Nano alumina–zirconia blended epoxy polymeric composites for anticorrosive applications

Abstract

Amorphous alumina–zirconia (Al2O3–ZrO2) nanoparticles were produced by hot-air spray pyrolysis method. Two and six layers of anticorrosive coating of epoxy polyamide (EP) resin and mixture of amorphous Al2O3–ZrO2 nanoparticles in epoxy polyamide resin (NEP), respectively, were applied on SS 316L specimens. The performance of EP and NEP coated samples was comprehensively characterized. The results show that the sample with six layers of NEP coating (SSNEP6) has enhanced thermal, elastic properties and chemical resistance than that with six layers of EP coating (SSEP6). Thermo gravimetric analysis reveals that EP sample decomposed at 523 °C whereas NEP sample has extended thermal stability up to 750 °C with minimum residual mass. The thermal conductivity of EP sample is 0.124 while for NEP is about 0.263 W/mK. The hardness and reduced elastic modulus of SSNEP6 sample were, respectively, 318.32 MPa and 5.98 GPa whereas those of SSEP6 sample were 233.69 MPa and 4.17 GPa. Further, in-situ scanning probe microscopy (SPM)-nanoindentation and atomic force microscopy (AFM) images were obtained to explore the formation of Al2O3–ZrO2 nano filler in EP matrix. The samples coated with multilayers of EP and NEP was exposed to acid immersion (10 % of H2SO4) for 48 h. The SPM and AFM microstructure images show that the NEP coated sample maintains its original surface feature with existing passive layer formation, whereas EP coated sample shows surface deterioration and deformation. In addition, stability of EP and NEP coated samples was measured in terms of surface roughness with respect to nano filler in epoxy matrix. This observation shows that Al2O3–ZrO2 nanofiller can be used to improve the desirable properties in host epoxy matrix.