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Environmentally-friendly magnesium alloy chemical conversion film, microarc oxide film hole sealing solution and hole sealing method

A technology of chemical conversion coating and micro-arc oxidation, which is applied in the direction of anodic oxidation, etc., can solve the problems of hexavalent chromium carcinogenicity, high sealing temperature, environmental hazards, etc., and achieve the effect of improving adhesion, simple composition, and slowing down corrosion

Inactive Publication Date: 2010-05-19
JIANGXI SCI & TECH NORMAL UNIV
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

Although hydration sealing is simple, effective and convenient to use, it has high sealing temperature and high energy consumption
Hexavalent chromium is carcinogenic and has great harm to the environment, so it is rarely used now

Method used

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Examples

Experimental program
Comparison scheme
Effect test

Embodiment 1

[0022] The magnesium alloy to be processed can be extruded AZ91D magnesium alloy or other forms of magnesium alloy, the size is 50×50×10mm 3 Cuboid, the specific operation steps are:

[0023] (1) Mechanical pretreatment: use sandblasting or sandpaper grinding to initially remove burrs, firm oxides, lubricants for extrusion, release agents, casting sand, cutting oil foreign matter, reduce surface roughness; wash with water;

[0024] (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 and cutting agents attached to sintering; the temperature is controlled at 70°C, and the time 5 minutes; wash with water;

[0025] (3) Pickling: wash with an acid solution compounded with hydrofluoric acid and phosphoric acid at 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...

Embodiment 2

[0031] The magnesium alloy to be processed can be extruded AZ91D magnesium alloy, or other forms of magnesium alloy.

[0032] The sample is cut into 50×50×10mm by wire 3 Cuboid, use 180-1000 # The water sandpaper is sanded in sequence from coarse to fine, then cleaned in distilled water, finally scrubbed with acetone and dried in the air, then placed in a desiccator for use.

[0033] The difference from Example 1 is:

[0034] (1) Sealing treatment: Seal the holes in an aqueous solution of phytic acid or phytate, the solution is composed of 8g / L sodium hydroxide and 8g / L phytic acid, the order of ingredients is: first add sodium hydroxide and part of distilled water, then Add phytic acid to avoid direct contact between sodium hydroxide and phytic acid, which will cause violent chemical reactions. The temperature of the solution was controlled at 80° C., and the sealing time was 20 minutes.

[0035] The salt spray test method is the same as that in Example 1. After 48 hours ...

Embodiment 3

[0037] Using die-casting AM60 magnesium alloy:

[0038]The sample is cut into 50×50×10mm by wire 3 Cuboid, use 180-1000 # Grinding with water sandpaper from coarse to fine, then cleaning in distilled water, finally scrubbing with acetone and drying in the air, then put it in a desiccator for use.

[0039] The difference from Example 1 is:

[0040] Put the pretreated magnesium alloy sample into the chemical conversion solution, the solution is composed of calcium nitrate and ammonium hydrogen phosphate (calcium nitrate 25g / L, NH 4 h 2 PO 4 25g / L). The pH value of the solution is 3.0, the temperature is 40° C., and the deposition time is 5 minutes.

[0041] The hole sealing method is the same as that in Example 1. After 24 hours of salt spray test, a corrosion point is formed on the surface of the sample.

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PUM

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Abstract

The invention relates to an environmentally-friendly magnesium alloy chemical conversion film, microarc oxide film hole sealing solution and a hole sealing method. The hole sealing solution comprises phytate or phytic acid and one or more following substances of alkali metal hydroxide, silicate, phosphoric acid or phosphate. The hole sealing method is operated according to the following steps: preliminary treatment; chemical conversion or micro-arc oxidation; post treatment: in phytate, one of or several kinds of silicate, phosphoric acid or phosphate are added, the pH value of solution is adjusted by the alkali metal hydroxide or ammonia water, solution temperature is controlled at 30-100 DEG C, and hole sealing treatment is carried out. The hole sealing solution used by the invention does not contain Cr6 and F-, thus causing no pollution to environment. After sealing holes, the size of the crack or the micropore of the chemical conversion film or oxide film is obviously decreased, and corrosion resisting property is improved; meanwhile, the film layer and the organic coating obtained by next-step painting have favourable adhesive force.

Description

technical field [0001] The invention relates to a magnesium alloy oxide film sealing treatment technology, in particular to an environment-friendly magnesium alloy chemical conversion film and micro-arc oxidation film sealing solution and a method for sealing holes. 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 automob...

Claims

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Application Information

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IPC IPC(8): C25D11/30
Inventor 张荣发张淑芳
Owner JIANGXI SCI & TECH NORMAL UNIV
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