Dielectric and mechanical properties of the SiC_f/SiC-MgO composites prepared with precursor infiltration and pyrolysis

SiC_f/SiC composites with inert fillers MgO were fabricated with the precursor infiltration and pyrolysis (PIP) method. The effects of different MgO content on microstructure, mechanical and dielectric properties of SiC_f/SiC composites were investigated. The results indicate that the MgO fillers can help to compensate for volume shrinkage of matrix precursor. The flexural strength of the SiC_f/SiC composites is increasing with the increasing of MgO content. The maximum flexural strength of 213 MPa is obtained for composites with 15 wt% MgO, which is much higher than that of composites without fillers. The MgO particles with large specific surface area can result in the enhancement of energy dissipation and space charge distributions at the MgO/SiC interface. Both the ε′ and ε″ values of SiC_f/SiC composites increase from 12.7 to 30 and i10.8-i21.7 as the MgO content increases from 0 to 20 wt%.