Correlations Between Stress Distributions and Coating Adhesion Strength as Tested by Tensile Adhesion Methods

Among the adhesion measurement techniques, the Tensile Adhesion Test (TAT) has been unanimously adapted in the industry. The TAT provides a commercially viable and convenient method to test the adhesion/cohesion strength of Thermally Sprayed Coatings. Over the last 50 years, multiple standards have been developed to provide guidelines for the TAT. The tests conducted in compliance with such standards yield the Adhesion/Cohesion Strength of the coatings, which can be used for quality control and/or acceptance testing at industrial sites.

However, these standards do not provide a systematic procedure for incorporating the adhesive while preparing samples for the TAT. Thus, different sites have independently optimized curing procedures which potentially affect the measurements. Historically, it has been documented that adhesion strength depends on parameters like coating thickness, interface roughness, substrate properties, etc. It is suspected these parameters influence the stress in the coating which might relate to the adhesion strength.

In this study, the effects of differences in curing procedures on the adhesion strength have been investigated. Additionally, coatings of multiple thicknesses were deposited on several substrates with different interface properties and, the variations in stress distributions were examined. Deviations in the stress were linked to observed differences in coating adhesion strengths.