| range up to 200°C. It also
shows that ECD-006 has an acceptable outgassing rate at 300°C where Viton
literally decomposes, as indicated by violent pressure bursts observed on
the gauges. ECD-006, even when heated at 400°C, did not decompose as
violently as Viton at 300°C. It is also interesting to note that the
initial outgassing rate of ECD-006 at 300°C is only 3-5 times greater
than that of the stainless-steel blank.
The valve test that was performed used a valve that was
designed to have a maximum bake temperature of 125°C in the closed
position and 200°C in the open position if Viton-A was used for the main
seal. A later design of this valve (Varian 951-5012) can be baked to
200°C in both open and closed positions because of a mechanical
modification to reduce the problems of expansion and thermal set. With the
ECD-006, bakeout at 300°C in the old style valve was accomplished without
difficulty. Also, within the precision of these measurements, the room
temperature outgassing rate of ECD-006 was comparable to polyimide. |
The evidence of this
study indicates that the vacuum properties of ECD-006 are such that it
canbe used as a substitute for polyimide in the room temperature to 300°C
operating regime. The measurements also indicate that more accurate tests
should be made of the outgassing rates of ECD-006 and that its helium
permeability, water absorption, and radiation resistance should be
determined along with chemical character of the outgassing.
ACKNOWLEDGMENT
We wish to acknowledge the able assistance of R. P. Smus
in various phases of this work.
1C.
M. Van Atta, Vacuum Science and Engineering (McGraw-Hill, New York, 1965).
2 B. R. F. Kendall and M. F. Zabielski, J. Vac. Sci. Technol.
3, 114 (1966).
3 A. L. Barney, G. H. Kalb, and A. A. Khan, Rubber Chem.
Technol. 44 660 (1971).
4 G. H. Kalb, R. W. Quarles, and R. S. Graff, Appl. Polym. Symp.
22, 127 (1973).
6ECD-006 has been given the trade name
Kalrez. |
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