Need to Degrease and Pickle in one bath.

Hello,

We plate Mild Steel with zinc and nickel chrome plating and of late are examining the possibility of doing away with alkaline soak cleaning + anodic cleaning and subsequent rinsing before pickling. The idea is to combine the degreasing and pickling in one operation, thereby minimising rinse water and also obnoxious HCl fumes .

We are trying some home brews by mixing HCl with a neutral Ph anionic surfactant which is doing up to 85 % of the job but does not as good a job as the conventional alkali + acid dip.

Any ideas as to what else may work ? If we were to use anodic current in our mixture, what material could we possibly use as a cathode for it to survive the HCl Cathodic current ?

An alternative home brew which works will also be most welcome.

Many thanks in advance,

Don't you just hate it when someone says something can't be done. And then you ask them why, and they just say because it hasn't been done before? It's not going to work.

Ted Mooney, P.E.
Striving to live Aloha
finishing.com - Pine Beach, New Jersey

It's a good thinking indeed. You cannot process through electrolytic way. If you have high oil load on components then better to go via a manual solvent wipe on before going to pickling cum degreasing process. further, you can also try with an non ionic emulsifier like nonyl phenol ethoxylate with 9.5 to 20 moles of ehoxylation. Hope for the best.

Dear Mr Mooney and Mr Sen,

I am continuing my trials and you are unfortunately right in your predictions that the anodic is not working, but however I am having a fair amount of success with degreasing and pickling with immersion alone. My main idea is to have a comfortable working relationshp with HCl inside my plant sans the fumes .

Dr Sen, the non ionic emulsifier recommended by you is not locally available. Does it have an expanded name or can you recommend a supply source? Does it have to be added to the HCl and how much ?

Thanks again,

Regards,