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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...
Structural and electrochemical characterization of Zr–C–N–Ag coatings deposited...
Velasco, S. Calderon; Lopez, V.; Alves, C .F. Almeida; Cavaleiro, A.; Carvalho, S.ZrCN coatings with incorporated silver were deposited on 316L stainless steel by dual reactive magnetron sputtering to evaluate the silver influence on the structural properties and corrosion resistance of the films. Samples composition was assessed by electron probe microanalysis. Glow discharge optical emission spectroscopy was used to determine the distribution of silver in the films. Structural characteriza...
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 ...
Novel two-step processing route combining mechanical alloying and microwave hyb...
Santos, Mário J. G.; Alves, Cátia; Oliveira, F. A. Costa; Marcelo, Teresa; Mascarenhas, João; Cavaleiro, A.; Trindade, B.In this work, microwave hybrid sintering at 1300 and 1350 °C was carried out for densification of La9.33Si2Ge4O26 mechanically alloyed powder with apatite structure. The pellets sintered at these two temperatures present the same structure (apatite) with relative densities of 92 and 96%, respectively. Mechanical analysis performed on sintered materials revealed the following results: hardness of 7.1 and 8.0 GPa...
Endurance of methanogenic archaea in anaerobic bioreactors treating oleate-base...
Salvador, A. F.; Cavaleiro, A. J.; Sousa, D. Z.; Alves, M. M.; Pereira, M. A.Methanogenic archaea are reported as very sensitive to lipids and long chain fatty acids (LCFA). Therefore, in conventional anaerobic processes, methane recovery during LCFA-rich wastewater treatment is usually low. By applying a start-up strategy, based on a sequence of step feeding and reaction cycles, an oleate-rich wastewater was efficiently treated at an organic loading rate of 21 kg COD m(-3) day(-1) (50 ...
Biochemical Methane Potential of raw and pre-treated meat-processing wastes
Cavaleiro, A. J.; Ferreira, T.; Pereira, F. R.; Tommaso, Giovana; Alves, M. M.Raw and pre-treated greaves and rinds, two meat-processing wastes, were assessed for biochemical methane potential (BMP). Combinations of temperature (25, 55, 70 and 120°C), NaOH (0.3 g g-1 waste volatile solids) and lipase from Candida rugosa (10 U g-1 fat) were applied to promote wastes hydrolysis, and the effect on BMP was evaluated. COD solubilisation was higher (66% for greaves; 55% for rinds) when greaves...
Ag+ release and corrosion behavior of zirconium carbonitride coatings with silv...
Calderon Velasquez, S.; Galindo, R. Escobar; Oliveira, J. C.; Cavaleiro, A.; Carvalho, S.Zirconium carbonitride coatings with silver nanoparticles were produced by DC unbalanced dual magnetron sputtering system, using two targets, Zr and Zr/Ag in an Ar, C2H2 and N2 atmosphere. Stainless steel 316L and silicon (100) substrates were used for electrochemical and structural characterization, respectively. Silver was found to be well distributed throughout the coatings, maintaining the films' compositio...
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...
Ag+ release inhibition from ZrCN–Ag coatings by surface agglomeration mechanism...
Calderon Velasquez, S.; Escobar Galindo, R.; Benito, N.; Palacio, C.; Cavaleiro, A.; Carvalho, S.Published 17 July 2013 ; New multifunctional materials based on well-established materials to which functional properties are added, such as antibacterial performance, have become a relevant research topic, in order to meet the requirements of today's technological advances. This paper reports the results of a detailed structural and chemical characterization study of ZrCN–Ag coatings produced by reactive magn...
Addition of electron acceptors stimulates methanogenesis from lipids by anaerob...
Guedes, Ana P.; Cavaleiro, A. J.; Silva, Sérgio; Alves, M. M.; Stams, A. J. M.; Sousa, D. Z.Incubation of anaerobic sludge with triolein or oleate in the presence of nitrate or sulphate led to an increased methane production, relatively to incubations without inorganic electron acceptor. Faster methane production was obtained in assays amended with nitrate. Methanogenesis occurred after the reduction of alternative electron acceptors.
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