Additive Manufacture of Porous Ti Using Sacrificial Porogens

Porous Ti structures for medical applications can be made by additive manufacture but are usually built as lattice structures, which not only requires complex programming of the laser path, but also fails to achieve the pore geometry and connectivity required for the necessary cell response. Recent investigations have shown that porous Ti structures and be built by "conventional" methods using a mixed powder bed comprised of both Ti and fine salt (NaCl). The porosity is revealed by dissolving away the residual salt (the porogen) in water. The structures obtained look very promising, but the geometry of the pores is not always a direct replication of the geometry of the porogen.
This PhD research programme will seek to develop a greater understanding of the process of pore generation so that it might be tailored for these exacting applications. The build process will be simplified to understand how the salt powder "reacts" to the laser (melting or evaporating) as a function of heat input, salt size and different laser paths, where possible developing a model to mimic the phenomena observed. Information from observations and modelling will then be used to create porous Ti structures with variable pore geometries by simple "in-process" adaptations. The outcome is expected to be a "map" of the effect of material and process parameters on the pore structure in porous Ti structures. This will enable processing to be adapted to tailor the pore structures to match those required for optimum mechanical performance, fluid transport and cell response.