Design And Application Research Of On-line Corrosion Monitoring Sensor Based On Impedance Analysis

In recent years,the corrosion problem of aircraft structures in coastal and maritime areas caused by the high temperature,high salt and high humidity environment has become increasingly serious.The inspection and maintenance of aircraft structure corrosion is very important for the process of the whole lifetime maintenance of aircrafts.In order to effectively control the corrosion of aircraft structures,the research of sensors for on-line corrosion monitoring has attracted much attention of researchers at home and abroad.Based on the design concepts of miniaturization,integration,diversification and embedding for airborne equipment,three design schemes of sensors for on-line direct monitoring of corrosion are proposed.The relationship between mechanical impedance,electrical impedance,electrochemical impedance of structures with coatings and the corrosion degree of the structures was analyzed respectively by using different testing methods.Based on the electromechanical impedance method,a flexible active piezoelectric sensor was used to monitor the coating corrosion according to its response to the change of stiffness of structure with coatings.On the basis of response of flexible coil eddy current sensor to the change of electrical impedance of metal structure under coatings,a scheme of on-line corrosion monitoring by measuring the electrical impedance information of eddy current was applied.Referring to the method of measuring electrochemical impedance spectroscopy(EIS),a corrosion monitoring scheme for organic coatings was proposed,which can be used to evaluate the protectiveness and damage of coatings in gas-phase environment without reference electrodes and electrolytes.In this paper,the feasibility of the schemes and the performance of the sensors were evaluated by methods of on-line monitoring of salt spray corrosion tests and finite element simulation,which provides supports of theoretical simulation and experimental data for the future research of on-line corrosion monitoring sensor for airborne equipment.This research intends to solve the problem that the corrosion damage of the structure under the protective coating of airborne equipment may not be found timely,and to reduce economic losses and safety accidents caused by corrosion.