Improvement of mechanical properties of nanometer period multilayer films at interfaces of each layer

Abstract

By controlling the time period for which the substrate was positioned opposite each of the graphite and boron nitride semicircular targets, nanometer period carbon nitride and boron nitride multilayer films were deposited one after another in an argon and nitrogen atmosphere. Both the nanoindentation hardness and microwear resistance of the multilayer films changed with the layer period. The multilayer film with a 4 nm period had the highest hardness and microwear resistance. To clarify the reason for this, the atomic scale wear was characterized. The rate of increase of wear depth was almost zero at the depth which corresponds to each layer thickness. It is suggested that the interfaces prevent the defect elongation. The preventive effect of the interface on defect elongation of a 4 nm period multilayer film is greater than that of a 2 nm period multilayer film.