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Electrochemistry processing method for generating oxide film on surface of aluminium or aluminium alloy material

The technology of an aluminum alloy material and a treatment method, applied in the field of electrochemical treatment, can solve the problems of inability to use protective decoration, long oxidation time, limitation, etc., and achieve good wear resistance and decoration properties, simple composition system, and little environmental pollution. Effect

Inactive Publication Date: 2011-04-20
HUNAN UNIV
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

After literature search, it was found that "Corrosion Science and Protection Technology" 1996: 8 (2): 144-148 published an article by Cheng Yufeng and others introducing the AC oxidation process of sulfuric acid, "The influence of additives on the performance of AC oxidation film of LY12 cast aluminum alloy" , the paper proposes adding special additives to the sulfuric acid solution, and AC oxidation can form a thick oxide film at room temperature on Al-Cu alloys that are difficult to oxidize by direct current. Long, not conducive to industrial production
Chinese Patent Publication No. 87103213 proposes the process of forming a porous oxide film on the surface of aluminum by alternating current oxidation in the mixed electrolyte of sulfuric acid and aluminum sulfate, but the hardness and wear resistance of the obtained oxide film layer are not good, so it cannot be used for aluminum and aluminum The protective decoration of its alloy surface limits the application of AC oxidation technology

Method used

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Examples

Experimental program
Comparison scheme
Effect test

Embodiment 1

[0030] The L3 industrial pure aluminum after chemical pretreatment is hung on two electrodes, and its size is 30mm×40mm×1mm. Control process conditions: Control the voltage to rise slowly to 120V within 2 minutes and keep it constant until the end of the test. The current density increases as the voltage increases, reaching a peak current density of 8A / dm 2 After that, with the formation of the film layer, the current density gradually decreases, and finally drops to 1A / dm 2 .

[0031] The electrolyte composition and process parameters are:

[0032] Benzene hexacarboxylic acid: 40g / L

[0033] Citric acid: 60g / L

[0034] Ammonium phosphate: 30g / L

[0035] Voltage: 120V

[0036] Oxidation time: 30min

[0037] Temperature: 15+2℃

[0038] After AC oxidation, the thickness of the film is 28μm, the microhardness is 410HV, and the film is off-white.

Embodiment 2

[0040] The L3 industrial pure aluminum after chemical pretreatment is hung on two electrodes, and its size is 30mm×40mm×1mm. Control process conditions: Control the voltage to rise slowly to 100V within 2 minutes and keep it constant until the end of the test. The current density increases as the voltage increases, reaching a peak current density of 7A / dm 2 Afterwards, with the formation of the film layer, the current density gradually decreased.

[0041] The electrolyte composition and process parameters are:

[0042] Benzene hexacarboxylic acid: 100g / L

[0043] Citric acid: 10g / L

[0044] Ammonium phosphate: 20g / L

[0045] Voltage: 100V

[0046] Oxidation time: 15min

[0047] Temperature: 15±2℃

[0048] After AC oxidation, the thickness of the film is 17μm, the microhardness is 380HV, and the film is off-white.

Embodiment 3

[0050] The chemically pretreated LY11 aluminum alloy is hung on two electrodes, and its size is 30mm×40mm×1.5mm. Control process conditions: Control the voltage to rise slowly to 60V within 2 minutes and keep it constant until the end of the test. The current density increases as the voltage increases, reaching a peak current density of 6A / dm2 After that, the current density gradually decreased.

[0051] The electrolyte composition and process parameters are:

[0052] Sulfophthalic acid: 80g / L

[0053] Oxalic acid: 30g / L

[0054] Triethanolamine: 50g / L

[0055] Voltage: 60V

[0056] Oxidation time: 10min

[0057] Temperature: 20±2℃

[0058] After AC oxidation, the thickness of the film is 12 μm, the microhardness is 290HV, and the film is gray-black.

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Abstract

The invention relates to an electrochemical treatment method for forming oxide film on the surface of aluminum or aluminums alloy material, pertaining to the surface protection and finishing field of aluminum or aluminum alloys. The aluminum or aluminum alloy is placed in a compound electrolyte solution, with oxidation by alternating current, and then a film with the thickness of 10-30Mum, hardness 200-450HV and excellent finishing performance can be produced. The compound electrolyte solution is composed of aromatic dicarboxylic acid and derivatives of aromatic dicarboxylic acid, aliphatic carboxylic acid and ammonium salt or organic amine compounds. The work pieces to be oxidized are hung at the two ends of AC electrode while being oxidized; therefore, the efficiency of electro-oxidation in alternating current is one time higher than the efficiency of electro-oxidation in direct current and simultaneously the rectifying installation is saved. The electrochemical treatment method solves the problems such as thinness (less than 10Mum), yellowing and low hardness of the oxide film produced by sulfuric acid alternating current.

Description

technical field [0001] The invention relates to an electrochemical treatment method for forming an oxide film on the surface of an aluminum or aluminum alloy material, which is used in the field of protective decoration on the surface of the aluminum or aluminum alloy material. Background technique [0002] The electrochemical oxidation of aluminum and its alloys is an important means of aluminum surface treatment. Most of the research on aluminum anodic oxidation uses direct current, but less research on the use of alternating current oxidation. Alternating current oxidation is an oxidation method that directly uses commercially available alternating current after step-down without rectification equipment. During AC oxidation, two electrode workpieces can be oxidized at the same time, no counter electrode material is needed, and high current can be used to achieve high-speed oxidation. Therefore, compared with DC oxidation, it has the advantages of high efficiency, energy s...

Claims

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Application Information

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Patent Type & Authority Patents(China)
IPC IPC(8): C25D11/04C25D11/10
Inventor 旷亚非张斗周海晖付超鹏
Owner HUNAN UNIV
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