In metal surface treatment, electrogalvanized steel occupies a large share of all plating types. The traditional galvanizing treatment is mainly hexavalent chromium passivation, but it is a strong carcinogen, which will cause serious pollution to the environment and endanger the health of workers. Therefore, since 2005, China's export of electronic, communications and automotive products began to apply the trivalent chromium passivation process on a large scale. However, at present, more mature processes use Co2+ as a sealing agent to improve the corrosion resistance of the passivation film, and promote the film formation with F-organic acid, resulting in the following three problems: (1) Heavy metal ions Co2+ is also toxic and will be limited in future applications; (2) F—corrosive, need to be heated by a heater coated with PTFE, resulting in increased energy consumption and rising cost; (3) It is difficult to ensure NSS ≥ 96h in large-scale production and it needs to be closed. In addition, post-passivation film discoloration and Cr(VI) exceeding the standard cause enterprise compensation or rework, which is the most serious problem of trivalent chromium passivation process. In summary of the above, an improved novel trivalent chromium color passivation solution formulation has been experimentally put into production, and the formulation is as follows: GCC-6A 120mL/L GCC-6B 40g/L pH 1.3～1.7 θ 10～40°C t 15～55s Among them, GCC-6A is a Cr3+ complex, containing m(Cr3+)≥10g as a film-forming substance per 120mL; GCC-6B is an organic acid containing Cl-, SO42- and F-, which promotes film formation. And ensure that the film is dense. The passivation solution has the following outstanding features: (1) The additive does not contain Co2+, F-, and has higher environmental protection; (2) The passivation film is bright and bright, light red, purple green; (3) The process is stable, the adjustment is convenient, and the cost is low; (4) Passivation film has good corrosion resistance, using zincate galvanizing solution, rolling and hanging plating can guarantee NSS96h under large production conditions. No white rust, such as closed processing NSS200h no white rust, to meet the needs of automotive parts production; (5) The passivation film was tested negative for Cr(VI) according to the standard condition IEC62321:2008 UV-VIS method. After the same batch of parts (unclosed) was placed for six months, Cr(VI) was also negative according to IEC62321 boiling water extraction method. This product shows that the process has good anti-tarnishing and Cr(VI) performance, which is suitable for manual and automatic line production. Concerned about surprises Label: Passivation Process Trivalent Chromium Anti-Discoloration Film Formation Electroplating Zinc Previous: IKO bearing selection, use, disassembly, lubrication All Next: Why should metal pipe surface be degreased? Xi'an Jmlai Bio-Tech Co., Ltd. , https://www.jmlaisarms.com