Corrosion of Al–Sn–Bi alloys in alcohol at high temperatures. Part I: Effects of the metallurgical structure of the alloys and the metal salt additions to alcohol

Corrosion of free machining Al alloys that contain Sn and Bi was investigated at 391-415K in 2-(2-(2-methoxyethoxy)ethoxy)ethanol (MEEE) and 2-(2-(2-butoxyethoxy)ethoxy)ethanol (BEEE) with/without SnCl2, Sn(OC2H5)4, FeCl3, and CuCl2. The Al-Sn-Bi alloy displayed severe pitting corrosion in MEEE as did the Al-Sn alloy in BEEE at 415K, and Sn and Sn/Bi were enriched on the surface of pits. Immersion tests of pure Al in MEEE containing Sn/Cu-salts at 415K also showed severe corrosion and the deposition of metallic Sn and Cu on the surface. The corrosion mechanisms are discussed in terms of the electro-catalytic activity of the Sn enriched on the surface.