STUDY OF ELECTRICAL RESISTANCE AND ABSORPTION OF MICROWAVE RADIATION IN AlN–SiC COMPOSITES WITH A HIGH SILICON CARBIDE CONTENT

Abstract

AlN–SiC ceramic composites suitable for for use as bulk microwave absorbers. With a large amount of experimental data, a relationship between the volume electrical resistance, the quality factor, and the absorption of microwave radiation in the frequency range of 30–40 GHz has been established in AlN–SiC semiconductor composites with a high content of silicon carbide particles. In the same batch of 100 products, the absorption of microwave radiation changes by only 10–15%. It is shown that the absorption of radiation increases with a decrease in the volume resistance in the AlN–50% SiC composites: the absorption coefficient increases by a factor of 5 (from 1.58 to 8.0 dB/mm) with a decrease in resistance by a factor of 8.9 (from 17.8 up to 2.0 kΩ). The scatter in the values of volumetric electrical resistance is probably related to the resistance of leading chains of different lengths, consisting of silicon carbide particles of different sizes. To increase the absorption of electromagnetic energy, AlN–SiC ceramic composites with a high content of silicon carbide should have a reduced volume resistance on the order of 1–2 kΩ.