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Chromate-free passivation method for chemically-plated Ni-P coating

A chromium-free passivation and chemical plating technology, applied in liquid chemical plating, coating, metal material coating process, etc., can solve the problems of insufficient moisture and heat resistance, human and environmental toxicity, oxidation and discoloration of chemical nickel plating layer, etc. , to achieve the effect of good discoloration resistance, excellent corrosion resistance and good corrosion resistance

Active Publication Date: 2015-03-04
SOUTH CHINA UNIV OF TECH
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

[0005] The purpose of the present invention is to solve the defects that the electroless nickel plating layer is easy to oxidize and discolor, and the resistance to heat and humidity is insufficient, and the more important purpose is to solve the problem of poisoning the human body and the environment by the traditional hexavalent chromium process of the electroless Ni-P coating

Method used

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  • Chromate-free passivation method for chemically-plated Ni-P coating
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  • Chromate-free passivation method for chemically-plated Ni-P coating

Examples

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Effect test

Embodiment 1

[0038] Electroless Ni-P coating molybdate passivation process of the present invention comprises the steps:

[0039] (1) Sample preparation: use low-carbon steel (A3) as the plating substrate for electroless nickel plating, cut the steel plate into 20×50×3mm samples, and punch holes at one end of the sample for hanging;

[0040] (2) Pre-plating treatment: The cut steel sheet is processed according to the following process, grinding → degreasing → water washing → activation → water washing. Among them, sandpaper of different grain sizes is used for grinding step by step from low to high (500#→1000#→1500#); degreasing is alkaline degreasing at room temperature for 10 minutes; activation uses 5.0% HCl solution, activation at room temperature for 10-30s , after cleaning with distilled water, electroless plating is carried out;

[0041] (3) Electroless nickel plating is carried out on the steel sheet, and the plating solution used is composed of: NiSO 4 ·6H 2 O 28g / L, NaH 2 PO ...

Embodiment 2

[0049] Step (1)-(3) is the same as embodiment 1.

[0050] (4) Preparation of passivation solution: prepare 1000ml of passivation solution, put 700ml of distilled water in a clean beaker, add in order:

[0051] NaOH 6.0g Na 2 CO 3 3.0g

[0052] Na 2 MoO 4 2H 2 O 40.0g C 6 h 5 o 7 Na 3 2H 2 O 8.0g

[0053] Na 2 S 2 o 8 7.0g

[0054] (5) Preparation of passivation film: After the test piece is plated, it is immediately subjected to passivation treatment after being washed with distilled water. During the treatment, the temperature of the passivation solution is 75°C, and the passivation time is 20 minutes. After the passivation treatment, the test piece is immediately rinsed and dried or dried to complete the passivation treatment.

Embodiment 3

[0056] Steps (1)-(3) are the same as in Example 1.

[0057] (4) Preparation of passivation solution: prepare 1000ml of passivation solution, put 700ml of distilled water in a clean beaker, add in order:

[0058] NaOH 4.0g Na 2 CO 3 7.0g

[0059] Na 2 MoO 4 2H 2 O 35.0g C 6 h 5 o 7 Na 3 2H 2 O 6.0g

[0060] NaClO 5.0g

[0061] (5) Preparation of passivation film: After the test piece is plated, it is immediately subjected to passivation treatment after being washed with distilled water. During the treatment, the temperature of the passivation solution is 60°C, and the passivation time is 25 minutes. After the passivation treatment, the test piece is immediately rinsed and dried or dried to complete the passivation treatment.

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Abstract

The invention discloses a chromate-free passivation method for a chemically-plated Ni-P coating. The method comprises the following treatment steps of (1) preparing a chromate-free passivation solution, and sequentially adding 3-20g / L of sodium hydroxide, 1-10g / L of sodium carbonate, 10-60g / L of molybdate, 2-25g / L of film forming accelerant and 2-15g / L of buffering agent in distilled water; (2) carrying out chemical nickel plating on a substrate to be subjected to nickel plating; and (3) after ending the nickel plating operation, immediately cleaning a nickel-plated piece and carrying out passivation treatment on the nickel-plated piece, washing the nickel-plated piece twice after ending the treatment, and drying by blowing or baking. Through the passivation treatment, a layer of transparent passivation film can be formed on the surface of the Ni-P coating, so that the appearance of the coating is not influenced, and the anti-tarnish property and corrosion resistance of the coating are remarkably improved. Elements such as O, C, Ni and Mo can be detected in the passivation film. The chromate-free passivation method is relatively simple in process, simple and convenient to operate, low in cost, chromate-free, environment-friendly and capable of easily realizing industrialization.

Description

technical field [0001] The invention belongs to the technical field of metal material surface treatment, and in particular relates to a method for chromium-free passivation of electroless Ni-P coating. Background technique [0002] Electroless Ni-P alloy plating has good throwing ability, compactness, smooth surface, excellent corrosion resistance and wear resistance, no vacuum conditions are required during plating, less pollution, and lower process temperature; at the same time, it does not require expensive, Special equipment conditions, and can be deposited on metal and non-metal (glass, ceramics and plastics, etc.) substrates. In addition, by adjusting the P content of the coating, the crystalline properties of the coating can also be changed. Many advantages make Ni-P coatings widely used in aerospace, petroleum, chemical, national defense, energy and other industrial sectors. [0003] But there are still some defects in electroless Ni-P layer. For example, the coati...

Claims

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Application Information

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IPC IPC(8): C23C22/60C23C22/73C23C18/36
CPCC23C18/36C23C22/60C23C22/73
Inventor 穆松林庞浩良张明康李文芳杜军
Owner SOUTH CHINA UNIV OF TECH
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