Obtention, Characterization and Deposition of Hydroxyapatite Obtained from Scales of the Amazonian Fish Pirarucu (Arapaima gigas) Using the High Velocity Suspension Plasma Spray (HVSPS) Process

In this study, a hydroxyapatite (HA) coating derived from the scales of the Amazonian fish pirarucu ( Arapaima gigas ) was produced using calcination at 500 and 750 °C and deposited on AISI 316 stainless steel substrate using the process of thermal spraying, high velocity suspension plasma spray (HVSPS). To verify its potential, this material was characterized by X-ray diffraction (XRD), by which characteristic peaks of hydroxyapatite were evidenced. Via X-ray fluorescence (XRF) of the samples, it was observed that the Ca/P ratio was equal to 2.00. Using the Fourier transform infrared (FTIR) spectroscopy and Raman spectroscopy, it was possible to observe the characteristic bands of the HA. For the coating, the mechanical nanoindentation test showed mean Vickers microhardness (VH) values of 93.25 VH for the hydroxyapatite and of 196.57 HV for the substrate. The modulus of elasticity (EIT) was 77.85 GPa for the hydroxyapatite coating and 136.45 GPa for the substrate. Optical microscopy showed that the coating was homogeneously deposited.