Hydrophobic Al2O3/SiO2/PDMS Composite Coatings for Anti-corrosion Application of 304 Stainless-Steel

Polymer coatings for steel anticorrosion are usually susceptible to damage by invading water, oxygen and chloride ions, therefore, it is still a great challenge to reduce these corrosive species to penetrate into coatings/substrate interface. Herein, new binary nanoparticles (SiO2 and Al2O3) filled polydimethylsiloxanes (PDMS) composite coatings are developed for anticorrosion application of 304 stainless-steel (304s) by combining with advantages of PDMS, silica and nano-Al2O3. Surface wettability, chemical compositions, microstructure, corroded morphologies, mechanical properties and thermal stability of the new PDMS composite coatings on the treated 304s sheets are studied, respectively. Subsequently, corrosion resistances of the 304s sheets treated with the composite coatings are also evaluated in corrosive medium (3.5 wt% NaCl solution) through potentiodynamic polarization tests and electrochemical impedance spectroscopy techniques, respectively. Interestingly, the Al2O3/SiO2/PDMS composite coatings show superior mechanical properties, desirable stability and excellent corrosion resistance compared to the PDMS coating without adding Al2O3 nanoparticles. Moreover, the PDMS composite coating with Al2O3 content of 7.37% displays the best anticorrosion performance due to excellent barrier effect between the 304s sheets and corrosive species. This work not only presents a simple and cost-efficient approach to exploiting hydrophobic PDMS coatings by use of binary nanoparticles and PDMS matrix, but also paves the way to anticorrosive application for 304s.