High temperature synthesis and material properties of boron-enriched balk pyrolytic carbon.

[Display omitted] • A macroscopic amount of boron-enriched pyrolytic carbon is fabricated by the high-temperature low-pressure CVD process. • A two-phase crystalline system consisting of intertwined graphene layers nterspersed with boron carbide provids high microhardness of the material. • Tree-like dendritic structures are formed by adding into reactor a small amount of oxygen-containing compounds. • Vertical orientation of the graphite substrate planes allows comparative studying the material depending on the boron content. In this paper we report the synthesis and characterization of the boron-enriched pyrolytic carbon (B-PyC). In the research we aimed to propose a material demonstrating high strength characteristics and heat resistance, durability, chemical inertness and biocompatibility. The material has been synthesized by high temperature low pressure CVD method. The synthesis is carried out on the inner surface of a vertically oriented hollow graphite hexagonal prism heated to the temperatures 1450–1570 °C. Controlled low-density flows of nitrogen, boron trichloride and carbonaceous gas react in this zone producing B-PyC film deposited on the vertical graphite plates. Morphology, mechanical and physical properties of this material was investigated using X-ray diffraction, scanning and transmission electron microscopy, mechanical testing instrumentations, thermogravimetric and thermal analysis. It was found that during the synthesis a two-phase crystalline system is organized comprising fragments of graphene layers (pyrolytic carbon) and boron carbide B 4 C. Such a structure provides high mechanical properties of the material and their stability in a wide temperature range, heat resistance, chemical inertia and biocompatibility. Depending on the synthesis conditions, the micro hardness may vary in a wide range including the range 100–140 HV the most attractive for traumatology and cardiac surgery as well as for a variety of engineering applications. [ABSTRACT FROM AUTHOR]