Synthesis of Nb₂O₅, Al₂O₃ and Nb₂O₅/Al₂O-3 via Pechini Method as alternative pretreatment for carbon steel AISI 1005 coating systems

The use of industrial painting is one of the methods for corrosion protection of metals and requires a suitable surface treatment on the metallic substrate for better adhesion between metal and paint film. In cases where the substrate presents low thickness (less than 2 mm), the phosphating pretreatment is widely used, despite of such process generates harmful residues to environment and human health. In this context, the sol-gel method has been highlighted as an easy and a cheap process, and less harmful to the environment. This work shows the development of carbon steel AISI 1005 pre-treatment by sol-gel method using niobium and/or aluminium-containing-resins, synthetized by Pechini method. Electrochemical and performance analysis were carried out in samples coated by the resins, which showed analogous behavior to phosphated systems. The proposed pre-treatment has potential for phosphating process replacement, because the morphology of the deposited layers enhanced the metallic contact surface with the organic coating, increasing its mechanical and polar adhesion. Such observation can justify its better anti corrosive performance, comparing to the untreated substrate. (author)