Surface structuring aluminum

Allara D L and Nuzzo R G 1985 Spontaneously organized molecular assemblies. 2. Quantitative infrared spectroscopic determination of equilibrium structures of solution-adsorbed normal-alkanoic acids on an oxidized aluminum surface Langmuir 1 52-66... 

Rider and Amott were able to produce notable improvements in bond durability in comparison with simple abrasion pre-treatments. In some cases, the pretreatment improved joint durability to the level observed with the phosphoric acid anodizing process. The development of aluminum platelet structure in the outer film region combined with the hydrolytic stability of adhesive bonds made to the epoxy silane appear to be critical in developing the bond durability observed. XPS was particularly useful in determining the composition of fracture surfaces after failure as a function of boiling-water treatment time. A key feature of the treatment is that the adherend surface prepared in the boiling water be treated by the silane solution directly afterwards. Given the adherend is still wet before immersion in silane solution, the potential for atmospheric contamination is avoided. Rider and Amott have previously shown that such exposure is detrimental to bond durability. 

ASTM D3933, Standard Guide for Preparation of Aluminum Surfaces for Structural Adhesives Bonding, Phosphoric Acid Anodization, A.STM, West Conshohocken, PA. El-Mashri, S.M., Jones, R.G. and Forty, A.J., Philo.s. Mag. A, 48, 665 (1983). 

Mazza, J.J. and Kuhbander, R.J., Grit blast/silane (GBS) aluminum surface preparation for structural adhesive bonding, WL-TR-94-4111. Materials Laboratory, Air Force Materiel Command, September 1999. 

Figure 1. Structure of a Forest Products Laboratories (FPL) prepared aluminum surface (7).

Figure 2. Structure of a sulfuric acid-anodized (SAA) aluminum surface.

The above findings indicate that two kinds of surface structures exist even on the surface of HNi and one kind can be removed by pretreatment with hydroxy acid. On the surface of RNi, aluminum does not directly participate in the formation of the differentiating site, but must participate in the formation of the surface structure of nickel which is removed by the pretreatment with hydroxy acid. 

The nature of the surface acidity is dependent on the temperature of activation of the NH4-faujasite. With a series of samples of NH4—Y zeolite calcined at temperatures in the range of 200° to 800°C, Ward 148) observed that pyridine-exposed samples calcined below 450°C displayed a strong infrared band at 1545 cm-1, corresponding to pyridine bound at Brpnsted (protonic) sites. As the temperature of calcination was increased, the intensity of the 1545-cm 1 band decreased and a band appeared at 1450 cm-1, resulting from pyridine adsorbed at Lewis (dehydroxylated) sites. The Brtfnsted acidity increased with calcination temperature up to about 325°C. It then remained constant to 500°C, after which it declined to about 1/10 of its maximum value (Fig. 19). The Lewis acidity was virtually nil until a calcination temperature of 450°C was reached, after which it increased slowly and then rapidly at calcination temperatures above 550°C. This behavior was considered to be a result of the combination of two adjacent hydroxyl groups followed by loss of water to form tricoordinate aluminum atoms (structure I) as suggested by Uytterhoeven et al. 146). Support for the proposed dehydroxylation mechanism was provided by Ward s observations of the relationship of Brpnsted site concentration with respect to Lewis site concentration over a range of calcination tem-... 

Bonnerot et al. studied LB layers of docosanoic and co-tricosenoic acids on aluminum surfaces (34). They observed a structural transition when the thickness... 

D 3933 Practice for Preparation of Aluminum Surface for Structural Adhesive Bonding... 

High-purity aluminum has excellent corrosion resistance. Information collected over the years from manufacturers and users has shown that aluminum structures will provide reliable service for periods in excess of 30 yr. The factor that assures the long life of aluminum is a self-forming microscopically thin surface layer of aluminum oxide. The air-formed film on new aluminum surfaces is about 2.5 nm thick, while the film on aluminum that is several years old may be 10 nm thick or more. The film is composed of two parts ... 

It was mentioned above that the cluster modeling of the surface sites of highly coordinated oxide lattices faces certain difficulties. This is probably the reason why only a few computations were performed for such systems. The aluminum oxide structure is just of this type. 

Amorphous aluminum orthophosphate with particular local surface structures could also be present in hydrotreating catalysts. It has been... 

After anodization and subsequent selective dissolution of anodic oxide the aluminum surface is a replica of back side of anodic alumina. Such surfece structure has ultrasharp tips with 20-100 nm height distanced ixom 10 to 500 nm, respectively. It is obvious that external part of anodic alumina has tip-like morphology too. However partial tip dissolution and smoothing during anodization in acidic solutions results in increasing of tip radii [4]. Thus taking into account known experimental results and our observations it can be concluded that the proposed approach allows to form sharp tips. 

In this Chapter, we focus on alkali-aluminum surface alloys where the geometrical structure has been determined in detail. As can be seen from Table 1, which contains a list of the adsorbed phases formed by adsorption of alkali metals on aluminium surfaces, this limitation is not a serious restriction, since studies exist for a quite a number of low index aluminum surfaces and alkali metals. Although most of the structures of the phases listed in Table 1 have been determined by low energy electron diffraction (LEED), the crucial, first observation of substitutional adsorption for alkali-aluminium systems was made in a combined surface extended x-ray fine structure (SEXAFS) and density functional theory (DFT) study of the Al(l 11)—(v 3 x 3)7 30°—Na phase formed by adsorption of 1/3 ML Na at room temperature by Schmalz et al [7] in 1991. The structure of the Al(lll)-(4 x 4)—Na phase was also determined by SEXAFS. 

Xiong G, Elam JW, Feng H, Han CY, Wang HH, Iton LE, Curtiss LA, Pellin MJ, Rung M, Kung H, Starr PC (2005) Effect of atomic layer deposition coatings on the surface structure of anodic aluminum oxide membranes. J Phys Chem B 109 14059... 

Asakura K, Yamada M, Iwasawa Y, Kuroda H (1985) Spectroscopic studies on the surface structures of ruthenium catalysts derived from triruthenium dodecacarbonyl/y-aluminum oxide or -silicon dioxide. Chem Lett 14 511... 

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