The vacuum brazing of aluminum is an established industrial process which relies on strict process and materials control for the successful joining of products such as heat exchangers. The operating procedures developed for vacuum brazing are largely empirical and the interaction between materials and processing on brazeability continue to be reviewed.
Changes to the surface of the filler metal and vacuum composition during simulated brazing cycles have been systematically investigated using a combination of surface analytical techniques together with residual gas analysis of the vacuum furnace atmosphere. This approach has been found to be particularly informative in characterizing the surface chemical and topographical changes which occur to the aluminum sheet during the brazing process. From this work a mechanistic model for vacuum brazing of aluminium has been developed.