Sublimation behavior of silicon nitride /Si3N4/ coated silicon germanium /SiGe/ unicouplesFor 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 is under way to determine the effective vapor suppression of this coating as a function of temperature and gas environment. The results of weight loss experiments, using Si3N4 coated hot shoes (SiMo), operating over a temperature range from 900 C to 1200 C, are analyzed and discussed. These experiments were conducted both in high vacuum and 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 lifetime of the coating.
Document ID
19750061919
Acquisition Source
Legacy CDMS
Document Type
Conference Proceedings
Authors
Stapfer, G.
Truscello, V. C. (California Institute of Technology, Jet Propulsion Laboratory, Pasadena Calif., United States)
Date Acquired
August 8, 2013
Publication Date
January 1, 1975
Subject Category
Nonmetallic Materials
Meeting Information
Meeting: Energy 10; Annual Intersociety Energy Conversion and Engineering Conference