An In-Situ Phosphating Coating Catalyzed by Phenylphosphonic Acid on AA6061

In order to solve the problems of that exist in traditional multi-stage phosphating process (such as error-prone operation, cost and waste), a novel in-situ phosphating coating (ISPC) system was developed. This was achieved by predispersing an optimum amount of in-situ phosphating reagent (ISPR) into the paint formulation. The corrosion protection performance of the ISPC comprised of alkyd ready-mixed paint catalyzed by phenylphosphonic acid (PPA) as in-situ phosphating reagent (ISPR) was investigated using electrochemical measurement and salt water immersion (SWI) test. The results indicated that adding 2% phenylphosphonic acid in alkyd ready mixed paint system can obviously improve the corrosion protection performance of the paint coating cured at 50°C for 8h.