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I want to get known myself regarding a problem of Galvanizing, I'm facing problem in sst (salt spray test) that the part is not going to qualify, although the thickness of plating is as per standards, their peel strength test is also qualified but the sst of 48 hrs is not qualifying.
I need help regarding this problem. If any one can help me I will be highly obliged.
I did work for a galvanizer that required a 40 hour salt spray test. To pass this test we used sodium dichromate and acetic acid (and HCl to adjust pH) as a post galvanizing treatment. The concentrations are important but the pH was the most important feature.
I also did work for highway guardrail companies in the USA and again the pH was the key feature that made the hexavalent chromate passivate the zinc. With the proper pH these chromate tanks have a useful lifetime of 5 years or more and 40 hour salt spray tests are very easy to pass.
Galvanizing Consultant - Hot Springs, South Dakota, USA