Synthesis and characterization of MoB2-x thin films grown by nonreactive DC magnetron sputtering
2016 (English)In: Journal of Vacuum Science & Technology. A. Vacuum, Surfaces, and Films, ISSN 0734-2101, E-ISSN 1520-8559, Vol. 34, no 3, 031511Article in journal (Refereed) PublishedText
DC magnetron sputtering was used to deposit molybdenum boride thin films for potential low-friction applications. The films exhibit a nanocomposite structure with similar to 10 nm large MoB2-x (x > 0.4) grains surrounded by a boron-rich tissue phase. The preferred formation of the metastable and substoichiometric hP3-MoB2 structure (AlB2-type) is explained with kinetic constraints to form the thermodynamically stable hR18-MoB2 phase with a very complex crystal structure. Nanoindentation revealed a relatively high hardness of (29 +/- 2) GPa, which is higher than bulk samples. The high hardness can be explained by a hardening effect associated with the nanocomposite microstructure where the surrounding tissue phase restricts dislocation movement. A tribological study confirmed a significant formation of a tribofilm consisting of molybdenum oxide and boron oxide, however, without any lubricating effects at room temperature.
Place, publisher, year, edition, pages
2016. Vol. 34, no 3, 031511
IdentifiersURN: urn:nbn:se:uu:diva-300575DOI: 10.1116/1.4948234ISI: 000379792200027OAI: oai:DiVA.org:uu-300575DiVA: diva2:951646
FunderSwedish Research Council, 621-2012-4359; 622-2008-405Knut and Alice Wallenberg FoundationSwedish Foundation for Strategic Research , RMA11-0029