ULTRA LOW OUTGASSINGTM SILICONE MATERIALS

摘要

The Aerospace Industry has used silicone adhesives and coatings for over five decades1. Silicones ability to maintain its elasticity and low modulus over a broad temperature range, -130 to 260 deg C, provides excellent utility in space, where spacecraft are often exposed to these extreme temperatures. The National Aeronautics & Space Administration (NASA) and the European Space Agency (ESA) recommend testing low outgassing materials per ASTM E-595 prior to use in space. 2 These materials should meet the specifications outlined in NASA SP-R-0022A and ESA PSS-014-702, which require a maximum Total Mass Loss (TML) of 1 percent and Collected Volatile Condensable Material (CVCM) of 0.1 percent . TML and CVCM levels higher than this specification can cause outgassing and subsequent contamination of expensive equipment. Although a standard for many years, many in the industry question whether these specifications are low enough. Boeing Satellite suspects gaseous emission contamination has caused excessive power degradation on six 702 satellites The large solar panel temperatures reach greater than 120 deg C and surface temperature strongly affects contamination buildup and can volatilize larger molecules. The Aerospace Corporation performed a contamination analysis comparing two different temperature solar arrays. This comparison showed high temperature arrays can contaminate to a greater degree. This paper will characterize newly developed ultra low outgassing. materials with TML and CVCM one-tenth the previous specifications. Characterization will include physical, outgas, and optical testing and comparisons will be made to standard materials meeting the basic outgassing requirements.