Preparation,dielectric property and microwave absorption property of Cu doped SiC nanopowder by combustion synthesis

Cu doped SiC nanopowders have been prepared via combustion synthesis, using silicon powder and carbon black as the raw materials, copper powder as the doping source and polytetrafluoroethylene as the chemical activator respectively. The microstructure of prepared nanopowders has been characterised by X-ray diffraction and scanning electronic microscope. The electric permittivities of prepared SiC nanopowders in the frequency range of 8·2–12·4 GHz have been determined. Results show that prepared β-SiC nanopowders have fine spherical particles and narrow particle size distribution, and a quantity of SiC whisker increases with increasing Cu doping content. The Cu₃Si impurity has been generated when Cu content is up to 10%. The β-SiC doped with 10% Cu has the highest real part ϵ′ and dielectric loss tanδ values. The 5% Cu doped SiC nanopowder with matching thickness of 2 or 2·5 mm exhibits the best microwave absorption properties in the frequency range of 8·2–12·4 GHz.