| Magnesium alloys has been wildly applied in the fields of aerospace, transportation and electronics due to their low density, high specific strength, high specific stiffness, and Easy recycling. Recently, magnesium alloys is used widely, which lead to magnesium alloy scraps is more and more. How to deal with recycling magnesium alloy scraps has attracted widespread attention.Usually, the surface of magnesium alloy have been surface-treated in one or more of the process. The coating of the surface can not be effectively removed by the cleaning solution. It will generate a lot of harmful gases in the smelting process and pollute the environment without removing the coating.In this paper, in order to solve these problems, respectively prepared inorganic and organic solvent to remove surface coatings on the laptop case, research the best process conditions. Metallography. SEM, XRD, FTIR, Raman Spectra, electrochemistry testing are used to study the removal mechanism. Factors, such as the temperature, NaOH concentration, time, solution NaOH/ethanol (volume ratio),were studied by orthogonal test. The results show that, when NaOH solution/ethanol (volume ratio) is1, the concentration of NaOH was10mol/L, the sample at a temperature of70℃water bath heating constant temperature is70min, the optimal removal efficiency.The temperature range is96.75bigger than the NaOH concentration, time and NaOH solution/ethanol (volume ratio) range, and the F of the temperature is larger than the critical value of F, temperature is the main factor.Organic coatings were removed on magnesium alloy metallographic diagram observed, detect a-Mg and Mg17Al12by XRD, while further observes in the SEM is a continuous distribution of phosphate layer, this corrosion potential from electrochemical corrosion tests for-1.176V, in a forward to the potential value of AZ91magnesium alloy is further proof. A series of physical action is took place when alkaline solution to remove the organic coating. The the alkaline solution can be used repeatedly.Prepared a benzaldehyde-based solvents. The results show that: benzaldehyde/formic acid in a volume ratio of13/7, the processing time of10min as the best process parameters. Agents for suppressing volatilization of liquid paraffin was added in an amount of2mLThe organic solution treatment after coating benzaldehyde was completely removed, leaving only the phosphate layer and the main component of the magnesium alloy base a-Mg and Mg17Al12, metallograph, SEM and XRD test results are consistent with an inorganic alkaline solution. Benzene formaldehyde and formic acid by osmosis, adsorption effects a large number entered is located in the space between the phosphate and organic coatings mesh structure by reducing the phosphate layers with organic coating’s forces, prompted the separation of coating and substrate of magnesium alloys.A Benzyl alcohol-based solvent was prepared with, cosolvent acid, sodium lauryl sulfate as a surfactant, methyl cellulose as thickener, and sodium nitrite as corrosion inhibitors. The results show that when the benzyl alcohol/acid volume ratio of5/15, the processing time was15min the optimum content of Sodium nitrite is0.2g, the optimum content of Sodium lauryl sulfate is0.3g time, the optimum content of Methyl cellulose is0.2g best.The organic coating is completely removed. was treated by benzaldehyde layer leaving, only phosphate layer and a-Mg and Mg17Al12test results metallograph, SEM and XRD are consistent with the effect of an inorganic alkaline solution and benzene-formaldehyde treatment solution. A chemical reaction does not occur between the benzyl alcohol type solvent solution of the coating polymer molecules, the coating was removed only by swollen coating. Description The benzene solution of methanol can be used repeatedly. |
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