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The Improved Thermal Conductivity of a Potting Material for High-Power Fast Warm-Up Cathodes

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Abstract

With higher power, frequency and longer life of microwave tubes, cathode heater assembly is being modified to enhance the warm-up performance and reliability, which are governed by ceramics thermal conductivity, electrical resistivity and shrinkage. In present work, a potting material with a high thermal conductivity of 22.14 W/(m K) and low linear shrinkage of 5.5% was prepared using two kinds of alumina powders with different size and morphology. Aqueous slurries were produced for centrifugal casting. The highest solid loading slurries with 70 vol.% were obtained. Green body with relative density above 70% was easily made from slurries using centrifugal casting. Relative sintered density reached 86.75% maximum without any sintering aids. Rheological behavior of slurries, potting microstructure, sintering shrinkage and thermal conductivity were analyzed. Continuous particle distribution, series and parallel models were used to guide the powders proportion and explain the thermal conductivity. The potting material thermal conductivity experimental data agreed with the series and parallel models when the weight parameter ξ was between 0.3 and 0.5.

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Acknowledgments

This work was supported by the State Key Lab of Advanced Metals and Materials (Grant No. 2018-Z06). AV acknowledges support from the National Science Foundation (IRES 1358088).

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Authors and Affiliations

  1. Institute for Advanced Materials and Technology, University of Science and Technology Beijing, 30 Xueyuan Road, Haidian District, Beijing, 100083, China

    Xiaodong Zhang, Junjie Hao, Zhimeng Guo, Zhenhui Ji, Ji Luo, Cunguang Chen & Fang Yang

  2. Department of Mechanical Engineering, University of South Florida, Tampa, FL, 33620, USA

    Alex A. Volinsky

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  1. Xiaodong Zhang
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  2. Junjie Hao
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Correspondence to Junjie Hao.

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Zhang, X., Hao, J., Guo, Z. et al. The Improved Thermal Conductivity of a Potting Material for High-Power Fast Warm-Up Cathodes. J. of Materi Eng and Perform 27, 6701–6708 (2018). https://doi.org/10.1007/s11665-018-3760-5

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  • DOI: https://doi.org/10.1007/s11665-018-3760-5

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