The major limiting reliability component of cryogenic systems has always been seals. Besides contributing to gas contamination and debris particle accumulation, seals have physically failed; as a result, seals have been responsible for the majority of failures occurring in cryogenic liquefaction and refrigeration systems. A potentially viable solution is the development of long-life cryogenic seals employing hard-on-hard, wear-resistant materials combination, i.e., an unlubricated hard material sealing against, another hard material with minimal ensuing wear. This approach has been utilized before for seals on machinery operating in both abrasive and extreme temperature environments. The Phase I primary objective is the design and analysis of a seal configuration promising 30,000 hours MTBF and suitable for further development during Phase II. Divided into four tasks, Phase I includes ambient and cryogenic temperature wear and friction testing of candidate hard materials and preliminary design and analysis of several proposed seal configurations. The anticipated results are the selection of several candidate ceramic-like hard materials suitable for cryogenic seal applications, measurement of the wear and friction coefficients at ambient and cryogenic temperatures for several hard materials, including ceramics, cermets, and intermetallics, and the preliminary design and analysis of several candidate long-life cryogenic seals.The potential applications as described by the company: Except for a very few cases, cryogenic refrigeration and liquefaction systems have always been primarily support systems for other major technologies, and the cryogenic systems have been the "Achilles heel" in relationship to the total systems. Consequently, the major benefit, though indirect, of the proposed research and development of long-life cryogenic seals, is the rapid acceptance and/or increased market viability of several new high-technology areas, e g., superconducting power generation and transmission systems, advanced superconducting computers, cryopumps, cryocoolers for instrumentation, airborne, and spacecraft applications, and small, dedicated laboratory cryogenic systems.
