Aluminum wedge test

ASTM D3762-03 Standard test method for adhesive bonded surface durability of aluminum (wedge test). 

Adhesive Bonded Surface Durability of Aluminum (Wedge Test) [Pg.791]

Adhesive Bonded Surface Durability of Aluminum (Wedge Test) (D 3762) Working Life of Liquid or Paste Adhesive by Consistency and Bond Strength, Test for (D 1338)... 

ASTM D 3762. (1981). Standard test method for adhesive-bonded surface durability of aluminum (wedge test), Part 22 wood adhesives. American Society for Testing and Materials, West Conshohoken, PA. 

Fig. 9. Wedge test results of aluminum adherends with the following surface preparations FPL, PAA, and FPL followed by an NTMP treatment. Adapted from Ref. [42].

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.)...

Sol-gel film.s deposited on a grit-blasted aluminum surface give performance close to PAA bonds (Fig. 22) with generally cohesive failures observed in wedge tests. Given that one application of this treatment is repair, the performance is... 

Primer Epoxy vs. Nitrile-Modified Epoxy. The compatibility of the epoxy-polyamide primer with the nitrile-modified epoxy adhesive facsimile and the aluminum oxide surface was also evaluated by the wedge test, since earlier tests using the primer as the adhesive had failed immediately. As shown in Fig. 8, the addition of the primer directly to the prepared... 

Figure 5. Wedge test results for inhibitor-treated SAA 7075-T6 aluminum specimens.

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. 

Fig. 9. Schematic diagram of the failure mechanism proposed by Venables et al.85), in aluminum/poly-mer joint systems during wedge testing in humid environments. (Reprinted with permission from Chapman and Hall LTD.)...

Fig. 16a and b. Wedge-test crack length (in.) of aluminum/thermoset (American Cyanamid FM123-2) joints as a function of exposure time to a 100% r. h.,60 °C environment, a) FPL, PAA, FPL + 10 ppm nitrilotris (methylene phosphonic acid (NTMP)831 and b) PAA and PAA + 300 ppm NTMP pretreatments were employed 1391 (Reprinted with permission from Chapman and Hall, LTD.)... 

Figure 9 Wedge test results for FPL-etched aluminum adherends with FM-123 (moisture-wicking) adhesive, with FM-300 (moisture-resistant) adhesive, with an NTMP treatment and FM-123, and with BR-127 primer and FM-300. 

A number of ASTM tests and practices involve durability, but one of the most important is the Wedge Test, ASTM D3762-03. In this method, a wedge is forced into the bond line of a flat-bonded aluminum specimen, thereby creating a tensile stress in the region of the resultant crack tip. The stressed specimen is exposed to an aqueous environment at an elevated temperature, or to any other desired environment. The resultant crack growth with time and failure modes is then evaluated. The test is primarily qualitative, but it is discriminatory in determining variations in adherend surface preparation parameters and adhesive environmental durability. 

The history of airplane corrosion testing includes many successful tests that are now performed routinely, e.g., ASTM G 85 Annex A2 and ASTM G 44. Some other successful tests, such as the wedge test (ASTM D 3762, Test Method for Adhesive-Bonded Surface Durability of Aluminum), discovered as a result of bond line corrosion problems on airplanes, are not described here because they are not strictly corrosion tests. Many of the tests described here are ASTM standards. With others, standardization is being pursued, e.g., electrochemical impedance, or ANCIT (Aluminum-Nitrate Chloride Immersion Test), to replace EXCO [4], Corrosion may never be totally eliminated from an airplane however, further refinements in corrosion testing, made... 

FIGURE 10. Wedge-test results (crack length vs. time) for FPl treated aluminum surfaces (a) FPL with FM-123 (moisture wicking), (b) FPL with FM-300 (moisture resistant), (c) FPL with an organic hydration inhibitor and FM-123, (d) FPL with BR-127 primer and FM-300. Data are compilations from References 14, 17, 22, and 47. FM-123, FM-300, and BR-127 are trademarks of American Cyanamid Corp., Havre de Grace, MD. 

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