The search for trivalent chromates complying with End of Life of Vehicle (ELV) and RoHS compliance from the European Union (EU) has emphasized trivalent chromates that are clear/blue and black. This has left the choice of yellow behind because of the challenges in achieving an acceptable color to the hexavalent yellow chromate and the performance of the trivalent clear/blue chromates salt spray corrosion resistance equals or exceeds hexavalent yellow chromate. Another challenge with the existing technology is that multiple dips are necessary to achieve the corrosion protection required for the yellow trivalent chromate processes. This paper will discuss two new processes available for the zinc electroplater; but before we go into the details of these two exciting new processes, let's review the facts regarding hexavalent yellow chromate.
展开▼
