MECHANISTIC STUDIES OF ELECTRODEPOSITION FOR BIOCERAMIC COATINGS OF CALCIUM PHOSPHATES BY AN IN-SITU PH-MICROSENSOR TECHNIQUE

A pH-microsensor technique was developed to measure in-situ the pH val ue at the titanium alloy \ solution interface for the first time durin g the electrodeposition process of calcium phosphate coatings. Electro chemically prepared iridium oxide was used as a pH sensitive material, which is of a good response behavior in the measured solutions. The p H response slope was - 70.2 mV/pH at 60 degrees C. The results indicat ed that the interfacial pH increased with the applied current density, first jumped to a maximum, then slowly decreased at the controlled cu rrent density during the electrodeposition process. Incorporating the results of composition and structure of electrodeposition coatings cha racterized by X-ray diffraction (XRD) patterns and Raman spectra, the measurement of the interfacial pH was informative for further understa nding of the electrodeposition mechanism of calcium phosphates. The in terfacial pH may determine the precipitation reaction and the electrod eposition products at the titanium surface. (C) 1998 Elsevier Science S.A. All rights reserved.