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The effect of increasing V content on the structure, mechanical properties and ...
Fernandes, F.; Loureiro, A.; Polcar, T.; Cavaleiro, A.In the last years, vanadium rich films have been introduced as possible candidates for self-lubrication at high temperatures, based on the formation of V2O5 oxide. The aim of this investigation was to study the effect of V additions on the structure, mechanical properties and oxidation resistance of Ti–Si–V–N coatings deposited by DC reactive magnetron sputtering. The results achieved for TiSiVN films were comp...
Frictional behavior of self-adaptive nanostructural Mo–Se–C coatings in differe...
Gustavsson, F.; Jacobson, S.; Cavaleiro, A.; Polcar, T.Sliding properties of Mo–Se–C coatings with two different carbon content deposited by magnetron sputtering were investigated in different sliding environments (argon, nitrogen, dry and humid air). Both coatings had a structure that was identified as randomly oriented structures of MoSe2 embedded into amorphous carbon matrix. The worn surfaces, i.e. the wear tracks and the wear scars of the balls, were analyzed ...
Influence of ag content on mechanical and tribological behavior of DLC coatings
Manninen, N. K.; Ribeiro, F.; Escudeiro, A.; Polcar, T.; Carvalho, S.; Cavaleiro, A.Ag–DLC coatings with Ag contents ranging from 1.3 at.% to 13.1 at.% were deposited by DC magnetron sputtering. The coatings were characterized with respect to their structure (by means of XRD and Raman spectroscopy), mechanical and tribological properties (by scratch test, nanoindentation, residual stress measurements and pin-on-disk test). The incorporation of 13.1 at.% Ag resulted in the formation of Ag grain...
High temperature properties of the Cr-Nb-Al-N coatings with increasing Al contents
Li, W. Z.; Polcar, T.; Evaristo, M.; Cavaleiro, A.Cr-Nb-Al-N coatings with Al content from 0 to 12 at.% were deposited by d.c. reactive magnetron sputtering. The coatings were annealed in protective atmosphere at 800 and 900 °C for 1 h and exposed to air at 800, 900 and 1200 °C for different times. The chemical composition, structure, microstructure, hardness and adhesive/cohesive strength of the coatings, in as-deposited and annealed conditions, were investig...
Carbon-based coatings doped by copper: Tribological and mechanical behavior in ...
Balestra, R. M.; Castro, A. M. G.; Evaristo, M.; Escudeiro, A.; Mutafov, Petr; Polcar, T.; Cavaleiro, A.We deposited C-based films doped with Cu and tested their sliding properties in olive oil as environment-friendly lubricant, which can be used in many mechanical systems, particularly in agriculture engineering. The coatings were deposited in a four unbalanced magnetron sputtering device combining C and C/Cu targets; argon (hydrogen-free films) and Ar/CH4 (hydrogenated films) atmospheres were used. Cu content o...
Structural and tribological characterization of tungsten nitride coatings at el...
Polcar, T.; Parreira, N. M. G.; Cavaleiro, A.Transition metal nitrides exhibit excellent mechanical properties (hardness and Young's modulus), high melting point, good chemical stability and high electrical conductivity. However, tungsten nitrides still stand aside of the main attention. In our previous study, tungsten nitride coatings with different nitrogen content showed excellent wear resistance at room temperature. Nevertheless, many engineering appl...
In situ structural evolution of arc-deposited Cr-based coatings
Neves, A. M.; Severo, V.; Cvrcek, L.; Polcar, T.; Louro, C.; Cavaleiro, A.Cr-based coatings were prepared by cathode arc-evaporation technology using N2 and C2H2 as reactive gases. Three compositions were investigated, Cr60N40, Cr41N27C32 and Cr67C33. ; http://www.sciencedirect.com/science/article/B6TVV-4SS1H9J-8/1/d2e621d9de5bfac3c95a1de278808f4d
Tungsten oxide with different oxygen contents: Sliding properties
Polcar, T.; Parreira, N. M. G.; Cavaleiro, A.In this study, tungsten oxide coatings with 13 and 75 at% of oxygen were prepared by DC reactive magnetron sputtering from a pure W target in an Ar+O2 atmosphere. The coating hardness (H) decreased with increasing oxygen content from 25 to 7.7 GPa. The values of H/E ratio were 0.08 and 0.07 for W87O13 and W25O75, respectively. ; http://www.sciencedirect.com/science/article/B6TW4-4NG3T6T-3/1/f9d8350fca3dc06d1...
Thermal stability of reactive sputtered tungsten oxide coatings
Parreira, N. M. G.; Polcar, T.; Cavaleiro, A.The thermal stability of different W-O coatings, W100, W90O10, W54O46, W30O70 and W25O75, were studied by in-situ X-ray diffraction at elevated temperatures up to 900 °C. The coatings were deposited by DC reactive magnetron sputtering from a pure tungsten target in an Ar + O2 atmosphere onto Fecralloy alloy. The evolution of the structure of the coatings was studied in both protective and oxidant atmospheres. T...
Tribological characterization of tungsten nitride coatings deposited by reactiv...
Polcar, T.; Parreira, N. M. G.; Cavaleiro, A.The structure, hardness, friction and wear of tungsten nitrides prepared by d.c. reactive magnetron sputtering were investigated. The coatings were deposited with different nitrogen to argon ratios; the total pressure was kept constant. The tribological tests were performed on a pin-on-disc tribometer in terrestrial atmosphere with 100Cr6 steel, Al2O3 and Si3N4 balls as sliding counter-bodies. The wear tracks, ...
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