
plating, anodizing, & finishing Q&As since 1989
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Comparing Phosphating Treatments
2004
Q. Hi, Firstly I want to know about the advantages / benefits of Phosphating (Iron,Zinc)Processes. Secondly which phosphating treatment is better (Iron, Zinc or Mn) and why? Thirdly, what are the applications of phosphating treatments (Iron, Zinc & Mn).
Muhammad AsifPakistan Ordnance Factories - WAH CANTT, Punjab, PAKISTAN
"Practical Guide to Industrial Metal Cleaning"
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A. Hi cousin Asif. Phosphating offers "key" to help paints adhere, forms corrosion resistant conversion compounds on the surface, helps relieve anodic "hot spots", minimizes undercutting after a scratch, and probably fights corrosion a few other ways as well. Iron phosphates are the thinnest and offer the least protection, but in combination with proper paints and powder coatings, they can still be outstanding. Zinc phosphates are heavier. Manganese phosphates are generally used for "break in" on mechanical parts rather than as a base for paint.
There is a book "Phosphating of Metals" [affil link on Amazon, ... on AbeBooks -->] by Rausch & Rauch that you may want to obtain. There was another book devoted to similar issues, Samuel Spring's "Preparation of Metal for Painting" [affil link on Amazon]. Unfortunately, I lost my copy, but it's excellent.
Amazon offers "Practical Guide to Industrial Metal Cleaning" by David S. Peterson.
which I haven't read, but which sounds quite good from the excerpts. The Metal Finishing Guidebook has a good introduction to phosphatizing.

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