Research On Rapid Corrosion Meter Based On Electrochemical Impedance Principle

The essence of most electrochemical corrosion process is based on electrochemical properties. Therefore, electrochemical method is more widely used for preventing corrosion. The commonly used electrochemical methods are linear polarization method, resistance probe, coupon method and AC impedance method, etc. They are all applied in corrosion monitoring according to their respective advantages and disadvantages, different measurement requirements and corrosive environment. Classical linear polarization method commonly used two-electrode or three-electrode system, through dynamic potential scanning method to control current or potential, to measure polarization curves and calculate the corrosion current density and other information. Corrosion testing equipment effectively reduces the economic losses, greatly reducing the incidence of accidents. Because corrosion rate is proportional to corrosion current density, it can be real-time monitored. In technology aspect, the development of computer technology and telecommunication, contributed to the birth of intelligent corrosion monitoring instruments.This thesis introduced a portable corrosion monitoring instrument based on AC impedance. The instrument used the C8051F series SCM as MCU. It carried on the polarization through the MCU's interior DAC generating low frequency sine sweep signal and the high frequency sine sweep signal to the survey system, and carried on sampling the polarization potential and the polarization current synchronously by the internal 16 bits high accuracy ADC to the survey system. Finally, through using digital correlation analyzing, we could obtain the polarization resistance and the solution resistance of the survey system. According to electrochemical corrosion monitoring theory, based on the polarization resistance value, the instrument can calculate the corrosion current and corrosion rate and other corrosion information. This instrument that combines the advantage of linear polarization method and AC impedance method can be more accurate to get the measurements. The experimental results indicated that the instrument's stability and accuracy both achieve the industry standard.