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On the Stability of c-BN-Reinforcing Particles in Ceramic Matrix Materials.
- Source :
-
Materials (1996-1944) . Feb2018, Vol. 11 Issue 2, p255. 17p. 1 Black and White Photograph, 1 Diagram, 3 Charts, 5 Graphs. - Publication Year :
- 2018
-
Abstract
- Cubic boron nitride (c-BN) composites produced at high pressures and temperatures are widely used as cutting tool materials. The advent of new, effective pressure-assisted densification methods, such as spark plasma sintering (SPS), has stimulated attempts to produce these composites at low pressures. Under low-pressure conditions, however, transformation of c-BN to the soft hexagonal BN (h-BN) phase can occur, with a strong deterioration in hardness and wear. In the present work, the influence of secondary phases (B2O3, Si3N4, and oxide glasses) on the transformation of c-BN was studied in the temperature range between 1100 °C and 1575 °C. The different heat treated c-BN particles and c-BN composites were analyzed by SEM, X-ray diffraction, and Raman spectroscopy. The transformation mechanism was found to be kinetically controlled solution–diffusion–precipitation. Given a sufficiently low liquid phase viscosity, the transformation could be observed at temperatures as low as 1200 °C for the c-BN–glass composites. In contrast, no transformation was found at temperatures up to 1575 °C when no liquid oxide phase is present in the composite. The results were compared with previous studies concerning the c-BN stability and the c-BN phase diagram. [ABSTRACT FROM AUTHOR]
Details
- Language :
- English
- ISSN :
- 19961944
- Volume :
- 11
- Issue :
- 2
- Database :
- Academic Search Index
- Journal :
- Materials (1996-1944)
- Publication Type :
- Academic Journal
- Accession number :
- 128259839
- Full Text :
- https://doi.org/10.3390/ma11020255