AVS 53rd International Symposium
    Applied Surface Science Monday Sessions
       Session AS-MoA

Paper AS-MoA5
X-ray Photoelectron Spectroscopy (XPS) Multi-Spectral Imaging of Aluminum Alloy Surfaces using Principle Component Analysis

Monday, November 13, 2006, 3:20 pm, Room 2005

Session: Developing Methods for Data Analysis
Presenter: C.H. Lee, University of Manchester, UK
Authors: C.H. Lee, University of Manchester, UK
J. Walton, University of Manchester, UK
G.E. Thompson, University of Manchester, UK
M.R. Alexander, University of Nottingham, UK
Correspondent: Click to Email
Aluminum alloys are of technological importance in most market sectors, ranging from architecture through aerospace to electronics products. Consequently, such alloys are the subject of much interest, particularly the near-surface and surface properties, which influence behaviour such as corrosion and adhesion of subsequent coatings. The aim of this study is to spatially resolve constituent particles in selected aluminium alloys and to disclose their contributions to the adsorption of a self-assembled flourinated alkyl phosphonic acid (C@sub 10@F@sub 21@C@sub 2@H@sub 4@PO(OH)@sub 2@). Thus, XPS images have been obtained at small energy steps on both AA2024 T3 and AA6016 T4 aluminium alloys to maximize the acquired spectral information, which has been extracted using a multivariate statistical analysis approach (MVA) consisting of singular value decomposition (SVD) and principal component analysis (PCA).@footnote 1@ As a result, noise-reduced and background-corrected multispectral imaging has revealed the constituent second phase particles in the respective alloy systems, the particles distribution has been correlated with scanning electron microscope (SEM) and optical microscope images. Comparison of the surfaces before and after in-situ argon ion etching indicated preferential oxidation of aluminium formed with a copper enriched phase immediate beneath the oxide layer in the AA 2024 T3 aluminium alloy. As for, AA 6016 T4 aluminium alloy, the behaviour of Al-Fe-Si and Mg@sub 2@Si particles has been compared. The previous finding has been used to examine the chemisorption of flourinated alkyl phosphonic acid self-assembled layer onto the oxidised alloy systems. The multispectral XPS images show that the molecule assembled relatively uniformly on the 2024T3 compared to a heterogeneous distribution observed on the 6016T4. @FootnoteText@ @footnote 1@J. Walton and N. Fairley J. Electron Spectrosc. Relat. Phenom. (2005) 148 29-40.