The modification of mechanical properties and adhesion of boron carbide sputtered films by ion implantation

Abstract

Mechanical and tribological properties of boron carbide films have been modified by nitrogen ion implantation in the near surface region. For nanocrystalline boron carbide films, hardness, friction coefficient and linear wear intensity were reduced from 3000 to 2800, from 0.18 to 0.09 and from 5.0 × 10 −8 to 2.7 × 10 −8, respectively. For amorphous boron carbide films the hardness and the linear wear intensity increased while the friction coefficient decreased. These modifications were attributed to the creation of defects and to the formation of boron nitride phases. The interface between boron carbide films and Si or WC substrates has also been modified by ion beam mixing and MeV-ion irradiation. Adhesion of B 4C films to the substrate was assessed by measurements of critical loads in scratch tests. For films on Si-substrates the critical load increased from 10 N to 14 N after ion beam mixing and from 10 N to 20 N after MeV-ion irradiation.