@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.} } @inbook {1447, title = {Surface science studies of the effect of Al alloy microstructure on the formation of chromate coatings}, booktitle = {Aluminium Alloys 2006, Pts 1 and 2 - Research through Innovation and Technology}, series = {Materials Science Forum}, volume = {519-521}, year = {2006}, note = {ISI Document Delivery No.: BEZ41Times Cited: 3Cited Reference Count: 22Kulinich, S. A. Akhtar, A. S. Susac, D. Wong, K. C. Wong, P. C. Mitchell, K. A. R.Proceedings Paper10th International Conference on Aliminium Alloys (ICAA-10)JUL 09-13, 2006Vancouver, CANADABRANDRAIN 6, CH-8707 ZURICH-UETIKON, SWITZERLAND}, pages = {621-628}, publisher = {Trans Tech Publications Ltd}, organization = {Trans Tech Publications Ltd}, address = {Zurich-Uetikon}, abstract = {Surface science methods including scanning Auger microscopy (SAM), scanning electron microscopy (SEM), X-ray photoelectron spectroscopy (XPS) and Raman spectroscopy have been used to study the initial growth of chromate conversion coatings on aluminum 2024-T3 alloy, using a coating bath formed by dissolving CrO3, Na2Cr2O7 and NaF in water. The objective is to learn more about growth mechanism on the different microstructural regions of this alloy surface, including the second-phase particles and the alloy matrix.}, keywords = {2024-T3 ALUMINUM-ALLOY, AA2024-T3, aluminum alloy, ATOMIC-FORCE MICROSCOPY, CHEMISTRY, chromate conversion coating, CONVERSION COATINGS, corrosion, NUCLEATION, PAINT ADHESION, photoelectron, Raman spectroscopy, scanning Auger microscopy, scanning electron microscopy, SPECTROSCOPY}, isbn = {0255-54760-87849-408-1}, url = {://000240309000097}, author = {Kulinich, S. A. and Akhtar, A. S. and Susac, D. and Wong, K. C. and Wong, P. C. and Mitchell, K. A. R.}, editor = {Poole, W. J. and Wells, M. A. and Lloyd, D. J.} } @article {1153, title = {Pre-treatments applied to oxidized aluminum surfaces to modify the interfacial bonding with bis-1,2-(triethoxysilyl)ethane (BTSE) - Part II. Anodized 7075-T6 Al alloy}, journal = {Applied Surface Science}, volume = {252}, number = {5}, year = {2005}, note = {ISI Document Delivery No.: 993WHTimes Cited: 6Cited Reference Count: 46}, month = {Dec}, pages = {1305-1312}, type = {Article}, abstract = {The methods of X-ray pbotoelectron spectroscopy (XPS), secondary-ion mass spectrometry (SIMS), and scanning electron microscopy (SEM) have been used to investigate aspects of the bonding of bis-1,2-(triethoxysilyl)ethane (BTSE) onto anodized samples of 7075-T6 aluminum alloy that have been subjected to the various pre-treatments considered in Part I. The oxide layer thins when this sample is subjected to a Forest Products Laboratory (FPL) treatment; topographical changes are detected by SEM after only 5 min, and the "scallop structures" increase in size for longer times of the FPL treatment. These 7075-Al surfaces adsorb more BTSE than the high-purity Al samples considered in Part I, although the interfacial bonding indicated by the [AlOSi](+)/[Al2O](+) SIMS ratios measured for the former samples are constant for different times of FPL treatment, unlike the situation for high-purity Al. Heating anodized 7075-Al samples, either before or after FPL treatment, has no significant effect on the subsequent BTSE adsorption, but a H-2 plasma treatment can enhance the interfacial Al-O-Si bonding with a decrease in the total BTSE polymerization. (c) 2005 Elsevier B.V. All rights reserved.}, keywords = {2024-T3, AGENTS, aluminum, corrosion, COUPLING, ESCA, HYDROXIDES, silane adsorption, SIMS, SPECTROSCOPY, surface pre-treatment, THIN-FILMS, X-ray photoelectron, XPS, XPS INVESTIGATIONS, ZIRCONIUM-OXIDE}, isbn = {0169-4332}, url = {://000233985900015}, author = {Kim, J. and Teo, M. and Wong, P. C. and Wong, K. C. and Mitchell, K. A. R.} } @article {999, title = {Comparison of a chromic acid and a BTSE final rinse applied to phosphated 2024-T3 aluminum alloy}, journal = {Surface \& Coatings Technology}, volume = {187}, number = {2-3}, year = {2004}, note = {ISI Document Delivery No.: 860VHTimes Cited: 10Cited Reference Count: 31}, month = {Oct}, pages = {216-224}, type = {Article}, abstract = {Dilute chromic acid and the organosilane bis-1,2-(triethoxysilyl)ethane (BTSE) were compared by their abilities to act as post-treatment rinses for samples of 2024-T3 aluminum alloy, which had previously been coated by zinc phosphate. The first approach is conventionally used to improve corrosion protection, but alternatives are needed because of environmental concerns with Cr(VI). Variations in conditions for application of the final rinse, especially through changes in solution concentration, were compared by measuring polarization curves, which provide an indication of corrosion stability. These comparisons were related to coating morphology, which was studied using scanning electron microscopy (SEM), and to studies of chemical composition with X-ray photoelectron spectroscopy (XPS) and energy dispersive X-ray (EDX) spectroscopy. Immersion tests in NaCl solution were applied to post-treated zinc phosphate coatings that had been formed on mirror-polished alloy surfaces. Overall, the post-treatment in 4\% BTSE at 25 degreesC appears to provide a comparable corrosion resistance to that found when the final rinse is done in a conventional CrO3 Solution (concentration 0.5 g/l) at 70 degreesC. At the microstructural level, initial observations were also made for comparing the effects of the post-treatments at protecting alloy matrix areas adjacent to Al-Cu-Mg second-pbase particles. (C) 2004 Elsevier B.V. All rights reserved.}, keywords = {AL, aluminum alloy, chemical conversion, CHEMISTRY, CONVERSION COATINGS, corrosion, metals, PAINT ADHESION, phosphating, photoelectron spectroscopy, post-treatment, scanning electron microscopy, SPECTROSCOPY}, isbn = {0257-8972}, url = {://000224371300012}, author = {Susac, D. and Leung, C. W. and Sun, X. and Wong, K. C. and Mitchell, K. A. R.} } @article {1004, title = {Investigations of interfaces formed between bis-1,2-(triethoxysilyl)ethane (BTSE) and aluminum after different Forest Product Laboratory pre-treatment times}, journal = {Applied Surface Science}, volume = {221}, number = {1-4}, year = {2004}, note = {ISI Document Delivery No.: 759CXTimes Cited: 11Cited Reference Count: 28}, month = {Jan}, pages = {340-348}, type = {Article}, abstract = {The adhesion performance of bis-1,2-(triethoxysilyl)ethane (BTSE) coatings on high-purity aluminum surfaces, which have been subjected to a Forest Products Laboratory (FPL) pre-treatment for different times, has been assessed with secondary-ion mass spectrometry (SIMS), X-ray photoelectron spectroscopy (XPS) and scanning electron microscopy (SEM). After coating, SIMS measurement of the ratio of peak intensities at 71 to 70 amu is used to identify the direct Al-O-Si bonding. The overall strength of the silane adhesion is assessed by comparing measurements of the Si 2p signals before and after application of an ultrasonic rinse to the coated sample. For the shorter FPL pre-treatment times (<10 min), substantial BTSE adsorption occurs on less-firmly anchored parts of the oxide which can be removed by the sonication test. The optimal adhesive bonding is indicated by these more microscopic studies to occur with the pre-treatments in the 10-25 min range, and this is in close correspondence with the normal FPL recipe that has been identified by performance in macroscopic tests. Pre-treatments longer than 25 min modify the surface topography further and give less direct Al-O-Si bonding, although the total BTSE adsorption is essentially constant and the adhesion remains strong enough to survive the sonication test. (C) 2003 Elsevier B.V. All rights reserved.}, keywords = {ADHESION, ALLOY-COATED STEEL, aluminum, corrosion, DURABILITY, GAMMA-GLYCIDOXYPROPYLTRIMETHOXYSILANE, metals, silane adsorption, SILANES, SIMS, surface pre-treatment, SURFACES, TECHNOLOGY, TOF-SIMS, XPS}, isbn = {0169-4332}, url = {://000187721700043}, author = {Teo, M. and Kim, J. and Wong, P. C. and Wong, K. C. and Mitchell, K. A. R.} } @article {513, title = {Some observations for effects of copper on zinc phosphate conversion coatings on aluminum surfaces}, journal = {Surface \& Coatings Technology}, volume = {155}, number = {1}, year = {2002}, note = {ISI Document Delivery No.: 563RDTimes Cited: 13Cited Reference Count: 9}, month = {Jun}, pages = {46-50}, type = {Article}, abstract = {X-Ray photoelectron spectroscopy (XPS), scanning electron microscopy (SEM) and electrochemical measurements have been used to characterize zinc phosphate (ZPO) conversion coatings, formed on high-purity aluminum surfaces, after dipping in coating baths containing different concentrations of Cu2+ up to 50 ppm. Significant variations in the morphology, adhesion and corrosion protection afforded by the ZPO coatings are especially observed as the Cu2+ in the bath varies from 0 to 10 ppm. Comparisons are made with the effects of surface Cu segregation on ZPO coatings formed in a previous study made on Al-2024-T3 alloy. (C) 2002 Elsevier Science B.V. All rights reserved.}, keywords = {ALLOY, aluminum, corrosion, photoetectron spectroscopy, scanning electron microscopy, zinc phosphating}, isbn = {0257-8972}, url = {://000176268600007}, author = {Sun, X. and Susac, D. and Li, R. and Wong, K. C. and Foster, T. and Mitchell, K. A. R.} } @article {4253, title = {Observations related to the phosphating of aluminium alloy 7075-T6 using a spraying technique}, journal = {Journal of Materials Science}, volume = {33}, number = {6}, year = {1998}, note = {ISI Document Delivery No.: ZA655Times Cited: 5Cited Reference Count: 15}, month = {Mar}, pages = {1541-1547}, type = {Article}, abstract = {An initial review is made of the effects of changing parameters involved in forming a zinc phosphate coating layer by spraying an aluminium alloy 7075-T6. Various coatings were evaluated by X-ray photoelectron spectroscopy, scanning electron microscopy and adhesion tests. The coating solution reported represents a modification of that previously used for coating the same system by the dipping method (J. Mater. Sci. 31 (1996) 565), but for spraying it was necessary to add the accelerators KClO3 and NaNO2 in order to achieve an adequate phosphate layer. For this solution, the favoured coating conditions by spraying corresponded to 1 min at 85 degrees C. A significant effect on the phosphating process is also indicated for the polishing pre-treatment of the substrate; the coating formed on a surface polished by 1200 grid aluminium oxide sandpaper showed good adhesion to paint, whereas that polished with 1200 grid silicon carbide failed to form an adhesive phosphate coating. In general, conditions for spraying are less easy to control than for dipping, but directions are indicated for obtaining promising coatings by the former approach. (C) 1998 Chapman \& Hall.}, keywords = {corrosion, XPS}, isbn = {0022-2461}, url = {://000072387800018}, author = {Fang, J. and Wong, P. C. and Mitchell, K. A. R. and Foster, T.} } @article {4161, title = {Chemical properties of a Nb/Zr interface studied by XPS}, journal = {Surface Review and Letters}, volume = {4}, number = {1}, year = {1997}, note = {ISI Document Delivery No.: XA621Times Cited: 1Cited Reference Count: 15}, month = {Feb}, pages = {33-37}, type = {Article}, abstract = {A film of niobium (similar to 15 A thick) deposited under ultrahigh vacuum (UHV) conditions on polycrystalline zirconium was studied by x-ray photoelectron spectroscopy (XPS) as it was taken through a series of sequential treatments. The Nb-Zr interface, associated with a Nb 3d(5/2) peak at 203.4 eV, is indicated to passivate the underlying Zr to oxygen and hydrogen plasma treatments, which in the absence of Nb would yield substantial oxidation. On heating to 500 degrees C, the pure metallic Nb 3d(5/2) component at 202.2 eV appears, and this change is accompanied by removal of the passivation effect on the substrate.}, keywords = {corrosion, electron, HYDROGEN, NUCLEAR-REACTION ANALYSIS, SURFACES, THIN-FILMS, WT-PERCENT NB, ZIRCALOY-2, ZIRCONIUM-OXIDE, ZR}, isbn = {0218-625X}, url = {://A1997XA62100005}, author = {Wong, K. C. and Wong, P. C. and Li, Y. S. and Mitchell, K. A. R.} } @article {3746, title = {XPS investigations of the reactivities of oxidized Zr/Nb interfaces formed by deposition on a gold substrate}, journal = {Applied Surface Science}, volume = {103}, number = {4}, year = {1996}, note = {ISI Document Delivery No.: VX979Times Cited: 6Cited Reference Count: 18}, month = {Dec}, pages = {389-393}, type = {Article}, abstract = {The interaction of a film of Zr (similar to 38 Angstrom thick) deposited under ultrahigh vacuum (UHV) on to an approximately 12 Angstrom film of NbO on a gold substrate has been studied with X-ray photoelectron spectroscopy (XPS). Evidence is presented for an interfacial conversion from Zr and NbO to ZrO2 and Nb. The reactivity of this sample was studied through a series of sequential treatments. Although changes occur in the topmost layer, the Zr/Nb interfacial region, as identified by a shoulder at similar to 180 eV in Zr 3d and the 203.0 eV peak in Nb 3d, appears to be remarkably inert on heating at 300 degrees C under UHV, as well as on subjecting to O-2 and hydrogen plasma treatments.}, keywords = {corrosion, HYDROGEN, NUCLEAR-REACTION ANALYSIS, THIN-FILMS, WT-PERCENT NB, ZIRCALOY-2, ZIRCONIUM-OXIDE, ZR}, isbn = {0169-4332}, url = {://A1996VX97900009}, author = {Li, Y. S. and Wong, K. C. and Wong, P. C. and Mitchell, K. A. R.} }