The performance of reinforced materials, including ceramics, can be augmented by adding reinforcing fibers or particles and orienting them along a specific direction. In most conventional processes, these reinforcements are aligned parallel to each other with one preferential direction. However, concrete applications may require a material to exhibit locally specific properties. Also, at the macroscopic level, local tuning of the microstructure can benefit the global performance of an object, within a complex 3D shape. To investigate the local microstructural effects in ceramics and their composites, fabrications methods also need to be developed.
In this talk, I will present how to control the local microstructure of ceramics in 3D objects and our recent research on the microstructure-mechanical and other functional properties. More specifically, I will introduce 3D printing direct-ink-writing methods augmented with magnetic alignment capability that locally orient the reinforcing ceramic microplatelets as the liquid ink gets deposited. After printing, highly concentrated and oriented stacks of microplatelets were obtained which are then turned into polymer composites or ceramics after sitnering. By varying the chemical composition of the reinforcing microplatelets, for example graphite, BN, alumina, even copper, bulk objects can be obtained with locally designed properties for optimization of the performance of the object. Inks can also be printed together in a multimaterial platform for even more capabilities. For example, we printed a mechanical sensor whose sensibility is designed by the microstructural patterns and that cools down thanks to the integrated thermal management. Using local microstructural patterns also enable to obtain unique properties such as a high thermal conductivity of 12 W/mK in BN composites, directed heat transfer in bulk materials, strength and toughness, etc. By locally microstructuring composite materials, we can therefore design the performance of 3D objects.
 
References:
L. Guan, J. Fan, X.Y. Chan, H. Le Ferrand, Continuous 3D printing of microstructured multifunctional materials, Additive manufacturing 62, 103373 (2023).
W.C. Liu, V. Chou, R.P. Behera, H. Le Ferrand, Magnetically assisted drop-on-demand 3D printing of microstructured multimaterial composites, Nature Communications, 13 (2022), 5015.  
H. He, W. Peng, J. Liu, X.Y. Chan, S. Liu, L. Lu, H. Le Ferrand, Microstructured BN composites with internally designed high thermal conductivity paths for 3D electronic packaging, Advanced materials, 34 (2022), 2270266.