3D Printed Composites of Copper–Aluminum Oxides

The development of three-dimensional (3D) patterned Cu-based composites with Al2O3 matrix has significant potential for an array of uses in industrial applications ranging from aerospace to catalysis. However, to date, it was not possible to fabricate complex structures of these composites by applying conventional techniques. The 3D printing technique makes it possible to control the interconnectivity and porosity of printed materials such as ceramics, metals polymers, or composites. In this work, the 3D printing technique is used to fabricate 3D CuO/Al2O3 composites with complex geometries. To that end, Cu/Al2O3 inks were synthesized using copper nitrate as the copper precursor. Initially, the stability of two Al2O3 suspensions containing copper nitrate and copper sulfate was investigated by zeta potential measurements. The results showed that the suspension with copper sulfate possesses low stability, whereas the suspension with copper nitrate increases the stability of the Al2O3 suspension. Therefore, copper nitrate was the copper precursor selected to prepare the Cu/Al2O3 inks. Rheological tests (steady-state, dynamic oscillatory, and creep–recovery) were performed to investigate the effect of copper nitrate on printability of the ink. The results show that Cu-based inks have higher viscosity, yield stress, and elasticity than pure Al2O3 ink. Finally, complex composite structures were fabricated by 3D printing, and then consolidated by thermal sintering at 1400°C for 2 h in air. Characterization of crystalline phases, morphology, and distribution of Cu in the Al2O3 matrix was performed by X-ray diffraction, scanning electron microscopy, and energy dispersive spectroscopy measurements. The results supplied a simple approach to prepare stable and printable Cu/Al2O3 inks, which can also be used to fabricate periodic structures by 3D printing that should find new promising applications.