Study on the Effect of the Coating Thickness on Corrosion Behavior of AZ91D Magnesium Alloy in m-SBF

摘要

The CaP/chitosan coating on AZ91D magnesium alloy substrate was prepared by electrophoreticdeposition technique (EPD) and formation mechanism of the coating was also put forward. CaP/chitosan coating and micro-arc oxidation (MAO) film effectively protected the AZ91D magnesiumalloy from corroding in m-SBF. The composite coating had a good protection effect on AZ91Dmagnesium alloy when the thickness of CaP/chitosan coating was 0.40~ 0.61 mm and the effect ofcoating thickness on degradation rate of AZ91D magnesium alloy based CaP/chitosan material in m- SBF was elaborated. By analyzing the mathematical description of Faraday impedance, the CDC codeof Nyquist equivalent circuit of two capacitive reactance loops and one inductance loop was Ru (Cd(Rct (CSRS (RLL)))) that was more in tune with the physical meaning of the degradation behavior ofthe AZ91D magnesium alloy based CaP/chitosan material in m-SBF.