Analysis of Adhesively Bonded Ceramics Using an Asymmetric Wedge Test

Report No. ARL-TR-4665
Authors: Andres Bujanda; Craig Copeland; Jessica Dibelka; Aaron Forster; Larry Holmes; Robert Jensen; Wendy Kosik; Steven McKnight; Stephen Koellhoffer; John Gillespie, Jr.
Date/Pages: December 2008; 32 pages
Abstract: Quantitative determination of adhesive performance when bonding to ceramic substrates has traditionally been a challenge. The brittleness of ceramic materials limits the ability to easily machine these substrates into the specific geometries required for rigorous adhesive fracture energy measurements. In this research, a mixed-mode loading scheme was implemented using an asymmetric wedge test configuration to study the effects of adhesion, promoting surface treatments on fracture energy and bond line durability of titanium bonded to alumina using a structural epoxy film adhesive. This testing scheme limited bending to the more compliant titanium and minimized deformations in the thicker alumina. Additionally, machining the alumina was avoided due to the relative simplicity of the testing configuration. X-ray photoelectron spectroscopy showed that sandblasting the ceramic surface yielded improved reactivity toward the sol-gel adhesion promoter used in this study, which resulted in increased hot/wet bond durability. Weibull modulus calculations and field emission-scanning electron microscopy imaging of the ceramic fracture surfaces showed that surface flaws induced while sandblasting the ceramic did not decrease the flexural strength.
Distribution: Approved for public release
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Last Update / Reviewed: December 1, 2008