Pradeep metallurgical products manufactures unichrome-p, a green phosphate-chromate process, which is a wonderful pre-treatment for aluminum and its alloys, by dipping processes. This unichrome-p treatment leaves on the aluminium metal substrate very uniform, lustrous green phosphate-chromate coating. The colour intensity and the coating thickness will depend upon the bath concentration, immersion period, composition of the metals, etc. The phosphate-chromate conversion coating provides effective corrosion resistance [more than 250 hours on a 5% sodium chloride salt-spray test] and added bonding with the paints, powder coatings and organic coatings deposited on the metal. The treated components are then instantly oven dried/forced air-dried and painted preferably within 24 hours. In the case of aluminium alloys, a 5 minutes dip in a 5 percent solution of activator solution for the removal of the oxide scales and the rust spots is recommended. Unichrome-p from pradeep metallurgical products is used at a concentration of 5% v/v, for a dipping period of 8-10 min at room temperature. Periodic checking of ta/fa and water rinsing and drying after chromatizing are recommended.
