Speaker
Description
Existing societal challenges require advancing innovative, eco-friendly technologies and the capacity to manufacture 3D structures sustainably and profitably. Progress in caloric materials, such as magneto- or elasto-caloric compounds, as integral components of the forthcoming generation of energy-efficient devices, offer new opportunities for exploring potential breakthroughs in additive manufacturing. Metamagnetic shape memory alloys emerge as promising candidates for magnetic refrigeration due to their high entropy change through the first-order martensitic transformation. Nonetheless, it is essential to note that their crystalline phase destabilizes at elevated temperatures exceeding 300 $^{\circ}$C.
In this work, we formulated original inks and pastes tailored for cold extrusion printing techniques, enabling the fabrication of intricate 3D structures using high-performance NiMnSn-based magnetocaloric powders. A sustainable matrix of hydroxypropyl cellulose and deionized water as a solvent was used. The ink, comprising over 95 wt.$\%$ of powder, was carefully optimized to attain ideal viscosity, resulting in the capability to deposit a maximum of 250 layers with the utmost printing resolution (0.5 mm wall thickness).
The proposed post-processing for the printed structures involves two main steps: (i) specialized thermal treatments for desiccating the printed structures, eliminating the polymer via calcination, succeeded by sintering to achieve an all-metal structure, and (ii) nickel electrodeposition to protect the printed structure against corrosion. Furthermore, we demonstrate that incorrectly printed workpieces can be recycled by dissolving them in water, significantly minimizing material loss and improving the cost-effectiveness and environmental sustainability of the printing process.
Acknowledgements
The author gratefully thanks the support received from the Spanish Ministry of Science, Innovation and Universities through the grant number MCIN/AEI/10.13039/501100011033.
