Surface pretreatment process for improving film forming quality of magnesium alloy conversion film

Abstract

According to the experiment, the magnesium alloy surface is treated and compared under the condition that glyoxylic acid and ammonium bifluoride serve as pickling solutions and hydrochloric acid and hydrofluoric acid serve as pickling solutions. A large number of black spots can be found on the surface treated by hydrochloric acid and hydrofluoric acid, and the surface quality requirement of a sample in the film forming process cannot be met. Glyoxylic acid and ammonium bifluoride are used as the pickling solutions for treatment, so that corrosion pits on the surface of the sample and at the junction of a secondary phase and a matrix can be effectively reduced. Glyoxylic acid and ammonium bifluoride are adopted as the pickling solutions, so that a very good surface treatment effect can be achieved, and the surface quality is greatly improved. The film forming quality of the magnesium alloy conversion film is improved.

Description

technical field [0001] The invention relates to a surface pretreatment process for improving the film-forming quality of a magnesium alloy conversion film. Background technique [0002] Magnesium alloys have the advantages of light weight, high specific strength and specific stiffness, and good impact resistance and compression resistance. The density of magnesium is 1.74g / cm 3 , is 2 / 3 of aluminum, 1 / 4 of zinc, and 1 / 5 of steel, and is currently the lightest metal structure material. [1, 2]. With the increasingly serious environmental problems such as the greenhouse effect, people's demand for lightweight structural materials continues to rise, and my country is one of the countries with the most abundant magnesium resources in the world, with good development potential. Due to environmental factors and strategic deployment considerations, the development of the magnesium alloy industry is of great significance. However, magnesium alloys have poor corrosion resistance. ...

AI Technical Summary

Problems solved by technology

At room temperature, the surface of magnesium reacts with oxygen in the air to form a magnesium oxide film, but because the magnesium oxide film is loose and porous, its compactness coefficient is only 0.79, that is, the volume of magnesium oxide generated after magnesium oxidation shrinks, which cannot affect the magnesium substrate. play an effective protective role

The conversion coating on the surface of magnesium alloy is one of the main methods to solve the corrosion problem of magnesium alloy. However, the acid and alkali pretreatment will cause great damage to the surface and seriously affect the film quality. The surface state of the substrate is closely related to [3]

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