Fabrication of minimal capital‐intensive scratch‐resistant and hydrophobic tungsten oxide film on stainless steel through spray pyrolysis

In this contribution, a pure and robust tungsten oxide (WO3) film was accomplished on stainless steel (SS) substrate at 400 degrees C through a minimal capital intensive, simplistic spray pyrolysis method by utilizing a precursor comprising tungsten hexachloride and 2-methoxyethanol. Thermal analysis revealed the precursor's thermal decomposition and crystallization at similar to 230 degrees C and 255 degrees C, respectively. The fabricated polycrystalline (monoclinic crystal structured) film was uniform and dense in nature, exhibiting surface porosity and average surface roughness of 4.7 % and 15.9 nm, respectively. The average grain size and thickness of film were 360 +/- 70 nm and similar to 3.6 mu m, respectively. W, O elemental presence with a close atomic ratio of 1:3 on the film's surface was acquired along with 91 % lattice oxygen. Regardless of applied normal load in the range of 5 to 15 N, an increment of similar to 22 % in scratch hardness was gained in WO3-coated SS compared to uncoated one. Hydrophilic natured WO3 film (water contact angle, WCA, of similar to 31 degrees) was efficaciously transformed into hydrophobic (WCA, 136 degrees) by chemical modification with octadecyltrichlorosilane to create a self-assembled monolayer on the surface of the film. The hydrophobicity of octadecyltrichlorosilane (OTS)-treated film was found to be preserved even after 100 days.