Improvement of Apatite-Forming Ability of Tantalum Metal by CaCl2 Treatment
Tantalum metal was soaked in NaOH and CaCl2 solutions, and then subjected to heat treatment at 500°C. EDX analysis showed that about 6.5 at. % of Na was incorporated into the surface of the tantalum metal by the first NaOH treatment. These Na+ ions were replaced by Ca2+ ions by the subsequent CaCl2 treatment. According to TF-XRD patterns, an amorphous sodium tantalate was seemed to be formed on the tantalum metal by the NaOH treatment and transformed into amorphous calcium tantalate by the CaCl2 treatment. This phase was crystallized into Ca2Ta2O7 by heat treatment. Critical detaching load of the surface of the CaCl2-treated tantalum metal was as low as 5mN, while as high as 42mN after the heat treatment. Apatite-forming ability of the NaOH-treated tantalum metal in a simulated body fluid (SBF) was appreciably increased by the CaCl2 treatment and maintained even after the heat treatment.
Guy Daculsi and Pierre Layrolle
D. K. Pattanayak et al., "Improvement of Apatite-Forming Ability of Tantalum Metal by CaCl2 Treatment", Key Engineering Materials, Vols. 361-363, pp. 681-684, 2008