Microstructure, mechanical and tribological properties of magnetron sputtered Ti-BN films.

Abstract

Titanium boron nitride (Ti-B-N) films with various boron contents were deposited using titanium and boron targets in a reactive magnetron sputtering system. The boron content in the film was varied from 0 at.-% to 8.7 at.-%, to evaluate its properties. Various analytical techniques such as X-ray diffraction, high-resolution electron microscopy, nanoindentation and ball-on-disk dry sliding etc. were used. Incorporation of B into the film influenced the microstructure, mechanical and room-temperature tribological properties. At a B content of 0.2 at.-%, the film exhibited the highest hardness of ∼27 GPa. It also presented the lowest wear rate of ∼2.9 × 10−7 mm3 N−1 mm−1. However, there was a gradual decrease in coefficient of friction (CoF) values of the film when the B content was increased, with a minimum of 0.2 attained at 8.7 at.-% boron. The increased volume fraction of amorphous boron nitride phase contributed to the decrease in coefficient of friction.