Fabrication of mechanically durable slippery surface on HVOF sprayed WC-Co coating

Abstract

The limitations of the existing art and the fragility of the developed hydrophobic surfaces limit its applications to the real field. Hence, the fabrication of slippery surface with the required durability has been considered to be an important academic and industrial challenge. The WC-Co coating possesses exceptional mechanical and tribological properties and is considered as one of the most durable surfaces available. The WC-Co coating with nanoscale surface roughness is in high demand in aerospace and automobile industries. In this study, shape adaptive grinding (SAG) is conducted to attain nanoscale surface roughness on hard WC-Co coatings. The static and dynamic wetting behaviour of as-sprayed, ground and nanofinished WC-Co coating are studied by analysing the static contact angle, sliding angle, and contact angle hysteresis (CAH). A model is proposed to predict the apparent contact angle of the coatings. The nanofinished coating exhibits a lower sliding angle and contact angle hysteresis and the water droplets get completely released from the surface in dynamic condition. This is attributed to the lower surface retention force and the presence of trapped air inside the porosities and the nano-well of the coating surface. The durability test of the nanofinished surface is also performed by abrasion test and sand impact test and it is observed that the surface can retain its original topographical features and wetting properties. This report presents a sustainable method for the fabrication of a mechanically durable slippery surface.