CHARACTERIZATION OF CALCIUM-PHOSPHATE POWDERS BY ESCA AND EDXA

Calcium phosphate (CaP) materials can be well characterized by traditi onal methods such as wet chemistry and X-ray diffraction (XRD). These methods, however, offer limitations when non-destructive evaluation of CaP coatings on curved surfaces is required. Since the source powders for these coatings are generally commercially available CaP powders, careful characterization of the source powders may allow inferences to be made regarding the effects of plasma spraying on coating compositi on. Nine commercially available CaP powders were characterized by scan ning electron microscopy, wet chemistry and XRD. These techniques show ed that major differences exist between individual powders claiming to be hydroxyapatite. Analysis of these nine powders by electron spectro scopy for chemical analysis (ESCA) and energy dispersive X-ray analysi s (EDXA) suggest that these techniques can provide the chemical compos ition of CaP in a non-destructive manner and thus may be of use in det ermining the composition of CaP in configurations (such as coatings on metal surfaces) not readily amenable to traditional methods. A calibr ation curve is required, however, to relate this surface chemical comp osition result to the material's bulk composition as determined by wet chemistry analysis. Errors of less than 10% can be obtained using ESC A and EDXA. These studies suggest that non-destructive chemical compos ition evaluation by EDXA and ESCA may also be applicable to CaP coatin gs.