The analysis of problems concerning thin film (1–5 μ) microhardness measurement by means of different techniques is conducted in case of diamond-like carbon coatings. It is shown experimentally that the extrapolation of the lg(Hm−Hs) vs. d dependence to zero d values, where Hs is microhardness of the film substrate, Hm is formal microhardness of the substrate with coating and d is Berkovich pyramid depth, leads to reliable coating microhardness values Hf independent on substrate properties and characterizing the properties of the coating itself. This approach is used to obtain the average Hf values of multilayer coatings. It is found that the surface roughness of the coatings impedes the correct determination of the coating microhardness by means of nano-indentor techniques. The coating surface smoothening (mechanical or by ion etching) provides the conditions for correct microhardness measurement. It is concluded that the real Hf values of diamond-like carbon coatings obtained by pulse arc graphite sputtering exceeds 100 GPa.
