Journal of Inorganic Materials ›› 2013, Vol. 28 ›› Issue (5): 479-484.doi: 10.3724/SP.J.1077.2013.12349

• Orginal Article • Previous Articles     Next Articles

Synthesis and Microwave Absorbing Properties of PyC/BN Composite Powders

Wei ZHOU, Peng XIAO, Yang LI, Heng LUO, Liang ZHOU   

  1. State Key Laboratory of Powder Metallurgy, Central South University, Changsha 410083, China
  • Received:2012-05-25 Revised:2012-07-12 Online:2013-05-10 Published:2013-04-22
  • About author:ZHOU Wei. E-mail: zwzn@yahoo.cn

Abstract:

PyC/BN composite powders were synthesized via chemical reaction of boric acid, urea and PyC powders at 1750℃ for 6 h in nitrogen. The phases, chemical compositions, surface morphologies and oxidation resistance of PyC/BN composite powders were characterized by XRD, XPS, SEM and DTA/TGA instruments, respectively. The microwave absorption properties of PyC/BN composite powders were measured by using a microwave network analyzer in the frequency range of 2-18 GHz. The results show that generated h-BN particles are coated on the surfaces of PyC powders with the dimension from tens of nanometers to hundreds of nanometers. Compared with PyC powders, the oxidation resistance of PyC/BN composite powders is improved. The mass of PyC/BN composite powders remains over 50% at 1200℃ whereas PyC powders are oxidized completely at 940℃. Due to higher microwave impedance, electronic displacement polarization, interface polarization, multiple scattering and λ/4 destructive interference effect, the reflectivity peak of PyC/BN composite powders reaches -27.2 dB and the bandwidth of the reflectivity below -10 dB is 2.6 GHz under the same thickness (2 mm). And the reflectivity peaks are all less than -10 dB and multiple absorbing peaks appear with the increase of thickness. PyC/BN composite powders are supposed to be ideal microwave absorbers with lighter weight, high temperature resistance and strong microwave absorption.

Key words: PyC/BN composite powders, boron nitride, oxidation resistance, microwave absorption properties

CLC Number: 

  • TM25