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Hexagonal Boron Nitride from a Borazine Precursor for Coating of SiBNC Fibers using a Continuous Atmospheric Pressure CVD Process

Authors

  • Yaping Ye,

    1. Fraunhofer Institut für Silicatforschung, Würzburg (Germany)
    2. present address: Department of Functional Materials in Medicine and Dentistry, Universitätsklinikum Würzburg (Germany)
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  • Uta Graupner,

    1. Fraunhofer Institut für Silicatforschung, Würzburg (Germany)
    2. present address: Department of Earth and Environmental Sciences, Ludwig-Maximilians-Universität München (Germany)
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  • Reinhard Krüger

    Corresponding author
    1. Fraunhofer Institut für Silicatforschung, Würzburg (Germany)
    2. present address: Police Hamburg, LKA 33, Hamburg (Germany)
    • Department of Functional Materials in Medicine and Dentistry, Universitätsklinikum Würzburg (Germany)
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  • This work was funded by the Federal Ministry of Education and Research under grant number 03X 3514 B. We thank Anna Hilbig (Chair Chemische Technologie der Materialsynthese, Universität Würzburg) for her piece of work regarding the CVD reactor setup and Sabine Stöckel (Physical Chemistry Technische Universität Chemnitz) for helpful discussions in a previous project.

Abstract

The aim of this work is the coating of SiBNC fibers with hexagonal boron nitride (h-BN) for ceramic composite applications. h-BN is deposited from borazine in a vertical, hot-wall, atmospheric pressure (AP)CVD system. The effects of deposition parameters (e.g., temperatures, reactant concentrations, and gas velocity) on the deposition rates are investigated using Si(100) substrates statically placed at various positions in the reactor. The highest deposition rates are observed at 1090 °C. It is found that ammonia is necessary for a satisfying coating deposition and for low oxygen incorporation, though high concentrations decreased the deposition rate. The coating structures are characterized using scanning electron microscopy (SEM), X-ray diffraction (XRD), and Fourier transform infrared (FTIR) spectroscopy. Based on the results of static h-BN deposition on Si substrates, h-BN is continuously and homogenously coated on SiBNC multifilaments with a fiber draw speed of 5 m h−1. The thickness of the coating on SiBNC fibers is 180–200 nm as measured by SEM. The h-BN coatings from our experiments have no influence on the mechanical strength of the SiBNC fibers.

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