Additive Manufacture of Porous Ti Using Sacrificial Porogens

用于医疗应用的多孔钛结构可以通过增材制造制成，但通常构建为晶格结构，这不仅需要对激光路径进行复杂的编程，而且无法实现必要的细胞响应所需的孔几何形状和连通性。最近的研究表明，多孔钛结构，并建立了“传统”的方法，使用混合粉末床组成的钛和细盐（NaCl）。孔隙度是通过溶解掉水中的残余盐（致孔剂）来显示的。所获得的结构看起来非常有前途，但孔的几何形状并不总是成孔剂的几何形状的直接复制。这个博士研究计划将寻求发展孔隙生成过程的更好的理解，以便它可能是为这些严格的应用程序量身定制。构建过程将被简化，以了解盐粉如何作为热输入、盐尺寸和不同激光路径的函数对激光进行“反应”（熔化或蒸发），并在可能的情况下开发模型来模拟观察到的现象。然后，通过简单的“过程中”调整，将观察和建模信息用于创建具有可变孔几何形状的多孔钛结构。预计结果将是材料和工艺参数对多孔钛结构中孔结构影响的“图谱”。这将使加工能够适应于定制孔结构，以匹配最佳机械性能、流体输送和细胞响应所需的孔结构。

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.