Sublimation behavior of silicon nitride (Si$sub 3$$N$$sub 4$) coated silicon germanium (SiGe) unicouples

Conference · Wed Jan 01 00:00:00 EST 1975

OSTI ID:4170704

Stapfer, G; Truscello, V C

For the Multi-Hundred Watt (MHW) Radioisotope Thermoelectric Generator (RTG), the silicon germanium unicouples are coated with silicon nitride to minimize degradation mechanisms which are directly attributable to material sublimation effects. A program has been underway at JPL to determine the effective vapor suppression of this coating as a function of temperature and gas environment. The results of weight loss experiments, using Si$sub 3$$N$$sub 4$ coated hot shoes (SiMo), operating over a temperature range from 900$sup 0$C to 1200$sup 0$C, are analyzed and discussed. These experiments were conducted both in high vacuum as well as at different pressures of carbon monoxide (CO) to determine its effect on the coating. Although the results show a favorable vapor suppression at all operating temperatures, the pressure of the CO and the thickness of the coating have a decided effect on the useful life-time of the coating. (auth)

• Research Organization: Jet Populsion Lab., Pasadena, CA
• NSA Number: NSA-33-005663
• OSTI ID: 4170704
• Resource Relation: Conference: 10. intersociety energy conversion engineering conference, Newark, Delaware, USA, 17 Aug 1975; Other Information: See CONF-750812--. Orig. Receipt Date: 30-JUN-76; Related Information: Tenth intersociety energy conversion engineering conference
• Country of Publication: United States
• Language: English

Related Subjects

N47200* -Isotope & Radiation Source Technology-Isotopic Power Sources
070301* -Isotope & Radiation Source Technology-Isotopic Power Supplies-Design & Fabrication
*THERMOCOUPLES- COATINGS
*THERMOELECTRIC GENERATORS- THERMOCOUPLES
GERMANIUM
MIXTURES
PERFORMANCE TESTING
RADIOISOTOPE HEAT SOURCES
SILICON
SILICON NITRIDES
NESDPS Office of Nuclear Energy Space and Defense Power Systems