Realization of vat photopolymerisation of dense SiC ceramics with SiO₂/MgSO₄ coated sub-micron powders for efficient heat dissipation

• Main Authors: Ho, Terence Yan King, Ng, Andrew Yun Ru, Ye, Pengcheng, Tan, Hui Teng, Lock, Daniel Wen Hao, Du, Zehui, Gan, Chee Lip
• Other Authors: School of Materials Science and Engineering
• Format: Article
• Language: English
• Published: 2023
• Subjects: Engineering; Vat photopolymerisation 3D printing; Cure depth
• Online Access: https://hdl.handle.net/10356/171426
• Institution: Nanyang Technological University

Vat photopolymerisation (VP) 3D printing of SiC ceramics offers significant geometrical flexibility in shaping and thus enable their wider applications in energy management, aerospace and defence. However, their fabrication via VP remains challenging due to strong UV absorption and high refractive index of the SiC particles. Current approaches in realizing VP of SiC ceramics have been largely limited to improving cure depths of SiC ceramic paste, but at the detriment of sintering activity. In this work, we present a novel SiO2/MgSO4 bilayer coating strategy to modify SiC sub-micron particle surfaces which results in a simultaneous improvement on the cure depth of derived pastes and the densification of the printed green bodies. High cure depths of 40 – 50 µm were achieved and printed SiC ceramics with relative density of 82.8 ± 3.0% were realized without any post-infiltration processing. The effects of the bilayer coating on the cure depth and width of derived SiC pastes were studied systematically, and mechanistic insights were elucidated. The obtained SiC ceramics possessed flexural strength of ∼160 MPa and thermal conductivity of 40 W m−1 K−1, comparable to that of many other printed SiC ceramics which required tedious post-infiltration processing for densification. Furthermore, the application of the printed SiC ceramics as a heat sink was demonstrated to exhibit heat dissipation efficiency comparable to conventional aluminium heat sinks, despite possessing about 2–8 times lower thermal conductivity. Our work paves a way for VP 3D printing of various carbide ceramics where similar challenges are faced.