Article

Hierarchically structured titanium foams for tissue scaffold applications.

Department of Materials, Imperial College London, London SW7 2AZ, UK.
Acta biomaterialia (Impact Factor: 5.68). 12/2010; 6(12):4596-604. DOI: 10.1016/j.actbio.2010.06.027
Source: PubMed

ABSTRACT We present a novel route for producing a new class of titanium foams for use in biomedical implant applications. These foams are hierarchically porous, with both the traditional large (>300μm) highly interconnected pores and, uniquely, wall struts also containing micron scale (0.5-5μm) interconnected porosities. The fabrication method consists of first producing a porous oxide precursor via a gel casting method, followed by electrochemical reduction to produce a metallic foam. This method offers the unique ability to tailor the porosity at several scales independently, unlike traditional space-holder techniques. Reducing the pressure during foam setting increased the macro-pore size. The intra-strut pore size (and percentage) can be controlled independently of macro-pore size by altering the ceramic loading and sintering temperature during precursor production. Typical properties for an 80% porous Ti foam were a modulus of ∼1GPa, a yield strength of 8MPa and a permeability of 350 Darcies, all of which are in the range required for biomedical implant applications. We also demonstrate that the micron scale intra-strut porosities can be exploited to allow infiltration of bioactive materials using a novel bioactive silica-polymer composite, resulting in a metal-bioactive silica-polymer composite.

0 Bookmarks
 · 
187 Views
  • [Show abstract] [Hide abstract]
    ABSTRACT: Analysis of equations governing specific energy absorption for cellular solids indicates that silicate glass-based materials should outperform other cellular solids, including metallic foams. Quasi-static compression tests of silicate glass cellular materials fabricated by thermally bonding hollow spheres above the glass transition temperature (Tg) experimentally supports the analysis. Materials with some of the highest energy-absorbing capacities in the literature (14.8 MJ m−3 or 26.5 kJ kg−1) are reported. Fabrication techniques are generalizable to any amorphous hollow spheres with thermal stability above Tg.
    Scripta Materialia 08/2014; s 84–85:7–10. · 2.97 Impact Factor
  • Polymer 08/2014; · 3.77 Impact Factor
  • [Show abstract] [Hide abstract]
    ABSTRACT: Porous 316L stainless steel deposits were fabricated by flame spraying semi-molten particles with different melting degrees and spray angles to understand the deposition behavior of semi-molten spray particles. The effects of spray angle relative on the deposition efficiency and deposit porosity were investigated. The morphology of individual splats deposited on flat surface at different angles was examined. The results show that the spray angle had a significant influence on the deposit porosity, pore structure, and deposition efficiency. The slipping of solid core in semi-molten spray particle was clearly observed when semi-molten particles impacted on the polished substrate with an inclined angle. A random model was proposed to simulate the process of particle deposition. It was found that after considering the effects of both solid particle slipping upon impact and particle melting degree, the porosity calculated by simulation with the model agreed well with the experimental observation.
    Journal of Thermal Spray Technology 08/2014; 23(6):991-999. · 1.49 Impact Factor