Characteristics of Rich Phytic Passivator without Cr for Brass Strip
The surface of brass strip is easily oxidized to cause discoloration when exposed in the air. If it contacts with the electrolyte, there will be an electrochemical reaction in the surface that lead to increasing dezincification corrosion. To improve the anti-tarnish ability, the best method is to form a protective membrane in the strip surface. Phytic acid is easily formed a stable chelate complex compound with metal ions, so that forming a dense layer to protect brass strip. It is necessary to develop a new type surface passivator which rich in phytic acid and aquae hydrogenii dioxide but without Cr which pollutes the environment. The study results show that: This passivator enable the anti-tarnish capacity significantly, and do much better results and without so much pollution than now often used dichromate passivator. The passivator solution is stable and can use longer.
Zhong Cao, Xueqiang Cao, Lixian Sun, Yinghe He
W. Cai et al., "Characteristics of Rich Phytic Passivator without Cr for Brass Strip", Advanced Materials Research, Vols. 239-242, pp. 2257-2260, 2011