The fracture behavior of a CVD crystalline Si{sub 3}N{sub 4}/amorphous Si{sub 3}N{sub 4} composite
Conference
·
OSTI ID:10104112
The mechanical properties of a chemically vapor deposited {alpha}-Si{sub 3}N{sub 4}/amorphous Si{sub 3}N{sub 4} composite were examined at 25{degree}C and up to 1400{degree}C using a microhardness tester. The composite consists of an amorphous matrix containing elongated {alpha}-Si{sub 3}N{sub 4} particles (5--50 {mu}m in diameter) which in some cases are radially microcracked. The conditions for spontaneous microcracking due to thermal residual stress are derived for a cylinder embedded in a matrix. Heat treatment of the composite at 1200{degree}C results in a microstructure where the matrix consists of nanometer-sized particles separated by thin (50 {angstrom}) layer of carbon. The indentation fracture toughness of the heat treated material improves remarkably due to extended microcracking through the carbon layer.
- Research Organization:
- Los Alamos National Lab., NM (United States)
- Sponsoring Organization:
- USDOE, Washington, DC (United States)
- DOE Contract Number:
- W-7405-ENG-36
- OSTI ID:
- 10104112
- Report Number(s):
- LA-UR--93-3614; CONF-931142--2; ON: DE94002646
- Country of Publication:
- United States
- Language:
- English
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