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Indentation and scratch testing of DLC-Zr coatings on ultrafine-grained titaniu...
Wang, Chuan Ting; Escudeiro, Ana; Polcar, Tomas; Cavaleiro, Albano; Wood, Robert J. K.; Gao, Nong; Langdon, Terence G.High-pressure torsion was employed to refine the microstructure of grade 2 Ti under an imposed pressure of 3.0 GPa at room temperature. The microhardness of grade 2 Ti increased from 1.82 GPa for the coarse grain state to 3.05 GPa after high-pressure torsion processing, where this value is very close to the hardness of the Ti–6Al–4V alloy. Subsequently, several diamond-like carbon (DLC) coatings with thicknesse...
Ultra-low friction W–S–N solid lubricant coating
Gustavsson, Fredrik; Jacobson, Staffan; Cavaleiro, Albano; Polcar, TomasW–S–N films were deposited by reactive magnetron sputtering from WS2 target in Ar/N2 atmosphere. Besides the standard evaluation of composition, structure, morphology, hardness and cohesion/adhesion, the core objective of this paper was to analyze coating tribological behavior. The chemical composition was 34 at.% N, 12 at.% O, 29 at.% W and 25 at.% S, and the as-deposited films were completely amorphous. The f...
Self-adaptive low friction coatings based on transition metal dichalcogenides
Polcar, Tomas; Cavaleiro, AlbanoThis paper deals with three fundamentally different concepts of self-lubricant coatings based on the transition metal dichalcogenides (TMD) and deposited by magnetron sputtering. The first two designs could be considered as traditional: the TMD films doped by carbon or nitrogen. The main attention is aimed at qualitative description of surface and sub-surface modification of the films as the result of the slidi...
How can H content influence the tribological behaviour of W-containing DLC coat...
Silva, Carlos W. Moura e; Branco, José R. T.; Cavaleiro, Albanohttp://www.sciencedirect.com/science/article/B6W6W-4VCH71Y-1/2/9b50f04850d12009018cd55f8983a391
Tribological behaviour of C-alloyed transition metal dichalcogenides (TMD) coat...
Evaristo, Manuel; Polcar, Tomas; Cavaleiro, AlbanoAbstract W-S-C films were deposited by non-reactive sputtering from a carbon target incrusted with WS2 pellets in the eroded zone. This process allows depositing coatings with a wide range of compositions, with a precise control of their carbon content. Before the deposition, a Ti interlayer was interposed between the film and the substrate to improve the final adhesion. The carbon content in W-S-C system was ...
Modelling of Magnetron Sputtering of Tungsten Oxide with Reactive Gas Pulsing
Kubart, Tomáscaron; Polcar, Tomáscaron; Kappertz, Oliver; Parreira, Nuno; Nyberg, Tomas; Berg, Sören; Cavaleiro, AlbanoReactive sputtering is one of the most commonly employed processes for the deposition of thin films. However, the range of applications is limited by inherent instabilities, which necessitates the use of a complex feedback control of reactive gas (RG) partial pressure. Recently pulsing of the RG has been suggested as a possible alternative. In this report, the concept of periodically switching the RG flow betwe...
Friction of Self-Lubricating W-S-C Sputtered Coatings Sliding Under Increasing ...
Polcar, Tomas; Evaristo, Manuel; Cavaleiro, AlbanoW-S-C films were deposited by non-reactive magnetron sputtering from a carbon target with several pellets of WS2 incrusted in the zone of the preferential erosion. The number of the pellets was changed to modify the carbon content in the films, which varied from 26 up to 70 at.-%. Alloying W-S films with carbon led to a substantial increase in the hardness in the range of 4-10 GPa; the maximum hardness was obta...
From Ti–Al- to Ti–Al–N-sputtered 2D materials
Vieira, Maria; Ramos, Ana; Castanho, José; Oliveira, João; Cavaleiro, AlbanoAbstract This paper reviews thin films constituted by elements based on the Ti–Al–N system, bearing in mind the role of the condensed phases in the development of structural components and functional devices. In recent decades, the Ti–Al, Ti–N and Al–N nanocrystalline binary systems have rapidly attracted research and industry interest. These systems have revealed a great performance via atomic-level structura...
The nanostructure and microstructure of steels: Electrochemical Tafel behaviour...
Alves, Valéria A.; Paquim, Ana M. Chiorcea; Cavaleiro, Albano; Brett, Christopher M.A.The influence of chemical composition and heat treatment on a low-carbon steel, chromium steel and high speed steel has been examined by polarisation curves and electrochemical parameters deduced from the Tafel plots. The electrochemical corrosion resistance, which is small between the as-received steels become greater after heat treatment, following the order: carbon steel < chromium steel ~ high speed ste...
Electrochemical corrosion of magnetron sputtered WTiN-coated mild steels in a c...
Alves, Valéria A.; Brett, Christopher M. A.; Cavaleiro, AlbanoThe electrochemical corrosion behaviour of WTiN coatings, of composition W 31, Ti 28 and N 40 at.% sputtered on carbon steel, chromium steel and high speed steel (HSS) has been investigated and the effect of the steel heat treatment on the steel/WTiN system performance explored. Open circuit potential measurements, polarisation curves and electrochemical impedance spectroscopy were used, together with X-ray dif...
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