The use of the scratch test to measure the fracture strength of brittle thin films

The feasibility of the use of the scratch test to measure the fracture strength of brittle thin films has been proved. In particular, amorphous diamond-like carbon (DLC), SiC and TiO2 films deposited on a soda-lime glass substrate, in which damage initiated on the film surface in the form of partial cone cracks, have been considered. Optical inspection of the scratch tracks allowed the normal and lateral force at the point of fracture to be determined. The critical values were subsequently used to calculate the fracture strength. The great advantage of this method is that it allows the contribution of surface defects to strength to be obtained. Weibull analysis of the strength data was carried out, showing that the SiC film possess higher strength and reliability compared to DLC and TiO2 films.