Investigation on surface topography in photochemical machining of Co-Cr L605 alloy using a new etchant for cell growth

The experimental study evaluates surface topography using a suitable etchant in photochemical machining (PCM) of Co-Cr L605 for cell growth on the bio-implants. A new etchant is defined by considering etchant chemistry, the composition of alloying elements, its application, and its implications. Experiments were performed with six different etchants at 50°C for 30 min. The study includes a comparative evaluation based on pH and conductivity, and also analyzes their effects on the depth of etching and surface roughness (R a ). Surface quality was evaluated using a scanning electron microscope (SEM) and a 3D optical profilometer. From the results, a novel etchant was found to be a blend of etching (FeCl3), oxidizing (H2SO4), a reducing agent (HCl), and an alkaline solvent (CH3OH) in weight percentages of 0.09, 0.26, 0.13, and 0.52, respectively. The optimum etch rate and Ra were found to be 0.3 µm/min and 0.85 µm, respectively, for the novel etchant. The confocal imaging technique was used for cell growth examination, and results were supported by contact angle measurements. Overall, the surface topography created by the novel etchant shows better results for cell growth.