Identification and mapping of the amorphous phase in plasma-sprayed hydroxyapatite coatings using scanning cathodoluminescence microscopy

The presence and distribution of the amorphous phase is a key factor in the performance and bone-bonding behavior of plasma-sprayed hydroxyapatite coa tings. Microanalysis of coatings was conducted with microprobe Raman and sc anning cathodoluminescence microscopy. It was confirmed that the darker reg ions in polished cross sections represent the amorphous phase. The more in tense cathodoluminescence emission from the amorphous phase during electron -beam irradiation compared with the crystalline phase was used to detect th e two structurally different areas within the sample. By selecting the peak of the emission at 450 nm it was possible to raster the surface with the e lectron beam and produce a map of the amorphous phase in polished sections, a fracture surface and an as-sprayed surface of the plasma-sprayed coating . Cathodoluminescence microscopy, based on the different light emission fro m the amorphous phase and hydroxyapatite, is a useful tool for identifying and mapping of the amorphous-phase constituent in plasma-sprayed coatings. (C) 1998 Kluwer Academic Publishers.