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Method and tooling for stripping chromium coatings of small holes of chrome-plated part of nuclear control rod driving mechanism of nuclear power unit

A technology of driving mechanism and nuclear power unit, applied in the direction of electrolysis components, electrolysis process, etc., can solve problems such as uneconomical, and achieve the effect of reducing workload and achieving significant benefits

Inactive Publication Date: 2015-02-04
DONGFANG TURBINE CO LTD
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

However, the small hole coating area accounts for a very small proportion in the total coating area of ​​the part, so it is obviously very uneconomical to do so. method is undoubtedly very meaningful

Method used

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  • Method and tooling for stripping chromium coatings of small holes of chrome-plated part of nuclear control rod driving mechanism of nuclear power unit

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Experimental program
Comparison scheme
Effect test

Embodiment 1

[0050] Embodiment 1, the deplating method and tooling of the nuclear control rod drive mechanism φ9.5mm small hole chrome plating layer are specifically described.

[0051] The φ9.5mm small hole deplating tool is composed of a cathode 3, a cathode positioning nut 1, a cathode insulating sleeve 2, and an anode protection sleeve 5. Among them: the axial direction of the small hole 4 is perpendicular to the depth direction of the bath liquid, and a liquid guide hole is designed on the cathode insulating sleeve 2 so that the whole device forms a circuitous cavity for gas and solution. Use the φ14mm counterbore at both ends of the φ9.5mm hole 4 to position the cathode insulating sleeve 2, so that the axis center of the cathode 3 and the axis center of the φ9.5mm hole 4 are relatively small. Both ends of the cathode 3 are tapped with external threads, and the cathode positioning nut 1 is applied bidirectionally to fasten, and the cathode 3 is a stainless steel cathode 3 with a diame...

Embodiment 2

[0056] Embodiment two, the deplating frock is similar to embodiment one, and the process parameters and sequence steps of its small hole deplating are as follows:

[0057] (1) Clean and degrease the workpiece containing small hole 4 and its tooling with organic solvents to remove oil and foreign matter on the surface of small hole 4 to be plated and the tooling. The organic solvent is generally alcohol or acetone; then use B-grade pure water to clean ;

[0058] (2) Press figure 1 In principle, the small hole chromium layer deplating device is assembled.

[0059] (3) Using NaCO 3 60g / l, NaOH 100g / l solution for the deplating of hole 4, the solution temperature is controlled at 70°C, and the current density is 8A / dm 2 , the deplating time is 2h; after deplating, disassemble the tooling and rinse with B-grade pure water. When the pH value of the pure water on the rinsed parts meets 6~8, use compressed air to dry it.

Embodiment 3

[0060] Embodiment three, the deplating frock is similar to that of embodiment one, and the process parameters and sequential steps of the small hole deplating are as follows:

[0061] (1) Clean and degrease the workpiece containing small hole 4 and its tooling with organic solvents to remove oil and foreign matter on the surface of small hole 4 to be plated and the tooling. The organic solvent is generally alcohol or acetone; then use B-grade pure water to clean ;

[0062] (2) Press figure 1 In principle, the small hole chromium layer deplating device is assembled.

[0063] (3) Using NaCO 3 40g / l, NaOH 70g / l solution for the deplating of hole 4, the solution temperature is controlled at 60°C, and the current density is 6A / dm 2 , The deplating time is 2.5h; after deplating, disassemble the tooling and rinse with B-grade pure water. When the pH value of the pure water on the rinsed parts meets 6~8, use compressed air to dry.

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Abstract

The invention discloses a stripping tooling and process for stripping the chromium coatings of small holes of a chrome-plated part of a nuclear control rod driving mechanism of a nuclear power unit. According to the stripping tooling, an anode protective sleeve is applied between two small holes to be stripped, a cathode insulation sleeve is applied outside each small hole, a liquid guide hole is formed on the insulation sleeve to form a gas and liquid circulating cavity, and the axis of the cathode insulation sleeve passes through a cathode and is fixed by a cathode locating nut. The stripping process sequentially comprises the following steps: (1) cleaning and removing grease with organic solvent and washing with B-level pure water; (2) assembling a striping device; and (3) carrying out stripping to the small holes with phi 9.5mm in alkaline stripping solution. The tooling and the process for stripping the small holes of the chrome-plated part of the nuclear control rod driving mechanism of the nuclear power unit have good effect and low cost, the small holes after stripping can be chrome-plated again directly, the qualified chrome-plated layer at other chrome-plated positions of the workpiece is not influenced, the stripping and re-stripping workload can be alleviated and the benefit is remarkable.

Description

technical field [0001] The invention relates to a deplating process and tooling for a small hole chromium plating layer of a nuclear control rod driving mechanism of a nuclear power unit, and belongs to the technical field of surface treatment. Background technique [0002] In the nuclear control rod driving device of nuclear power units, there are some chrome-plated parts, three of which contain small holes of φ9.5mm, and the uniformity of the thickness of the hole wall coating is very high. After plating, the axis of the coating must not deviate along the radial direction. More than 10μm; no microcracks in the coating. However, due to the small aperture, the distance between the cathode and the anode is extremely close during plating. Not only is it extremely difficult to control the uniformity of the coating thickness, but also the short distance between the cathode and the anode leads to the rapid growth of the coating, which easily initiates cracks and easily leads to u...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): C25F5/00C25F7/00
Inventor 王焱周科林亮姜英金硪馨张道军陈瑞芳龙正茂李秀丽娄霞
Owner DONGFANG TURBINE CO LTD