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Proceedings Paper

Dimensional stability of high-purity Invar 36
Author(s): Witold M. Sokolowski; Stephen F. Jacobs; Marc S. Lane; Timothy P. O'Donnell; Cheng Hsieh
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Paper Abstract

High performance requirements for the Imaging Science Subsystem/Narrow Angle Camera (NAC) instrument on the NASA/Jet Propulsion Laboratory (JPL) Cassini spacecraft impose very stringent demands for dimensional stability of metering rods in the camera's athermalizing system. Invar 36 was chosen as a baseline material because it possibly could meet these requirements through high purity control and appropriate thermomechanical processes. A powder metallurgy process appears to be the manufacturing method to ensure high purity and cleanliness of this material. Therefore, a powder metallurgy manufacturer was contacted and high purity (HP) Invar 36 was produced per JPL engineering requirements. Several heat treatments were established and heat treated HP Invar 36 samples were evaluated. Coefficient of thermal expansion (CTE), thermal hysteresis and temporal stability test results are reported here. The test results indicate that JPL has succeeded in obtaining possibly the most dimensionally stable (lowest CTE plus lowest temporal change) Invar 36 material ever produced. CTE < 1 ppm/ degree(s)C are reported here along with temporal stability < 1 ppm/year. These dimensional stability properties will meet the requirements for metering rods on the NAC.

Paper Details

Date Published: 7 December 1993
PDF: 12 pages
Proc. SPIE 1993, Quality and Reliability for Optical Systems, (7 December 1993); doi: 10.1117/12.164978
Show Author Affiliations
Witold M. Sokolowski, Jet Propulsion Lab. (United States)
Stephen F. Jacobs, Optical Sciences Ctr./Univ. of Arizona (United States)
Marc S. Lane, Jet Propulsion Lab. (United States)
Timothy P. O'Donnell, Jet Propulsion Lab. (United States)
Cheng Hsieh, Jet Propulsion Lab. (United States)

Published in SPIE Proceedings Vol. 1993:
Quality and Reliability for Optical Systems
James W. Bilbro; Robert E. Parks, Editor(s)

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