Vacuum components of aluminum for UHV and XHV - weldability and outgassing behavior

It has been shown that present-day aluminum alloys possess sufficient stability to produce aluminum CF flanges for multiple tightening cycles. In order to preserve the mechanical strength it is vitally important that the critical limiting temperature of the materials is not exceeded both during the production process and later in the application. Reproducible welding parameters guarantee vacuum tight welding seams with neat root formation. It could be verified experimentally that critical temperatures in the knife edge area will not be exceeded in case of design according to material properties and special welding parameters. Comparative measurements of identically designed vacuum chambers of stainless steel and aluminum proved that UVH conditions can be achieved much faster and with less energy input (lower bakeout temperature) with aluminum than with stainless steel.