Characterization of AlN-based Ceramic Composites for Use as Millimeter Wave Susceptor Materials at High Temperature: Hig
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MRS Advances © 2019 Materials Research Society. This is an Open Access article, distributed under the terms of the Creative Commons Attribution licence (http:// creativecommons.org/licenses/by/4.0/), which permits unrestricted re-use, distribution, and reproduction in any medium, provided the original work is properly cited. DOI: 10.1557/adv.2019.142
Characterization of AlN-based Ceramic Composites for Use as Millimeter Wave Susceptor Materials at High Temperature: High Temperature Thermal Properties of AlN:Mo with 0.25% to 4.0% Mo by Volume Brad W. Hoff1, Frederick W. Dynys2, Steven C. Hayden3, Rachael O. Grudt3, Martin S. Hilario1, Anthony E. Baros1, Michele L. Ostraat3 1
Air Force Research Laboratory, Kirtland AFB, NM, 87117, USA
2
NASA Glenn Research Center, Cleveland, Ohio 44135, USA
3
Aramco Research Center – Boston, Aramco Services Company, Cambridge, MA 02139, USA
ABSTRACT In order to begin to evaluate and model the suitability of high temperature ceramic composites, such as AlN:Mo, as susceptor materials for power beaming applications, the electromagnetic, thermal, and mechanical properties of the material must be known at elevated temperatures. Work reported here focuses on the development of thermal property datasets for AlN:Mo composites ranging from 0.25% to 4.0% Mo by volume. To calculate thermal conductivity of the AlN:Mo composite series, specific heat capacity, thermal diffusivity, and density data were acquired. The calculated specific heat capacity, Cp, of the set of AlN:Mo composites was, on average, found to be approximately 803 J/kgK at 100 °C and to increase to approximately 1133 J/kgK at 1000 °C, with all values to be within +/- 32 J/kgK of the average at a given temperature. These calculated specific heat capacity values matched values derived from DSC measurements to within the expected error of the measurements. Measured thermal diffusivity, α, of the set of AlN:Mo composites was, on average, found to be approximately 3.93 x 10-1 cm2/s at 100 °C and to increase to approximately 9.80 x 10-2 cm2/s at 1000 °C, with all values within +/- 1.84 x 10-2 cm2/s of the average at a given temperature. Thermal conductivity, k, for the set of AlN:Mo composites was found to be approximately 108 W/mK at 100 °C and to decrease to approximately 38 W/mK at 1000 °C, with all values within +/- 5.3 W/mK of the average at a given temperature.
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Data trends show that increasing Mo content correlates to lower values of of Cp, α, and k at a given temperature.
1. INTRODUCTION: In some wireless power transfer systems employing thermo-mechanical conversion methodologies [1]–[3], bulk susceptor materials are required to convert microwave or millimeter wave radiation into thermal power, which is, in turn, converted into electrical power by external means. These bulk suscept
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