Single-step approach to tune the wettability of plasma sprayed crystalline and amorphous Fe-based coating

In the present work, we have adopted plasma spraying as a one-step fabrication technique for styling the wetting characteristics of the Fe-based coatings. Two types of Fe-based powders - amorphous and crystalline, were used and plasma spray parameters were successfully tailored to alter the coating property from hydrophilic to hydrophobic. While the complete melting of the coatings has given rise to a smooth surface resulting in a hydrophilic coating, the presence of hierarchical structures consisting of nano-grains on the islands of micropillars imparted hydrophobicity in the other coatings. For the first time, Fe-based coatings have been tailored instantly from hydrophilic to significantly hydrophobic behaviour by a single-step approach. The coating showed a good stability by maintaining its water-repelling property for 15 days when exposed to ambient conditions. Mechanical robustness test by chafing the coating surface on emery paper for 5 min also revealed good robustness in the hydrophobicity as there was no decline in the water contact angle after chafing the coating surface.