In-Vitro Assessment on Surface Functionality of CoCrMo Alloy Manufactured by Laser Powder Bed Fusion

Recent advancements in laser powder bed fusion (LPBF) techniques have revolutionized the manufacturing of biomedical devices using metallic biomaterials. For hip-joint prosthetics, CoCrMo has emerged as a preferred material. Therefore, this study examines the surface functionality of the as-printed and mechanically post-processed 3D-printed CoCrMo specimen. Surface functionality includes the study of surface integrity, wettability, and in-vitro biotribology in the physiological environment. The 3D surface topographical analysis was conducted on both samples. The obtained 3D profiles revealed that the as-printed samples exhibited small-scale balling effects, resulting in micro-pores that persisted after polishing. The topographical parameters, such as Ra, Rq, Rz, Rku, and Rsk, were measured, and polished samples showed better surface characteristics. Surface wettability tests indicated a transition from hydrophobic to hydrophilic behavior, with lower surface free energy observed in the as-printed parts compared to the post-processed counterpart. Further, in-vitro biotribology tests were conducted under the physiological environment for the hip-joint prosthesis condition. The biotribological results indicated a reduced coefficient of friction and frictional force for the as-printed compared to the polished sample. The 3D wear profiles also showed visible wear marks for the polished samples, which exhibited higher volumetric wear loss than the as-printed counterpart. These findings emphasize the importance of achieving optimal surface roughness to enhance surface functionality in 3D-printed components through surface finishing methods.