A holistic analysis of surface, chemical bonding states and mechanical properties of sol-gel synthesized CoZn-oxide coatings complemented by finite element modeling

This article presents a comprehensive study on surface chemical bonding states, morphological features, mechanical properties, finite element modeling, and water contact angle measurements of wet chemical based dip coated CoZn-oxide thin film coatings. Atomic force microscopy (AFM), X-ray photoelectron spectroscopy (XPS), Nanoindentation, finite element method (FEM) modeling, and drop shape analysis techniques were used to carry out the detailed measurements. AFM studies showed that the surface roughness values of all the coatings sturdily increased with the increase in sol concentrations. The gradual increase in sol concentrations and annealing temperature also had a remarkable influence over the Co-, and Zn-contents of these coatings given by XPS analysis. The deconvolution of Co 2p(3/2) photoelectron lines revealed the formation of Co(OH)(2), CoO, Co2O3, and Co3O4 phases from the coatings surface while low intensity satellite peaks developed due to a partial spinel lattice structure of Co-ions. The occurrence of Co3O4, CoO, and ZnO phases were also confirmed from the deconvolution of O 1s photoelectron lines. The elastic modulus, E, of CoZn-oxide thin film coating, varied within the range of 43.7-69.2 GPa was comparable with that in CoCuO thin film coatings. The maximum stress level induced was estimated to be in the range of 4.0-6.5 GPa. However, as the thickness of the coatings is increased, the maximum stress level slightly decreased. The coatings were moderately hydrophobic.