Novel passivating anticorrosive Primer for Mg and Al alloys

摘要

A new innovative corrosion protection primer ("G-Primer") is introduced which makes use of the interaction of Mg-implants with human blood causing dense coatings of carbonated calcium phosphates. This coating leads to higher polarization resistance values on AZ31 compared to commercially available conversion coatings. During anodic polarization, the presence of a pronounced passive region becomes obvious which leads to an effective reduction of the dissolution current densities (up to a factor of 1000 compared to some commercial systems). Especially in the case of galvanic coupling (e.g. with Al-alloys) this would lead to significantly decreased Mg-dissolution rates. AZ31 + "G-Primer" + electrocoating + powder coating exhibited excellent results concerning filiform corrosion features at scratches and stone chip defects after the INKA-Test exposure. The appearance of the corrosive attack was comparable with those of the high-performance plasma electrolytic oxidation coatings.