KR100489296B1 - Method for electroless nickel plating and means thereof - Google Patents

Abstract

In the present invention, plating is required due to the necessity of corrosion resistance, abrasion resistance, etc., but the plating solution is flowed to the surface of the material when the electrode is not easy to be installed or when it is not easy to be immersed in the plating solution or when plating between narrow gaps. It provides a method and apparatus for plating in a manner.

Description

Electroless Nickel Thin Film Plating Method and Plating Apparatus {METHOD FOR ELECTROLESS NICKEL PLATING AND MEANS THEREOF}

Plating refers to the process of coating a metal on the surface of a material. Generally, plating is used to prevent corrosion, to impart wear resistance (resistance to scratches), or to protect metals used at high temperatures. It is used for various purposes, such as to provide or to obtain proper electrical properties, or to reflect the material and improve the appearance. In particular, in the parts exposed to high temperature and high pressure environment, such as the parts used in the reactor, the importance of plating is increased. For example, in the case of CRDM nozzles, which are the upper head penetrating parts of nuclear reactor vessels, various environmentally induced cracks are generated here, and the combination of the reactor upper head made of low alloy steel and the CRDM nozzle made of nickel alloy 600 In order to weld to the inner surface of the upper head of the reactor, such a welding process, the residual stress is present in the nozzle portion in the operating conditions. Combined with the residual stress, the high operating temperature, the hydrochemical environment and the metallurgical properties of the nozzle material create a predominantly circumferential environmentally induced crack on the inner wall of the nozzle, which is produced by continuous operating temperature and pressure. If it grows up to a through crack, it causes cooling water leakage. From a conservative point of view, it can proceed to a control rod withdrawal accident due to breakage at both ends of the nozzle. Environmental cracks, such as in the CRDM nozzles play a very important role in the safety of the entire nuclear power system. As such, the metal thin film plating technology may be applied as a method for preventing environmental cracking of the reactor CRDM nozzle portion, resistance to heat generation of the steam generator, and crack generation resistance of the inner wall.

 As a metal thin film plating method, there is an electrolytic thin film plating method. An electrolytic thin film plating method continuously supplies electrical energy from the outside to form a metal thin film on the surface of an object by using electrolysis at an anode and a cathode. In order to put an electrode in a solution containing a metal ion to pass a current through the metal ions are reduced in the cathode to form a high-purity metal layer. This results in a thin film with a metallic bond directly on the surface of the workpiece placed on the cathode. Generally used for the surface finishing process and to improve the corrosion resistance and wear resistance. However, this electroplating method has a disadvantage in that it is difficult to make the thickness constant, and it is difficult to use for a complicated structure in which the electrode is difficult to install, and it is applicable to only conductors.

Another method that can be applied is the electroless plating method, which also has a drawback in that the material to be plated must be directly immersed in a plating solvent. Therefore, it is possible to apply the plated parts after assembling them and use them. However, when the welded part is to be plated as described above, the material cannot be directly immersed in the solvent. There is this. In addition, since the solvent is directly immersed, the plating solution is consumed a lot, and the device for plating is disadvantageous.

In addition, none of the above methods are easy when welding is made between the parts and the gaps formed between them after the parts are assembled.

In order to solve the problems described above, the present invention has a corrosion resistance and abrasion resistance, but even for complex structures that are difficult to apply the electroplating method or the existing electroless plating method, the thickness of the plating to be uniform without having to directly immerse the material to be plated in the material It is an object of the present invention to provide such a thin film plating method and plating apparatus, and also to provide an apparatus and method for plating between thin gaps between components.

In order to solve the problems as described above, the present invention provides an electroless nickel thin film plating method, the plating method is

Providing a material to be plated;

A degreasing step for cleaning the surface of the material;

A surface activation step of reacting the solvent with the surface of the material;

A plating step of plating the surface of the material using a plating solution containing phosphorus, the plating step including flowing a plating solution on the surface of the material;

Include.

The plating method may further include a degreasing step of washing the surface of the material between each step.

The plating step of the plating method, the expansion and contraction of the expansion and contraction of the plating solution injecting the bladder (bladder) inserted into the inside of the gap to be plated, and the fluid flowing into the bladder Sealing the gap without leakage, and flowing the plating solution through the entrance and exit tube inserted into the bladder may further include.

The plating solution used in the plating step may include nickel and phosphorus (P) of 8 to 10% by weight.

In addition, the present invention provides an electroless nickel thin film plating apparatus, the plating apparatus is

A plurality of tanks;

A driving device capable of drawing out the contents of the tank to the outside;

Is connected to the end of the valve may include a plating solution inlet and outlet having at least one plating solution inlet and outlet pipe flowing the plating solution.

In the plating apparatus, the plating solution inlet and outlet, the plating solution inlet and outlet pipe further comprises a bladder (bladder) that is mounted to the outside of the plating solution inlet and the fluid is allowed to expand therein, and expands. To facilitate the insertion, the expansion of the bladder may be easy to seal between the gaps.

In the plating apparatus, the bladder is a donor shape having a hole in the center and a plurality of plating solution entrance and exit pipes may be mounted on the bladder.

Hereinafter, exemplary embodiments of the present invention will be described in detail with reference to the accompanying drawings.

1 is a schematic view of a method of electroless nickel plating in a CRDM nozzle portion, which is the top through-head of a reactor vessel using the method presented in the present invention. First, the lower end of the thermal sleeve A was cut to plate the gap inside the CRDM through part. This is to ensure smooth insertion of the bladder 11 into the gap and is not an essential step. Then, the bladder 11 into which the plating solution inlet / outlet 12 is inserted is pushed into the gap. Since the tube is passing through the gap here, the bladder 11 used a donor-shaped thing. In addition, the bladder 11 may be inserted with a plurality of plating solution entry and exit pipe 12 in order to smoothly plate the interior of the gap. Fluid such as air or oil is introduced into the bladder 11 through the fluid supply hose 13 to cause the bladder 11 to expand and seal the gap so that there is no leakage, and then the nickel plating solution is passed through the plating solution inlet / outlet tube. It is made to flow in and electroless plating is performed. Thereafter, the bladder 11 is advanced little by little to plate the entire interior of the gap. The shape of the bladder 11 may vary depending on the shape of the material to be plated, and in order to simply plate the outside of the welded portion, the plating solution may be simply flowed to the surface of the material. Plating materials commercially available for the corrosion protection of structural materials include nickel, nickel-phosphorus, nickel-boron, chromium, copper and the like. As described above, nickel electroplating technology has been developed for crack suppression of heat pipes, and has been applied to steam generators in operating nuclear power plants in Europe and North America, and has a life extension performance of more than 15 years. Accordingly, although nickel is selected as the thin film metal in the present embodiment, the present invention is not limited thereto.

Table 1 below shows one embodiment of a plating method according to the present invention.

sequence of the work Work process solution Working condition Note One Solvent degreasing III TCE Temperature: 20-30 ℃ Time: 15 minutes No foreign substance, no oil 2 Degreasing Degreasing Alkaline degreasing liquid Temperature: 30-60 ℃ Time: 20 minutes 3 Ultrasonic degreasing Alkaline degreasing liquid Temperature: 30-60 ° C Time: 5 minutes Ultrasonic Cleaning 4 3-stage washing Industrial water Temperature: Room temperature time: 1 minute No foreign substance adhered 5 Electrolytic degreasing Alkaline degreasing liquid Temperature: 30-60 ° C. Time: 1 minute Voltage: 5-7 V Anode: Workpiece Cathode: Nickel 6 Two steps Industrial water Temperature: Room temperature time: 1 minute No foreign substance adhered 7 Surface activation HCl 10% Temperature: 20-30 ℃ Time: 1 minute 8 Two steps Industrial water Temperature: Room temperature time: 1 minute No foreign substance adhered 9 Ni-P Plating Electroless Nickel Plating Solution (Contains 8-10% P) Temperature: 85-92 ° C pH: 4.7-4.9 hours: 10 minutes (2-2.5 μm standard) 15 μm: 60 minutes 30 μm: 120 minutes 10 Two steps pure Temperature: Room temperature time: 1 minute No foreign substances or chemicals attached 11 Probation pure Temperature: 60 ℃ Time: 1 minute 12 dry Temperature: 60-70 ℃ Time: 1 minute No foreign substance adhered 13 inspection Thickness measurement

2 is a schematic diagram of an experimental apparatus used for the high temperature oxidation test. As one of the methods for evaluating the performance of the thin film plating technology according to the present invention, the corrosion test was performed for a long time in a high temperature underwater atmosphere.

Specimen ID Materials Description Comments Alloy 600 J310 0.03% C J320 0.03% C J610 0.06% C J620 0.06% C Ni-plated Alloy 600 ES15 Electroless Nickel Plating, 15 ㎛ Contains 7-8% P ES30 Electroless Nickel Plating, 30 μm Contains 7-8% P

Four alloy 600 specimens with different carbon contents and heat treatment conditions and nickel plated specimens with different plating conditions and thicknesses were used. The electroless plating method according to the present invention was applied and had a thickness of 15 µm and 30 µm for each plating condition. Two specimens of eight specimens were prepared and subjected to oxidation tests. The test solution used was a solution containing 2 wppm Lithium and 1000 wppm Boron in a 200 L reservoir made of Ti to simulate the primary power of a nuclear power plant and deaeration for about 3 hours using high purity hydrogen gas. ) Process to remove dissolved oxygen and create reducing atmosphere. In a real plant, about 25-30 cc (STP) / kg of H ₂ O dissolved hydrogen is present in the primary water, corresponding to 2.232 to 2.678 wppm of dissolved hydrogen. After the deaeration process, a pressure of about 10 psig was applied to the vessel to keep the dissolved hydrogen constant at about 2.65 wppm during the test period. Test temperature and pressure were maintained at 320 ° C., 150 kg _f / cm 2. Specimens were mounted in a 1 gallon (3.78 L) volume pressure vessel made of 316SS. The flow rate was about 1 L / hr and the oxidation test was conducted continuously for 4 weeks. After the oxidation test, the specimens were taken out, and the surface corrosion was analyzed by visual observation and transmission electron microscopy (TEM).

Figure 3 shows the result of performing the TEM analysis whether the oxide film formed on the nickel plated specimen. FIG. 3A shows a bright field image of the interface between the oxide film and the Ni film, and FIG. 3B shows the results of EDS line analysis between the AB section shown in FIG. You can see that it changes rapidly.

4 shows a schematic view of a plating apparatus according to the present invention. The device makes it possible to easily plate using an electroless plating method in the case where the plating is not easy with the conventional method. First, each tank 15 contains degreasing, electrolytic, plating solution, water, and the like necessary for plating, and each solution can be flowed out through the nozzle by operating the pump 16 attached to the tank 15. . At this time, after each solution flows once, the water flows to wash the plating apparatus. In this manner, plating can be performed in the same manner as the method described in Table 1 above. At this time, plating is performed by flowing the plating solution to the surface of the material. In addition, a device such as that described in FIG. 1 may be installed in the plating solution inlet / outlet unit 14, and a bladder 11 that expands due to inflow of fluid and an outlet tube 12 that penetrates the bladder 11 may be installed. Plating is also easy for parts where plating is not easy, such as gaps. In addition, since the device 10 is movable, the existing method and the device 10 may not be easily plated, that is, a part which is difficult to install an electrode, or parts that are not easily immersed in a plating solution, for example, When there is a need to plate the joint after joining by screws, etc., or when there is a need to plate the weld after joining the material by welding, etc. It becomes possible. In addition, the device can be made easy to move by adjusting the size of the tank (15). The material of the bladder must be a material that can withstand this temperature and expand relatively well because the temperature rises to 90 degrees.

The present invention is a thin film plating method and plating apparatus that can be plated to have a constant thickness without having to immerse a material to be plated directly into a material even for a complex structure having corrosion resistance and abrasion resistance, which is difficult to apply an electroplating method or a conventional electroless plating method. The present invention also provides an apparatus and method for plating a thin gap between parts.

1 is a schematic diagram of a method for electroless nickel plating in a control rod drive mechanism (CRDM) nozzle portion of a reactor vessel upper head penetration using the method presented in the present invention.

Figure 2 is a schematic diagram of the experimental apparatus used for the high temperature oxidation test

Figure 3 shows the results of performing the transmission electron microscope (TEM) analysis of the formation of the oxide film of the nickel plated specimens

4 is a schematic view of a plating apparatus according to the present invention;

<Explanation of symbols for the main parts of the drawings>

10: plating apparatus 11: bladder

12: Plating solution inlet / outlet tube 13: Fluid supply hose

14: plating solution inlet and outlet 15: storage tank

16: drive unit 17: nozzle

Claims (7)

Providing a material to be plated; A surface activation step of reacting the solvent with the surface of the material; A plating step of plating the surface of the material using a plating solution containing phosphorus, the plating step including flowing a plating solution on the surface of the material; Including, electroless nickel thin film plating method. The method of claim 1, wherein the plating step is to shrink and expand and insert the bladder inserted into the plating solution inlet and out into the gap of the material to be plated;  Introducing a fluid into the bladder to expand the bladder to seal the gap without leakage; Electroless nickel thin film plating method comprising the step of flowing a plating solution through the entrance and exit tube inserted into the bladder. The method of claim 1 or 2, further comprising a degreasing step of washing the surface of the material between each step. The electroless nickel thin film plating method according to claim 1 or 2, wherein the plating solution used in the plating step comprises nickel and 8 to 10 wt% of phosphorus (P). A plurality of tanks; A driving device capable of drawing out the contents of the tank to the outside; A plating solution inlet / out section having at least one plating solution inlet / out tube connected to an end of the valve for flowing a plating solution;  Including, electroless nickel thin film plating apparatus. The method of claim 5, wherein the plating solution inlet and outlet pipe, The apparatus further includes a bladder mounted on the outside of the plating solution inlet / outlet tube and expands by introducing a fluid therein to facilitate the insertion of the plating solution inlet / outlet tube between the narrow gaps and the expansion of the bladder. Electroless nickel thin film plating apparatus, characterized in that the sealing between the gap is easy. 7. The electroless nickel thin film plating apparatus according to claim 6, wherein the bladder has a donor shape having a hole in the center thereof and a plurality of plating solution inlet and outlet tubes are mounted on the bladder.