Mechanical Durability and Wear Resistance of Superhydrophobic AISI 304 Steel Fabricated by Laser Texturing and Candle Soot Deposition

Laser surface texturing and candle soot deposition were used to fabricate superhydrophobic coatings on AISI-304 steel. For this purpose, circular micro-textures (100 µm pitch and diameter) were generated by fiber-laser marking, raising average surface roughness (Ra) from 2.8 µm to 14.58 µm. After that, a paraffin-wax intermediary and candle-soot deposit built a conformal carbon layer, yielding initial water contact angles of 158.23 ± 1.08° and surface energy of 12.07 ± 0.13 mN/m. After 365 days of ambient aging, the water contact angle remained at 154.87 ± 1.33° and the surface energy rose to 16.41 ± 0.46 mN/m; at 730 days, the water contact angle was 153.87 ± 0.78° with surface energy 25.49 ± 0.74 mN/m. Tape-peeling tests (25 cycles, 100 g roller) reduced water contact angle by < 1.5° on day 1 and < 1.2° after 730 days, demonstrating excellent adhesive durability. Sandpaper abrasion (25 cycles, emery paper) lowered the water contact angle from ~ 158° to 134.32 ± 0.22° on day 1 but to only 139.33 ± 0.20° after 730 days, indicating improved abrasion resistance with aging. Pin-on-disk wear (10 N load, 0.1 m/s, 1000 m sliding) fractured the micro-textures and stripped soot, resulting in 18.5 g weight loss and water contact angle collapse to 34.89°, revealing limitations under severe tribological contact. SEM and EDS confirmed uniform carbon coverage and progressive texture damage.