Two step porosification of biomimetic thin-film hydroxyapatite/alpha-tri calcium phosphate coatings by pulsed electron beam irradation

Stuart, Bryan W.; Murray, James W.; Grant, David M.

Abstract

Here we show a new and effective methodology for rapid/controllable porosification of thin-film ceramics, which may be applied, in medical devices/electronics and membrane nano-filtration. Dense hydroxyapatite applied to Ti6Al4V by plasma-assisted PVD was electron-beam irradiated to induce flash melting/boiling. Deposited coatings contained amorphous and nano-crystalline/stoichiometric hydroxyapatite (~35 nm). Irradiation (voltages 13-29 kV) led to ablation (up to 45% mass loss) and average/maximum pore areas from (0.07-1.66)/(0.69-92.53) μm2, mimicking the human cortical bone. Vitrification above 1150 °C formed (~62-30 nm) crystallites of α-Tri Calcium Phosphate. Unique porosification resulted from irradiation-induced sub-surface boiling and limited thermal conductivity of hydroxyapatite, causing material to expand/explode through the more quickly solidified top surface. Commercially applicable, roughened Ti6Al4V exacerbated the heating and boiling explosion phenomenon in certain regions, producing an array of pore sizes. Scaffold-like morphologies were generated by interconnection of micron/sub-micron porosity, showing great potential for facile generation of a biomimetic surface treatment for osseointegration.

Citation

Stuart, B. W., Murray, J. W., & Grant, D. M. (2018). Two step porosification of biomimetic thin-film hydroxyapatite/alpha-tri calcium phosphate coatings by pulsed electron beam irradation. Scientific Reports, 8, Article 14530. https://doi.org/10.1038/s41598-018-32612-x

• Journal Article Type: Article
• Acceptance Date: Sep 5, 2018
• Publication Date: Sep 28, 2018
• Deposit Date: Sep 24, 2018
• Publicly Available Date: Sep 28, 2018
• Journal: Scientific Reports
• Electronic ISSN: 2045-2322
• Publisher: Nature Publishing Group
• Peer Reviewed: Peer Reviewed
• Volume: 8
• Article Number: 14530
• DOI: https://doi.org/10.1038/s41598-018-32612-x
• Keywords: Hydroxyapatite; Tri-Calcium phosphate; Sputtering; Coating; Micro-porous
• Public URL: https://nottingham-repository.worktribe.com/output/1128456
• Publisher URL: https://www.nature.com/articles/s41598-018-32612-x