Hydrophobicity and tribology of large-area textured copper with nanogrown copper oxide

Abstract

Copper (Cu) is widely used as an engineering material for automotive industries. Herein, a two-step surface innovation process was evolved to enhance the hydrophobicity and wear resistance of the copper surface. Rapid fabrication of large-area texturing was performed by the abrasive water jet technique followed by nanogrowth of copper oxide (CuO) film on the copper substrate. Increased hydrophobicity is observed for textured copper (120°) and copper with nanogrown CuO (133°) compared to that of copper without these features (63°). It may be noted that synergistic texturing and nanogrowth of CuO has resulted in the highest contact angle (155°). X-ray photoelectron spectroscopy revealed the least percentage contribution of Cu–OH group to synergetic texture and nanogrowth (1·25 %). Further, the fretting wear test divulged the high wear resistance of synergistically textured copper with nanogrown CuO, as its coefficient of friction was lowest (0·46) when compared with that of copper (0·52). The observed improvement in wear resistance is attributed to textured pillars trapping the wear debris and reduction in the real contact area due to nanogrown CuO. Thus, this novel large-area texturing technique combined with nanogrown CuO may provide potential self-lubrication and render superhydrophobic surfaces for automotive applications.