Process and composition for coating titanium surfaces

Claim 1

IN A PROCESS FOR COATING THE SURFACES OF ARTICLES OF TITANIUM BASE ALLOYS CONTAINING ABOUT 5% CHROMIUM AND ABOUT 3% ALUMINUM, THE STEPS OF CLEANING THE ARTICLES TO BE COATED, IMMERSING THE ARTICLES IN AN ACID ETCH BATH, REMOVING SAID ARTICLES AND RINSING THE SAME, IMMERSING THE ARTICLES IN AN AQUEOUS SOLUTION OF FROM ABOUT 0.01% TO ABOUT 15% BY WEIGHT OF HYDROFLUORIC ACID, FROM ABOUT 0.1% BY WEIGHT TO THE SATURATION POINT OF A COMPOUND SELECTED FROM THE GROUP CONSISTING OF CHROMIC ACID AND WATER SOLUBLE SALTS OF A CHROMIUM ACID, AND FROM ABOUT 0.01% BY WEIGHT TO THE SATURATION POINT OF A SOLUBLE SALT OF A HEAVY METAL SELECTED FROM THE GROUP CONSISTING OF COPPER, ZINC, SILVER, CADMIUM AND NICKEL FOR A PERIOD OF ABOUT 60 SECONDS AT A TEMPERATURE CORRESPONDING APPROXIMATELY TO THE BOILING POINT OF SAID SOLUTION, TO DEPOSIT SAID HEAVY METAL UPON THE SURFACES OF SAID ARTICLES, REMOVING SAID ARTICLES AND RINSING THE SAME, AND ELECTROPLATING SAID ARTICLES IN A PLATING SOLUTION.