Compound-mixed tea polyphenol-rare-earth salt conversion liquid for magnesium alloy surface treatment and use method thereof

Abstract

The invention discloses compound-mixed tea polyphenol-rare-earth salt conversion liquid for magnesium alloy surface treatment. The conversion liquid selects rare-earth salts as a major film forming agent; substances such as sodium fluoride, zinc acetate and polyvinylpyrrolidone are used as auxiliary agents; meanwhile, tea polyphenol is added; a good antioxidation effect is achieved; meanwhile, the efficacy of fixing metal ions is achieved; the fastness of the conversion film can be improved in an assisted way; the anticorrosion period is prolonged; the antioxidation capability of the magnesium alloy surface is improved; in addition, added nanometer manganese sesquioxide particles can further improve the anti-corrosion capability of the rare-earth salt conversion film; the excellent adhesion force between the rare-earth salt conversion film and an organic coating is obtained. The prepared conversion liquid has the advantages that the stability is high; all ingredients are uniformly dispersed and coexist; the compact, high-corrosion-resistant and antioxidation long-acting protection film can be fast formed on the magnesium alloy surface. Compared with a conventional rare-earth salt conversion film, the long-acting protection film achieves an efficient protection effect; the performance of the magnesium alloy material is further improved.

Description

technical field [0001] The invention relates to the technical field of magnesium alloy surface treatment, in particular to a compound tea polyphenol-rare earth salt conversion liquid used for magnesium alloy surface treatment and a use method thereof. Background technique [0002] Magnesium alloy is a lightweight, high-strength metal material. Products with the same strength can even be lighter than plastics. Its ability to withstand impact loads is greater than that of aluminum alloys. At the same time, magnesium alloys also have good processing performance, fast heat dissipation, Anti-seismic, anti-electromagnetic wave, recyclable and other advantages are widely used in aerospace, 3C products, sports equipment and other fields. Especially in recent years, 3C products have gradually developed in the direction of thinner and shorter, making high-performance magnesium alloys more favored by manufacturers. . [0003] Although magnesium alloys have the above advantages, due to...

AI Technical Summary

Problems solved by technology

At present, the commonly used chemical treatment solutions for magnesium alloys mainly include chromate, permanganate, phosphate, permanganate-phosphate and other solution systems. Among them, the process of chromate conversion coating is the most mature, but hexavalent chromium is a high Carcinogens are currently banned from use. Although other types of treatment solutions are more environmentally friendly to a certain extent, the conversion coatings formed have problems such as poor corrosion resistance and cracks in the film layer, which are difficult to meet engineering needs.

In order to improve these defects in the chemical conversion coating, researchers can significantly improve the microstructure of the conversion coating by adding nanoparticles to the conversion solution, as shown in the research results of the article "Influence of Nanohardness on the Microstructure of Chemical Conversion Coating". Nano-Al 2 o 3 , nano-SiO 2 Adding can effectively increase the number of conversion coating grains, increase the density of the conversion coating, and obtain higher corrosion resistance, but improving the dispersion of nano-powders in the conversion solution is still a difficult problem to overcome. High requirements, limited application