AVS 60th International Symposium and Exhibition
    Vacuum Technology Tuesday Sessions
       Session VT-TuP

Paper VT-TuP4
Vacuum Thermal Oxidation of a Stainless Steel Vacuum Chamber Following Citric Acid Cleaning

Tuesday, October 29, 2013, 6:00 pm, Room Hall B

Session: Vacuum Technology Poster Session and Student-Built Vacuum System Poster Competition
Presenter: T. Ha, POSTECH, Republic of Korea
Authors: T. Ha, POSTECH, Republic of Korea
S. Chung, POSTECH, Republic of Korea
C.D. Park, POSTECH, Republic of Korea
Correspondent: Click to Email
We perform vacuum thermal oxidation with a stainless steel vacuum chamber after citric acid cleaning to reduce the outgassing rate. Pure and dense chromium oxide layer on the surface of the stainless steel is considered to be a diffusion barrier for hydrogen atoms from the bulk. How to form such a high quality chromium oxide layer onto the surface is the key to reduce hydrogen outgassing and to reach extreme high vacuum with stainless steel vacuum systems. The vacuum thermal oxidation at 450oC in vacuum with low oxygen partial pressure is a proven treatment for that. We enhance the purity of the chromium on the surface of the stainless steel by citric acid cleaning before this vacuum thermal oxidation using the property that the citric acid is effective to reduce surface iron contents. The surface analysis results and the vacuum characteristics for this treatment are discussed in this paper.