Preparation for aluminum or aluminum alloy trivalent chromium chemical conversion film

A technology of chemical conversion coating and trivalent chromium, which is applied to chemical instruments and methods, cleaning methods using liquids, cleaning methods and utensils, etc., can solve problems such as toxicity, achieve low cost, short film forming time, and simple and easy process line effect

Inactive Publication Date: 2009-12-09
CENT SOUTH UNIV
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

[0003] The object of the present invention is to provide a method for preparing aluminum or aluminum alloy trivalent chromium chemical conversion film, which uses low-toxic trivalent chromium compound as raw material to carry out chemical conversion film treatment on the surface of aluminum and aluminum alloy, solving the problem of the original Hexavalent chromium as the main component of aluminum and aluminum alloy surface conversion coating process has the disadvantage of high toxicity, so as to meet the requirements of environmental protection, while not changing the quality of the chromium conversion coating

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  • Preparation for aluminum or aluminum alloy trivalent chromium chemical conversion film

Examples

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Embodiment 1

[0014] Example 1: Trivalent chromium chromization of 6061 aluminum alloy

[0015] Build a 500L degreasing bath: clean the container thoroughly before building the bath. For a new container or a new production line, wash it with 20% sulfuric acid solution first, and then wash it twice with water, each with 100L water, and then add 10kg Henkel's Ridoline212, a degreaser, is diluted to 500L with deionized water, and the pH is controlled to 8.

[0016] Build an activation bath: thoroughly clean the container before building the bath. For a new container or a new production line, clean it with 15% sulfuric acid solution first, then clean it with water, add 75kg sodium hydroxide, and then dissolve it with deionized water. And then dilute to 500L with deionized water, mix well, and keep the temperature at 25℃.

[0017] Build a 500L chromium bath: clean the container thoroughly before building the bath. For a new container or new production line, clean it with 15% sulfuric acid solution f...

Embodiment 2

[0019] Example 2: Trivalent chromium chromization of 6063 aluminum alloy

[0020] Build a 400L degreasing bath: thoroughly clean the container. For new containers or new production lines, first wash with 40L 20% sulfuric acid solution, then wash twice with water, each time 80L of clean water, and then add 8KG Henkel degreasing powder Ridoline212 is diluted to 400L with deionized water and the pH is controlled at 7.8.

[0021] Build a 400L activation bath: clean the container thoroughly before building the bath. For a new container or new production line, clean it with 15% sulfuric acid solution first, then clean it with water, add 50kg sodium hydroxide, and then dissolve it with deionized water And then dilute to 400L with deionized water, mix well, and keep the temperature at 30°C.

[0022] Build a 400L chromium bath: thoroughly clean the container before building the bath. For a new container or new production line, clean it with 15% sulfuric acid solution first, then clean it w...

Embodiment 3

[0024] Example 3: Trivalent chromium chromization of aluminum alloy die castings

[0025] Build a 300L degreasing bath: clean the container thoroughly. For a new container or new production line, first wash with 50L of 20% sulfuric acid solution, then wash twice with water, 60L of clean water each time, and then add 6kg of degreasing powder Ridoline212, and then Dilute to 300L with deionized water and keep the pH at 7.

[0026] Build 300L activation bath: clean the container thoroughly before building the bath. For a new container or new production line, clean it with 15% sulfuric acid solution first, then clean it with water, add 25kg of sodium hydroxide, and then use deionized water Dissolve and dilute to 300L with deionized water, mix well, and keep the reaction temperature at 5°C.

[0027] Build a 300L chromium bath: clean the container thoroughly before building the bath. For a new container or new production line, clean it with 15% sulfuric acid solution first, then clean it...

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Abstract

The invention discloses a method for preparing an aluminum or aluminum alloy trivalent chromium chemical conversion film: activating the aluminum or aluminum alloy workpiece in 50-100 g / L sodium hydroxide aqueous solution for 1-2 minutes, and the activation reaction temperature is 5-30 ℃; wash with deionized water; put the cleaned workpiece into the mixed aqueous solution of soluble trivalent chromium salt and phosphoric acid for chromization for 6-10 minutes, the concentration of trivalent chromium ion is 1-20g / L, and the concentration of phosphoric acid is 1-25g / L, adjust the pH value of the reaction system to 1.6-4.0 with dilute sodium hydroxide or dilute sulfuric acid, and the chromating temperature is 10-60°C. The invention solves the disadvantage of high toxicity of hexavalent chromium in the prior art, the technological process and products meet the requirements of environmental protection, and the prepared trivalent chromium chemical conversion film has the same quality as the hexavalent chromium chemical conversion film.

Description

Technical field [0001] The invention relates to surface treatment of aluminum alloys, in particular to a method for preparing chemical conversion films on the surface of aluminum or aluminum alloys. Background technique [0002] The natural oxide film on the surface of aluminum and aluminum alloy is about 5nm. Because of its thin thickness, it is easy to wear and scratch, and has poor corrosion resistance. If exposed to severe corrosive environments such as outdoors or seaside, the surface will quickly form a Layer of aluminum rust. In order to improve the corrosion resistance of the oxide film on the surface of aluminum and aluminum alloy, it is necessary to manually treat the surface of the aluminum and aluminum alloy to increase the thickness of the oxide film. At present, the most widely used ones are chemical conversion film and anodic oxidation treatment. Compared with anodic oxidation, chemical conversion coating has the advantages of simple operation, low cost, less energ...

Claims

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Application Information

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Patent Type & Authority Patents(China)
IPC IPC(8): C23C22/04B08B3/04
CPCC23C2222/10
Inventor 余会成陈白珍徐徽杨喜云石西昌
Owner CENT SOUTH UNIV
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