IMPROVING SEALING ELEMENT QUALITY BY ION-PLASMA SPUTTERING

Abstract

The purpose of the work is to study the possibility of reducing leakages in the seals with metal O-rings (on example of a vacuum flange joint of the ConFlat standard) by ion-plasma sputtering deposition of a soft metal on the ring surface. The coating was applied using an original ion-plasma source with a liquid anode. The hermeticity of sealing o-rings of the CF40 joint was tested on an ultrahigh vacuum test bench with a XT-100M mass spectrometer quadrupole gas analyzer tuned to control the in-leakage of helium in the test bench vacuum chamber. Conducted experiments allowed to determine that the amount of in-leakage decreases under the reusing of a sealing ring sputtered with a copper coating. Ring surface micrographs were obtained using a scanning electron microscope. Sputtering deposition of a soft metal layer on the contact surfaces of a single-used metal ring restores surface sealing properties as well as reduces in-leakage as compared to a new liner. The effect is provided by the formation of a tight contact of the flange wedge solid metal with the surface of the plastic coating leveled along the entire circumference, which was restored by smoothing ring cavities formed during the previous tightening of the flange joint.