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In the 1990s, setting off a worldwide craze development and application of magnesium alloys. As unique properties of magnesium, are becoming the steel, aluminum, after the third big metal engineering materials, known as \However, poor corrosion resistance has become a constraining its performance advantage to play one of the main factors. Therefore, proper surface treatment to enhance the existing corrosion resistance of magnesium alloys has important practical significance. Chemical conversion treatment because of its simple operation, low cost, a magnesium alloy corrosion effective way. The techniques are generally acidic or neutral solution for containing hexavalent chromium, but very harmful to human health chromium. At present, magnesium alloy chromium conversion treatment method is widespread concern by rare earth conversion treatment, rare earth salt solution generated based conversion coating non-toxic, less harmful to the environment and the human body, can significantly improve the corrosion resistance of magnesium alloys sex. This research and development, respectively, and mixed rare earth cerium nitrate salts mainly two rare earth magnesium alloy surface treatment liquid chemical conversion coating formulations and related processes. Initially identified by orthogonal experiment priority of factors affecting, and analyzed various factors on the conversion of film growth processes and performance. On this basis, this paper analyzes the process parameters on the rare earth conversion coating film thickness, surface morphology, corrosion resistance. Secondly, through the drip experiment, immersion corrosion test, such as hydrogen corrosion test different experimental method into two kinds of magnesium alloy film coating corrosion resistance, and through the microscope, SEM, XRD techniques and systematic research best conversion coating process parameters and two kinds of morphology, adhesion strength, composition and other basic information. The results showed that the two rare earth conversion coating processes are able to make the corrosion resistance of magnesium alloys has been greatly improved, two kinds of conversion coatings are uniform, dense, completely covering the surface of the substrate, comparison of the two rare earth conversion coating, cerium conversion membrane structure in morphology and corrosion performance are slightly better than the mixed rare earth conversion coating, but that can provide temporary surface of magnesium alloy corrosion protection; while the mixed rare earth cerium in the price cheaper than using the mixed rare earth conversion coating preparation can save costs, so the two membranes have good application prospects. Finally, using scanning electron microscopy were formed for different deposition time two magnesium alloy rare earth conversion coating surface morphology further analysis, proposed rare earth magnesium alloy chemical conversion film formation theory, and two chemical conversion coating structure and formation mechanism of a preliminary study, and then have some experimental facts give a reasonable explanation, the subject of research will broaden rare earth magnesium alloy surface treatment in the practical application.
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