Investigation on hydrophobic films from a hydrophobic powder

A hydrophobic powder was prepared based mainly on an organosiloxane and a corrosion inhibitor with the addition of a reaction promoter. Structure and thermal stability of the hydrophobic powder were characterized by FTIR and TG/DSC, respectively. Hydrophobic property and corrosion resistance of the hydrophobic film formed on phosphatized steel by immersion in 3 wt% NaCl aqueous solution were evaluated together with the electrochemical behavior. Results showed that the skeleton of the hydrophobic powder was composed mainly of single bondSisingle bondOsingle bondSisingle bond which comprises longer and more hydrophobic groups of single bondSisingle bondR compared with the conventional BH-102 water-repellent agent. A thin hydrophobic film with a thickness of 15–20 μm was formed on surface of the phosphatized steel after immersion in the solution of 5 g/L of the hydrophobic powder in ethanol for 5 min. The hydrophobic film exhibited excellent stability at a temperature below 135 °C. Water contact angle on the film is about 117–132° and it was until 30 h later when a corrosion spot occurred on the film covered on steel which revealed better water-repellent and corrosion resistant properties compared to that of the BH-102.