6. Microtextural and Microstructural Evolution in Poly[(Alkylamino)Borazine]-Derived Fibers During Their Conversion Into Boron Nitride Fibers

  1. Edgar Lara-Curzio
  1. Samuel Bernard,
  2. Fernand Chassagneux,
  3. David Cornu and
  4. Philippe Miele

Published Online: 26 MAR 2008

DOI: 10.1002/9780470291221.ch6

Mechanical Properties and Performance of Engineering Ceramics and Composites: Ceramic Engineering and Science Proceedings, Volume 26, Number 2

Mechanical Properties and Performance of Engineering Ceramics and Composites: Ceramic Engineering and Science Proceedings, Volume 26, Number 2

How to Cite

Bernard, S., Chassagneux, F., Cornu, D. and Miele, P. (2005) Microtextural and Microstructural Evolution in Poly[(Alkylamino)Borazine]-Derived Fibers During Their Conversion Into Boron Nitride Fibers, in Mechanical Properties and Performance of Engineering Ceramics and Composites: Ceramic Engineering and Science Proceedings, Volume 26, Number 2 (ed E. Lara-Curzio), John Wiley & Sons, Inc., Hoboken, NJ, USA. doi: 10.1002/9780470291221.ch6

Author Information

  1. Laboratoire des Multimatériaux et Interfaces (UMR CNRS 5615) University Claude Bernard - Lyon 1 43 Bd du 11 novembre 1918 Villeurbanne, France, 69622

Publication History

  1. Published Online: 26 MAR 2008
  2. Published Print: 1 JAN 2005

ISBN Information

Print ISBN: 9781574982329

Online ISBN: 9780470291221

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Keywords:

  • boron nitride fibers;
  • nanocrystals;
  • polymer-derived ceramic;
  • polymer fibers;
  • transmission electron microscopy

Summary

Boron nitride (BN) fibers were efficiently prepared from a B-aminoborazine-based polymer according to the Polymer-Derived Ceramic (PDC) route via melt-spinning and heat-treatments up to 1800°C in a controlled atmosphere. The microtextural and microstructural changes in the material during the polymer-to-ceramic conversion were investigated by means of electron microscopy and XRD observations. The microtexture of the fibers was featureless as glassy-like materials when fibers were exposed at temperatures below 1400°C. Mechanical properties of such amorphous fibers were poor at these temperatures. Upon further heating to 1500°C, the microstructure changed from disordered nanocrystals embedded into an amorphous phase to a turbostratic phase. This amorphous-to-crystalline transition was accompanied with a large increase in the mechanical properties. At 1800°C, the microtexture of the fibers was coarse-grained and was correlated to the identification of a “meso-hexagonal” BN phase with basal layers almost aligned along the fiber-axis in the material. Polycrystalline BN fibers exhibited high mechanical properties (σ = 1.4 GPa, E = 360 GPa) after curing of the polymer fibers at 400°C and subsequent pyrolysis of cured fibers at 1800°C.