Aluminium alloy chromium-free chemical converting liquid and its using method

A chemical conversion, aluminum alloy technology, applied in the direction of metal material coating process, etc., can solve the problems of inability to achieve industrial continuous production, difficult to obtain uniform color protective film, low concentration of dissolved titanium ions, etc., to achieve excellent surface quality and cost. The effect of reducing and increasing the concentration of titanium ions

Inactive Publication Date: 2005-10-19
郭瑞光
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  • Summary
  • Abstract
  • Description
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  • Application Information

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Problems solved by technology

[0005] For the "chromium-free conversion coating" announced by U.S. Patent 6,638,369, its treatment solution has the advantage of not containing hexavalent chromium, and the fluoride in the same range as the existing hexavalent chromium conversion process has been added to the treatment solution, but due to The sodium titanate or potassium titanate used in this process has extremely low solubility in water, so the effective concentration of dissolved titanium ions is low, which cannot guarantee the quality of the film in the continuous production process, cannot meet the requirements of industrial continuous production, and contains extremely toxic Potassium ferricyanide
[0006] For high-strength aluminum alloys, due to the dissolution of many metal ions during the conversion reaction, such as Cu 2+ , Zn 2+ etc., the treatment solution of this patent does not contain ingredients to remove these ion interferences, therefore, it is difficult to obtain a protective film with uniform color for this type of aluminum alloy

Method used

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Examples

Experimental program
Comparison scheme
Effect test

specific Embodiment 1

[0057] Specific embodiment 1: the surface of aluminum alloy LC4CS is cleaned with gasoline, then immersed in 3 to 5% sodium hydroxide solution at a temperature of 40 to 60°C for 3 minutes to degrease, and after washing, the alloy is immersed at room temperature for 1 to 3 minutes. 10% nitric acid solution for about 1 to 10 minutes, rinsed with deionized water and then immersed in chemical conversion solution. The composition of the chemical conversion solution is sodium silicate 0.10g / L, titanyl sulfate 3g / L, sodium titanate 5g / L, hydrogen peroxide 1.0g / L, sodium fluoride 5g / L. Sulfuric acid is used to adjust the pH of the conversion solution to 4.5-8.5, and the temperature is 80-90°C. After reacting for 10 minutes, the alloy is taken out and washed with water to dry. The formed film passed the 336-hour neutral salt spray test (ASTM B117) test.

specific Embodiment 2

[0058] Specific Example 2: After the aluminum alloy LD2CS is subjected to the same pretreatment as in Example 1, the alloy is immersed in 0.05g / L sodium silicate, 2g / L titanyl sulfate, 0.5g / L hydrogen peroxide, and fluorinated In the conversion solution of sodium 4.5g / L, sulfuric acid adjusts the pH value of the solution. Reaction condition is with embodiment 1. The surface of the aluminum alloy LD2CS treated above forms a layer of white film layer and still does not rust after 336 hours of neutral salt spray (ASTM B117) test.

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Abstract

The present invention relates to surface treatment of aluminum alloy, and especially a kind of chromium-free chemical aluminum alloy converting solution capable of endowing aluminum alloy surface with excellent corrosion resistance and its usage. The chromium-free chemical aluminum alloy converting solution consists of silicate, titanium salt, peroxide, fluoride, and water solution of sulfuric acid. The solution is used in 50-99 deg.c and pH 4-9 and has aluminum alloy contacting time of 2-20 min. The solution contains no hexavalent chromium and potassium ferricyanate, and has less environmental pollution, low cost, easy filming and high corrosion resistance.

Description

(1) Technical field [0001] The invention relates to an aluminum alloy surface treatment method, in particular to a chromium-free metal surface conversion solution that imparts superior corrosion resistance to the aluminum alloy surface, and a metal surface treatment method using the chemical conversion solution. (2) Background technology [0002] Chromium plating is a traditional processing technology. For nearly a century, chrome plating has been widely used in the fields of functional coatings and decorative coatings, such as aerospace, electronics, automobiles, pharmaceuticals, printing, In machinery, chemical, food processing and other manufacturing industries, chrome plating is worth $8 billion a year in the United States. [0003] In the past, the surface treatment method of aluminum and its alloys was treated with chromate conversion solution. There are many chemical conversion treatments for the hexavalent chromium compounds of aluminum and its alloys, such as the A...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): C23C22/34C23C22/66C23C22/68
Inventor 郭瑞光
Owner 郭瑞光
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