Synthesis of Fine‐Grained Polycarbosilane‐Derived Ti₃SiC₂ with High‐Phase‐Fraction and Investigation of their Microwave Absorption Properties

Ti 3 SiC 2 (Titanium Silicon Carbide) represents a MAX phase that uniquely combines the merits of metals and ceramics. However, synthesis of fine‐grained Ti 3 SiC 2 especially through the polymer‐derived ceramic (PDC) route remains a challenge. This study synthesizes fine‐grained, high‐phase‐fraction Ti 3 SiC 2 using polycarbosilane (PCS) and nanosized Ti, Al, and Si powders as raw materials. Results reveal that the addition of 15 wt.% Al significantly enhance the formation of Ti 3 SiC 2 by promoting mass diffusion and reducing oxide impurities, resulting in a maximum Ti 3 SiC 2 content of 73.5 wt.%, compared to 27.7 wt.% from the sole addition of nanosized Ti powders. Further incorporation of 15 wt.% Si facilitates near‐complete conversion of residual TiC into Ti 3 SiC 2 due to the promotion of Ti 5 Si 3 formation and inhibition of excess TiC formation, yielding a high‐phase‐fraction Ti 3 SiC 2 phase (83.4 wt.%) with an average grain size of ≈473 nm. The synthesized Ti 3 SiC 2 phase can be reserved up to 1600 °C and superior electromagnetic wave (EMW) absorption performance, with a minimum reflection loss (RL) of −40.21 dB at 17.20 GHz and an effective absorption bandwidth (EAB) of 1.41 GHz for the Ti‐15Al‐PCS sample. The enhanced polarization loss attributed to interfacial effects, and optimized impedance matching, are responsible for this superior absorption performance.