RELEASE OF WATER AND HYDROGEN DURING OUTGASSING OF SOME MATERIALS

An outgassing (vacuum annealing) procedure was used in combination wit h mass spectrometry to study gas release from pure copper, pure silico n, an Al97Mg alloy, and type 316 stainless steel, This paper focuses o n the possibility of separating the different contributions to the tot al outgassing of a sample that has undergone a typical surface prepara tion 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 qu artz and stainless steel, and the water release from these surfaces wa s measured separately. In air exposure of the reaction chamber walls, an uptake corresponding to one to two monomolecular layers of water wa s measured. This water layer was 85% desorbed in vacuum after 120 h at room temperature, The detection limit of the method is similar to 50 ppb hydrogen, and all samples investigated contained hydrogen in the 1 000 ppb range. The species introduced during grinding were considerabl e, except for silicon. A significant hydrogen release was found for si licon and Als?Mg as a result of air exposure at room temperature, but not for copper or type 316 stainless steel.