Crystallization behavior of cubic boron nitride from an amorphous BN precursor via high-pressure, high-temperature treatment with controlled water addition. Issue 15 (November 2016)

• Record Type: Journal Article
• Authors: Mochizuki, Takahiro; Yamamoto, Yusuke; Idota, Naokazu; Kawamura, Fumio; Taniguchi, Takashi; Sugahara, Yoshiyuki
• Is Part Of: Journal of the European Ceramic Society. Volume 36:Issue 15(2016)
• Page Start: 3565
• Page End: 3569
• Publication Date: 2016-11
• Subjects: Cubic boron nitride -- High-pressure -- High-temperature treatment -- Amorphous boron nitride; Ceramic materials -- Periodicals; Composite materials -- Periodicals; Matériaux céramiques -- Périodiques; Composites -- Périodiques; Ceramic materials; Composite materials; Periodicals; Electronic journals; 666.05
• DOI: 10.1016/j.jeurceramsoc.2016.06.027
• Languages: English
• ISSNs: 0955-2219

Abstract

Abstract: Crystallization behavior of cubic boron nitride (c-BN) from amorphous boron nitride (a-BN) by high-pressure, high-temperature (HP-HT) treatment with the intentional addition of a controlled amount of water was studied. The a-BN precursor was prepared by pyrolysis of a boric acid-urea complex with urea/boric acid = 2 at 1000 °C for 3 h under an ammonia atmosphere. Hexagonal BN (h-BN) were initially crystallized from a-BN containing 2 mass% of water after HP-HT treatment at 7.7 GPa and 1200 °C, and the formation of c-BN was observed after 5 min. The crystallization of c-BN from a-BN containing 8 mass% of water after HP-HT treatment at 7.7 GPa and 1200 °C was observed even after 1 min, indicating that the crystallization of c-BN was promoted by increasing the amount of water added. In addition, since neither h-BN nor c-BN was crystallized from a-BN without intentional water addition after the same HP-HT treatment, the addition of water promoted the crystallization of both h-BN and c-BN from a-BN. Since no transformation from h-BN to c-BN was observed during HP-HT treatment at 7.7 GPa and 1200 °C, it was concluded that c-BN was directly crystallized from a-BN. After HP-HT treatment at 7.7 GPa and 1650 °C for 1 min, both h-BN and c-BN were crystallized from a-BN containing 8 mass% of water. These results clearly indicate that the addition of water has a positive effect on crystallization of c-BN from a-BN.