# Study of the Friction Contact of HIPIMS Magnetron-Sputtered TiB2 Against Aluminium at Temperatures up to 300 °C

## TL;DR

This study examines how TiB2 coatings perform under friction with aluminum at high temperatures, showing better performance than TiN and CrN coatings.

## Contribution

The study reveals a temperature-dependent transition in adhesion behavior of TiB2 coatings during friction with aluminum.

## Key findings

- TiB2 coatings showed hardness of about 39 GPa and a dense microstructure with 51–68 nm grain sizes.
- TiB2 exhibited low adhesion to aluminum at temperatures up to 175 °C, transitioning to severe adhesion between 175 °C and 200 °C.
- TiN and CrN coatings showed low–medium adhesion at room temperature but severe transfer at 150 °C.

## Abstract

In this study, we investigated the frictional properties of TiB2 films produced by high-power impulse magnetron sputtering and compared them with those of TiN- and CrN-sputtered coatings also made using high-power pulsed discharges. The films were characterised by scanning electron microscopy, Electron Probe Micro-Analysis, nanoindentation and friction tests. Sliding friction analyses were performed against aluminium surfaces at different temperatures, ranging from room temperature to 300 °C. The TiB2 coatings exhibited hardness values of about 39 GPa, regardless of the bias potential used between −50 V and −100 V, a low modulus of around 300 GPa and a dense compact columnar microstructure with grain sizes between 51 and 68 nm in diameter. The friction behaviour on aluminium produced the transfer of this element to the films, at rates that depended on the test temperature. The TiN and CrN coatings exhibited low–medium adhesion to aluminium at room temperature and severe transfer during the friction tests at 150 °C. In the case of the TiB2 films, the adhesion of aluminium during friction tests was low for temperatures up to 175 °C. In fact, a clear transition of the mild-to-severe adhesion of aluminium on TiB2 was observed in the temperature range of 175 °C to 200 °C for the testing conditions evaluated in this study, which was concomitant with the evolution observed for the friction coefficients.