Abstract
Here we show the deposition of 2.7μm thick phosphate based glass films produced by magnetron sputtering, followed by post heat treatments at 500°C. Variations in degradation properties pre and post heat treatment were attributed to the formation of Hematite crystals within a glass matrix, iron oxidation and the depletion of hydrophilic P-O-P bonds within the surface layer. As deposited and heat treated coatings showed interfacial tensile adhesion in excess of 73.6MPa; which surpassed ISO and FDA requirements for HA coatings. Scratch testing of coatings on polished substrates revealed brittle failure mechanisms, amplified due to heat treatment and interfacial failure occurring from 2.3 to 5.0N. Coatings that were deposited onto sandblasted substrates to mimic commercial implant surfaces, did not suffer from tensile cracking or trackside delamination showing substantial interfacial improvements to between 8.6 and 11.3N. An exponential dissolution rate was observed from 0 to 2h for as deposited coatings, which was eliminated via heat treatment. From 2 to 24h ion release rates ordered P>Na>Mg>Ca>Fe whilst all coatings exhibited linear degradation rates, which reduced by factors of 2.4–3.0 following heat treatments.
Highlights
Hydroxyapatite (HA) emerged as an osteoconductive coating in the 1980s and remains an industrial surface treatment for orthopaedic integration [1]
Fe2O3-4 mol% was investigated to observe the effect of heat treatment on the coating topography, crystallinity, degradation and mechanical properties
Elemental mol% compositions of MQ, C1, C2 and C3 were observed to vary by a maximum of 1.24, 1.53, 1.22, 0.82, 0.63 mol% for P2O5, MgO, CaO, Na2O, Fe2O3, respectively
Summary
Hydroxyapatite (HA) emerged as an osteoconductive coating in the 1980s and remains an industrial surface treatment for orthopaedic integration [1]. Plasma sprayed HA is a ceramic coating layer with a Ca/P ratio of 1.67, similar in composition to the cortical bone. Bone like layers on metallic hip stems or dental screws promote adhesion of osteoblast cells and protein attachment for bone regeneration and osseointegration [3,4,5]. Plasma sprayed HA layers have been known to delaminate entirely at the interface, preventing complete osseointegration via the coating layer or causing integration directly with the implant surface. Aseptic loosening remains the biggest cause of implant failure, responsible for ≈40% of revisions [7]
Sign-in/Register to view highlights & summary Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
