Electrochemical corrosion behavior of Al₁₈B₄O ₃₃w/Al composite

The effects of the volume fraction of alumina borate (Al₁₈B ₄O₃₃) whisker and the scan rate of potentiodynamic technique on the localized corrosion behaviors of Al₁₈B ₄O₃₃w/Al composite were investigated. Potentiodynamic polarizations and cyclic polarizations were performed to examine the electrochemical corrosion behavior of the composites. The surface morphologies of the as-cast composite were observed by optics microscopy and the surface morphologies of the composite after corrosion tests were observed by scanning electronic microscopy (SEM). The results of electrochemical measurement indicated that the anodic passive region reduced with the increasing in the volume fraction of Al₁₈B₄O₃₃ whisker in the composites (at the same scan rate), and the anodic passive region reduced with the decreasing in the scan rate of potentiodynamic technique (in the same volume fraction of whisker). The results of cyclic polarization indicated that increase in the volume fraction of Al₁₈B₄O₃₃ whisker in the composites results in a significant decrease of protection potential and an increase of the area of cyclic hysteresis loop.