《Characterization of AZ91 magnesium alloy and organosilane adsorption on its surface》.pdf

Applied Surface Science 253 (2007) 4197–4207 /locate/apsusc Characterization of AZ91 magnesium alloy and organosilane adsorption on its surface J. Kim a, K.C. Wong a, P.C. Wong a, S.A. Kulinich a, J.B. Metson b, K.A.R. Mitchell a,* a Department of Chemistry, University of British Columbia, 2036 Main Mall, Vancouver, British Columbia, Canada V6T 1Z1 b Light Metals Research Centre, University of Auckland, Private Bag 92019, Auckland, New Zealand Received 30 June 2006; received in revised form 29 August 2006; accepted 12 September 2006 Available online 16 October 2006 Abstract Oxide formation on a clean AZ91-Mg alloy surface has been characterized by X-ray photoelectron spectroscopy (XPS), while the chemical composition of a mirror-polished sample was assessed by scanning Auger microscopy (SAM) and scanning electron microscopy (SEM) at different microstructural regions, referred to as the grain boundary, matrix and particle regions. XPS and SAM confirmed that Mg and Al are always present in the surface regions probed, whereas bulk characterization with energy dispersive X-ray (EDX) analysis was necessary to detect the additional alloying elements, Mn and Zn. Coating by 1% solutions of BTSE, g-GPS and g-APS at their natural pH values gave etching of the surface Mg oxide. Adsorption occurs on the different regions, but the attachment is weak, especially because of the fragile nature of the underlying substrate. However, increasing the concentration of BTSE to 4% formed a thicker and denser coating with better prospects for substrate protection. # 2006 Elsevier B.V.