A chemical conversion film on the surface of a magnesium alloy and its preparation method

Abstract

The invention provides a chemical conversion film on the surface of a magnetism alloy and a preparation method thereof. Rare earth cerium ions are injected in the surface of the magnesium alloy in anion injecting mode to form anchoring points so as to improve the adaptation between a conversion film layer and the surface of the magnesium alloy; meanwhile, a surface treating agent with metallic oxysalt and sulfydryl-contained silane as a film forming agent is applied to the surface of the magnesium alloy; the type and the components of the surface treating agent are screened; the treatment process is improved to finally prepare the conversion film layer with high compactness and excellent corrosion resistance; and the conversion film layer can achieve excellent lubricity, alkali resistanceand coating property in subsequent cold working.

Description

technical field [0001] The invention belongs to the technical field of chemical conversion coatings, in particular to a chemical conversion coating on the surface of a magnesium alloy and a preparation method thereof. Background technique [0002] Magnesium alloy has the advantages of low density, high specific strength and specific stiffness, good thermal conductivity, easy cutting and processing, etc., and is easy to recycle, and can realize 100% recycling, which is in line with the development direction of circular economy. Therefore, magnesium alloys are widely used in automobiles, aerospace, microelectronics and other fields, and are known as "green engineering materials in the 21st century". Magnesium alloy is also used in the medical field as an implant material because of its degradability and biocompatibility. [0003] However, the corrosion resistance, wear resistance, creep resistance and high chemical reactivity of magnesium alloys affect its application under h...

AI Technical Summary

Problems solved by technology

[0004] However, the solution chemical treatment with chromic anhydride or dichromate as the main component has an Achilles’ heel that the treatment solution contains highly toxic hexavalent chromium, which is harmful to human health and pollutes the environment; the solution chemical treatment with phosphate as the main component The Achilles heel of chemical treatment is that the film layer is low in density and thin, and the micropores in the film will weaken its corrosion resistance and alkali resistance; the solution chemical treatment with rare earth ions as the main component has its Achilles heel in anti-corrosion The protection time of the performance is short, and it cannot provide long-term protection for magnesium alloys; the solution chemical treatment with fluozirconic acid and its salts as the main component, although it can show good corrosion resistance under mild conditions, it can resist the damage of crushed stone chips. very weak

Looking at the treatment of magnesium alloys by the above various surface treatment agents, although they can have certain anti-corrosion effects, there are still shortcomings such as environmental pollution, poor anti-corrosion effect, loose film layer, and weak environmental adaptability.