A thermodynamic approach to surface modification of calcium phosphate implants by phosphate evaporation and condensation

Nicola Döbelin, Yassine Maazouz, Roman Heuberger, Marc Bohner, Ashley A. Armstrong, Amy J. Wagoner Johnson, Christoph Wanner

Research output: Contribution to journalArticlepeer-review

Abstract

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.

Original languageEnglish (US)
Pages (from-to)6095-6106
Number of pages12
JournalJournal of the European Ceramic Society
Volume40
Issue number15
DOIs
StatePublished - Dec 2020

Keywords

  • Bioceramics
  • Calcium phosphate
  • Evaporation
  • Surface modification

ASJC Scopus subject areas

  • Ceramics and Composites
  • Materials Chemistry

Fingerprint

Dive into the research topics of 'A thermodynamic approach to surface modification of calcium phosphate implants by phosphate evaporation and condensation'. Together they form a unique fingerprint.

Cite this