Research On Surface Protection Performance Of Magnesium Alloy

Due to the advantages of low density,good ductility and high specific stiffness,magnesium alloys are widely used in industrial production and daily life.However,due to its high chemical activity,magnesium alloy is prone to corrosion in practical application.The quality and service life of magnesium alloy products are greatly affected,which limits the wider application of magnesium alloy to a certain extent.In this paper,a coating with excellent protective properties on magnesium alloy was prepared by high temperature heating,phase transformation and solution hydrothermal growth.The phase composition,anti-corrosion,microstructure and other preparation related issues were explored.From the experimental exploration and theoretical analysis,the corrosion protection of magnesium alloy was studied,which broadened the research scope.However,there are still some problems in the existing methods,such as complex process,expensive equipment and poor environmental protection,which limit the development and application of magnesium alloy protection technology.In this paper,a coating with excellent protective properties to the substrate was prepared on the surface of magnesium alloy by thermal oxidation method,phase transformation method and solution hydrothermal growth method.The phase composition,corrosion protection,microstructure and other preparation related issues were studied.The corrosion protection of magnesium alloy was studied from the experimental exploration and theoretical analysis,which broadened the research scope.(1)A layer of marine coral like microstructure was prepared on the surface of magnesium alloy by high temperature heating in a muffle furnace.Then,the coating was modified with low surface energy materials,which made the coating have good protection performance and excellent wettability.The contact angle decreases with the increase of heating temperature and holding time.The best heating temperature is385℃,and the best holding time is 60 min.The self corrosion current density of magnesium alloy surface is increased by two orders of magnitude.(2)Firstly,a layer of oxide layer was prepared on magnesium alloy by micro arc oxidation.After that,Mg(OH)2 was grown by hydrothermal treatment with KOH solution.Then,Mg(OH)2 was transformed into Mg O by heating in a horse oven at345℃.Finally,a film with strong corrosion resistance was prepared.The results show that the corrosion current density of the coating prepared under the condition of heating and holding for 100 min is four orders of magnitude lower than that of the substrate,and the corrosion resistance of the coating is almost unchanged after friction test.(3)A film containing silicon and sodium was prepared by one-step hydrothermal growth method.The film has good protection to the substrate.The formation of the coating is related to the heating temperature and holding time.The best heating temperature is 170℃,and the best holding time is 3h.The prepared coating has good corrosion protection performance.The self corrosion current density decreases by two orders of magnitude.After the subsequent friction test,the corrosion resistance is still stable.