3D printing of porous SiC ceramics added with SiO2 hollow microspheres

Porous SiC ceramics were fabricated by 3D printing through selective laser sintering (SLS) and adding hollow spheres (AHS). The process was based on the mullitization of Al2O3 and kaolin, and the SiC particles were bonded by the mullite and melted SiO2. The pores were produced by the stacking of SiC particles, debonding of epoxy, and adding of SiO2 hollow microspheres. The phase composition, microstructure, porosity, and flexural strength of the porous SiC ceramics with and without SiO2 hollow microspheres were compared. Additionally, the effect of the sintering temperature, size, and mass fraction of the SiO2 hollow microspheres on the porous SiC ceramics was investigated. After the addition of the SiO2 hollow microspheres, an open porosity of 62.51% and flexural strength of 40.93 MPa were obtained for the porous SiC ceramics. Using the results, three types of hierarchically porous SiC structures with porosities ranging from 92-97% were manufactured by SLS combined with AHS.