Electrochemical study on performance of CF8611/AC531 composite and galvanic corrosion coupled with 7B04 aluminum alloy

Abstract

By means of the electrochemical workstation, scanning electron microscope, energy spectrometer and so on, the polarization curves and galvanic corrosion parameters of the front surface (FS) specimen and side surface (SS) specimen of CF8611/AC531 composite and the 7B04-T74 aluminum alloy in the electrolyte of 3.5% (mass fraction, the same below) NaCl or 3.5%NaCl+12.5% Cu2SO4 were measured, meanwhile the microstructure were observed. Based on the electrochemistry theory, steady corrosion field and parametric scanning technology, a dynamic model for galvanic corrosion under the wear status of composite was established. The results show that the performance of this composite is stable, but there are some carbon fibre exposed defects on the original surface. The defects are often located at the overlap area of carbon fibre bundles. There are 4.3 defects per square millimetre and the average area of each defect is 0.0184mm2; the cathodic reaction rate is closely related to the area of the defects and consequently its surface is divided into the active and the inert cathode region; in the galvanic corrosion the main corrosion form of the aluminum alloy is pitting and no failure is found in the composite. The galvanic corrosion model established here is valid and available. There is a positive linear correlation between the total galvanic current Ig and the defect area S; the galvanic effect of FS and SS on the aluminum alloy is the same when SFS:SSS is about 5.53:1.

Keywords

• composite
• aluminum alloy
• performance
• galvanic corrosion
• electrochemistry