Talk:Chromate conversion coating

Latest comment: 2 years ago by 68.197.84.230 in topic Comṕosition of the coating?

Comṕosition of the coating?

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This article mentions hexavalent chromium, but that species is present in the bath used to apply the coating. The article should give the composition of the coating itself. Does it too contain hexavalent chromium, or just trivatent chromium? --Jorge Stolfi (talk) 23:01, 16 June 2020 (UTC)Reply

The coating itself will initially be primarily either hexavlent or trivalent based on the bath chemistry. However, as it degrades and protects the underlying metal, it will randomly oxidize as hexavent or trivalent. The formation of chrome 3 is preferred in the lab condition, thermodynamically speaking, but in the real world with other factors its impossible to know which will be more prevelent.
This is also why the epa limits the total chromium in water and does not specify whether its chrome 3 or chrome 6-- Have ing intense UV light can also sporadically cause chrome 3 to change to chrome 6. 68.197.84.230 (talk) 15:56, 29 August 2022 (UTC)Reply