Standard Test Method for Measurements of Internal Stresses in Organic Coatings by Cantilever (Beam) Method

Importancia y uso:

5.1 Stresses in coatings arise as a result of their shrinkage or expansion if expected movements are prevented by coating adhesion to its substrate.

5.2 There are several causes leading to arrival of stresses in the coatings: film formation (cross-linking, solvent evaporation, etc.); differences in thermal expansion coefficients between coating and substrate; humidity and water absorption; environmental effects (ultraviolet radiation, temperature and humidity), and others.

5.3 Knowledge of the internal stresses in coatings is very important because they may effect coating performance and service life. If the internal stress exceeds the tensile strength of the film, cracks are formed. If stress exceeds adhesion between coating and substrate, it will reduce adhesion and can lead to delamination of coatings. Quantitative information about stresses in coatings can be useful in coating formulation and recommendations for their application and use.

5.4 This method has been found useful for air-dry industrial organic coatings but the applicability has not yet been assessed for thin coatings (thickness <0.0254 mm (.001 in.), for powder and thermally-cured coatings.

Subcomité:

D01.23

Volúmen:

06.01

Número ICS:

25.220.60 (Organic coatings)

Palabras clave:

cantilever; deflection; internal stress; organic coatings;