Characterization of plasma sprayed seashell derived hydroxyapatite coating on titanium alloy (Ti-6Al-4V ELI)

Abstract

Surface coating is the process of modifying the surface of the material to enhance its properties. The investigation of the project is depositing the spray-dried synthesized hydroxyapatite (HA) powder on titanium alloy substrate by using an atmospheric plasma spray process and characterizing the coatings to explore mechanical and microstructural properties. Vickers microhardness and scratch tests are performed to calculate the hardness value and adhesion strength of the coatings, respectively. Ball on disc test on the coatings is conducted to to analyze the wear resistance and mass loss. The crystalline phase and roughness of coated samples are analyzed through an X-ray diffractometer (XRD) and stylus profilometer, respectively. A field emission scanning electron microscope (FESEM) is used to characterize the coated samples microstructurally. The XRD graph shows that the stable phase and almost pure hydroxyapatite are obtained at 1000 °C synthesized temperature. The roughness of the coating increases first, and further decreases as the synthesized temperature rises, and minimum roughness is obtained at 1000 °C. It has been noticed as the synthesizing temperature is raised from 700 to 900 ℃, the coating hardness increases first, and maximum hardness is reached at 900 ℃ and then decreases further. The minimum porosity is observed for coating obtained from 1000 ℃ synthesis temperature HA.