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Method for electrodepositing nanocrystalline chromium-nickel alloy coating with carboxylic acid or its salt -urea impulse

A technology of pulse electrodeposition and nanocrystals, applied in the field of surface engineering and surface treatment, can solve the problems of high toxicity, high energy consumption, and high pollution of hexavalent chromium electroplating process, and achieve strong bonding, low energy consumption, and easy sewage treatment Effect

Inactive Publication Date: 2008-01-23
CENT SOUTH UNIV
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

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Problems solved by technology

[0003] In order to solve the problems of high pollution, high toxicity and high energy consumption of the hexavalent chromium electroplating process, the present invention makes full use of pulse electrodeposition technology and Cr-containing 3+ The characteristics of the complexing agent plating solution system provide a method for pulse electrodeposition of nanocrystalline chromium-nickel alloy coating on the surface of metal or metal alloy. This method has the characteristics of economical practicability and low toxicity

Method used

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  • Method for electrodepositing nanocrystalline chromium-nickel alloy coating with carboxylic acid or its salt -urea impulse

Examples

Experimental program
Comparison scheme
Effect test

Embodiment 1

[0021] 1) Take an ordinary carbon steel sample with a dimension of 40mm×20mm×2mm, using 2 # 、4 # 、6 # Metallographic sandpaper is polished and polished sequentially, washed with tap water; and then treated with NaOH 40-60g / l 2 CO 3 60~80g / l, OP emulsifier 5~10ml / l alkaline degreasing liquid, degreasing at 60~70℃ for 8~12min, wash with tap water immediately after degreasing; 2 SO 4 100~200ml / l, HCl 40~70g / l, HNO 3 In 20-40ml / l polishing activation solution, the temperature is 40-60°C, activate for 2-3 minutes, and the pretreated sample to be plated can be obtained.

[0022] 2) Take the pretreated sample to be plated as the cathode and the insoluble anode (graphite) as the anode. Under the condition of stirring, directly insert the 3 ·6H 2 O 0.6mol L -1 , NiSO 4 ·6H 2 O 0.075mol L -1 , trisodium citrate 0.4mol L -1 , sodium oxalate 0.3mol L -1 , CH 3 COONa 0.2mol L -1 , Lactic acid 0.1mol L -1 , CO(NH 2 ) 2 2.0mol·L -1 , Cr 2 (SO 4 ) 3 ·6H 2 O 0.1mol L ...

Embodiment 2

[0024] 1) The pretreatment of the plated part is the same as "Example 1"

[0025] 2) Take the pretreated sample to be plated as the cathode and the insoluble anode (graphite) as the anode. Under the condition of stirring, directly insert the 3 ·6H 2 O 0.6mol L -1 , NiCl 2 ·6H 2 O 0.075mol L -1 , citric acid 0.4mol L -1 , oxalic acid 0.3mol L -1 , CH 3 COOH 0.2mol L -1 , CO(NH 2 ) 2 2.0mol·L -1 , Cr2(SO 4 ) 3 ·6H 2 O 0.1mol L -1 , H 3 BO 3 0.72mol·L -1 , NaCl 2.0mol·L -1 In the plating solution, the temperature of the plating solution is 35°C, and the current density is 8A·dm -2 , the pH of the plating solution is 2.0, the pulse working ratio is 0.3, the reversing time is 2ms, the pulse frequency is 50Hz, and the pulse electrodeposition time is 60min, the nanocrystalline chromium-nickel coating sample is obtained, and the coating thickness is about 14.45 μm, the average particle size of coating crystal particles is about 65nm.

Embodiment 3

[0027] 1) The pretreatment of the plated part is the same as "Example 1"

[0028] 2) Take the pretreated sample to be plated as the cathode and the insoluble anode (graphite) as the anode. Under the condition of stirring, directly insert the 3 ·6H 2 O 0.6mol L -1 , NiSO 4 ·6H 2 O 0.075mol L -1 , trisodium citrate 0.8mol L -1 , sodium oxalate 0.6mol L -1 , CH 3 COONa 0.1mol L -1 , Lactic acid 0.0mol·L -1 , CO(NH 2 ) 2 2.0mol·L -1 , H 3 BO 3 0.72mol·L -1 , NaCl 2.0mol·L -1 In the plating solution, the temperature of the plating solution is 35°C, and the current density is 8A·dm -2 , the pH of the plating solution is 2.0, the pulse working ratio is 0.3, the reversing time is 2ms, the pulse frequency is 50Hz, and the pulse electrodeposition time is 60min, the nanocrystalline chromium-nickel coating sample is obtained, and the coating thickness is about 13.25 μm, the average particle size of coating crystal particles is about 53nm.

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Abstract

A process for pulse electro-deposition nanometer Cr-Ni alloy plating of carboxylic acid or the salt-urea system of carboxylic acid is provided, which relates to the technology for surface engineering and surface treatment, comprises the pretreating and pulse electro-deposition treatment of the plating. The current efficiency of the plating solution system in the invention is up to 45.28%, about 35% higher than the 10% current efficiency in conventional trivalent Cr plating solution system; the toxicity of Cr3+ in the plating solution is only 1% of Cr6+, and the Cr content in the plating solution is only 1 / 7 of that in the plating solution of chromic acid. The invention is characterized by low toxicity and energy consumption, and greatly reduces the production cost of Cr-Ni plating and the environmental pollution during the production. The nanometer Cr-Ni plating prepared by the present invention is bright, intense, flat, and strongly bonded with the substrate, and is of excellent resistance to wear and corrosion in air. The invention is applicable for corrosion protection and decoration of metallic or metal alloy surfaces.

Description

technical field [0001] The invention relates to surface engineering and surface treatment technology, in particular to the technology of preparing chromium-nickel alloy coating by pulse electrodeposition method. Background technique [0002] Chromium alloy coating has excellent corrosion resistance, wear resistance and decorative properties and has been widely used as a functional coating. Electrodeposition of hexavalent chromium to prepare chromium alloy coatings has always been the main method used in the chrome plating industry because of its simple process, bright and smooth coating, and high hardness. However, the hexavalent chromium electrodeposition process has attracted widespread attention from all over the world due to its high toxicity and environmental pollution. Electrodeposition of hexavalent chromium and chromium alloy coatings, such as El-Sharif, etc., use aminoacetic acid as a complexing agent, and use trivalent chromium plating solution electrodeposition t...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): C25D3/56C25D5/18
Inventor 何新快邱冠周陈白珍吴璐烨
Owner CENT SOUTH UNIV
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