| 1. |
- Lauridsen, Jonas, et al.
(författare)
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Ti-B-C nanocomposite coatings deposited by magnetron sputtering
- 2012
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Ingår i: Applied Surface Science. - : Elsevier. - 0169-4332 .- 1873-5584. ; 258:24, s. 9907-9912
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Tidskriftsartikel (refereegranskat)abstract
- Ti-B-C nanocomposite coatings with a B content of 8-17 at.% have been deposited by magnetron sputtering from B4C, Ti, and C targets. X-ray diffraction, photoelectron spectroscopy, and electron microscopy show that the coatings consist of nanocrystalline (nc) TiC: B embedded in a matrix of amorphous (a) C, BCx, TiOx and BOx. The fraction of amorphous phase scales with the Ti concentration, where the matrix predominantly consists of free C with some BCx in coatings with a C/Ti ratio andgt; 1, while the matrix predominantly consists of BCx with some free C in coatings with a C/Ti ratio andlt; 1. nc-TiC:B/a-BCx/a-C coatings with low amount of free C exhibit a contact resistance comparable to the contact resistance of an Ag sputtered coating at loads of similar to 1 N against an Au probe, despite the O content of similar to 16 at.%.
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| 2. |
- Nygren, Kristian, et al.
(författare)
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Influence of deposition temperature and amorphous carbon on microstructure and oxidation resistance of magnetron sputtered nanocomposite Cr-C films
- 2014
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Ingår i: Applied Surface Science. - : Elsevier BV. - 0169-4332 .- 1873-5584. ; 305, s. 143-153
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Tidskriftsartikel (refereegranskat)abstract
- It is known that mechanical and tribological properties of transition metal carbide films can be tailored by adding an amorphous carbon (a-C) phase, thus making them nanocomposites. This paper addresses deposition, microstructure, and for the first time oxidation resistance of magnetron sputtered nanocomposite Cr C/a-C films with emphasis on studies of both phases. By varying the deposition temperature between 20 and 700 C and alternating the film composition, it was possible to deposit amorphous, nanocomposite, and crystalline Cr C films containing about 70% C and 30% Cr, or 40% C and 60% Cr. The films deposited at temperatures below 300 degrees C were X-ray amorphous and 500 C was required to grow crystalline phases. Chronoamperometric polarization at +0.6 V vs. Ag/AgCl(sat. KG) in hot 1 mM H-2 SO4 resulted in oxidation of Cr C, yielding Cr203 and C, as well as oxidation of C. The oxidation resistance is shown to depend on the deposition temperature and the presence of the a-C phase. Physical characterization of film surfaces show that very thin C/Cr2O3/Cr C layers develop on the present material, which can be used to improve the oxidation resistance of, e.g. stainless steel electrodes. (C) 2014 Elsevier B.V. All rights reserved.
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| 3. |
- Sundberg, Jill, et al.
(författare)
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Understanding the effects of sputter damage in W–S thin films by HAXPES
- 2014
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Ingår i: Applied Surface Science. - : Elsevier. - 0169-4332 .- 1873-5584. ; 305, s. 203-213
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Tidskriftsartikel (refereegranskat)abstract
- WS2 is an excellent solid lubricant in dry conditions, and can be applied as thin films. The analysis of WS2 and WS2-based films by x-ray photoelectron spectroscopy (XPS) can be challenging, due to contaminationand oxidized material on the surface. The investigations have traditionally therefore included sputter etching by ion bombardment, which however leads to changes of the remaining material. In this study, hard x-ray photoelectron spectroscopy (HAXPES) has been used to study W–S films deposited bymagnetron sputtering. High-resolution reference measurements for crystalline WS2 and metallic W are also presented. The W–S films were analyzed before and after sputter cleaning by Ar+ ion bombardment, using photon energies of 3 and 6 keV. The as-deposited films were found to consist mainly of a WSx phase,similar to WS2 but with a broader range of chemical states. It is shown that ion bombardment of the surface not only removes the outermost oxidized material, but also leads to preferential sputtering of sulfur and the formation of metallic tungsten. The results are of strong interest for the analysis of WS2-based materials, as they demonstrate that spectra from sputter-cleaned films include effects of sputter damage,and may not be representative of the original sample.
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