| Aluminum and aluminum alloy is the light metal which has been widely applied on industry.Due to its large reserves,wide source,high melting point,good ductility,in machinery industry sectors such as auto artifacts,the aircraft fuselage has large demand.Aluminum alloy has a high plasticity,which can be processed into a variety of sheet,profiles,casting application in industrial production.When contact with oxygen it form a oxide layer on aluminum alloy to prevent corrosion,but in the industrial acids,salts and atmospheric environmentl erosion is stronger,and their oxidation film cannot satisfy the needs of corrosion resistant,corrosion will cause severe economic loss in production and safe trouble,so aluminum and aluminum alloy corrosion research get the attention of people.According to the requirements of industrial production,need high efficiency,green environmental,simplify technology.Compare zirconate,RE salt,molybdate salt,organic passivation system,selecting K2ZrF6 passivation system.K2ZrF6 system composed of strong oxide has strong oxidation,membrane layer has good corrosion resistance,but the passivation solution is not stable.K2ZrF6 as the main film-forming material,research using additive instead of strong oxide,make the membrane layer corrosion resistant performance improve and preparation a stable and reusable passivation solution.Salt fog corrosion test and electrochemical polarization test of single factor experiment determine the K2ZrF6 content is 2.0g/L.Then optimize its passivation process.Passivation time 7min,temperature 25℃,pH 3.2.On the basis of K2ZrF6 system,addition Mn（NO3）2 and LaCl3 on membrane layer to improve the performance of corrosion resistance was studied.When Mn（NO3）2 concentration is2.4g/L,its oxidation can increase the corrosion resistance of aluminum alloy to 87 hours.La Cl3 in 0.3g/L can promote the film-forming process,the passivation film is more compact,corrosion resistance increased by 20%,up to 103 hours.Resin as the organic composition has good sealing effect and hydrophobic,has protective effect on aluminum alloy,so this paper also studied the K2 Zr F6-resin as main film forming material system of inorganic-organic composite.On the basis of optimum passivation technology,composite passivating fluid formulation system determined by single factor experiment,the amount of resin obtained by the orthogonal experiment is10g/L,adding NaVO3 1.0g/L,silane 3ml/L,curing condition is: 80 ℃,60 min.The passivation system and process can make the salt fog corrosion time of aluminum alloy up to 138 hours.The hydrophobic property of composite membrane layer greatly improved,the adhesion of film grade is level one.Microstructure and the composition of membrane layer was studied through SEM and EDS. |
