Thermal stability of hard nanocomposite Mo-B-C coatings. (April 2017)

• Record Type: Journal Article
• Authors: Zábranský, L.; Buršíková, V.; Souček, P.; Vašina, P.; Dugáček, J.; Sťahel, P.; Buršík, J.; Svoboda, M.; Peřina, V.
• Is Part Of: Vacuum. Volume 138(2017)
• Page Start: 199
• Page End: 204
• Publication Date: 2017-04
• Subjects: Thermal stability -- Mo2BC coatings -- Hardness -- Fracture resistance; Vacuum -- Periodicals; 621.55
• DOI: 10.1016/j.vacuum.2016.12.016
• Languages: English
• ISSNs: 0042-207X

Abstract

Abstract: In the present work, nanocomposite Mo-B-C coatings were deposited on high speed steel and hard metal substrates by magnetron sputtering of three targets. These coatings were subjected to annealing to final temperatures in the range from 500 °C to 1000 °C. It was found that the as deposited Mo-B-C coatings exhibited hardness of ∼20 GPa, nanocomposite microstructure with very fine grains (∼2 nm) and low degree of crystallinity. The X-ray diffraction and transmission electron microscopy together with selective area electron diffraction were used to study the temperature induced changes of the microstructure of the coating and its crystallinity. The annealing process significantly improved the hardness (from ∼20 GPa to ∼30 GPa) and effective elastic modulus (from initial 330 GPa–500 GPa) of coatings while their resistance to fracture was kept sufficiently high. Highlights: Thermal annealing of nanocomposite Mo2 BC coatings improved their hardness and elastic modulus. The XRD did not show any changes in the microstructure for samples annealed up to 900 °C even though their mechanical properties were improved. Annealing to 1000 °C resulted in strong increase of the crystallinity. All coatings kept their excellent ductile properties up to 600 °C.