Scratch Adhesion Test

A coating adhesion test that uses a stylus (usually diamond) applied to the coating surface at an applied load and moving relative to the coating at a specified velocity. The observed damage to the coated surface is observed and recorded. Commonly, the reported value is the critical load where the coating is fully removed from the substrate. In general, however, this is only one simplistic view of a complex set of results. As with other adhesion tests, this test unfortunately does not measure only the adhesion of the coating. It is affected by many other parameters such as the substrate material and hardness, the coating material, thickness and hardness, and the geometry of the part. But, it is repeatable if these variables are kept fairly consistent.