The Study On Corrosion Behavior Of Foamed SiC/Cu Co-continuous Composite

Due to the special characteristics, ceramic/metal bi-continuous (co-continuous) phase composites have attracted great attention. This work studied the corrosion behavior of foamed SiC/Cu bi-continuous phase composite which was prepared by squeeze casting method. The foamed SiC/Cu co-continuous composites and pure Cu in the atmospheric environment of ocean and marine environment were investigated comparatively by corrosion weight loss, electrochemical, dynamic analysis, surface analysis and corrosion products analysis, as summarized in the following.The existence of SiC foam reinforcement in the composite has great influence on the corrosion, which makes the corrosion sensitivity bigger than pure copper.The special bi-continuous structure makes the Cu in the two phase interface and foam holes easily corrode. The possible reasons of this phenomenon are as follows. Firstly, the interface between two phase which may has microscopic defects made the protective layer destroyed early, so the serious local corrosion phenomena happen. Secondly, the existence of residual stress in the composite causes serious corrosion of Cu in these places. Thirdly, Cl- plays an important role in the destruction of protective layer.SiC was not corroded. XRD shows that the components of the corrosion products of the foamed SiC/Cu co-continuous composite are the same as that of pure copper material corrosion products. The upper layer is Cu₂Cl(OH)₃ and the lower is Cu₂O protective layer.With etching time increasing, the corrosion weightlessness has a linear ascendant trend, and the corrosion depth deepens linearly. The corrosion rate of foamed SiC/Cu co-continuous composites is almost a constant in the whole process of corrosion.Potentiodynamic polarization curves show that SiC foam reinforcement changes anodic polarization behavior of matrix Cu. The corrosion potential of the foamed SiC/Cu bi-continuous composite is much same as the pure copper's, but the corrosion current density of the composite is bigger than that of the pure copper, in aqueous 3.5mass% NaCl solution.