Design and Formulation of Bioactive Coatings Using Thermal Spray Process

Abstract

Hydroxyapatite Ca10(PO4)6(OH)2, commonly referred to as HA, has attracted wide spread interest from both the orthopaedic and dental fields due to its excellent biocompatibility and tissue bioactivity properties. Hydroxyapatite is chemically similar to the mineral component of bones and hard tissues in mammals. It is one of the few materials that are considered bioactive, meaning that it will support bone growth when used in orthopaedic and dental applications. Despite excellent properties as a biomaterial, the ceramic nature and the inherent mechanical properties of HA specifically brittleness, poor tensile strength and poor impact resistance have restricted its application in many load-bearing applications. HA coated implants combines the good strength with the excellent biocompatibility and bioactivity of the HA. In the present investigation, an attempt is made to develop HA powder from fishbone and Chicken egg shell, a natural apatite rich substance through heat treatment method. Fishbone, a cheaper source of HA is generated as waste material during fish processing. Fourier transform-infrared spectroscopy (FT-IR) and X-ray diffraction (XRD) techniques are employed to investigate the proof of formation of HA phase. The OH group is found at 3404.25cm-1 for fish bone and 3414.31cm-1 for egg shell powder and the same peak is also traced in HA powder. Similarly, The P-O group is also found at 1024.19cm-1 for fish bone and 875.73cm-1 for egg shell powder and the same peak is also traced in HA powder. SEM / EDX of powder is also done to show the microstructure of powders and the traces of the various elements like Ca, Mg etc. Further the blood clotting test shows that both the powders are efficient and compatible with human blood. The coating of this HA powder is developed on SS 304L metal substrate by using High velocity oxy-fuel (HVOF) spray technique. Coated samples are obtained at various HVOF parameters. Samples are tested for Micro structural analysis, Hardness, Micro hardness, corrosion resistance etc., to find the optimum HVOF parameters.