Aluminum bonding

Fig. 2. SEM cross-section of a 60° ultramilled aluminum bonded to epoxy resin. Also indicated is a diagrammatic representation of the ultramill profile showing the base angle [52].

Fig. 20. Wedge test results showing PAA, CAA, and BSAA treated aluminum bonds. (Note that this test involved thicker adherends than is typical and therefore crack lengths cannot be compared to those of other tests.)...

Minl ord, J.D., Handbook of Aluminum Bonding Technology and Data. Marcel Dekker, New York, 1993. 

Honeycomb core. Honeycomb core used for aluminum bonded sandwich structure is exclusively aluminum. The core is fabricated by printing offset stripes of adhesive (the node adhesive) on aluminum foil, stacking a large number of these foils and then curing the adhesive in a heated press. The resulting block is called a hobe. Slices are machined from the edge of the hobe and then expanded to... 

A living radical polymerization mechanism was proposed for the polymerization of MMA23 -240 and VAc241 initiated by certain aluminum complexes in the presence of nilroxides. It was originally thought that a carbon-aluminum bond was formed in a reversible termination step. However, a more recent study found the results difficult to reproduce and the mechanism to be complex.242... 

A1 (CH2 0113)3 1 indicates that aluminum bonds to three CH2 CH3 fragments. There are 42 valence electrons, all of which are used to complete the bonding framework. Each of the six carbon atoms in triethylaluminum has an octet of electrons and a steric number of 4. Thus, each ethyl group of A1 (CH2 0113)3 described exactly... 

Because of the polarity of the carbon-aluminum bond, organoaluminum compounds are valuable intermediates in organic synthesis, which exhibit higher reac-... 

According to El-Mashri et al.,190 the A106 A104 ratio determines the hydration capacity of anodic oxides. Tetrahedral sites are hydrated easily to form a boehmite-like structure, which is known to be composed of double layers of Al-centered octahedra, weakly linked by water molecules to other layers.184 As the oxide formed in H3P04 contains about 70% tetrahedral aluminum bonds, its hydration ability should be higher than that of the oxide formed in tartrate solution. However, this has not been found in practice, which is interpreted by El-Mashri et al. as being due to some reduction of A104 by incorporated phosphate species. 

The results suggest that once hydroalumination has occurred at one end of the diene, the course of the reaction at the other double bond is significantly affected by the alkylaluminum group, possibly due to chelation in which a palladium-chloride-aluminum bond is thought to be important. 

Transition joints are used to join dissimilar metals where flanged, screwed, or threaded connections are not practical. They are used when fusion welding of two dissimilar metals forms interfaces that are deficient in mechanical strength and the ability to keep the system leak-tight. Transition joints consist of a bimetallic composite, a stainless steel, and a particular kind of aluminum bonded together by some proprietary process. Some of the types in use throughout the cryogenic industry are friction- or inertia-welded bond, roll-bonded joint, explosion-bonded joint, and braze-bonded joint. 

The Third-Group Elements.—The B—F bond has about 63 percent ionic character, B—O 44 percent, B—Cl 22 percent, and so forth. Bor,on forms normal covalent bonds with hydrogen. The aluminum bonds are similar to those of beryllium in ionic character. 

On hydrolysis with D20, the oxygen-aluminum bond is cleaved and DCH2OD is formed. 

Aluminum-alkynyl covalent bonds, characteristics, 9, 249-250 Aluminum-aluminum bonds in A1(I) compounds, 9, 261 in Al(II) compounds, 9, 260 Aluminum aryloxides, reactivity, 9, 254—255 Aluminum(III)ates, in organic group-selective transfers, 9, 279 Aluminum(I)-boron bonds, characteristics, 9, 263 Aluminum(III)-boron exchange, process, 9, 266 Aluminum-calix[4]arene catalyst, for alternating epoxide-CC>2 co-polymerization, 11, 617... 

Minford, J. D., Durability of Aluminum Bonded Joints in Long-Term Exposure, International Journal of Adhesion and Adhesives, vol. 2, no. 1, 1982, p. 25. 

Once the surface considerations are taken care of, there are many types of epoxy adhesives that can bond well to aluminum. The selection will depend on the strength needed, the type of stress involved (e.g., peel or shear static or dynamic), and the operating environment. Reynolds Metals Company21 offers some general observations in selecting an adhesive for aluminum bonding. 

Chapters 5 and 6 signal the growing importance of combinations between aluminum and fluorine in living systems. Fluorine forms aluminum bonds... 

Most of these discussions regarding fluorine contamination of aluminum surfaces have focused on the conversion of aluminum oxide to fluoride or oxyfluoride. Evidence for similar conversions was included, and in extreme cases conversion to aluminum bonding quite similar to that in AIF3 was found. However, the poor adhesion of the samples skipping the O2 plasma treatment is related not to the fluorine contamination as such, but rather to the carbonaceous nature of the adsorbed materials, which is subjected to the plasma polymerization of TMS. Oxygen plasma cleaning removes this carbonaceous component, while the surface fluorine concentration is enhanced. 

Depending upon the nature of the hydroaluminating agent (R2AIH, MAIR3H or LAH), the organoaluminum product will have one to four new carbon-aluminum bonds at which cleavage or insertion reactions can be conducted. Two such reactions are protodealumination (equation 13) and carbonation (equation 14). ... 

Only with reagents that attack all available carbon-aluminum bonds (H2O, D2O, O2, X2, SO2, etc.) will the hydroalumination of alkenic substrates and the derivatization of such adducts prove useful. That two of three C—Al bonds of adduct (23) are expended in the formation of side products, which have to be separated, may be an acceptable price to pay for the convenient, high-yielding generation of a desired specifically deuteriated reduction product, (24) or (25), ° primary alcohol (26), primary halide (27) or sulfinic acid. Of course the isobutylated side products should, in each case, be easily separable (Scheme 6). 

Fourthly, the vinylic hydroaluminum adduct (30) can either insert a second mole of (30) into the vinyl-aluminum bond and thereby dimerize (equation 22), or it can insert a second mole of alkyne (equation 23). ... 

The second side reaction with alkenes is the configurational change at the jp -hybridized carbon-aluminum bond in the hydroalumination adduct (equation 31). ... 

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