The thermal conductivity of silicon nitride with molybdenum disilicide additions

Conference · Fri Dec 31 04:00:00 EST 1993

OSTI ID:10178256

Beecher, S C; Dinwiddie, R B; Abeel, A M; Lowden, R A

Room-temperature thermal conductivity has been measured for a series of silicon nitride (Si{sub 3}N{sub 4}) matrix composites with molybdenum disilicide (MoSi{sub 2}) additions of 2, 5 10, 25 and 50 wt. %. Included in these measurements were a pure MoSi{sub 2} sample and a Si{sub 3}N{sub 4} sample containing only sintering aids. Aluminum oxide (Al{sub 2}O{sub 3}) and yttrium oxide (Y{sub 2}O{sub 3}) were added as the sintering aids, at approximately 6 and 2 respectively. When the amount of MoSi{sub 2} was increased to greater than 10 wt. %, the amount of the sintering aids necessary to densify the composite was decreased. No sintering aids were added to the pure MoSi{sub 2} sample. Thermal conductivities of the Si{sub 3}N{sub 4} sample without MoSi{sub 2} and the pure MoSi{sub 2} sample wee 36 W/m.K and 52 W/m.K respectively, which agree very well with the literature values for similar materials. No statistically significant changes were observed in the thermal conductivity for those samples containing up to 10 wt. % MoSi{sub 2}. However, between 10 and 25 wt. % MoSi{sub 2} there was a dramatic decrease in the thermal conductivity from 37 to 20.9 W/m.K. The thermal conductivity then increased steadily with further additions of MoSi{sub 2} up to 52 W/m.K for the pure MoSi{sub 2} specimen.

• Research Organization: Oak Ridge National Lab., TN (United States)
• Sponsoring Organization: USDOE, Washington, DC (United States)
• DOE Contract Number: AC05-84OR21400
• OSTI ID: 10178256
• Report Number(s): CONF-9311131--5; ON: DE94017757
• Country of Publication: United States
• Language: English

Related Subjects

36 MATERIALS SCIENCE
360204
360606
COMPOSITE MATERIALS
CONCENTRATION RATIO
MOLYBDENUM SILICIDES
PHYSICAL PROPERTIES
SILICON NITRIDES
THERMAL CONDUCTIVITY