Characterization of a non-organofunctional silane film deposited on Al, Znand Al-43.4Zn-1.6Si alloy-coated steel - Part II. Interfacial characterization by ToF-SIMS and AES

Time-of-night secondary ion mass spectrometry (ToF-SIMS) has been used to a nalyse the interface between a non-organofunctional silane and three differ ent metal substrates (aluminium, zinc and an aluminium-zinc alloy). Ion etc hing using Ga+ ions was used to expose the interfacial region. Ion fragment s from the samples were examined carefully where supposed metal-oxygen-sili con ion fragments should appear in the mass spectra. From high mass resolut ion spectra it was concluded that there exists an AlOSi+ ion fragment at no minal mass m/z = 71 amu on the aluminium and aluminium-zinc alloy substrate s and a ZnOSi+ ion fragment at nominal mass m/z = 108 amu on the zinc and a luminium-zinc alloy substrates. These results are further enhanced by the f act that the characteristic ion pattern of ZnOSi+-type ion fragments, compo sed of different naturally stable zinc and silicon isotopes, in the mass ra nge m/z = 108-112 amu showed the expected relative peak height relations. The presence of these metal-oxygen-silicon ion fragments is a strong indica tion that chemical interaction between the silane and the metal substrates exists and that the nature of this interaction is due to the formation of a covalent bond between the silane and the metal substrate. Copyright (C) 20 01 John Wiley & Sons, Ltd.