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Process for producing phosphate coatings

  • US 4,539,051 A
  • Filed: 01/10/1985
  • Issued: 09/03/1985
  • Est. Priority Date: 03/02/1983
  • Status: Expired due to Fees
First Claim
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1. An improved process for phosphating metal surfaces which comprises the steps of providing an activating composition comprising a mixture of about 60% to about 90% by weight of a particulated dried reaction product of a titanium-containing compound and a sodium phosphate compound containing at least about 0.005% by weight titanium and the balance comprising tetrasodium pyrophosphate, dispersing said activating composition in water at a concentration of about 0.1 to about 10 g/l to provide an activating solution, contacting a clean metal surface with said activating solution at a pH of about 7 to about 10 for a period of time of at least about 15 seconds to provide an activated metal surface, contacting the activated metal surface with an aqueous high-zinc phosphating solution for a period of time to produce a desired thickness of a zinc phosphate coating thereon, rinsing the zinc phosphate coating with a dilute aqueous solution containing chromium ions, and thereafter applying an electrophoretic organic coating to the rinsed zinc phosphate coating.

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