Micro-PIXE analysis of bioconductive hydroxyapatite coatings on titanium alloy

Bioconductive materials and in particular implants using Ti alloy (Ti6-Al4-V) coated with hydroxyapatite (HAp) have proved to be a suitable surgical procedure. However, experience has shown that these implants not always have the required reliability to guarantee their expected life-span of approximate 15 years. In this research, experimental Ti alloy-implants coated with HAp and incubated in a simulated body fluid (r-SBF) under controlled physiological conditions were studied by nuclear microprobe (NMP). Selected HAp coatings, were analysed by micro-PIXE using protons of 1.5 MeV at the iThemba LABS NMP facility. Major elements (Ti, Al, V, Ca and P) as well as trace elements (Si, K, Fe, Zn and Sr) were determined. The effect of longer incubation time was of particular interest. Results confirmed that secondary Ca-deficient defect hydroxyapatite precipitated from the simulated body solution onto the HAp coating surface after prolonged incubation. This newly formed layer is thought to be of vital importance for bonding of implants with living bone tissue. (author)