Element of arc oxidation electrolyte of environmental protection type magnesium alloy, and method of element of arc oxidation

A technology of micro-arc oxidation and magnesium alloy, which is applied in the direction of anodic oxidation, can solve environmental and human health hazards, water resource pollution, environmental hazards and other problems, and achieve the effect of stable process, smooth surface and slow corrosion

Inactive Publication Date: 2009-07-08
INST OF METAL RESEARCH - CHINESE ACAD OF SCI
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

However, hexavalent chromium is carcinogenic and has great harm to the environment, so it is rarely used now
Fluoride and phosphate are now widely used. They have different degrees of harm to the environment and human health. The use of phosphate will cause a greater degree of pollution to water resources.

Method used

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Examples

Experimental program
Comparison scheme
Effect test

Embodiment 1

[0026] The sample is an extruded AZ91D magnesium alloy with a size of 50×50×10mm 3 Cuboid, the specific operation steps are:

[0027] 1. Mechanical pretreatment: Grinding with sandblasting or sandpaper to remove burrs, firm oxides, lubricants for extrusion, release agents, casting sand, cutting oil and other foreign matter, reduce surface roughness; wash with water;

[0028] 2. Degreasing: wash with a compound solution of 10g / l sodium hydroxide, 15g / l sodium phosphate, and 15g / l sodium carbonate to remove general dirt, lubricants, cutting agents, etc. 5 points; wash with water;

[0029] 3. Pickling: Wash with concentrated hydrofluoric acid and phosphoric acid in a volume ratio of 1:1, wherein the mass percentage concentration of HF in hydrofluoric acid is not less than 40%, and the concentration of H in phosphoric acid is not less than 40%. 3 PO 4 The mass percentage concentration is not less than 85%, to remove the unremoved scale, corrosion products, sintered lubricants, ...

Embodiment 2

[0038] Die-cast AZ91D magnesium alloy is used.

[0039] The sample is cut into 50×50×10mm by wire 3 For the cuboid, sand it with 180-1000# water sandpaper from coarse to fine, then wash it in distilled water, and finally scrub it with acetone and dry it in the air, then put it in a desiccator for use.

[0040] The difference from Example 1 is:

[0041] 1. Micro-arc oxidation: put the pretreated magnesium alloy sample into the anodic oxidation electrolyte, the solution is composed of phytic acid, sodium silicate, sodium carbonate and sodium tetraborate (phytic acid 10g / L, sodium silicate 20g / L, sodium carbonate 15g / L, sodium tetraborate 20g / L). The order of ingredients is: first add phytic acid and part of distilled water, then add sodium silicate, sodium tetraborate, etc., then add sodium hydroxide to make the solution alkaline, then add sodium carbonate, and finally adjust the pH value to 13.36 with sodium hydroxide. Use a stirring and cooling device, control the solution ...

Embodiment 3

[0047] Die-cast AM60 magnesium alloy is used.

[0048] The sample is cut into 50×50×10mm by wire 3 For the cuboid, sand it with 180-1000# water sandpaper from coarse to fine, then wash it in distilled water, and finally scrub it with acetone and dry it in the air, then put it in a desiccator for use.

[0049] The difference from Example 1 is:

[0050] Put the pretreated magnesium alloy sample into the anodic oxidation electrolyte, the solution is composed of phytic acid and sodium silicate (phytic acid 20g / L, sodium silicate 10g / L). The order of ingredients is as follows: first add phytic acid and part of distilled water, then add sodium silicate, and finally add sodium hydroxide to adjust the pH value to 12.8. Using a stirring and cooling device, control the solution temperature at 16°C, use double pulse current, frequency 200 Hz, positive current density 30mA / cm 2 , positive duty cycle 25%, negative current density 20mA / cm 2 , The negative duty cycle is 25%, the oxidatio...

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Abstract

The invention relates to an environment-friendly magnesium alloy micro-arc oxidation electrolyte and a micro-arc oxidation method. The electrolyte includes: phytate or phytic acid 5g / L-20g / L, and one or more of the following substances: carbonate 5g / L-20g / L, silicate 5g / L-50g / L, boric acid Or borate 5g / L~50g / L, aluminate or aluminum hydroxide 5g / L~50g / L. It is operated according to the following steps: 1) Pretreatment: grinding, degreasing and pickling. 2) Micro-arc oxidation: In phytate (or phytic acid), add one or more substances of carbonate, silicate, boric acid or borate, aluminate (or aluminum hydroxide), and use alkali Metal hydroxide or ammonia water adjusts the pH value of the solution to 10-14, and then micro-arc oxidation. 3) post-processing. The anodic oxidation electrolytic solution used in the present invention does not contain Cr6+, F-, PO43-, even very little strong alkali is used, and there is no pollution to the environment. The obtained film layer has smooth surface, small hole diameter, good corrosion resistance and ceramic appearance. The raw materials of the method of the invention are easy to obtain and are suitable for industrial production.

Description

technical field [0001] The invention relates to a magnesium alloy surface treatment technology, in particular to an environment-friendly magnesium alloy micro-arc oxidation electrolyte and a micro-arc oxidation method. Background technique [0002] Magnesium alloy has small specific gravity, high specific strength and specific stiffness, good thermal and electrical conductivity, good damping and shock absorption and electromagnetic shielding functions, plus abundant storage capacity, easy to recycle, used as electronic products, such as mobile communications, portable computers, etc. The shell structural parts can replace the plastics that are widely used at present, and meet the requirements of lightness, thinness, miniaturization and high integration of electronic products, and are increasingly widely used. In particular, the extensive application of magnesium alloys on automobile bodies can realize the lightweight of automobiles. According to calculations, the weight of ...

Claims

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Application Information

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Patent Type & Authority Patents(China)
IPC IPC(8): C25D11/30
Inventor 张荣发单大勇韩恩厚
Owner INST OF METAL RESEARCH - CHINESE ACAD OF SCI
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