PVD Coatings Technology

Scratch tester - An easy method of testing coating adhesion.

An example of a scratch tester

If a coating is to be effective it must have excellent adhesion to the substrate. The most common method of testing PVD coating adhesion is the scratch tester.

Scratch tester - basics

In the scratch test a Rockwell diamond tip with a radius of 200µm is moved across the coated surface of a substrate at a constant velocity with a controlled force applied that is increased at a constant loading rate. During such a scratch test stresses to the interface between coating and substrate occur that cause delamination or chipping of the coating. The force at which the first failure of the coating is detected is termed the critical load Lc. For more information about the scratch tester click the link.