Relationship Between Corrosion Failure Degree of Organic Coatings and Mechanical Properties for Dissimilar Metal Assamblies
As one of the most common methods for galvanic corrosion control,organic coating has wildly used in an aerospace field.However,the failure of organic coatings often leads to the deterioration of mechanical properties of the dissimilar metal assemblies.In this work,selected organic coatings were applied on plates of 300M steel,2024,and 5A06 Al-alloy respectively,then which were coupled with Ti-al-loy plate by different modes.Afterwards,the dissimilar metal assemblies were subjected to lab accelerat-ed tests in conditions of hot-humid,with mucedine,and of salt-spray in succession.Then,the acquired test results were analyzed and a comprehensive evaluation model for organic coating failures was estab-lished according to the so-called"Analytic Hierarchy Process(AHP)",and which was verified by the mea-sured results of electrochemical impedance spectroscopy(EIS)of the above assmeblies after lab acceler-ated tests.Furthermore,the mechanical properties of the dissimilar metal assemblies were examined by using a universal tensile testing machine after accelerated tests,and so that the relationship between the failure degree of organic coatings and damage degree of mechanical property of the dissimilar metal as-semblies was established.The results indicate that the tensile strength and fracture elongation of the as-semblies decrease to a certain degree after accelerated tests,which depend on the coupling modes.Meanwhile,there is a significant negative correlation between the mechanical properties and the compre-hensive evaluation values for the dissimilar metal assemblies.
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