Differences between black oxide and phosphating processes
December 24, 2011
Q. Dear Sir,
I want to know the difference between the Blackening and phosphate coatings on a hydraulic vane pump.
Bindu Karipoola - Hyderabad, A.P., India
December 26, 2011
Black oxide (with wax or oil) is usually a final finish. Phosphatizing is usually for surfaces which will be painted.
However, if you are talking about the internal parts of a pump, they are sometimes phosphatized for oil retention. Picture the parts during initial startup or after a prolonged downtime . . . phosphatizing can prevent the galling of metal to metal contact.
Ted Mooney, P.E. Striving to live Aloha finishing.com - Pine Beach, New Jersey
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