Surface wetting and friction studies of nano-engineered surfaces on copper substrate

Nano-engineered-textures on a material surface can dramatically improve the wetting and non-wetting properties of a surface, and they also show promise to address friction issues that affect surfaces in contact. In this work, aluminum-induced crystallization (AIC) of amorphous silicon (a-Si) was used to produce nano-textures on copper (Cu) substrates. A study was performed to examine the effects of changing the annealing conditions and a-Si thickness on nano-texture formation. The creation of various nano-topographies and chemically modifying them using octafluorocyclobutane (C4F 8) was performed to control hydrophilicity, hydrophobicity, and oil affinity of nano-textured surfaces. A video-based contact angle measurement system was used to measure the surface wetting properties. Scanning electron microscopy (SEM) was employed to characterize the surface nano-topographies and provide a basis for qualitative and quantitative analysis of the nano-texture formations. Scratch testing was performed using a TriboIndenter to assess the potential of the nano-textured Cu substrates to lower the coefficient of friction (COF). It was found that the thicker a-Si layer generated larger textures overall which contributed to water contact angle (CA) results ranging between superhydrophilic and superhydrophobic, as well as increased oil affinity of Cu substrate. The nano-textured surfaces also achieved COF values that were 40 % lower than as-received (AR) Cu.