Mechanical, Structural, Corrosion, and Dielectric Properties of Hydroxyapatite Doped with Varying Concentrations of Cu to be Used as Orthopedic Implants

Different weight percent ranging from 0.5 to 10% of Cu-doped hydroxyapatite (CuHA) pellets were prepared using water-based wet chemical method. Since HA is mechanically weak, copper was selected to increase the mechanical strength as well as its biocompatibility. HA powder was first prepared and Cu was homogeneously mixed for 6 hours for each set of samples using mortar pestle. Pellets were prepared and sintered at 600 °C. The functional group was confirmed using Fourier transform infrared spectroscopy & Raman spectroscopy. Compound formation was studied using x-ray diffraction. Rietveld analysis shows that crystallite size increases from 9.39 to 16.25 nm. Microstructural analysis was done using field emission scanning electron microscopy, where it is observed that the grain size decreased from 100.11 to 72.82 nm with the increase in Cu doping. Corrosion resistance was studied in Ringers solution using polarization. It is observed that the corrosion rate decreased from 12.186 × 10−3 to 7.84 × 10−4 mil/year with increase in Cu concentration from 0 to 10%. This may be collaborated with the total decrease in the pore volume with the increase in Cu concentration. Hardness of the samples increases with the increase in Cu doping. Ductility of the 1%Cu-doped sample was observed better than other samples. As the grain size decreases with the increase in Cu doping, hardness increases leading to the increase in corrosion resistance as well. Dielectric constant (ξ) is maximum for 1% CuHA and minimum for 10% CuHA at lower frequency. However, 5% CuHA shows maximum (ξ). Weight loss was minimum for 1% Cu-doped HA pellet which is better than pure HA as studied using thermal gravimetric analysis (TGA). Microstructure, microhardness, dielectric, and corrosion resistance of the different doped CuHA pellets are correlated and the best sample to be used as an orthopedic implant is reported. Graphical Abstract