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Method for improving corrosion resistance of nickel-aluminum bronze

A nickel-aluminum bronze, corrosion-resistant technology, applied in the field of surface treatment, can solve the problems of many cracks on the surface of the coating, low Cr content in the coating, restricting the application of the coating, etc., and achieve the effect of low porosity, uniform composition and high hardness

Inactive Publication Date: 2015-04-29
SHANGHAI JIAO TONG UNIV
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

However, the Ni-Cr alloy coating prepared by electroplating has problems such as low Cr content, poor coating thickness and many cracks on the coating surface, which restrict the application of the coating.
The present invention adopts the method for improving the corrosion resistance of the material by pulse electroplating a layer of smooth and compact Ni-Cr alloy on the surface of nickel-aluminum bronze, and there is no report yet

Method used

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  • Method for improving corrosion resistance of nickel-aluminum bronze
  • Method for improving corrosion resistance of nickel-aluminum bronze
  • Method for improving corrosion resistance of nickel-aluminum bronze

Examples

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Embodiment 1

[0037] This example relates to a method for improving the corrosion resistance of nickel-aluminum bronze, said method may further comprise the steps:

[0038] Step 1: Mechanically polish the surface of nickel-aluminum bronze with 180#-400#-800#-1200# water sandpaper in sequence, and then degrease in the prepared degreasing solution (containing 20g / LNaOH, 30g / LNa 2 CO 3 , 50g / LNa 3 PO 4 ) at 70°C for 10 minutes, remove residual grease, wash with water, then use 100mL / L HCl to activate it, and dry it with cold air for later use;

[0039] Step 2: Put the treated nickel-aluminum bronze in the following plating solution:

[0040]

[0041] Heat the electrolyte temperature to 30-35°C; adjust its pH value to 2.2-2.7 with NaOH and HCl solution; the applied current waveform is shown in figure 1 As shown, the pulse current I p 10~15A / dm 2 , the pulse frequency is 1000Hz, the power-on time t 通 0.90ms, power-off time t 断 0.10ms, that is, the duty cycle is 90%; the electroplating...

Embodiment 2

[0045] This example relates to a method for improving the corrosion resistance of nickel-aluminum bronze, said method may further comprise the steps:

[0046] Step 1: Mechanically polish the surface of nickel-aluminum bronze with 180#-400#-800#-1200# water sandpaper in sequence, and then degrease in the prepared degreasing solution (containing 30g / LNaOH, 40g / LNa 2 CO 3 , 20g / LNa 3 PO 4 ) at 80°C for 5 minutes, remove residual grease, wash with water, then use 100mL / L HCl to activate it, and dry it with cold air for later use;

[0047] Step 2: Put the treated nickel-aluminum bronze in the following plating solution:

[0048]

[0049] Heat the electrolyte temperature to 35-40°C; adjust its pH value to 2.5-3.5 with NaOH and HCl solution; the applied current waveform is shown in figure 1 As shown, the pulse current I p 15~20A / dm 2 , the pulse frequency is 10000Hz, the power-on time t 通 0.25ms, power-off time t 断 0.75ms, that is, the duty cycle is 25%; the electroplating...

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Abstract

The invention discloses a method for improving the corrosion resistance of nickel-aluminum bronze. The method comprises the following steps: firstly, grinding and polishing the surface of nickel-aluminum bronze, degreasing, pickling and activating, placing the treated nickle-aluminum bronze in a nickel-chromium plating solution of which the temperature is 30-40 DEG C and the pH value is 2.0-3.5 and electroplating the treated nickel-aluminum bronze serving as a cathode to obtain a crack-free Ni-Cr alloy coating having a smooth surface on the surface of the nickel-aluminum bronze. The chromium ion used in the plating solution is trivalent; the coating stress is released by virtue of a pulse plating process and the surface cracks are eliminated; the surface of the coating is smooth and clean, free of defects such as cracks and pinholes; good adhesion force is kept between the coating and the substrate, the surface hardness can reach 440-630HV, which is 2-3 times that of the substrate material; and the coating has excellent corrosion resistance and is used as a protective coating to isolate nickel-aluminum bronze from a corrosive medium so that the corrosion resistance is greatly improved. The method has the characteristics of low cost, no toxicity and the like and is simple and feasible and is a preparation method which integrates economy, high efficiency and high quality into a whole.

Description

technical field [0001] The invention relates to surface treatment technology, in particular to a method for improving the corrosion resistance of nickel-aluminum bronze, more specifically a method for pulse electroplating a Ni-Cr alloy coating on the surface of nickel-aluminum bronze. Background technique [0002] Nickel-aluminum bronze alloys are widely used in marine environments due to their good corrosion resistance and high mechanical properties, such as ship propellers, seawater valves, and offshore drilling platform equipment. However, due to the defects such as composition segregation, coarse grains, and loose structure of cast nickel-aluminum bronze, phase-selective corrosion, corrosion fatigue, and pitting corrosion are prone to occur in marine environments with high corrosion and high sub-alternating loads, which greatly reduces the It shortens the service life of materials and restricts the development of human ocean activities. [0003] At present, the methods ...

Claims

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Application Information

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IPC IPC(8): C25D5/18C25D3/56
CPCC25D3/562C25D5/18
Inventor 吴忠刘磊秦真波沈彬罗芹张琪刘德荣胡文彬
Owner SHANGHAI JIAO TONG UNIV
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