Preparation And Absorbing Properties Of CuAlO₂ Material Modified By Fe Doping

The development of radar military radar detection technology has put forward higher requirements on the "thin,wide,light and strong" absorbing materials.At present,the design and application of microwave absorbing materials in the normal temperature and low and medium temperature fields are relatively mature.The research on high temperature absorbing materials has been relatively lagging behind.Finding better high temperature absorbing agents has also been the research direction of researchers.TiB2,MoSi2,Ti3SiC2,CoZr4(PO4)6 and other high-temperature compound absorbents with good oxidation resistance have attracted everyone's attention.CuAlO2 is a ternary compound semiconductor that exhibits p-type conductivity without being doped.Due to the limitation of conductivity,the practical application and development of CuAlO2 have been greatly restricted.In this paper,sol-gel method and solid-phase method were used to prepare CuAl1-xFexO2 absorbing materials with different Fe3+ doping contents.The phase composition,microstructure,electromagnetic parameters,and absorbing properties of the absorbing materials were studied under different process conditions.The effects of Fe3+ doping on the electromagnetic parameters and absorbing properties of CuAlO2 materials were discussed,and the absorbing mechanism of CuAl1-xFexO2 materials was analyzed.The main contents are as follows:(1)CuAlO2 powders were successfully prepared by a sol-gel method combined with calcination process.The xerogel decomposes into CuO and Al2O3 at about 375?.The formation temperature of the mesophase CuAl2O4 is about 750?.The formation temperature of the CuAlO2 phase is about 1020?.After calcining at 1100? for 4 hours,the pure phase CuAlO2 begins to form.The calcination temperature and calcination time have a significant effect on the phase composition,microstructure,electromagnetic parameters and microwave absorption properties of CuAlO2 powders.The calculation results show that when the calcination temperature is 1200? and the calcination time is 4.0 h,the prepared CuAlO2 powder has the best microwave absorption performance.The results show that when the thickness of the sample was 3.7 mm,the sample showed the most excellent microwave absorption property with a minimum RL o f-11.8 dB at the frequency of 9.9 GHz and RL below-7 dB in the whole measured frequency(8.2-12.4 GHz)and-10 dB in the frequency range of 9.1-10.9 GHz.(2)For CuAlO2 powders(sol-gel method)with different Fe3+ doping content,when the doping content is low,no other product hybrid phases were found in the diffraction pattern.As the doping content increases,CuO phase,Al2O3 phase and FeAl2O4 phase appeared.The Fe3+ doping has a greater influence on the electromagnetic parameters of CuAlO2 powder.The results show that when the Fe doping was 5%and the thickness of the sample was 3.93 mm,the sample showed the most excellent microwave absorption property with a minimum RL of-20.5 dB at the frequency of 9.86 GHz and RL below-10dB in the whole measured frequency(8.2-12.4 GHz).(3)Using Cu2O,Al(OH)3,Fe(OH)3 as reaction raw materials,CuAlO2 and CuAl1-xFexO2 ceramic materials with different Fe3+ doping contents were prepared by a solid state reaction method.The effects of sintering conditions and Fe3+doping amount on the formation,micro-morphology and microwave absorption properties of CuAlO2 ceramics were studied.When the sintering temperature is 1200?,the CuAlO2 phase is fully formed.The sintering temperature and sintering time have a significant effect on the density and microstructure of CuAlO2.When the sintering temperature is 1200? and the holding time is 5 h,the relative density of CuAlO2 ceramics reaches the maximum value of 0.87.(4)For different content of Fe3+ doped CuAlO2 ceramics(solid state reaction method),XRD test found that the increase of doping ratio will increase the lattice constant of the sample,the lattice distortion occurs,and the diffraction peak tends to shift to a small angle.With the increase of Fe3+content,sintering.The Fe3+doping has a great influence on the electromagnetic parameters of CuAlO2 ceramics.The results show that when the Fe doping was 3%and the thickness of the sample was 3.4 mm,the sample showed the most excellent microwave absorption property with a minimum RL of-36.4 dB at the frequency of 10.1 GHz and RL below-10dB in the whole measured frequency(8.2-12.4 GHz).