Silane film obtained from a sol constituted with TMSPMA and TEOS and the hexavalent chromate conversion film: The comparative performance as a post-treatment of zinc coating

摘要

For many years, hexavalent chromate conversion coatings were used as the primary method to provide the corrosion resistance of zinc and its alloys. The process of chromate post-treatment is functional and offers a high corrosion protection, however it employs hexavalent chromium compounds in their formulation. These compounds are considered mutagenic and carcinogenic agents, which imply environmental restrictions for its use (1). Due to the Cr (VI) toxicity, non-toxic alternatives have been studied. The development of new processes free of hexavalent chromium has been investigated, and in that context, silanes coatings obtained by sol-gel process have been proposed as an alternative to environmentally acceptable replacement for chromate post-treatment of coatings zinc (2, 3, 4).