Hardness testing is a simple mechanical test developed to provide a quantitative measurement in a quick and efficient manner. Hardness testing is used in place of other techniques such as tensile testing. There is often good correlation to tensile strength, but requires significantly less time and effort, as well as being comparatively nondestructive.
Coatings are applied to materials for a wide variety of reasons including protection from the environment, wear resistance, and surface finish modification. They are often relatively thin, but the quality of the coating can be critical to the performance and lifetime of the coated component. A full understanding of the properties of the coating is therefore critical to quality control. Compliance checks are often carried out including thickness measurements, bond strength, continuity of interfaces, contamination and porosity among many others. Hardness testing can be a quick and effective tool for checking coating properties, especially in high volume production environments. However, selection of an appropriate approach and understanding key advantages and limitations is important to ensuring an accurate result.