Digital light processing and electromagnetic wave absorption performance tuning of SiOC/SiO₂ ceramics

SiOC ceramics have been applied to the fabrication of electromagnetic wave (EMW) absorbing metastructures by stereolithography and demonstrate excellent absorptivity due to the designability of the macrostructure. However, the pyrolysis of photosensitive polysiloxane preceramics may result in macroscopic cracking due to high mass loss and shrinkage. These factors can restrict the structural design flexibility. Combining high residual preceramics with appropriate solid phase fillers is one potential solution. In this study, two preceramics with high residual rates were physically blended with photosensitizing resins in various proportions. This was carried out with the objective of preparing photosensitized preceramics that have high ceramic yields and tunable dielectric properties in the final SiOC ceramics. Then, SiO₂ fillers were incorporated into the photosensitive preceramics for the first time to reduce pyrolytic shrinkage and used to match the impedance matching properties of SiOC ceramics in order to enhance EMW absorption performance. The SiOC/SiO₂ ceramics achieved a minimum reflection loss of −28.10 dB with a thickness of 1.90 mm. Additionally, the sample demonstrated an effective absorption bandwidth of 6.38 GHz at a thickness of 2.30 mm. The SiOC/SiO₂ ceramics have potential applications in the rapid preparation of all-dielectric electromagnetic metamaterials, which exhibit the simplicity of the raw material preparation process and the wide effective absorption bandwidth with a high ceramics yield.