| Authors: | Deepthi, B.; Barshilia, Harish C.; Rajam, K. S.; Konchady, Manohar S.; Pai, Devdas M.; Sankar, Jagannathan; Kvit, Alexander V. |
| Title: | Structure, morphology and chemical composition of sputter deposited nanostructured Cr-WS2 solid lubricant coatings. |
| Type: | Journal Article |
| Publisher: | Surf. Coat. Technol. |
| Year: | 2010 |
| Volume: | 205 |
| Issue: | 2 |
| Start Page: | 565 |
| End Page: | 574 |
| Abstract: | WS2 and Cr-WS2 nanocomposite coatings were deposited at different Cr contents (approx. 15-50 at.%) on silicon and mild steel substrates using an unbalanced magnetron sputtering system. X-ray diffraction (XRD) was used to study the structure of Cr-WS2 coatings and the bonding structure of the coatings was studied using XPS. The characterization of different phases present in Cr-WS2 coatings was carried out using micro-Raman spectroscopy. The XPS and Raman data indicated the formation of a thin layer of WO3 on the surface of Cr-WS2 coatings and the intensity of the oxide phase decreased with an increase in the Cr content, which was also confirmed using energy-dispersive X-ray anal. results. The surface morphologies of WS2 and Cr-WS2 coatings were examd. using field emission SEM (FESEM) and at. force microscopy. It has been demonstrated that incorporation of Cr in WS2 strongly influences the structure and morphol. of Cr-WS2 coatings. The XRD and FESEM results suggested that increase in the Cr content of Cr-WS2 coatings resulted in a structural transition from a mixt. of nanocryst. and amorphous phases to a complete amorphous phase. The cross-sectional FESEM data of WS2 coating showed a porous and columnar microstructure. For the Cr-WS2 coatings, a mixt. of columnar and featureless microstructure was obsd. at low Cr contents (? 23 at.%), whereas, a dense and featureless microstructure was obsd. at high Cr contents. Detailed cross-sectional transmission electron microscopy (TEM) studies of Cr-WS2 coatings prepd. at Cr content ? 23 at.% indicated the presence of both nanocryst. (near the interface) and amorphous phases (near the surface). Furthermore, high-resoln. TEM data obtained from the nanocryst. region showed inclusion of traces of amorphous phase in the nanocryst. WS2 phase. Potentiodynamic polarization measurements indicated that the corrosion resistance of Cr-WS2 coatings was superior to that of the uncoated mild steel substrate and the corrosion rate decreased with an increase in the Cr content. [on SciFinder (R)] |
| Keywords: | Corrosion (resistance; structure, morphol. and chem. compn. of sputter deposited nanostructured Cr-WS2 solid lubricant coatings); Coating materials (self-lubricating; structure, morphol. and chem. compn. of sputter deposited nanostructured Cr-WS2 solid lubricant coatings); Lubricants (solid; structure, morphol. and chem. compn. of sputter deposited nanostructured Cr-WS2 solid lubricant coatings); Interfacial structure; Magnetron sputtering; Metal matrix composites; Microstructure; Nanocomposites; Nanocrystallization; Nanostructures; Surface structure (structure, morphol. and chem. compn. of sputter deposited nanostructured Cr-WS2 solid lubricant coatings) |
