Sealing rinse for phosphate coatings of metal

• US 3,895,970 A
• Filed: 06/11/1973
• Issued: 07/22/1975
• Est. Priority Date: 06/11/1973
• Status: Expired due to Term

• Current Assignee: Elf Atochem North America, Inc. (Totalenergies Se)
• Original Assignee: Kurt Goltz, William A. Blum
• Inventors: Goltz, Kurt, Blum, William A.
• Primary Examiner(s): Kendall, Ralph S.
• Assistant Examiner(s): Wolfe, Jr., Charles R.
• Application Number:
  US05/365,019
• Time in Patent Office: 771 Days
• Field of Search: 148/6.15R,6.15Z,6.16
• US Class Current: 148/256
• CPC Class Codes: C23C 22/83 Chemical after-treatment

Abstract

This invention provides a new sealing rinse and process for sealing phosphate coated metals against porosity and to promote the adhesion of subsequent paint coatings. The new sealing rinse is an acidic aqueous solution containing simple or complex fluoride ions. In the application of the sealing rinse, steel, galvanized steel, aluminum or zinc are given a phosphate coating and then wetted with an acid aqueous solution containing fluoride ion.

Claims

1. The process of sealing a phosphate coating on a metal comprising wetting the phosphate coated metal with the composition consisting essentially of an acidic aqueous fluoride solution free of chromates and having a pH within the range of about 3 to about 7 and containing fluoride ion at a concentration ranging from about 0.01 to about 25 grams/liter which is supplied by at least one of the members selected from the group consisting of calcium fluoride, zinc fluoride, aluminum fluoride, titanium fluoride, zirconium fluoride, chromic fluoride, chromic zirconium fluoride, nickel fluoride, ammonium fluoride, hydrofluoric acid and fluoboric acid and then drying the said fluoride solution on the said wetted metal.

2. The process of claim 1 in which the fluoride ion is obtained from chromic fluoride.

3. THE PROCESS OF SEALING A PHOSPHATE COATING ON A METAL COMPRISING WETTING THE PHOSPHATE COATED METAL WITH THE COMPOSITION CONSISTING ESSENTIALLY OF AN ACIDIC AQUEOUS FLOURIDE SOLUTION FREE OF CHROMATES AND HAVING A PH WITHIN THE RANGE OF ABOUT 3 TO ABOUT 7 AND CONTAINING FLOURIDE ION AT A CONCENTRATION RANGING FROM ABOUT 0.01 TO ABOUT 25 GRAMS/LITER WHICH IS SUPPLIED BY AT LEAST ONE OF THE MEMBERS SELECTED FROM THE GROUP CONSISTING OF CALCIUM FLORIDE, ZINC FLOURIDE, ALUMINUM FLOURIDE, TIANIUM FLOURIDE, ZIRCOMIUM FLOURIDE, CHROMIC FLOURIDE, CHROMIC ZIRCONIUM FLUORIDE,NICKEL FLUORIDE, CHROMIC FLUOFLUORIDE, HYDROFLUORIC ACID AND FLUORIC ACID, DRYING THE SAID FLUORIDE SOLUTION OF THE SAID WETTED METAL AND THEREAFTER RISING THE METAL WITH WATER AND REDRYING THE METAL.

4. The process of claim 3 in which the fluoride ion is obtained from chromic fluoride.

5. The process of sealing a phosphate coating on a metal comprising wetting the phosphate coated metal with the composition consisting essentially of an acidic aqueous fluoride solution free of chromates and having a pH within the range of about 3 to about 7 and containing fluoride ion at a concentration ranging from about 0.01 to about 25 grams/liter which is supplied by at least one of the members selected from the group consisting of calcium fluoride, zinc fluoride, aluminum fluoride, titanium fluoride, zirconium fluoride, chromic fluoride, chromic zirconium fluoride, nickel fluoride, ammonium fluoride, hydrofluroic acid and fluoboric acid and thereafter rinsing the wetted metal with water.