Magnesium radical differential arc oxidization electrolytic solution and its differential arc oxidation process

A magnesium-based micro-arc and micro-arc oxidation technology, applied in anodizing and other directions, can solve the problems of reduced breakdown voltage, environmental and personal health hazards, poor corrosion resistance, etc., and achieves the effect of smooth surface, easy control and process stability

Inactive Publication Date: 2008-01-30
XI AN JIAOTONG UNIV
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

Use Cr in acidic solution 6+ (such as Dow17) have greater harm to the environment and human health
The use of alkaline solution also has its disadvantages, because the breakdown voltage decreases with the increase of pH value, and the higher the pH value, the easier it is to form Mg(OH) with poor corrosion resistance. 2 or MgO film

Method used

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  • Magnesium radical differential arc oxidization electrolytic solution and its differential arc oxidation process

Examples

Experimental program
Comparison scheme
Effect test

Embodiment 1

[0030] In deionized water, first add 2g / L oxalic acid C 2 h 2 o 4 .2H 2 O and 6 g / L sodium acetate CH 3 COONa, stir well to dissolve completely, pH value is 5, finally add 14g / L potassium fluozirconate K 2 ZrF6.

[0031] Using pure magnesium as the anode and stainless steel as the cathode, in the above prepared electrolyte, using a pulse power supply, under the conditions of a constant voltage of 550V, a frequency of 100Hz, a duty ratio of 26%, and a distance between the cathode and anode plates of 10cm. After arc oxidation treatment for 20 minutes, apply 550V within 30s, and maintain the temperature of the electrolyte at 20°C, a film with a thickness of 60μm and a surface hardness of 403Hv can be prepared. The microscopic morphology of the surface and cross-section of the film layer are shown in Figure 1 and Figure 2, respectively. The phase composition is shown in Figure 3.

Embodiment 2

[0033] In deionized water, first add 3g / L oxalic acid C 2 h 2 o 4 .2H 2 O and 8 g / L sodium acetate CH 3 COONa, fully stirred and dissolved completely, the pH value is 4.5, finally add 17g / L potassium fluozirconate K 2 ZrF 6 .

[0034] Using MB8 magnesium alloy as the anode and stainless steel as the cathode, in the above prepared electrolyte, using a pulse power supply, under the conditions of a constant voltage of 500V, a frequency of 100Hz, a duty cycle of 26%, and a distance between the cathode and anode plates of 9cm Perform micro-arc oxidation treatment for 60 minutes, apply 500V within 30s, and maintain the temperature of the electrolyte at 18°C ​​to obtain a film with a thickness of 130μm.

Embodiment 3

[0036] In deionized water, first add 10g / L oxalic acid C 2 h 2 o 4 .2H 2 O and 20g / L sodium acetate CH 3 COONa, stir well to dissolve completely, pH value is 5, finally add 3g / L potassium fluozirconate K 2 ZrF 6 .

[0037] Using pure magnesium as the anode and stainless steel as the cathode, in the above-mentioned prepared electrolyte, using a pulse power supply, under the conditions of a constant voltage of 650V, a frequency of 2000Hz, a duty ratio of 40%, and a distance between the cathode and anode plates of 12cm. Arc oxidation treatment was performed for 90min, and the temperature was increased to 650V within 40s, maintaining the temperature of the electrolyte at 30°C.

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Abstract

The invention relates to a magnesium matrix microarc oxidation electrolyte liquid and a microarc oxidation method thereof. The electrolyte liquid comprises: 3 - 40g / L of fluozicronate, 0.5 - 10 g / L of oxalate, 2 - 20 g / L of phosphoric acid, 1 - 20 g / L of acetate, 3 - 30 g / L of phosphate, 0.5 - 10 g / L of fluoride. The operation method is that: a magnesium workpiece is taken as anode, stainless steel is taken as cathode, a pulse power supply is adopted, constant voltage is 350 - 650V, frequency is 50 - 2000Hz, duty ratio is 10 - 40 percent, and the electrolyte liquid is oxidated through microarc under the condition that the distance between a cathode plate and an anode plate is 8 - 12 cm, the temperature of the electrolyte liquid is kept for 10 - 40 DEG C with the treatment time of 5 - 90min. the electrolyte liquid of the invention does not comprise Cr6+, thus having not too large pollution to environment; the obtained film layers which consists of anti-corrosive substances have the advantages of smooth surface, ceramics appearance, strong combination, comparatively larger thickness, high density and little pores, high hardness, etc.

Description

technical field [0001] The invention belongs to surface coating technology, in particular to a magnesium-based micro-arc oxidation electrolyte and a micro-arc oxidation method thereof. Background technique [0002] Magnesium and magnesium alloys have the characteristics of light weight, high specific strength, specific stiffness, good thermal conductivity, electrical conductivity, shock absorption performance, electromagnetic shielding performance, casting performance and good recyclability, so they are widely used in automobile manufacturing, aerospace , electronics, optical instruments, telecommunications, transportation and other fields. However, the standard electrode potential of magnesium is extremely negative, and its corrosion resistance is very poor. The oxide film naturally formed on the surface in the atmosphere is loose and porous, and basically has no protective effect. Under various environmental conditions, especially when chloride ions exist, magnesium is dam...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): C25D11/30
Inventor 憨勇慕伟意
Owner XI AN JIAOTONG UNIV
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