SiZrCN nanocomposite ceramics were successfully prepared by using a single-source precursor synthesized from polysilazane and tetrakis(dimethylamido)zirconium.The synthesis route for the precursors,the polymer-ceramic conversion process,and structural evolution in ceramics at high temperatures were studied.The results indicate that modification of precursor can precisely control Zr content in ceramics and improve ceramic yield.After pyrolysis at 1 100℃,SiZrCN ceramics are amorphous.When the heat treatment temperature is equal to or higher than 1 500℃,SiZrCN ceramics are converted into nanocomposite ceramics that contain Si3N4 as the main phase,and evenly distribute ZrCN nanoparticles and free carbon.The introduction of Zr inhibits the carbothermal reduction of nitrogen-containing phases during the heat treatment,which significantly improves the high temperature stability of the ceramics(the mass loss proportion of SiZrCN ceramic at 1 600℃is only 1/3 of that of SiCN ceramic).The dielectric parameters of SiZrCN ceramics are regulated by changing Zr contents and microstructures of the ceramics,leading to excellent electromagnetic wave absorbing performance.Among SiZrCN ceramics,the 15SiZrCN-1500 ceramic has a minimum reflection loss of-61.02 dB and an effective electromagnetic wave absorption band width of 4.56 GHz at a thickness of 1.8 mm.The hetero-interfacial polarization,defect-induced dipole polarization,the conductive network formed by ZrCN nanoparticles and free carbon are the main reasons for the excellent electromagnetic wave absorbing performance of SiZrCN ceramics.
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