The structural characteristics and mechanical behaviors of nonstoichiometric apatite coatings sintered in air atmosphere

Two types of nonstoichiometric apatite coatings on Ti6A14V substrates were prepared in our laboratory by electrodeposition and hydrothermal synthesis. One was composed of highly pure needle-like calcium-deficient hydroxyapati te, and the other consisted of needle-like calcium-deficient hydroxyapatite and plate-like brushite. In this paper, the morphology, phase transition, and bonding strength of these coatings sintered at 450 degrees-980 degrees C in an air atmosphere were studied. In addition, the residual stresses in pure calcium-deficient hydroxyapatite coatings and coatings sintered at 800 degrees C were measured by a hole-drilling method. The results show that a fter being sintered at a higher temperature, the coating/Ti6A14V samples ex hibited structural characteristics such as biphasic [hydroxyapatite + beta- Ca-3(PO4)(2)] coatings and dense TiO2 film/Ti6A14V in which the residual st resses in the coatings slightly increased. Ln addition, the results indicat e that bonding strength was improved. (C) 1999 John Wiley & Sons, Inc.