Epoxy aluminum

Fig. 4. The forees at the epoxy-aluminum interface resolved into shear and peel components. Shear component/peel component = tanfa) 52. ...

The ionic phosphonates like NTMP are effective hydration inhibitors because they can form an insoluble complex with the oxide surface. They are useful as epoxy adhesive couplers in cases where the adhesive and its curing cycle are compatible with the adsorbed phosphonate molecule. (14) Wedge test results indicate that in two epoxy-aluminum systems studied, certain organosilanes tend to both increase the epoxy-metal bond durability and maintain hydration resistance. The results of anodic polarization experiments further suggest that these silane films are effective against localized pitting. 

Thermal Stress Determination. The method selected to determine the thermal stress developed at the epoxy-aluminum interface was the bending beam technique utilized by Dannenberg (9), Shimbo, et al. (10) and others (12-13,17). The exact apparatus configuration is that of Dannenberg s except that thicker coatings were applied to the beam. 

Epoxy adhesives have cohesive properties that significantly depend on the crosslink density. For example, torsional butt shear strength of epoxy aluminum joints has been noticed to decrease as Mc increased.20 However, flexibility and toughness are increased with increasing Mc. Figure 3.12 shows the general physical relationship between Mc and the physical state of epoxy resins. 

Lin, C. J., and Bell, J. P., The Effect of Polymer Network Structure upon the Bond Strength of Epoxy- Aluminum Joints, Journal of Applied Polymer Science, vol. 16, 1972, p. 1721. 

A comparison of experimentally determined failure times for different stress levels and those predicted by the above equation for epoxy-aluminum lap shear joints aged at 60°C and 95 percent RH is presented in Table 15.3. These results indicate that the reaction rate method is satisfactory for predicting the effects of temperature and stress on the lifetime of adhesive bonds, provided that failure is cohesive within the adhesive. This, of course, should be validated by prototype testing. 

TABLE 15.3 Comparison of Experimental and Predicted Failure Times for Epoxy-Aluminum Joints5... 

Aluminum-epoxy-aluminum composite Aluminum-epoxy-polyethylene-epoxy-aluminum composite O Aluminum-epoxy—cross-linked polyethylene—epoxy-aluminum composite... 

The material and condition of the microtome knife are very important if one is to achieve a smear-free cut. Tungsten carbide knives have been found to produce excellent results on both thermosetting and thermoplastic polymers. Sectioning thickly coated metals is clearly not an option, but if thin (< 100 pm) metal foils are used as substrate material, it is quite possible to cut polymer/metal sections with a tungsten carbide knife. Model adhesive/substrate interfaces can usefully be prepared for microtoming and subsequent analysis from these foils of aluminum or iron, set into adhesives which are then cured. Fig. 1.11 shows a schematic of this concept which has been used for the study of epoxy/aluminum [24] and iron/polyamide interfaces [25]. 

Brewis et al. studied the effects of moisture and temperature on the properties of epoxy-aluminum joints by measuring changes in the mechanical strength properties of the soaked adhesive [90]. The Tg of the wet adhesive and relative strengths of wet and dry joints were evaluated for up to 2500 hours. They concluded that the joint weakening effect of water was due to plasticization of the adhesive that, in turn, was dependent on the rate of water diffusion within the adhesive. 

Reaction injection molding creates its own resin by mixing two highly reactive liquid components which react with each other by high-pressure impingement. The reaction is completed shortly after the resin is injected into the mold. This is accomplished at a pressure of 100 Ib/in, which permits the use of electro-formed and vapor-formed nickel lined epoxy, aluminum, and kirksite tools at a considerably reduced tooling cost. (Machined and plated cast steel molds can also be used.) As a closed-mold process, both sides of the part are finished and can have textures, raised numbers, and raised letters, but molded-in labels are not feasible. The finished part can be trimmed in the mold. 

Figure 9. Effect of surface treatment on the durability of epoxy/aluminum joints exposed to room temperature water immersion. (1) Anodized, (2) grit-blasted plus vapor degrease, (3) vapor degrease, (4) chromate conversion coating. Reprinted from ref. 3, p. 71, by courtesy of Marcel Dekker Inc.

Epoxy/aluminum oxide Epoxy/ferric oxide Epoxy/silica Epoxy/CFRP PMMA/aluminum oxide PMMA/ferric oxide... 

Epoxy is strong and gives good surface detail, but as mentioned earlier it is expensive. And because of that it will be one of those items I seldom use around the home shop. Better to experiment with plaster of paris and save a few bucks. If you plan to use a mold more than a couple of times then consider using epoxy. Aluminum filled epoxy may be a tough item to find at the local level. I purchased my epoxy and release agent by mail order from "lASCO," Which stands for Industrial Arts Supply Co., 5724 West 36th Street, Minneapolis, MN 55416-2564. Phone 612-920-7393. 

Flame Retardant Epoxy/Multifunctional Epoxy, Phosphorus Flame Retardant Epoxy/Multifunctional Epoxy, Aluminum Hydroxide Flame Retardant Epoxy/Multifunctional Epoxy, Phosphorus Flame Retardant... 

Epoxy/Multifunctional Epoxy, Aluminum Hydroxide Flame Retardant Polyphenylene Ether... 

A sample dispersion curve is illustrated in Fig. 9 for a three-layer adhesively bonded structure of aluminum-epoxy-aluminum. Points on the curve show pos-... 

Figure 6.1 Adhesive strength of epoxy-aluminum joints as a function of the applied etching pretreatments (a) abrasion, (b) alkaline, (c) optimized FPL, and (d) P2 (adhesives Ceys, 2MI, PAMS, and DDS are based on diglycidyl ether of bisphenol A, Diglycidyl ether of bisphenol-A(DGEBA), and differ in composition and/or cure conditions). ...

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