Current status, opportunities and challenges in chemical conversion coatings for zinc

The susceptibility of Zn-based materials to corrosion in an aggressive environment limits their broad applications. Innovative conversion treatment is the most interesting approach for enhanced corrosion performance of zinc. This review covers recent research that has led to advances in conversion coating technology for zinc; including the application of contemporary methods for chemical conversion coating, the establishment of a corrosion protection framework for zinc, the illumination of processing control effects, and the attempts at the inhibition mechanisms of zinc by coatings. This review drawing from many sources provides an impartial focus on new achievements. The environmentally acceptable conversion coating is reviewed in detail. This review also covers engineering application aspects, including cost-effectiveness technology and process productivity. Finally, future prospects and present challenges in the field of conversion treatment are reviewed, identifying the demerit of each technique, meanwhile attempting to also identify future developments and directions.