Adhesive bonding alloys

Thrall, E.W. and Shannon, R.W., Adhesive Bonding of Aluminum Alloys. Marcel Dekker, Inc., New York, 1985. 

Copper-zinc Copper-zinc alloys are deposited for two main purposes (a) as a decorative finish, e.g. on steel and (b) as a means of obtaining an adhesive bond of rubber to other metals. 

Metals such as aluminium, steel, and titanium are the primary adherends used for adhesively bonded structure. They are never bonded directly to a polymeric adhesive, however. A protective oxide, either naturally occurring or created on the metal surface either through a chemical etching or anodization technique is provided for corrosion protection. The resultant oxide has a morphology distinct from the bulk and a surface chemistry dependent on the conditions used to form the oxide 39). Studies on various aluminum alloy compositions show that while the oxide composition is invariant with bulk composition, the oxide surface contains chemical species that are characteristic of the base alloy and the anodization bath40 42). 

Secondary Ion Mass Spectrometry used as a solo Instrument or in concert with other methods has proven to be an excellent technique for studying the surface chemistry of adhesive bonding materials. The application of SIMS is shown in re.lation to pretreatments of metals and alloys, chemistry and structure of adhesives, and locus of failure of debonded specimens. 

Surface Preparations of Titanium Alloys for Adhesive Bonding... 

Ion beams provide useful information either as a diagnostic tool or as a precision etching method in. adhesive bonding research. The combination of SIMS with complementary methods such as ISS or AF.S provides a powerful tool for elemental end limited structural characterization of metals, alloys and adhesives. The results shown here indicate that surface chemistry (and interface chemistry) can be decidedly different from bulk chemistry. Often it is this chemistry which governs the quality and durability of an adhesive bond. These same surface techniques also allow an analysis of the locus of failure of bonded materials which fail in service or test. 

Joint alloy Adhesive Curing condition Spot weld, lb Adhesive bond, lb Weldbond, lb... 

If chlorinated solvents are used with titanium surfaces, they must be completely removed prior to bonding. Chlorinated solvents give rise to stress corrosion cracking in the vicinity of welds. Welding of titanium often occurs in the same plant as adhesive bonding, and it is sometimes done on the same parts. So the best practice is to avoid the use of chlorinated solvents completely. Several airframe manufacturers that fabricate titanium alloys no longer permit the use of chlorinated solvents. 

Keith, R. E., et al., Adhesive Bonding of Nickel and Nickel Base Alloys, NASA TMX-63428, October 1965. 

Important factors regarding incoming adherends are the chemical and physical properties of the material. This can be especially important with adhesive bonding because different metal alloys have different surface oxidation, and different elastomers and plastics can have different additives and modifiers. With elastomeric and plastic substrates, lot-to-lot differences should be tested. Often a supplier will change formulations but still be within the requirements of the specification. The difference in formulation may have a profound effect on the quality of the ultimate adhesive bond. 

E 229 E 864 Test Method for Shear Strength and Shear Modulus of Structural Adhesives Practice for Surface Preparation of Aluminum Alloys to be Adhesively Bonded in Honeycomb Shelter Panels... 

E 1512 E 1555 E 1793 Test Methods for Testing Bond Performance of Adhesive Bonded Anchors Specification for Structural Paste Adhesive for Sandwich Panel Repair Standard Practice for Preparation of Aluminum Alloy for Bonding in Foam and Beam Type Transportable Shelters... 

E 1826 Specification for Low Volatile Organic Compound (VOC) Corrosion Inhibiting Adhesive Primer for Aluminum Alloys to be Adhesively Bonded Sealants and sealing... 

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