Kinetics of thermal decomposition of hydroxyapatite bioceramics

• Published in: Journal of materials science Vol. 34; no. 24; pp. 6121 - 6131
• Main Authors: CIHLAR, J, BUCHAL, A, TRUNEC, M
• Format: Journal Article
• Language: English
• Published: Heidelberg Springer 01.12.1999; Springer Nature B.V
• Subjects: Applied sciences; Bioceramics; Biological and medical sciences; Building materials. Ceramics. Glasses; Ceramic industries; Ceramic molds; Ceramics; Chemical industry and chemicals; Conversion; Decomposition; Exact sciences and technology; Hydroxyapatite; Injection molding; Materials science; Medical sciences; Miscellaneous; Reaction kinetics; Reaction products; Surgery (general aspects). Transplantations, organ and tissue grafts. Graft diseases; Technical ceramics; Technology. Biomaterials. Equipments; Thermal decomposition; Time dependence; Calcium Phosphates; Thermal decomposition; Sintering; Injection molding; Hydroxyapatite; Biomaterial; Kinetics; Manufacturing; Experimental study; X ray diffraction
• ISSN: 0022-2461; 1573-4803
• DOI: 10.1023/A:1004769820545

The mechanism and kinetics of thermal decomposition of injection moulded hydroxyapatite ceramics were studied over the temperature range of 1473–1758 K. At temperatures below 1473 K the sintering and transformation of hydroxyapatite to hydroxyoxyapatite proceeded to a conversion degree of 0.4 to 0.5. At temperatures between 1473 and 1758 K the hydroxyapatite was decomposed to α-TCP, H2O and CaO. The decomposition of HOA started on the surface of the HOA ceramics. The rate of increase in the thickness of the reaction products (α-TCP) was described by the parabolic law. The kinetic analysis of the time dependence of HOA conversion to TCP by means of the J-M-A-J-K equation also showed that the thermal decomposition of HOA ceramics was controlled by diffusion of water from the reaction zone to the surface of the ceramic sample. The activation energy of the thermal decomposition of HOA ceramics amounted to 283.5 kJ/mol.