Strength degradation of steel-adhesive-joint in water environment.

Abstract

The strength degradation of steel adhesive joint in water environment was investigated. A model is proposed in which the process of progressive decrease in joint strength due to water uptake is considered as that of progressive growth of an apparent crack at the joint interface, and the strength degradation of adhesive joint can be analysed on the basis of fracture mechanics. It was found that in the specimens immersed in water for the same duration of time, the depth of the apparent crack increased with increasing water temperature, while the water concentration at the tip of respective crack was nearly the same. The fracture strength after immersing the joint in water at various temperatures was determined as a function of a single variable of Dt. The effect of side diffusion on the joint strength is not negligible in the case of longer immersion, especially at higher temperatures.

Critical and Subcritical Adhesion Measurements of a Model Epoxy Coating Exposed to Moisture Using the Shaft-Loaded Blister Test

“…This results from absorption of atmospheric moisture into the polymeric adhesive, which typically accumulates at the interface and displaces the polymer from the adherend surface [2,3]. Epoxy adhesives are particularly sensitive to moisture, resulting in a dramatic loss of adhesion strength when exposed to moisture above a critical relative humidity level [4][5][6][7][8][9][10][11][12]. The critical relative humidity level is typically between 50 and 70%.…”