Article ID: M2014270
Argon ion sputter-etching was applied to type 316 stainless steel and AISI M2 (JIS SKH 51) steel, and the sputter-coating of polytetrafluoroethylene (PTFE) film was carried out onto the sputter-etched surface. The sputter-etching of the steels formed fine and dense ridge- or column-shaped protrusions with a diameter of 100 nm to 1 µm on the surface. The protrusions of as-sputter-etched type 316 and M2 steels specimens showed low reflectance of visible light smaller than 8.5% and 4.4% respectively, and the sputter-coating of PTFE film reduced the reflectance further to 5.3% and 2.8% as long as the thickness of the film is thin. In addition, the protrusions of both steels sputter-coated with PTFE films showed superhydrophobicity with a contact angle of a water droplet of more than 165°. The superhydrophobicity of the type 316 specimen was still preserved after an ultrasonic vibration test of 3.6 ks in water.