Electromagnetic and microwave absorption properties of SiO₂-coated Ti₃SiC₂ powders with higher oxidation resistance

Dense SiO₂-coated Ti₃SiC₂ powders were prepared by the representative Stober route and heat treated process. The phase composition, microstructure, dielectric and microwave absorbing properties of the powders were characterized. XRD pattern reveals the existence of amorphous SiO₂ and SEM image shows the SiO₂ layer uniformly coated on Ti₃SiC₂ powders. Both the real and imaginary part of complex permittivity for the SiO₂-coated Ti₃SiC₂ powders decrease due to the insulating SiO₂ coating hiders the polarization and electric conductance loss effect. The oxidation resistance of the dense SiO₂-coated Ti₃SiC₂ powders at high temperature was improved. Although the complex permittivity of the powders decrease after oxidized at 600 °C, the dense SiO₂-coated Ti₃SiC₂ powders have larger dielectric constant compared with the bare Ti₃SiC₂ powders. In addition, the dense SiO₂-coated Ti₃SiC₂ presents better microwave absorption performance after oxidation. The results indicate the dense SiO₂ coating can improve oxidation resistance as well as microwave absorption performance of the Ti₃SiC₂ powders.