FABRICATION OF FUNCTIONALLY GRADED HYDROXYAPATITE/TITANIUM OXIDE COATING VIA DROP-ON-DEMAND TECHNIQUE

Abstract

Hydroxyapatite (HA) and titanium oxide (TiO2) suspensions were utilized to fabricate the functionally graded coating via the Drop-on-Demand (DOD) micro-dispensing technique. A three-layered structure was formed, with a bottom 100% TiO2 layer, an intermediate layer consisting of 50% TiO2 and 50% HA, and a top 100% HA layer. The coating was then subjected to various characterizations, including scanning electron microscopy (SEM), X-ray diffraction (XRD), energy dispersive X-ray spectroscopy (EDS), fourier transform infrared spectroscopy (FTIR), contact angle measurement, and adhesion test. The SEM, XRD, and FTIR techniques revealed that the DOD technique did not change the morphology, phase, and chemical composition of the coating materials. In addition, EDS results demonstrated the graded elemental distribution within the layer which confirmed the versatility of the DOD technique. A coating thickness of 20 μm was achieved, with a critical load to failure at 59 mN.