| AVS 57th International Symposium & Exhibition | |
| Vacuum Technology | Tuesday Sessions |
| Session VT+MS-TuM |
| Session: | Outgassing, Contamination Control, and Process Modeling |
| Presenter: | L.L. Wang, Los Alamos National Laboratory |
| Authors: | L.L. Wang, Los Alamos National Laboratory R.Y. Weinberg, Los Alamos National Laboratory K.A. Lao, Los Alamos National Laboratory |
| Correspondent: | Click to Email |
Hydrogen is dissolved in stainless steel during the initial phases of production and fabrication. At room temperature, the dissolved hydrogen slowly diffuses out of the stainless steel. For stainless steel vessels assembled from commercially available vacuum components, we consistently measured constant rates of gas pressure increase in these sealed stainless steel vessels after they had been evacuated to 1 x 10-7 torr. The pressure in a 97 cc stainless steel vessel can reach up to 0.8 torr in six months at room temperature. The gas accumulated in these vessels, previously vacuum baked at 150°C for 48 hours to remove adsorbed gas, was analyzed to be essentially hydrogen. To determine how effective high-temperature vacuum bake out is in reducing the hydrogen content in the stainless steel components, we undertook a study that involved vacuum bakeout of the components at 400°C for 10 days and analysis of the hydrogen contents of the components with and without the vacuum bakeout. The hydrogen concentrations were measured by a LECO analyzer. The results will be presented and compared with that predicted by the Fick’s law of diffusion.