Phosphate coating composition and method of applying a zinc-nickel phosphate coating

A method of coating substrates selected from the group consisting of steel, zinc-coated steel, and aluminum comprising the steps of:

• cleaning the substrates with an alkali cleaner;
• conditioning the surface of the substrates with an aqueous solution of Jernsted salts;
• preparing a coating composition by diluting in an aqueous bath first and second concentrates;
• said first concentrate consisting essentially of in weight percent:
• ______________________________________ Water 0-80% Phosphoric Acid (75%) 10-60% Nitric Acid (67%) 2-35% Zinc Oxide 2-15% Nickel Oxide 1.5-25% Sodium Hydroxide (50%) 0-10% Ammonium Bifluoride 0-10% Sodium Salt of 2 Ethyl 0-1% Hexyl Sulfate Nitro Benzene Sulfonic 0-trace % Acid ______________________________________
• said second concentrate consisting essentially of in weight percent:
• ______________________________________ Water 30-80% Phosphoric Acid (75%) 10-35% Nitric Acid 0-15% Sodium Hydroxide (50%) 0-30% Potassium Hydroxide (45%) 0-45% ______________________________________
• said aqueous bath having a zinc ion concentration of between about 300 and 750 ppm, an alkali metal ion concentration from an alkali metal phosphate of between about 1,200 and 10,000 ppm, and a nickel ion concentration of between about 300 and 1,500 ppm;
• applying said coating composition to the surface of the substrates at a temperature of between about 100.degree. and 140.degree. F. for between 30 and 300 seconds;
• rinsing said substrates;
• applying a chromate rinse to the substrates;
• and
• rinsing said substrates with water.

A method of coating a substrate selected from the group consisting of steel, zinc-coated steel, and aluminum comprising the steps of:

• cleaning the substrates with an alkali cleaner;
• conditioning the surface of the substrates with an aqueous solution of Jernsted salts;
• preparing a coating composition by diluting in an aqueous bath first and second concentrates;
• said first concentrate consisting essentially of in weight percent:
• ______________________________________ Water 10-50% Phosphoric Acid (75%) 20-45% Nitric Acid (67%) 5-25% Zinc Oxide 4-9% Nickel Oxide 3-18% Sodium Hydroxide (50%) 0-6% Ammonium Bifluoride 0.2-5% Sodium Salt of 2 Ethyl 0.2-0.5% Hexyl Sulfate Nitro Benzene Sulfonic 0-trace % Acid ______________________________________
• said second concentrate consisting essentially of in weight percent:
• ______________________________________ Water 30-60% Phosphoric Acid (75%) 20-35% Nitric Acid 0-10% Sodium Hydroxide (50%) 0-30% Potassium Hydroxide (45%) 0-45% ______________________________________
• said aqueous bath having a zinc ion concentration of between about 500 and 700 ppm, an alkali metal hydroxide ion concentration of between about 2000 and 7000 ppm, and a nickel ion concentration of between about 500 and 1,050 ppm;
• applying said coating composition to the surface of the substrates at a temperature of between about 100.degree. and 140.degree. F. for between 30 and 300 seconds;
• rinsing said substrates;
• applying a sealing rinse to the substrates;
• and
• rinsing said substrates with water.

A method of coating a substrate selected from the group consisting of steel, zinc-coated steel, and aluminum comprising the steps of:

• cleaning the substrates with an alkali cleaner;
• conditioning the surface of the substrates with an aqueous solution of Jernsted salts;
• preparing a coating composition by diluting in an aqueous bath first and second concentrates;
• said first concentrate consisting essentially of in weight percent:
• ______________________________________ Water 20% Phosphoric Acid (75%) 38% Nitric Acid (67%) 21% Zinc Oxide 5% Nickel Oxide 8% Sodium Hydroxide (50%) 4% Ammonium Bifluoride 2% Sodium Salt of 2 Ethyl 0.3% Hexyl Sulfate Nitro Benzene Sulfonic trace % Acid ______________________________________
• said second concentrate consisting essentially of in weight percent:
• ______________________________________ Water 34% Phosphoric Acid (75%) 28% Nitric Acid 5% Sodium Hydroxide (50%) 13% Potassium Hydroxide (45%) 20% ______________________________________
• said aqueous bath having a zinc ion concentration of between about 500 and 700 ppm, an alkali metal hydroxide ion concentration of between about 2000 and 7000 ppm, and a nickel ion concentration of between about 3000 and 1,050 ppm;
• applying said coating composition to the surface of the substrates at a temperature of between about 100.degree. and 140.degree. F. for between 30 and 300 seconds;
• rinsing said substrates;
• applying a chromate rinse to the substrates;
• and
• rinsing said substrates with water.