Release of water and hydrogen during outgassing of some materials

Abstract

An outgassing (vacuum annealing) procedure was used in combination with mass spectrometry to study gas release from pure copper, pure silicon, an Al97Mg alloy, and type 316 stainless steel. This paper focuses on the possibility of separating the different contributions to the total outgassing of a sample that has undergone a typical surface preparation procedure. These contributions have been divided into (1) release from bulk, (2) species introduced in grinding, and (3) species due to air exposure at room temperature. The reaction chamber was made of quartz and stainless steel, and the water release from these surfaces was measured separately. In air exposure of the reaction chamber walls, an uptake corresponding to one to two monomolecular layers of water was measured. This water layer was 85 % desorbed in vacuum after 120 h at room temperature. The detection limit of the method is ∼50 ppb hydrogen, and all samples investigated contained hydrogen in the 1000 ppb range. The species introduced during grinding were considerable, except for silicon. A significant hydrogen release was found for silicon and Al97Mg as a result of air exposure at room temperature, but not for copper or type 316 stainless steel.