Zirconium salt chemical conversion treatment method for surface of die-casting aluminum alloy

Abstract

The invention belongs to the field of metallic materials and relates to a chemical conversion solution and a treatment method for the surface of a die-casting aluminum alloy. The conversion solution is formed by compounding an A ingredient and a B ingredient, the A ingredient consists of a zirconium salt, a surfactant and a trivalent chromium salt; the B ingredient consists of a complexing agent and a film-forming accelerant; in the A ingredient, the content of the zirconium salt is 5-60 g/L, the content of the surfactant is 2-10 g/L, and the content of the trivalent chromium salt is 5-50 g/L; in the B ingredient, the content of the complexing agent is 4-20 g/L, and the content of the film-forming accelerant is 2-15 g/L; and the method comprises the pretreatment on the surface of the die-casting aluminum alloy and the zirconium salt chemical conversion treatment. A chemical conversion coating contains zirconium phosphate compounds and a small amount of trivalent chromium compounds, wherein the coating has uniform light blue and the thickness of about 0.5-1 micron. The zirconium salt chemical conversion coating prepared by the method has excellent corrosion resistance, the bonding strength between the coating and a substrate is high, the product, the waste water and the waste liquor obtained after the chemical conversion treatment do not contain hexavalent chrome which is harmful to the environment and the health of human bodies.

Description

technical field [0001] The invention belongs to the field of metal materials, and relates to a chemical conversion solution and a treatment method for the surface of a die-casting aluminum alloy, in particular to an environmentally friendly zirconium salt chemical conversion treatment on the surface of a die-casting aluminum alloy containing high silicon and copper elements. A uniform and dense protective film layer is obtained on the surface of the parts, and this film is used as a bare film of die-casting aluminum alloy parts to improve its corrosion resistance. Background technique [0002] Die-casting is a rapid production process. The mass production of parts is fast, low-cost, high-precision and can be used to manufacture parts with complex shapes. 95% of die-casting aluminum alloys are recyclable after machining, aluminum die-casting is a very green and sustainable alternative. The domestic die-casting industry has achieved rapid development since the 1990s, and the ...

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Problems solved by technology

[0004] The purpose of the present invention is to solve the problems existing in the prior art, such as the harm of hexavalent chromium to the environment and the human body, the high cost of organosilane treatment and the slow speed, and there is currently no Aiming at problems such as the deve

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