| AVS 58th Annual International Symposium and Exhibition | |
| Advanced Surface Engineering Division | Thursday Sessions |
| Session SE-ThM |
| Session: | Nanostructured Thin Films and Coatings |
| Presenter: | Olof Tengstrand, Linköping University, Sweden |
| Authors: | O. Tengstrand, Linköping University, Sweden N. Nedfors, Uppsala University, Sweden L. Fast, SP Tech. Res. Inst. of Sweden A. Flink, Impact Coatings AB, Sweden A.M. Andersson, ABB AB, Corporate Research, Sweden U. Jansson, Uppsala University, Sweden P. Eklund, Linköping University, Sweden L. Hultman, Linköping University, Sweden |
| Correspondent: | Click to Email |
Nanocomposite ceramic coatings are being explored based on their good tribological and electrical properties, which can be tailored by changing e.g. the composition, microstructure, and surface morphology. For example, the nc-TiC/a-SiC nanocomposite system has shown promising properties for electrical contact applications [1, 2]. The tendency to form oxides and carbides greatly influences these properties. For instance, NbC has similar electrical properties as TiC, but has a lower tendency to form oxides. Especially for low force electrical contact applications, this makes NbC a suitable choice as replacement for TiC. Ge is in the same group as Si, but does, as a more noble element, not form carbides or oxides as easily. Here, we investigate the Nb-Ge-C material system with respect to nanostructure and electrical properties.
Nb-Ge-C thin films were deposited onto Si(001) and Ni-electroplated bronze substrates using dc magnetron sputtering in an Ar discharge at a low temperature (200 ºC). By use of three elemental targets in current-regulating mode both the Nb/C ratio and the Ge content was varied to study the effect of composition. XRD, TEM, and SEM showed that the NbC films are columnar and exhibit a preferred 111 crystallographic orientation. With increasing Ge content up to 10 at.%, the NbC grain size was reduced to ~5 nm with a random orientation. While the nc-NbC/Ge nanocomposites have no discernable amorphous tissue phase, XPS showed predominantly Ge-Ge with only little Ge-C bonds. In contact resistance measurements the films performed well (1.7-3.7 mΩ) in comparison to Ag reference (1.2 mΩ) at a contact force of 10 N.
[1] Eklund,P., Surface Engineering, 23, (2007), 406
[2] Lauridsen,J.; et al. Surf. Coat. Technol., 205, (2010), 299