Synthesis of cubic boron nitride from boron nitride synthesized by pressure pyrolysis of borazine

Journal Article · Wed Aug 01 00:00:00 EDT 1990 · Journal of the American Ceramic Society; (USA)

DOI:https://doi.org/10.1111/j.1151-2916.1990.tb07582.x· OSTI ID:5855137

Hirano, S I; Fujii, A; Yogo, T; Naka, S ^[1]

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1. Nagoya Univ. (Japan). Faculty of Engineering

This paper reports cubic BN synthesized under high-temperature and -pressure conditions from BN Powder formed by Pressure pyrolysis of borazine below 700{degrees}C and 100 MPa. The conversion of BN powder to cubic BN was strongly influenced by the residual hydrogen identified by the BH/BN ratio of IR absorption band. The activation energy for cubic BN synthesis from BN powder-20 mol% AIN was 46 kJ/mol, when the starting BN was synthesized at 250{degrees}C. A mixture of BN powder and cubic BN particles was converted to cubic BN in the 100% yield by heat treatment at 1800{degrees}C and 6.5 GPa without any catalyst. The presence of cubic BN particles does enhance the conversion to cubic BN from BN powder. The energy required for the transformation of starting BN to cubic BN in the presence of cubic BN seed was 355 kJ/mol.

• OSTI ID: 5855137
• Journal Information: Journal of the American Ceramic Society; (USA), Journal Name: Journal of the American Ceramic Society; (USA) Vol. 73:8; ISSN JACTA; ISSN 0002-7820
• Country of Publication: United States
• Language: English

Related Subjects

36 MATERIALS SCIENCE
360201* -- Ceramics
Cermets
& Refractories-- Preparation & Fabrication
360202 -- Ceramics
Cermets
& Refractories-- Structure & Phase Studies
ACTIVATION ENERGY
BORON COMPOUNDS
BORON NITRIDES
CHEMICAL REACTIONS
DECOMPOSITION
ELEMENTS
ENERGY
HIGH TEMPERATURE
HYDROGEN
NITRIDES
NITROGEN COMPOUNDS
NONMETALS
PHASE TRANSFORMATIONS
PNICTIDES
POWDERS
PYROLYSIS
RESIDUAL STRESSES
STRESSES
THERMOCHEMICAL PROCESSES