Nb-B-C thin films for electrical contact applications deposited by magnetron sputtering
2014 (English)In: Journal of Vacuum Science & Technology. A. Vacuum, Surfaces, and Films, ISSN 0734-2101, E-ISSN 1520-8559, Vol. 32, no 4, 041503- p.Article in journal (Refereed) Published
The high wear resistance, high chemical inertness, and high electrical conductivity of magnetron-sputtered transition metal diborides (MeB2) make them a candidate material for sliding electrical contacts. However, their high hardness makes it difficult to penetrate surface oxides, resulting in a high electrical contact resistance. We have in this study investigated how the contact resistance can be improved by the formation of softer Nb-B-C films. The Nb-B-C films were deposited by magnetron sputtering and shown to exhibit a nanocomposite microstructure consisting of nanocrystalline NbB2-x grains with a solid solution of C separated by an amorphous BCx phase. The formation of the BCx phase reduces the hardness from 41 GPa for the NbB2-x film to 19 GPa at 36 at.% C. As a consequence the contact resistance is drastically reduced and the lowest contact resistance of 35 mΩ (contact force 5 N) is achieved for a film containing 30 at.% C. However, crack formation and subsequent delamination and fragmentation is observed for the C-containing Nb-B-C films in tribology tests resulting in high friction values for these films.
Place, publisher, year, edition, pages
2014. Vol. 32, no 4, 041503- p.
boride, structural characterization, electrical properties, mechanical properties, friction, nanocomposite
Research subject Chemistry with specialization in Materials Chemistry
IdentifiersURN: urn:nbn:se:uu:diva-219032DOI: 10.1116/1.4875135ISI: 000338718400015OAI: oai:DiVA.org:uu-219032DiVA: diva2:698063