Researchers from the Department of Electrochemical Systems and Surface Modification Technology of the Institute of Chemistry of the far East Branch of the Russian Academy of Sciences have developed a polymer composite coating to protect magnesium alloys. By using this method, a surface structure with almost no defects can be formed on the surface of magnesium alloy.
Magnesium alloys are widely used in automotive and aircraft parts manufacturing and other fields. Magnesium alloy is not only light, but also very strong, but it also has obvious defects such as susceptibility to corrosion and wear. Therefore, the service life of the equipment made of this material is relatively short, and the maintenance or replacement is more expensive. To protect this material, researchers are developing a coating that can prevent corrosive environments from damaging magnesium alloy components and structures. however, this coating is often prone to small holes and microcracks, and if exposed to an erosive environment for a long time, the coating does not completely protect mechanical parts from corrosion.
It is reported that Russian researchers used hyperdispersed polytetrafluoroethylene. This polymeric material is used in daily life for tableware non-stick coating, heat resistance, cold resistance, good elasticity and good water resistance. In addition, its chemical stability is better than that of all known synthetic materials and is not affected by acids and bases.
The researchers applied composite coatings to magnesium alloy samples in a new way: plasma electrolytic oxidation of (PEO) and then spraying polymers. First, the alloy surface was coated with PEO coating, then the holes and surfaces of the coating were uniformly sprayed with hyperdispersed polytetrafluoroethylene powder, and finally, the samples were dried in a furnace of 300C. The defect of the coating obtained in this way is only 1/3 of that of the PEO coating, because the polymer will seep into the pores and microcracks and seal it. Under the protection of composite coating, magnesium alloy samples are more resistant to corrosion than untreated materials. If it is sprayed repeatedly, it will be more protective.
In order to test the wear resistance of the coating, the researchers carried out friction tests on the samples for a long time. The results show that the loss of integrity (wear) of the alloy with composite coating is 27 times slower than that of the alloy with basic PEO coating.
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