title: High-strength nanograined and translucent hydroxyapatite monoliths via continuous hydrothermal synthesis and optimized spark plasma sintering.
abstract: The synthesis of high-strength, completely dense nanograined hydroxyapatite (bioceramic) monoliths is a challenge as high temperatures or long sintering times are often required. In this study, nanorods of hydroxyapatite (HA) and calcium-deficient HA (made using a novel continuous hydrothermal flow synthesis method) were consolidated using spark plasma sintering (SPS) up to full theoretical density in ∼5 min at temperatures up to 1000°C. After significant optimization of the SPS heating and loading cycles, fully dense HA discs were obtained which were translucent, suggesting very high densities. Significantly high three-point flexural strength values for such materials (up to 158 MPa) were measured. Freeze-fracturing of disks followed by scanning electron microscopy investigation revealed selected samples possessed sub-200 nm sized grains and no visible pores, suggesting they were fully dense.
authors.affiliation: Clean Materials Technology Group, Department of Chemistry, University College London, Christopher Ingold Laboratories, 20 Gordon Street, London WC1H 0AJ, UK. aqifanwar@gmail.com
authors.forename: Aqif A
authors.initials: AA
authors.lastname: Chaudhry
authors.forename: Haixue
authors.initials: H
authors.lastname: Yan
authors.forename: Kenan
authors.initials: K
authors.lastname: Gong
authors.forename: Fawad
authors.initials: F
authors.lastname: Inam
authors.forename: Giuseppe
authors.initials: G
authors.lastname: Viola
authors.forename: Mike J
authors.initials: MJ
authors.lastname: Reece
authors.forename: Josephine B M
authors.initials: JB
authors.lastname: Goodall
authors.forename: Ihtesham
authors.initials: I
authors.lastname: ur Rehman
authors.forename: Fraser K
authors.initials: FK
authors.lastname: McNeil-Watson
authors.forename: Jason C W
authors.initials: JC
authors.lastname: Corbett
authors.forename: Jonathan C
authors.initials: JC
authors.lastname: Knowles
authors.forename: Jawwad A
authors.initials: JA
authors.lastname: Darr
mesh_terms: D006882:Hydroxyapatites / Q000737:chemistry*; D008027:Light; D008422:Materials Testing / Q000379:methods*; D043942:Nanotubes / Q000737:chemistry* / Q000648:ultrastructure; D010316:Particle Size; D058626:Plasma Gases / Q000737:chemistry*; D012542:Scattering, Radiation; D013696:Temperature; D014867:Water / Q000737:chemistry*; D014961:X-Ray Diffraction
chemical_list: D006882:Hydroxyapatites; D058626:Plasma Gases; D014867:Water