Synthesis and Characterization of Hydroxyapatite Layer on Cobalt Alloys through Dip Coating Method as a Prosthetic Bone Implant Candidate

This research aims to determine the effect of dip coating process parameter, which are the concentration of the suspension, withdrawal speed and sintering temperature on the crystallinity, surface morphology, shear strength and the thickness of hydroxyapatite (HA) coating on cobalt alloys substrate as a prosthetic bone implant material candidate. The coating is done at 3 different concentrations of HA suspension: 0.02M, 0.04M and 0.06M by varying the speed of the withdrawal of 0.120; 0.198; and 0.266 mm/s followed sintering at temperature of 550 0 C with a holding time of 10 minutes. XRD test results showed that all concentrations formed the HA layer with hexagonal crystal structure as indicated by the appearance of the three highest peaks in the diffraction angle in 2θ = 25.9316 o ; 31.8858 o and 32.3164 o the highest peak occurs at 2θ = 31.8858 o . HA layer crystallinity higher than nano HA powder because of the influence of the sintering temperature. SEM results showed that the HA layer formed not cover the entire surface of cobalt alloy substrate. The higher of the HA suspense concentration and the withdrawal speed will makes the thicker of the HA layer and the greater of the shear strength. Based on the thickness value of the layers so the proper sample for prosthetic bone implant applications is sample with concentration 0.06M with withdrawal speeds of 0.120 mm/s, 0.198 mm/s and 0.266 mm/s.