Blistering Failure of Elastic Coatings with Applications to Corrosion Resistance

TL;DR

This paper develops a comprehensive mathematical model to predict blistering failure in elastic coatings used for corrosion resistance, capturing nonlinear growth dynamics and critical delamination thresholds without extensive data fitting.

Contribution

It introduces a general theoretical framework for blistering in polymeric coatings, enabling prediction of failure modes and critical conditions with minimal empirical parameters.

Findings

Model accurately predicts blister growth and failure modes.

Experimental data aligns with theoretical predictions.

Defines dimensionless numbers for coating design optimization.

Abstract

A variety of polymeric surfaces, such as anti-corrosion coatings and polymer-modified asphalts, are prone to blistering when exposed to moisture and air. As water and oxygen diffuse through the material, dissolved species are produced, which generate osmotic pressure that deforms and debonds the coating.These mechanisms are experimentally well-supported; however, comprehensive macroscopic models capable of predicting the formation osmotic blisters, without extensive data-fitting, is scant. Here, we develop a general mathematical theory of blistering and apply it to the failure of anti-corrosion coatings on carbon steel. The model is able to predict the irreversible, nonlinear blister growth dynamics, which eventually reaches a stable state, ruptures, or undergoes runaway delamination, depending on the mechanical and adhesion properties of the coating. For runaway delamination, the theory predicts a critical delamination length, beyond which unstable corrosion-driven growth occurs. The model is able to fit multiple sets of blister growth data with no fitting parameters. Corrosion experiments are also performed to observe undercoat rusting on carbon steel, which yielded trends comparable with model predictions. The theory is used to define three dimensionless numbers which can be used for engineering design of elastic coatings capable of resisting visible deformation, rupture, and delamination.