h-BNの水熱腐食挙動

概要

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Corrosion behavior of powdered, hot-pressed, and pyrolytic boron nitride was investigated under hydrothermal conditions at 120℃ to 300℃ and saturated vapor pressure of water for 1 to 11 days. The reaction kinetics of the corrosion of hexagonal boron nitride (BN) were found to obey linear rate law. Scanning electron microscopic (SEM) observations of the BN powder after hydrothermal corrosion showed that the rate of hydrothermal attack by H_2O was determined by anisotropy due to crystallographic orientation. The weight loss of hot-pressed BN specimens was greater than that of pyrolytic BN specimens at each temperature. This result may be explained by the difference in the B_2O_3 content and the microstructure due to the processing of materials. The corrosion rate of hexagonal BN in hydrothermal corrosion could be expressed by the chemical reaction controlled kinetics with the apparent activation energy around 60 kJ/mol.
1993-08-01