Surface study of Type 6063 aluminium alloys for vacuum chamber materials

Abstract

The surface characterization of Type 6063 aluminum alloy was performed with the use of various surface analysis techniques, such as Auger electron spectroscopy, scanning electron microscopy, optical microscopy, surface roughness factor and thermal desorption spectroscopy. The samples prepared by two different surface treatments were chosen for utilization as a uhv chamber material; namely, the surfaces prepared by extrusion (Sample A) and finished with diamond lathe (Sample B). The surface roughness factor of Sample A measured by xenon adsorption was 12.6 which was 2.6 times larger than that of Sample B. Carbon was the main impurity on the surface of Sample A, and oxygen on Sample B. Magnesium was found to segregate almost entirely on the surface of Sample B, while it segregated partially on Sample A after heating at 300°C. H 2O and CO were the main outgassing components below the practical baking temperature (150°C) for the aluminum alloys. The amount of gas released from Sample A was much larger than Sample B. This could be interpreted by the differences in the surface roughness factor and the thickness of the oxide layer.