Low Outgassing of Silicon-Based Coatings on Stainless Steel Surfaces for Vacuum Applications

摘要

Comparative tests of stainless steel vacuum chambers and components with and without silicon-based passivation coatings showed exceedingly low rates of gas evolution from the coated surfaces. A variety of approaches have been used to illustrate the low outgassing qualities of vacuum systems and vacuum components modified with an amorphous silicon (a-Si) deposition layer. For example, the samples are heated and cooled in turn while the outgassing rates are recorded at temperatures up to 250℃. Base pressures ranged from 10~(-7) Torr to 2.5 x 10~(-10) Torr. In other experimentation, the outgassing characteristics of systems in the 10~(-5) to 10~(-7) Torr vacuum range are compared. The coatings are resilient, inert and capable of withstanding temperatures above 400℃. As well as their obvious potential for reducing outgassing rates in vacuum chambers thereby allowing shorter pump-down times with smaller vacuum pump systems, they have proved useful in minimizing errors due to thermal desorption in experimental metal-envelope ionization gauges operating down to the low 10~(-10) Torr range.