Effect of an annealing treatment on the microstructure and EMW-absorbing properties of SiCw/Si3N4 ceramics fabricated by 3D printing

摘要

? 2022 Elsevier Ltd and Techna Group S.r.l.SiC whisker (SiCw)/Si3N4 ceramics were prepared via selective laser sintering (SLS) and precursor infiltration pyrolysis (PIP) to achieve good electromagnetic wave (EMW) absorption performance. The as-pyrolyzed composite ceramics were annealed at 1200–1600 °C in a N2 atmosphere. The microstructural variation, phase evolution, and EMW-absorbing properties of the SiCw/Si3N4 ceramics were subsequently studied. SiC whiskers were generated in the composite ceramics during pyrolysis, and their content increased as a function of the annealing temperature. An increase in the SiCw content of the annealed samples improved the reflection loss of the composite ceramics. The absorption properties of the SiCw/Si3N4 ceramics first degraded and then improved with increasing annealing temperature. Among all the samples tested, the composite ceramics annealed at 1600 °C showed the optimal EMW absorption performance in the range of 2–18 GHz due to the lower content of free carbon and higher content of SiCw. The ceramics annealed at 1600 °C exhibited a superior absorption loss of ?14.1 dB and an effective absorption bandwidth of 2.16 GHz. These results demonstrate that the EMW-absorbing performance of the SiCw/Si3N4 ceramics was significantly improved after annealing at 1600 °C. Thus, SiCw/Si3N4 composite parts with complex shapes were successfully manufactured by combining the SLS and PIP processes.