The authoritative public forum
  for Metal Finishing since 1989
  

  -----

Anti-corrosion AL 7175-T736 coating question

We are having problems with corrosion of our 7175-T736 anodized aluminum parts. The surface becomes exposed to seawater and Otto fuel, then corrodes rather quickly. The microcracks on the surface provide for a conductive environment. Can someone recommend a good protective coating? It may be either directly applied to the base aluminum or after anodizing.

Thanks,

Paul Taatjes
- Kingston, Washington, USA
2001

We recently solved a similar problem for one of our clients who used to be unhappy with the deterioration of horribly cast aluminium parts viv a vis extrusions which could be Alodine coated quite easily.

We copper plate and directly cobalt - zinc plate. The hard layer of cobalt zinc lasts better than ordinary zinc plate and the copper will fill up and level micropores in your Al. After Cobalt Zinc plating go for a passivation of your choice. I recommend yellow.

Regards,

Khozem Vahaanwala
Saify Ind

Bengaluru, Karnataka, India

2001