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Results of experimental studies of aluminum nitride based composites with addition of silicon carbide and molybdenum having high microwave absorption are presented. The interconnection between high level of absorption and volume electrical resistance was observed: maximum absorption of 6.5±1,0 dB/mm corresponds to the electrical resistance of (4—5)·105 Ohm·m. Level of absorption of 3.5±0,5 dB/mm is revealed for the dielectric material with electrical conductivity of 1012 Ohm·m. The patterns detected during the study allow to predict the minimum and maximum levels of absorption of microwave energy in the two-phase composites based on aluminum nitride with molybdenum or silicon carbide, based on the measured volume of electrical resistance.

The paper presents the results of experimental studies of thermal conductivity and microwave absorption in aluminum nitride based composites with different percentages of silicium carbide and molybdenum. It is shown that the optimal composition of the studied materials is the composite with 46% of silicium carbide and 4% of molybdenum. This composition reveals high UHF-energy absorption level of 42 dB/cm in the frequency range of 9.5—10.5 GHz and high thermal conductivity of 65 W/(m*K).

Microwave attenuation in samples of a diamond micron powder based composite material structured by a nanocarbon binder vapor-deposited at subatmospheric pressure is measured at frequencies of 34.09 to 34.19 GHz in a cylindrical resonator at H mode. Return losses are determined from the measurements. Volume resistivity of the samples is measured. The potential of using diamond-containing structured composite materials as microwave radiation absorbers is demonstrated. [ABSTRACT FROM AUTHOR]