Highly transparent nanocrystalline AlSiN coatings with enhanced hydrophobicity and mechanical durability deposited on sapphire substrates via RF magnetron sputtering

In this study, AlSiN coatings were deposited by RF magnetron sputtering in a reactive environment of Ar and N₂. Two distinct target materials, Si and Al, were used to deposit AlSiN coatings on Sapphire and SS-304 substrates. The deposition process was controlled by maintaining a constant Ar:N₂ gas ratio of 20:6 and a constant power application on the target materials. The effect of deposition time at a fixed temperature on microstructure, mechanical properties, hydrophobicity, and optical characteristics of the coatings were investigated using various characterization techniques. The average optical transmission of the coated sample exceeded 92 % for all coatings within the visible spectrum. The peak hardness of the coatings was recoded at 33 GPa when the deposition time was 3 h. The contact angle of the coated surface varied depending on deposition duration, ranging from 55° to 101°. Electrochemical studies revealed that after 8 h of immersion in an alkaline medium, the coating maintained a low corrosion rate of 0.089 mm/year with a surface energy of 14.21 mN/m. This comprehensive investigation highlights the potential of AlSiN coatings for applications that require high optical transparency, mechanical robustness, and corrosion resistance.