Abstract: The interaction of oxide film with molten flux during aluminum brazing has been studied by means of X-ray powder diffraction. The following conclusions have been deduced: The swell- ing of aluminum oxide film is caused by Li~+ inserting into the vacancies of octahedral or tetrahedral structure of 0 atom skeleton in у-Al_2O_3 . The strength of oxide film decreases as the crytallinity increases by the treating of flux containing LiF.

Key words: molten salt flux, aluminum oxide film, X-ray powder diffraction