Effects of black silicon surface structures on wetting behaviors, single water droplet icing and frosting under natural convection conditions

- A new type of two-stage black silicon surface is proposed and fabricated.
- Black silicon and two-stage black silicon surfaces show good hydrophobic property.
- The two kinds of surfaces behave anti-icing and anti-frosting characteristics.
- Two-stage black silicon surfaces have better low-temperature resistance property.

In this research, the effects of black silicon and two-stage black silicon surface structures on the characteristics of wetting, icing process of a single water droplet, and frost accumulation under natural convection conditions were investigated. Black silicon and two-stage black silicon surfaces were first designed and fabricated, and then examined by means of scanning electron microscopy (SEM). Wetting behavior was measured by contact angle measurement system. The icing and frosting processes were acquired through high-speed photography. The test surfaces were cooled down from room temperature to well below 0 °C by circulating ethyl alcohol via a constant temperature system. The results show that compared with uncoated silicon, black silicon and two-stage black silicon surfaces can largely increase the surface hydrophobicity, reduce the freezing thickness deformation and show anti-frosting performance. This study provides a new type of hydrophobic surface structure and plays an important role in designing anti-icing/anti-frosting surfaces for practical applications.