Alloys, adhesive

The first group, resins that are used primarily to toughen epoxy adhesive systems, is described in Chap. 8. This chapter focuses on the resinous modifiers that are used as alloy blends. Characteristics of commercially available epoxy alloy adhesives are presented in Table 7.1. Tensile shear and peel strengths that are typical of these hybrid adhesives are compared in Table 7.2. 

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

Polymer adhesives avoid most of these problems, but do not possess the high thermal or high electrical conductivities of metals or metal alloys. Adhesives also are limited in their temperature stabilities, decomposing, and outgassing above a certain temperature. 

Except for some epoxy compounds, heat and pressure are usually required for curing. Most alloy adhesives are solvent-based dispersions or 100% solids. These adhesives have a balanced combination of properties and are generally stronger over wider temperamre ranges than other adhesives. They are suitable as structural adhesives and are used where the highest and strictest end-use conditions must be met (regardless of cost) such as in military applications. ... 

Materials bonded include metals, ceramics, glass, and thermosetting plastics. Applications are primarily for high strengths and high temperatures. Examples of alloy adhesives are shown in Table 4.4. 

Film and tape adhesives are also frequently called two-polymer or alloyed adhesives. With few exceptions, all successful film and tape adhesive are, or have been, one of the types shown in Tables 5.3 and 5.4. The adhesive types based on phenohc cross-linking resins liberate volatiles during cure, while the types based on epoxies only need sufficient pressure to maintain aligmnent and compensate for cure shrinkage. ... 

These alloy adhesives are thermosetting phenolic resins blended with neoprene (polychloroprene) rubber. They are available in solvent solutions in toluene, ketones, or solvent mixtures, or as unsupported or supported films. The supporting medium may be glass or nylon cloth. Neoprene-phenolic adhesive may be used to bond a variety of substrates such as aluminum. 

Adhesives can be broadly classified as being thermoplastic, thermosetting, elastomeric, or alloy blend. These four adhesive classifications can be further subdivided by specific chemical composition as described in Tables 7.20 through 7.23. The types of resins that go into the thermosetting and alloy adhesive classes are noted for high strength, creep resistance, and resistance to environments such as heat, moisture, solvents, and oils. Then-physical properties are weU suited for structural-adhesive applications. 

Hagemaier, D.J., Nondestructive inspection (of A t alloy adhesive bonds). Adhesive Bond-... 

Alloy adhesives are obtained from the combination of resins of two different chemical groups selected from the thermoplastic, thermosetting, and elastomeric groups. This type of adhesive includes ... 

Notes AA, aluminum alloy adhesive layer thickness, where known... 

Armstrong KB (1997) Long-term durability in water of aluminium alloy adhesive joints bonded with epoxy adhesives. Int J Adhes Adhes 17(2) 89-105 Bauer P, Roy A, Casari P, Choqueuse D, Davies P (2004) Structural mechanical testing of a fidl-size adhesively bonded motorboat. J Eng Marine Environ 218(M4) 259-266... 

These alloy adhesives are thermosetting phenolic resins blended with neoprene (polychloroprene) rubber. They are available in solvent solutions in... 

Adhesives recommended include epoxies, vinyl alcohol—vinyl acetate copolymer, polyvinyl alkyl ether, polyacrylate (carboxylic), polyurethane (two-part), epoxy-phenolics, silicones, and cyanoacrylates. The high-strength thermoset and alloy adhesives are rarely justified for bonding lead. Even when other properties recommend these adhesives, the designer should check to see whether some low-cost or easier-to-use adhesive is also suitable. An exception is teme (lead-coated steel). This is a much stronger metal than lead, and lap-shear strengths exceeding 2.1 MPa are reported for adhesive joints with teme.° ... 

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