Effect of sandblasting, annealing and hydrophobic treatment on the nano-mechanical and corrosion behaviour of n-TiO₂-coated 316L stainless steel

In this article, the effect of hydrophobic coated and uncoated surfaces on the corrosion resistance, tribological property, and surface morphology and nanomechanical properties is presented. A hierarchical surface (micro/nano) was prepared by ultra shot penning of 316L stainless steel at 20 kHz. Chemical vapour deposition technique was used for deposition of the coating, and coating thickness of 0.5 μm was obtained. A maximum hardness of 6.7 and 6.32 GPa was exhibited by the sandblasted (SB), annealed (SBA) and coated (SBAT) samples respectively. The beneficial effect of annealing and surface roughness was clearly indicated by the sandblasted, annealed and coated specimens. They showed the highest value of reduced modulus maximum resistance to scratch tests and a high adhesion as indicated by scratch path profiles. The lowest corrosion rates were obtained by SBAT specimens (1.32 mpy) in 3.5 wt% NaCl. After application of 3.5% fluoroalkylsilane (FAS13), the corrosion rate was reduced to 0.04 mpy with no evidence of localized pitting. The water contact angle using DSA-100 system was measured to be 120° for SBAT and 80-90° for the samples.