Mechanical and tribological behaviour of titanium boride coatings processed by thermochemicals treatments

ABSTRACT

The present work aims to study the mechanical and tribological properties of titanium boride layer processed by a thermochemical boriding treatment, which was carried out in a salt bath consisting of 70% borax and 30% silicon carbide. The boriding temperatures were 850°C, 950°C and 1000°C with holding times of 2, 4, 6 and 8 h. The analysis by optical and scanning electron microscopy and X-ray diffraction method confirmed the formation of a single-phase layer of titanium diboride (TiB₂) in the substrate surface. The thickness of the boride layer increases with time and temperature, reaching a maximum value of 50 μm. The microhardness was evaluated for the substrate and the boride layer. Additionally, nanomechanical characterization of the layer was carried out by nanoindentation tests. The influence of this treatment on the coefficient of friction and on the wear rate in a simulated medium of the body fluid was also studied.

KEYWORDS:

• Boride layer
• borax
• hardness
• microstructure
• titanium alloy
• nanoindentation
• wear rate
• coefficient of friction‌

Acknowledgements

The authors would like to thank the National Polytechnic School of ORAN Maurice Audin of Algeria for the financial support and Mr. Salah Benouareth Manager of ORAN Médicat Company. The authors would also like to thank the Spanish government CICYT under grant MAT2016-76928-C2-2-R (DURESPRAY) for the financial support.

Disclosure statement

No potential conflict of interest was reported by the author(s).

Additional information

Funding

This work was supported by Comisión Interministerial de Ciencia y Tecnología: [Grant Number MAT2016-76928-C2-2-R (DURESPRAY)]; Research financed by National Polytechnic School of ORAN Maurice Audin (Algerian Ministry of Higher Education and Scientific Research)..