Synthesis of in situ TiB{sub 2}/TiN Ceramic matrix composites from dense BN-Ti and BN-Ti-Ni powder blends
In the present research, near-net-shape in situ TiB{sub 2}/TiN and TiB{sub 2}/TiN/Ni composites were fabricated from cold-sintered BN/Ti and BN/Ti/Ni powder blends by pressureless displacement reaction synthesis or thermal explosion under pressure. In both approaches, the processing or preheating temperatures ({le}1,200 C) were considerably lower than those typical of current methods used for the processing/consolidation of ceramic matrix composites. Microstructural characterization of the materials obtained was performed using X-ray diffraction, scanning electron microscopy (SEM), and transmission electron microscopy (TEM). Mechanical properties were evaluated by measuring microhardness, fracture toughness, and three-point bending strength. Application of a moderate external pressure ({le}250 MPa) during self-propagating synthesis (SHS) synthesis was shown to be sufficient to ensure full density of the TiB{sub 2}TiN/Ni composite. The entire procedure of thermal explosion under pressure could be performed in open air without noticeable oxidation damage to the final product. The high fracture toughness of the in situ synthesized TiB{sub 2}/TiN/Ni composite (20.5 MPa{radical}m) indicated that the finely dispersed ductile Ni phase was effective in dissipating the energy of cracks propagating in the ceramic matrix.
- OSTI ID:
- 282250
- Report Number(s):
- CONF-950201--
- Journal Information:
- Metallurgical Transactions, A, Journal Name: Metallurgical Transactions, A Journal Issue: 8 Vol. 27; ISSN 0360-2133; ISSN MTTABN
- Country of Publication:
- United States
- Language:
- English
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Related Subjects
BORON NITRIDES
CHEMICAL REACTIONS
COMPOSITE MATERIALS
FLEXURAL STRENGTH
FRACTURE PROPERTIES
MECHANICAL PROPERTIES
MICROHARDNESS
MICROSTRUCTURE
NICKEL
PRESSURE DEPENDENCE
SCANNING ELECTRON MICROSCOPY
SYNTHESIS
TITANIUM
TITANIUM BORIDES
TITANIUM NITRIDES
TRANSMISSION ELECTRON MICROSCOPY
X-RAY DIFFRACTION