AVS 50th International Symposium
    Vacuum Technology Wednesday Sessions
       Session VT-WeA

Paper VT-WeA10
High Vacuum Applications of Silicon-Based Depositions on Stainless Steel

Wednesday, November 5, 2003, 5:00 pm, Room 323

Session: Outgassing and Large Vacuum Systems
Presenter: D.A. Smith, Restek Corporation
Authors: D.A. Smith, Restek Corporation
B.R.F. Kendall, Elvac Associates
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Continuing tests of stainless steel components with a silicon-based deposition have shown progressively lower outgassing rates. Evolution of the coating process has led to significantly lower outgassing rates over a wide range of operating conditions when compared with untreated stainless steel and stainless steel surfaces cleaned via a combination of ultrasonic, heat and vacuum techniques. Experimentation was developed for comparing otherwise identical samples having various surface treatments and/or coating types. The samples are heated and cooled in turn while the outgassing rates are recorded at temperatures up to 250 degrees C. Base pressures ranged from 10@super -7@ Torr to 1.2 x 10@super -10@ Torr. The coatings are resilient, inert and capable of withstanding temperatures above 400 degrees C. Other surface aspects have been evaluated, including electronic characteristics and anti-galling traits. As well as the obvious potential for reducing outgassing rates in vacuum chambers thereby allowing shorter pump-down times with smaller vacuum pump systems, these coatings have proved useful in minimizing errors due to thermal desorption in experimental metal-envelope ionization gauges operating down to the low 10@super -10@ Torr range.