Electrophoretic Deposition of Hydroxyapatite Coating on TiNi Shape Memory Alloy

In this study, hydroxyapatite (HA) was used as a bioceramic on a TiNi shape memory alloy. Butanol and tri-ethanolamine were used as suspensions with HA particles. The electrophoretic deposition (EPD) process was performed at 20, 30, and 40 V for 1–5 min on the cathode. Samples were left at room temperature for 24 hours to obtain slow drying after deposition. Weight and layer thickness were then measured. Sintering was conducted in an Ar atmosphere at 800°C for 2 h. The phases and surface morphologies were examined using XRD and SEM. The results showed that a uniform, homogeneous, crack-free coating layer can be achieved at a voltage of 30 V and low sintering temperatures. Also, longer deposition times increased the coatings' weight and thickness. Compared to other deposition methods, such as sol-gel and plasma coating, the method presented in this research can be used as an alternative method for bioactive coatings. The hardness of the undecorated HA coatings obtained at 15 and 30 V EPD voltage reached 0.2245 ± 0.036 GPa and 0.0661 ± 0.008 GPa, respectively.