Effect of surface roughness and surface topography on wettability of machined biomaterials using flexible viscoelastic polymer abrasive media

Abstract

Unidirectional abrasive flow finishing process was used to finish stainless steel SS316L and titanium alloy Ti-6Al-4V materials which are widely used as implant materials. Viscoelastic polymer-based flexible abrasive media was used to finish these surfaces with different pressure and number of cycles. The obtained surface roughness and surface topography were measured using profilometer, and morphology of the surface was studied using a scanning electron microscope. Further, the wettability of the finished surface was studied by measuring the contact angle (θ) for three liquids—water, formamide, and diiodomethane using the sessile drop technique. The measured contact angles were used to ascertain the surface free energy components using Van Oss Chaudhury-Good equation. Significant difference was observed on surface roughness, contact angle, and surface energy of the machined surfaces at different finishing cycles. Also, the different tendencies of the droplet contact angle and surface energy have been observed along the direction parallel and perpendicular to the finishing direction and it gave a strong conclusion that surface roughness and surface textures play a significant role in wetting characteristics. So, this work provides an overview of the interaction between droplet and surface topography of finished SS316L and Ti-6Al-4V surfaces. Further, an empirical model has been developed using the response surface methodology (RSM) for output responses namely, average surface roughness (Ra) and material removed (MR). Interactive effects of number of cycles and pressure on average surface roughness and material removed are discussed in this paper.