@article {2007, title = {Microstructural effects on the formation and degradation of zinc phosphate coatings on 2024-Al alloy}, journal = {Applied Surface Science}, volume = {254}, number = {15}, year = {2008}, note = {ISI Document Delivery No.: 295YWTimes Cited: 2Cited Reference Count: 26Akhtar, A. S. Wong, P. C. Wong, K. C. Mitchell, K. A. R.}, month = {May}, pages = {4813-4819}, type = {Article}, abstract = {The formation of zinc phosphate (ZPO) coatings on 2024-T3 aluminum alloy was studied using scanning electron microscopy (SEM), scanning Auger microscopy (SAM) and X-ray photoelectron spectroscopy (XPS), with an emphasis on microstructural effects involving second-phase particles and the alloy matrix. Surface polishing results in an Al-Cu-Mg particle surface that contains metallic Cu as well as an overlayer of aluminum and magnesium oxide, while larger amounts of aluminum oxide are present on the Al-Cu-Fe-Mn particle and matrix. When dipped in an acidic ZPO coating solution, the oxide covering the Al-Cu-Mg particle is etched most easily, and metallic Cu near the surface makes that region most cathodic, allowing more coating deposition compared with the other regions. The oxides on the Al-Cu-Fe-Mn and matrix regions are similar, thereby confirming that the observed differences in ZPO coating characteristics at these two regions arise from their underlying electrochemical characteristics. Immersion of a coated 2024-Al sample in corrosive NaCl solution for extended periods indicates that the ZPO provides better protection to the second-phase particles than to the matrix. (C) 2008 Elsevier B.V. All rights reserved.}, keywords = {7075-T6, ALKALINE STABILITY, aluminum alloy, ALUMINUM-ALLOY, Auger electron spectroscopy, BEHAVIOR, corrosion, CORROSION PROTECTION, INITIATION, MICROSTRUCTURE, NI2+, PARTICLES, PHASE, surface oxide, zinc phosphating}, isbn = {0169-4332}, url = {://000255511700063}, author = {Akhtar, A. S. and Wong, P. C. and Wong, K. C. and Mitchell, K. A. R.} } @article {793, title = {The effect of Ni2+ on zinc phosphating of 2024-T3 Al alloy}, journal = {Surface \& Coatings Technology}, volume = {187}, number = {2-3}, year = {2004}, note = {ISI Document Delivery No.: 860VHTimes Cited: 27Cited Reference Count: 32}, month = {Oct}, pages = {208-215}, type = {Article}, abstract = {Zinc phosphate (ZPO) conversion coatings formed on 2024-T3 aluminum alloy, and on high-purity aluminum, after dipping in coating baths containing different amounts of Ni2+, have been studied by X-ray photoelectron spectroscopy (XPS), scanning electron microscopy (SEM), energy-dispersive X-ray (EDX) spectroscopy, scanning Auger microscopy (SAM) and electrochemical measurements. Significant variations are observed in coating morphology and in stability against corrosion for the 2024-Al alloy as the amount of Ni2+ in the coating solution increases through the 0-2000 ppm range. By contrast, for high-purity Al, the most marked changes in coating morphology occur only as the Ni2+ concentration reaches 2000 ppm. The presence of additional elements, and especially Cu, in the 2024-Al samples results in an increase in the number of cathodic sites and hence more coating is formed for corresponding conditions. Additionally, the existence of second-phase particles in the 2024-Al sample leads to variations in the coatings at the microstructural level across the surface. These differences include local variations in the amount of Ni2+ in the coatings, as well as the local coverage. (C) 2004 Elsevier B.V. All rights reserved.}, keywords = {aluminum alloy, ALUMINUM-ALLOY, Auger electron spectroscopy, chemical conversion, CHROMATE CONVERSION COATINGS, CORROSION PROTECTION, FILMS, Ni2+ additive, NICKEL, phosphating, photoelectron spectroscopy, STEEL, SURFACE, XPS}, isbn = {0257-8972}, url = {://000224371300011}, author = {Akhtar, A. S. and Susac, D. and Glaze, P. and Wong, K. C. and Wong, P. C. and Mitchell, K. A. R.} }