Development of selective laser melting irregular open-cell titanium lattice structure to mimic the human cancellous bone

Open-cell titanium lattice structures produced by selective laser melting (SLM) are attractive for creation of patient-specific implants with high level of bone ingrowth. In this work, irregular SLM lattice structures made of titanium (cp-Ti) with an average beam thickness of 300 μm and an average porous size of 600 μm were investigated. Optimal processing conditions of SLM for obtaining irregular open-cell cp-Ti lattice structures with mechanical and porous geometry close to human cancellous bone were developed. It was observed that the main parameter of SLM affected on beam thickness is volumetric energy density. Influence of orientation of cubic samples on the construction platform (on the plane, on the edge or on the corner) on properties of lattice structures was investigated. The corner orientation was found to be optimal. It was shown that chemical etching is effective post-treatment method for obtaining required beam thickness and removing the attached powder particles. Optimal chemical etching conditions are the following: etching solution contains 30 mL HNO 3 + 45 mL HF + 120 mL water, etching time is 10 s. The elastic modulus and the elastic limit of etched lattice samples are 1.4–1.9 GPa and 44–51 MPa, respectively, which correlates with characteristics of human cancellous bone. Compression of samples during mechanical tests occurred without beams destruction. Corrosion characteristics of obtained etched and non-etched lattice structures in Hank's Balanced Salt Solution (HBSS) have been improved compared with cp-Ti bulk samples. The biological and medical tests of the obtained samples will be carrying out to determine biocompatibility, influence on the growth of bone tissue, permeability, etc.