The Effect of Graphite Addition on Thermal Conductivity, Microstructure, and Electrochemical Impedance Spectroscopy of AlN Ceramics

Graphite/ aluminum nitride (AlN) multiphase ceramics are pressureless sintered under 1850°C using Dy2O3 and CaF2 as sintering additives. The effects of added graphite on microstructure, thermal conductivity, and electrochemical impedance spectroscopy of AlN ceramics were investigated. It was found that with 1wt% graphite addition the thermal conductivity of AlN in the through-plane to can achieve 210W/(m·K), which 25% higher than that of AlN without graphite. The graphite addition eliminates the oxygen impurity in AlN by a carbon reduction reaction in form of nanosized Dy2O3 particles. From electrochemical impedance spectroscopy manifested that the activation energy (Ea,g) of samples in grains is increased from 0.784 eV to 1.112 eV, suggesting that the concentrations of defects and impurities of Graphite/AlN multiphase ceramics are lower than those of monophase AlN ceramics.

Preparation of Ti3C2Tx/NiZn Ferrite Hybrids with Improved Electromagnetic Properties

Ti3C2Tx/NiZn ferrite composites were synthesized using a co-precipitation hydrothermal method, and further consolidated using electric current field-assisted sintering technology. Nano NiZn ferrites were inserted into the Ti3C2Tx interlayers with uniform coverage on their surfaces. The incorporation of MXenes promoted the sintering kinetics of the NiZn ferrite ceramics. The electrical conductivity increased by six orders of magnitude compared to pure NiZn ferrite ceramics at room temperature. The present work provides a potential way to develop a large family of dense MXenes/ferrite multiphase ceramics. The multiphase ceramics could be potentially used for the on-beam-line higher-order mode load in advanced particle accelerators.