Surface Treatment of Ti-45Nb Open Porous Structures towards Biomedical Applications: A Modified Approach

Open-porous structures from ß-type Ti-45Nb, as a new biomaterial with an excellent biocompatibility, are produced by selective laser melting (SLM). However, the products commonly suffer from uncontrolled surface issues such as staircase effect and non-melted (or partially fused) powder particles (originating from the SLM production stage). This work is to resolve these issues by modifying the chemical etching protocol, used for surface modification of Ti-based porous structures, by adding a preliminary thermal oxidation step. It is found that a successful removal of non-melted and partially fused powder particles can be achieved through the modified surface treatment protocol. The etching also decreases the surface roughness alternations of the struts as an inevitable consequence of the SLM process. These improvements are accompanied with side effects such as excessive strut thinning and preferential material removal at nodal zones. This, however, may be resolved through improving the design at the production stage.