Influence of oxidation on the dielectric and microwave absorption properties of the milled Ti₃SiC₂ powders

Ti₃SiC₂ powders with different characteristics were obtained by ball milling. The particle size decreased and the powder morphology changed from lamellar to flaky with the increasing milling time. As the milling time increased from 5 h to 20 h, the complex permittivity of Ti₃SiC₂ powders was enhanced and the absorption peak shifted toward the lower frequency range. The dielectric and microwave absorption properties of the Ti₃SiC₂ powders oxidized at high temperature were also investigated. The Ti₃SiC₂ powders milled for longer time were more easily oxidized because of the increasing surface area. The lamellar Ti₃SiC₂ powders were delaminated after oxidation at high temperature due to the mismatch of thermal expansion coefficients. The oxidation products (TiO₂ and SiO₂) formed on the surface slowed down the oxidation process of Ti₃SiC₂ powders. The complex permittivity and microwave absorption properties of Ti₃SiC₂ powders were decreased as the temperature raised from 25 °C to 700 °C.