TY - JOUR
T1 - A thermodynamic approach to surface modification of calcium phosphate implants by phosphate evaporation and condensation
AU - Döbelin, Nicola
AU - Maazouz, Yassine
AU - Heuberger, Roman
AU - Bohner, Marc
AU - Armstrong, Ashley A.
AU - Wagoner Johnson, Amy J.
AU - Wanner, Christoph
N1 - Funding Information:
The authors would like to thank Janine Glatthard for her tremendous support with the verification experiments.
PY - 2020/12
Y1 - 2020/12
N2 - It has been reported in the literature that thermal treatment of calcium phosphate ceramics chemically alters the surface composition by phosphate evaporation. To predict the compositional changes, we have developed a thermodynamic model for the evaporation of phosphorous species from CPP, TCP, HA, and TetCP. In an open atmosphere, the model predicts the formation of a surface layer consisting of a sequence of increasingly phosphate-depleted phases. In a closed system, the atmosphere reaches equilibrium with a single-phase surface layer. To verify our model, we performed a series of experiments which confirmed the predicted formation of phosphate-depleted surface layers. These experiments further demonstrated that controlled supersaturation of the atmosphere led to formation of a phosphate-enriched surface layer as a result of phosphate condensation. In conclusion, our thermodynamic model is capable of predicting the surface modification by phosphate evaporation and condensation of calcium phosphate phases during high-temperature processing in different environments.
AB - It has been reported in the literature that thermal treatment of calcium phosphate ceramics chemically alters the surface composition by phosphate evaporation. To predict the compositional changes, we have developed a thermodynamic model for the evaporation of phosphorous species from CPP, TCP, HA, and TetCP. In an open atmosphere, the model predicts the formation of a surface layer consisting of a sequence of increasingly phosphate-depleted phases. In a closed system, the atmosphere reaches equilibrium with a single-phase surface layer. To verify our model, we performed a series of experiments which confirmed the predicted formation of phosphate-depleted surface layers. These experiments further demonstrated that controlled supersaturation of the atmosphere led to formation of a phosphate-enriched surface layer as a result of phosphate condensation. In conclusion, our thermodynamic model is capable of predicting the surface modification by phosphate evaporation and condensation of calcium phosphate phases during high-temperature processing in different environments.
KW - Bioceramics
KW - Calcium phosphate
KW - Evaporation
KW - Surface modification
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U2 - 10.1016/j.jeurceramsoc.2020.07.028
DO - 10.1016/j.jeurceramsoc.2020.07.028
M3 - Article
AN - SCOPUS:85087011801
VL - 40
SP - 6095
EP - 6106
JO - Journal of the European Ceramic Society
JF - Journal of the European Ceramic Society
SN - 0955-2219
IS - 15
ER -