AVS 53rd International Symposium
    Vacuum Technology Wednesday Sessions
       Session VT-WeA

Paper VT-WeA4
Ground Simulation Studies of Commercially Available Coatings and Adhesives for Low Earth Orbit Space Environment Applications

Wednesday, November 15, 2006, 3:00 pm, Room 2000

Session: Space-based Vacuum Applications and Instrumentation; Panel Discussion on Vacuum Science and Technology
Presenter: A. Laikhtman, Soreq NRC, Israel
Authors: A. Laikhtman, Soreq NRC, Israel
R. Verker, Soreq NRC, Israel
Y. Noter, Soreq NRC, Israel
E. Grossman, Soreq NRC, Israel
I. Gouzman, Soreq NRC, Israel
Correspondent: Click to Email
This work is dedicated to comparative ground simulation studies of two representative groups of materials: (i) black paints and (ii) adhesive coatings. Some of them are already in use in orbiting spacecrafts, mainly in optical systems, while others are considered for such applications. The paints and coatings discussed here are silicone-based or inorganic, alumina-based. Outgassing properties of the discussed materials were first evaluated by a standard outgassing test according to ASTM E595. These measurements do not provide, however, any information about the kinetics of the outgassing processes. The kinetic parameters characterizing outgassing of materials are of great importance, since they are used to evaluate the contamination and the associated degradation of optical space systems. Silicone-based materials are known to be a threat as a source of contamination, while inorganic coatings may be highly porous and, therefore, may aggregate molecular fragments from their environment followed by desorption of these fragments and contamination of neighboring parts. The experimental procedure was based on in situ monitoring of the contaminants by a quartz crystal microbalance (QCM) in a modified ASTM E595 system. It involved the following stages: (a) holding the sample at high temperature while keeping the QCM at low temperature; (b) cooling the sample and keeping it at room temperature without changing the QCM temperature, in order to isolate the contaminants re-emission process; and (c) increasing the QCM temperature to study the effect of temperature on the re-emission kinetics. In addition, chemical identification of the residual contaminants was performed by FTIR and UV spectroscopic measurements. Considerable differences in the outgassing kinetic parameters and contamination potentials were observed between the discussed materials. An analytical model was developed to derive the outgassing and re-emission kinetic parameters from the experimental data.