Dense AlN/FeSiAl composite ceramics with high thermal conductivity and strong microwave absorption

A series of AlN/x wt% FeSiAl composite ceramics with 4 wt% Y2O3 sintering aid was fabricated by pressureless sintering in a nitrogen atmosphere. Effects of FeSiAl content (0-20 wt%) on the phase, microstructure, mechanical, thermal, electromagnetic, and corresponding microwave absorption properties of the composite ceramics were studied. AlN/FeSiAl composite ceramics comprised of AlN, AlYO3, and Al2Y4O9 phases, and were fully dense with uniform microstructure. The micro-hardness, flexural strength, and thermal conductivity of the composites decreased with an increase in FeSiAl content. AlN with 5 wt% FeSiAl composite ceramic exhibited the minimum reflection loss of - 57.31 dB at 14.32 GHz, an effective absorption bandwidth (< - 10 dB) of 1.48 GHz in 13.63-15.11 GHz, a high thermal conductivity of 130.18 W (m K)(-1), a micro-hardness of 1002.28 HV, and a flexural strength of 356.80 MPa, which is promising for microwave absorbing material.