bypass pipe 23 reaches the tank 15. The downstream end side of the plating solution recovery pipe 21 is connected to the plating solution outlet passage 11 of the plating solution supply pipe 22 via the connecting pipe 12, while the upstream end side thereof is connected to the tank 1.
It has reached 5.

The plating solution supply pipe 22 and the bypass pipe 2
3 are provided with automatic valves 17 and 20 for adjusting the plating solution supply amount, respectively. Further, the plating solution supply pipe 22 is provided with a manual valve 18 downstream of the automatic valve 17 and a flow rate sensor 19 for detecting the plating solution supply amount.

As shown in FIG. 2, the plating apparatus has
A controller 25 that integrally controls the plating operation is provided, and the automatic valves 17, 20 of the piping system, the flow rate sensor 19 and the like are all connected to this controller 25. When performing the plating process, the flow rate sensor 1
The supply amount of the plating solution to the processing apparatus main body 2 is adjusted by the opening / closing operation of the automatic valves 17 and 20 based on the detection signal from 9, so that the plating solution flowing between the flow path 9, that is, the electrode 7 and the work 1. The flow rate of is adjusted. That is, these automatic valves 17, 2
0, the flow rate sensor 19 and the like constitute flow velocity adjusting means.

Further, the sealing jig 4 of the processing apparatus main body 2 is
The holder 8 is connected to a rectifier 26 connected to an AC power supply (not shown), and the rectifier 26 is connected to the controller 25. The rectifier 26 supplies a rectified current to the electrode 7 through the holder 8 during plating, while the amount of the current is the controller 2 described above.
5, the current density of the current passing through the electrode 7 is adjusted. That is, the rectifier 26 also has a function as a current density adjusting means.

The controller 25 is provided with a timer 27 as a time measuring means, and the timer 27 controls the time during the plating process operation.

According to the above plating apparatus configured as described above, the plating process is performed as follows.

In the state shown in FIG. 1 in which the work 1 is supported by the processing apparatus main body 2, the plating solution is supplied and circulated through the piping system in FIG. 2 and the electrodes 7 are energized, whereby The inner peripheral surface of the work 1 is plated. More specifically, the plating solution supplied from the plating solution supply pipe 22 to the plating solution introduction passage 5 of the work supporting portion 3 is
As shown by the arrow in FIG. 1, the outer surface of the electrode 7 and the work 1
Flows through the flow path 9 between the wall surface of the hollow portion of the work piece 1, the upper end portion of the work 1 and the flow path 10 inside the electrode 7. Then, it further flows into the plating solution recovery pipe 21 through the plating solution outlet passage 11 and the connection pipe 12, and is returned to the tank 15. In this way, the plating solution is circulated and the plating solution flows along the wall surface of the hollow portion which is the surface to be plated of the work 1, while the current is passed between the electrode 7 and the work 1 to perform the plating. To be done.

By the way, according to the above-mentioned plating apparatus, if the flow rate of the plating solution is increased, the current density can be correspondingly increased, and thus the deposition rate of the plating metal can be increased. In the case of performing composite plating, the eutectoid of the dispersant tends to be significantly hindered if the plating solution flow rate and the current density are increased to a certain level or higher. Therefore, by controlling as follows, a single plating layer in which the dispersant is hardly codeposited and a composite plating layer in which the dispersant is codeposited are laminated on the surface of the work 1 from one type of plating bath. Is able to.

That is, the plating solution of the plating bath containing the dispersant is supplied to the processing apparatus main body 2 and circulated. Then, as shown in FIG. 3, first, a fixed time (first time range) T1 from the start of the plating process is the electrode 7 and the work 1.
The plating solution flowing between and is made to flow at a high speed and at a constant speed, and during this time, a current having a constant high current density is applied to the electrode 7. Then, next, the time (T
At a certain time (second time period) T2 after the passage of 1), the amount of the plating solution supplied to the processing apparatus main body 2 is reduced, whereby the plating solution flowing between the electrode 7 and the work 1 is at a low speed and is constant. While flowing at a speed, during this period, a constant low current density current is applied to the electrode 7.

Here, the flow rate and current density of the plating solution in the second time period T2 are set so that the sufficient amount of dispersant eutectoid is obtained (for example, the flow rate is about 2 m / sec).
The plating solution flow velocity and current density in the time region T1 are
It is set to a value considerably higher than each value in the second time region T2 (for example, the flow velocity is about 4 to 5 m / sec).

By doing so, the co-deposition of the dispersant is likely to be hindered during the period in which the plating solution is made to flow at a high speed and a current having a high current density is applied, and the dispersant is hardly co-deposited in the single plating. A layer is formed. On the other hand, when the plating solution is made to flow at a low speed and a current having a low current density is applied, the co-deposition of the dispersant is promoted and a composite plating layer in which the dispersant is sufficiently co-deposited is formed. Therefore, as described above, the process of flowing the plating solution at high speed and passing a current of high current density and the process of flowing the plating solution at low speed and passing a current of low current density are continuously performed. Thus, as shown in FIG. 4, the single plating layer Pa is first formed on the surface of the work 1, and then the composite plating layer P is formed on the surface.
b will be formed. Therefore, the single plating layer Pa and the composite plating layer Pb can be laminated and formed from one type of plating bath.

In this case, to be precise, the single plating layer Pa also contains some dispersant, but the amount thereof is almost negligible, and it can be said that it is functionally equivalent to a pure single plating layer. In the examples, a nickel bath and a silicon carbide were used as the plating bath and the dispersant, respectively, and the flow rate of the plating solution was 5 m / sec and the current density was 300 A.
After processing as / dm ² , the flow velocity is set to 2 m / sec and the current density is set to 100 A / dm ² , whereby the single plating layer and the composite plating layer are successfully laminated. .
In particular, in this case, there was almost no eutectoid of silicon carbide on the single plating layer, and a suitable single plating layer could be obtained.

As described above, according to the above control, it is possible to form a single plating layer in which the dispersant is not co-deposited and a composite plating layer in which the dispersant is co-deposited in the same plating bath. Therefore, it is extremely advantageous in terms of work efficiency, equipment, or cost, as compared with the conventional plating method of this type, in which the work is plated while being moved between a plurality of plating baths. In particular, when the single plating layer Pa is formed, the plating process is performed while applying a high current density current to the electrode 7, so that the deposition rate of the plating can be increased. Can be formed in an extremely short time, which is also advantageous in terms of work efficiency.

The above is the single plating layer P on the work 1.
a is formed, and a composite plating layer Pb is formed on the surface 2
Although the example of layer plating has been described, for example, when it is necessary to stack more plating layers for the purpose of corrosion resistance and the like, the flow rate of the plating solution and the current density of the energizing current are changed several times. You can do it like this.

For example, as shown in FIG. 5, if the flow rate of the plating solution and the current density of the energizing current are alternately changed in height at time intervals t1 to t4, as shown in FIG. It is possible to perform four-layer plating in which the single plating layers Pa and the composite plating layers Pb are alternately laminated on the surface of the work 1. This is advantageous for improving corrosion resistance and the like. In this case, in particular, it is possible to form the composite plating layers Pb having different eutectoid densities of the dispersants by making the flow rate of the plating solution and the current density of the applied current different for the two composite plating layers Pb. The advantage is that the plating can be diversified.

Further, as shown in FIG. 7, for a certain time T1 'from the start of the plating process, a high current density current is passed through the electrode 7 while the plating solution is flowing at a high speed, and this time T1' is passed.
At a certain time T2 'after the lapse of 1', the flow velocity of the plating solution and the current density of the energizing current are gradually reduced, whereby the dispersant is not applied to the surface of the workpiece 1 to be plated as shown in FIG. It is also possible to form the composite plating layer Pc in which a portion that is hardly codeposited is formed and the eutectoid density of the dispersant increases toward the plating layer surface side. According to this composite plating layer Pc, even though it is a single-layer composite plating, the single plating layer Pa is formed on the plating layer of the above-mentioned embodiment, that is, the surface to be plated of the work 1, and the composite plating layer Pb is formed on the surface. As in the case of the laminate-forming, the adhesion strength to the work can be increased while having the advantage of the composite plating.

[0044]

As described above, according to the plating method of the present invention, one type of plating bath containing a dispersant,
A plating layer in which the eutectoid density of the dispersant changes in the thickness direction of the plating layer can be formed.

In particular, in the plating treatment, if the flow rate of the plating solution and the current density of the supplied current are gradually decreased after the current having a high current density is passed while the plating solution is flowing at a high rate, a single layer can be formed. In composite plating, it is possible to form a plating layer in which the dispersant is almost co-deposited on the surface of the work to be plated and the eutectoid density of the dispersant increases toward the surface. As a result, composite plating having high adhesion strength to the work can be formed with one type of plating bath.

If the flow rate of the plating solution and the current density of the supply current are varied at predetermined time intervals, a plurality of plating layers having different eutectoid densities of the dispersant can form a laminate. . In this case, by supplying a high current density current while flowing the plating solution at a high speed, and then supplying a low current density current while flowing the plating solution at a low speed, First, a plating layer in which the dispersant is hardly codeposited can be formed, and a plating layer in which the dispersant is codeposited can be formed on the surface of the plating layer. It can be formed with any type of plating bath.

If a nickel bath is used as the plating bath and silicon carbide is used as the dispersant,
In the time zone in which the plating solution is made to flow at a high current density while flowing a high current density, a nickel plating layer in which silicon carbide is hardly codeposited is obtained, and a low current density current is made to flow while the plating solution is made to flow at a low speed. In the time zone when electricity is applied, a Ni-SiC composite plating layer in which silicon carbide is sufficiently codeposited is obtained.

[Brief description of drawings]

FIG. 1 is a schematic sectional view showing an example of a processing apparatus main body of a plating apparatus according to the present invention.

FIG. 2 is a schematic diagram showing a piping system and a control system of the plating apparatus according to the present invention.

FIG. 3 is a time chart showing an example of the plating method of the present invention.

4 is a schematic sectional view showing plating obtained by the method shown in FIG.

FIG. 5 is a time chart showing another example of the plating method of the present invention.

FIG. 6 is a schematic cross-sectional view showing plating obtained by the method shown in FIG.

FIG. 7 is a time chart showing another example of the plating method of the present invention.

8 is a schematic cross-sectional view showing plating obtained by the method shown in FIG.

[Explanation of symbols]

 1 Work 2 Processing Device Main Body 3 Work Support 4 Seal Jig 7 Electrode 8 Holder 15 Tank 16 Pump 17,20 Automatic Valve 18 Manual Valve 19 Flow Rate Sensor 21 Plating Liquid Recovery Pipe 22 Plating Liquid Supply Pipe 23 Bypass Pipe 25 Controller 26 Rectifier 27 timer

Claims (6)

[Claims] 1. A method of performing plating by applying an electric current while flowing a plating solution of a plating bath containing a dispersant between a surface to be plated of a work and an electrode, the flow rate of the plating solution and the supply thereof. The current density of the current is changed according to the passage of time during the plating process, and the eutectoid density of the dispersant of the plating layer formed on the plated surface of the work is changed in the thickness direction of the plating layer. Plating method. 2. The plating according to claim 1, wherein after flowing a current having a high current density while flowing the plating solution at a high speed, the flow rate of the plating solution and the current density of the supply current are gradually reduced. Method. 3. A method in which a plurality of plating layers having different eutectoid densities of dispersants are laminated as the plating layers by varying the flow rate of the plating solution and the current density of the supply current at predetermined time intervals. The plating method according to claim 1, which is characterized in that. 4. The plating solution is caused to flow at a high speed while a current having a high current density is passed through, and then the plating solution is caused to flow at a low speed to pass a current having a low current density. 3. The plating method described in 3. 5. A nickel bath is used as the plating bath,
5. The plating method according to claim 1, wherein silicon carbide is used as the dispersant. 6. An apparatus for performing plating by applying an electric current while flowing a plating solution of a plating bath containing a dispersant between a surface to be plated of a work and an electrode, and between the surface to be plated of the work and the electrode. Flow rate adjusting means for adjusting the flow rate of the plating solution, current density adjusting means for adjusting the current density of the energizing current, time measuring means for measuring the passage of time during the plating treatment, and the plating solution according to the passage of time. And a control means for controlling the flow velocity adjusting means and the current density adjusting means so as to change the flow velocity and the current density of the applied current.