| 0810 Graded Glass-Ceramic Coatings for Ti-based Implant Alloys | ||
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S. LOPEZ-ESTEBAN1, E. SAIZ1, S.J. MARSHALL2, G.W. MARSHALL2, and A.P. TOMSIA1, 1 Lawrence Berkeley National Laboratory, CA, USA, 2 University of California, San Francisco, USA Objective: This work sought to develop a new family of bioactive coatings for Ti-based implants that will improve their adhesion to bone while maintaining long-term chemical and mechanical stability. Methods: Bioactive silicate glasses and synthetic calcium phosphates (hydroxyapatite, HA, tricalcium phosphate, TCP, and dicalcium phosphate dihydrate, DCPD) were used to fabricate graded coatings by a sequential deposition technique followed by firing in air. Appropriate compositional gradients were designed to avoid the generation of large thermal stresses during fabrication. The glass-metal and glass-ceramic interfaces were analyzed using XRD, HRTEM, and SEM-EDS. Their adhesion was evaluated by Vickers indentation. The in vitro evolution of the coatings in simulated body fluid at 36.5° was analyzed by XRD, AFM, FTIRSM and SEM-EDS. Results: By controlling the compositional gradient and the firing schedule, coatings with a corrosion-resistant glass in contact with the metal and surface layers with ceramic contents up to 10±2 vol % have been successfully fabricated. No degradation of the calcium phosphates was observed after firing. Any reaction layer between the calcium phosphate and the glass was limited to a thickness <1±0.05 µm. Carbonated hydroxyapatite precipitates covered 80±5 % of the surface of those coatings containing synthetic HA after one month in SBF. However, TCP and DCPD did not promote the in vitro precipitation of new HA. A two way ANOVA and Tukey's tests showed that glass-metal and glass-ceramic adhesion (measured by indentation) were significantly better for coatings fired at temperatures between 780-820ºC for times up to 1 min. Conclusions: Enameling can be used to fabricate glass-ceramic coatings with optimum adhesion that do not crack after firing. Coatings containing HA precipitate apatite during in vitro tests suggesting that they can be used to enhance implant osseointegration while those containing other calcium phosphates slowly dissolve without promoting apatite precipitation. Supported by NIH/NIDR Grant 1R01DE11289. | ||
| Seq #108 - Ceramics: Properties, Composition, and Fabrication 9:00 AM-11:00 AM, Friday, 14 March 2003 Henry B. Gonzalez Convention Center Room 206B | ||
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