Plasma spraying of hydroxyapatite(HA)/Ti-6Al-4V composite coatings.
Quek, Chai Hia.
Date of Issue1999
School of Mechanical and Aerospace Engineering
Biomedical implants using metals, polymers, ceramics and composites are increasingly being used to restore body function and to facilitate healing. It is often the material design aspect of such implants that will determine the stability of the device. Hydroxyapatite (HA) coating on Ti-6A1-4V is a promising implant being used in the orthopaedics applications. HA is a bioactive but brittle material. Ti-6A1-4V is non-toxic, bioinert and mechanically strong. HA and Ti-6A1-4V provide an implant that is biocompatible, light and stable. Plasma spray technique is a popular method of depositing HA on Ti-6A1-4V. To bridge the gap in biomaterials with HA having low load bearing, Ti-6A1-4V is combined with HA to provide a higher load bearing capability. The deposition of brittle HA alone gives a coating with the tendency to crack. HA/Ti-6A1-4V composite coatings which bring together the bioactive HA with the bioinert Ti-6A1-4V are therefore developed. Two different compositions of HA and Ti-6A1-4V in the ratio of 50 wt.% HA : 50 wt.% Ti-6A1-4V and 80 wt.% HA : 20 wt.% Ti-6A1-4V are produced by a ceramic slurry mixing method. The influence of plasma spraying parameters such as plasma arc current, plasma gun transverse speed, standoff distance and helium gas flow rate, on the coating characteristics are studied.