Scratch Tester

  Facility and principle of the scratch test Copyright: © IOT Scratch tester (a) and principle of the scratch test (b)

A sufficient adhesion is a central criterion of a functional coating/substrate compound. One possibility to evaluate the adhesion is the scratch test. During the test a Rockwell C diamond is drawn across the coated surface with a defined load. The generated scratches and the occurring deformations are evaluated via light optical microscope, confocal laserscanning microscopy or scanning electron microscope. The critical load Lc is identified at which damage of the coating takes place. The type of failure is influenced by coating and substrate. It is for example possible to distinguish between cohesive failure (failure within the coating) or adhesive failure (failure between the coating and the substrate surface). The scratch test is standardised in DIN EN 1071-3.

Technical data:

Parameter Value [Unit]
Range of load

0 N – 250 N

Feed 0 mm/min - 350 mm/min

Continuous or increased load