Investigation of Surface and Bulk Electrical Resistance of Pressureless Sintered AlN-50 wt % SiC Composites

This study examines the electrical resistance of pressureless sintered ceramic composites of AlN-50 wt % SiC, which are suitable for use as bulk microwave radiation absorbers. For four groups of samples with quality factors Q = 30, 33, 37, and 44, the average surface resistances are 42, 64, 92, and 136 k Omega, respectively, while the average bulk resistances are 2.8, 4.1, 5.2, and 7.0 k Omega, respectively. An analysis of the experimental data revealed a correlation between surface and bulk electrical resistance. In general, higher bulk resistance corresponds to higher surface resistance. Moreover, as the quality factor increases from 30 to 44, the surface resistance exceeds the bulk resistance by factors ranging from 14.7 to 19.5.