Effect of milling on dielectric and microwave absorption properties of SiC based composites

The electromagnetic and microwave absorption properties of SiC-epoxy composites with the variation in particle size of SiC and dispersion of different metals in SiC have been studied. The micronsized SiC powder was reduced to nanosized SiC powder using high energy planetary ball mill. The results show the significant influence of particle size on the electromagnetic and microwave absorption properties. With the reduction in particle size, complex permittivity and microwave absorption of the epoxy composites have increased to a good extent. For further improvement in microwave absorption, different metal particles were dispersed in the SiC powder and as a result the microwave absorption properties were improved significantly. The values of RL for as-received SiC are improved from −16.23 dB at 10.888 GHz to −37.08 dB at 10.888 GHz with Cr-metal powder dispersion and −43.35 dB at 10.300 GHz with Mn-metal powder dispersion in SiC with 10 h milling. The corresponding 10 dB absorption bandwidth increased from 1.932 GHz to 3.024 GHz for Cr and Mn-metal powder dispersion. This study suggests that the reduction in particle size and metal dispersion in the SiC matrix are effective means to improve microwave absorption.