Formation, Testing, and Deposition of Bioactive Material Using Thermal Spray Additive Manufacturing Technique

Recently, hydroxyapatite (HA): Ca10 (PO4)6 (OH)2 has been gaining wide attention in medical implant applications owing to its good biocompatibility and chemical similarity with human bones. In the current experimental study, bioactive HA powder has been formed and tested using different techniques such as FTIR (Fourier transform infrared spectroscopy), SEM (scanning electron microscopy), and EDS (energy dispersive spectroscopy) to examine HA phases in the developed powder. Results revealed presence of hydroxyl (OH−), phosphate (PO43−), and carbonate (CO32−) groups at 3414.31 cm−1, 875.73 cm−1, 711.16 cm−1, 1797.88 cm−1, and 1417.89 cm−1, respectively, which signifies existence of hydroxyapatite compound in the developed powder. Furthermore, the layer of HA powder has been deposited on AISI 304L stainless steel substrate using thermal spray high-velocity oxy-fuel (HVOF) additive manufacturing process. Layered samples are examined for microhardness to find the optimum HVOF additive manufacturing parameters. It has been found that standoff distance (SOD) = 12 inch., acetylene supply rate (ASR) = 70 m3/min., oxygen supply rate (OSR) = 60 m3/min., and powder feed rate (PFR) = 74.87 gm/min. result in highest microhardness number, VHN = 504.998. The findings of this experimental study recommend additive manufactured bioactive layered samples as a viable substitute for costlier commercial available HA-coated implants.