Skip to main content
U.S. Department of Energy
Office of Scientific and Technical Information

The low temperature hexagonal to orthorhombic transformation in Si{sub 3}N{sub 4} reinforced BAS matrix composites

Journal Article · · Journal of Materials Research
;  [1]; ;  [2]
  1. Department of Mechanical and Aerospace Engineering and Materials Science and Engineering Program, University of Texas at Arlington, Arlington, Texas 76019-0031 (United States)
  2. High Temperature Materials Laboratory, Oak Ridge National Laboratory, Oak Ridge, Tennessee 37831-6064 (United States)
The amount of Si{sub 3}N{sub 4} in a Si{sub 3}N{sub 4}-BaO{center_dot}Al{sub 2}O{sub 3}{center_dot}2SiO{sub 2} (BAS) composite and the time of sintering was examined in the context of the low temperature hexagonal to orthorhombic transformation in BAS. It was found that with increasing amounts of Si{sub 3}N{sub 4} in the composite, the temperature of the hexagonal to orthorhombic transformation was decreased. As the sintering time was increased for a given composite composition, a drop in the temperature of the hexagonal to orthorhombic transformation was observed, which was linked to an increase in the {beta}-Si{sub 3}N{sub 4} content in the composite. In addition, as the Si{sub 3}N{sub 4} content in the composite was increased, a resultant drop in the coefficient of thermal expansion of the composite occurred. The extent of the linear dimensional change of the composite during the BAS hexagonal to orthorhombic transformation is reported.
Research Organization:
Oak Ridge National Laboratory
DOE Contract Number:
AC05-84OR21400
OSTI ID:
44515
Journal Information:
Journal of Materials Research, Journal Name: Journal of Materials Research Journal Issue: 5 Vol. 10; ISSN JMREEE; ISSN 0884-2914
Country of Publication:
United States
Language:
English