Mechanical behaviour and limits to the microhardness testing of hard multilayer coatings on soft substrates

摘要

Multilayer coatings of (Ti, Al) N{sub}x, (Ti, C)N{sub}x and (Nb, C)N{sub}x with bilayer thickness of 0.8-8 nm have been deposited by reactive sputtering on stainless steel substrates. Vickers microhardness measurements in the load range of 3.10{sup}-3 to I N were performed using a self-adjusting tester. It has been shown that in order to obtain the true hardness of multilayer coatings on a softer substrate, the indentation depth should not exceed about 10% of the coating thickness. Indentation criteria for polycrystalline, amorphous and nanostructured multilayer coatings are compared. The obtained criterion for multilayer coatings is close to that for amorphous films.