Electromagnetic wave absorbing materials at high-temperature are urgently needed for stealth aircrafts or aero-engines worked in harsh environments.In this contribution,cobaltcontaining siliconboron carbonitride(MOF/S...Electromagnetic wave absorbing materials at high-temperature are urgently needed for stealth aircrafts or aero-engines worked in harsh environments.In this contribution,cobaltcontaining siliconboron carbonitride(MOF/SiBCN)nanomaterials were prepared by pyrolyzing metal–organic framework,i.e.cobalt 2-methylimidazole(ZIF-67),and hyperbranched polyborosilazane.The rhombic dodecahedral ZIF-67 and cobalt element promoted in situ formation of dielectric loss phases,including SiC nanocrystals,CoSi nanocrystals and turbostratic carbons.The ZIF-67/SiBCN nanomaterials showed excellent microwave absorption both at room and elevated temperature.The minimum reflection coefficient(RC_(min))was-51.6dB and effective absorption bandwidth(EAB)is 3.93GHz at room temperature.At an elevated temperature of 600℃,the RC_(min) reached-30.29 dB and EAB covered almost the whole X-band(3.95GHz,8.45–12.4GHz).The ZIF-67/SiBCN nanocomposites are promising and useful platform for microwave absorbing materials at high-temperature.It may shed light on the downstream applications in designing next generation areo-engines and stealth aircrafts.展开更多
基金the grant from the National Natural Science Foundation of China(No.21875190)Innovation Team of Shaanxi Sanqin Scholars and the Natural Science Basic Research Plan for Distinguished Young Scholar in Shaanxi Province of China(No.2018JC-008)。
文摘Electromagnetic wave absorbing materials at high-temperature are urgently needed for stealth aircrafts or aero-engines worked in harsh environments.In this contribution,cobaltcontaining siliconboron carbonitride(MOF/SiBCN)nanomaterials were prepared by pyrolyzing metal–organic framework,i.e.cobalt 2-methylimidazole(ZIF-67),and hyperbranched polyborosilazane.The rhombic dodecahedral ZIF-67 and cobalt element promoted in situ formation of dielectric loss phases,including SiC nanocrystals,CoSi nanocrystals and turbostratic carbons.The ZIF-67/SiBCN nanomaterials showed excellent microwave absorption both at room and elevated temperature.The minimum reflection coefficient(RC_(min))was-51.6dB and effective absorption bandwidth(EAB)is 3.93GHz at room temperature.At an elevated temperature of 600℃,the RC_(min) reached-30.29 dB and EAB covered almost the whole X-band(3.95GHz,8.45–12.4GHz).The ZIF-67/SiBCN nanocomposites are promising and useful platform for microwave absorbing materials at high-temperature.It may shed light on the downstream applications in designing next generation areo-engines and stealth aircrafts.
