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Abstract: Nanostructured WC–12Co coating with crystal sizes below 30nm were deposited on low carbon steel substrate by high velocity oxy-fuel spraying. In this study, corrosion behavior of such coatings was investigated in artificial sea water electrolyte and compared with micron-sized (internal structure) coating of similar composition. Besides that, role of small amount Al alloying on corrosion behavior of such nanostructured coating was also investigated. Nanostructured WC–12Co coatings with or without Al exhibit lower corrosion potential and lower polarization resistance compared to micron-sized (internal structure) coating as well as higher Co dissolution as revealed by electrochemical impedance spectroscopy (EIS) together with other complementary electrochemical techniques. [Copyright &y& Elsevier]

Abstract: Activated carbons were developed by phosphoric acid activation of sawdust from Prosopis ruscifolia wood, an indigenous invasive species of degraded lands, at moderate conditions (acid/precursor ratio=2, 450°C, 0.5h). For in situ modification of their characteristics, either a self-generated atmosphere or flowing air was used. The activated carbons developed in the self-generated atmosphere showed higher BET surface area (2281m2/g) and total pore volume (1.7cm3/g) than those obtained under flowing air (1638m2/g and 1.3cm3/g). Conversely, the latter possessed a higher total amount of surface acidic/polar oxygen groups (2.2meq/g) than the former (1.5meq/g). To evaluate their metal sorption capability, adsorption isotherms of Cu(II) ion from model solutions were determined and properly described by the Langmuir model. Maximum sorption capacity (X m) for the air-derived carbons (X m =0.44mmol/g) almost duplicated the value for those obtained in the self-generated atmosphere (X m =0.24mmol/g), pointing to a predominant effect of the surface functionalities on metal sequestering behaviour. The air-derived carbons also demonstrated a superior effectiveness in removing Cd(II) ions as determined from additional assays in equilibrium conditions. Accordingly, effective phosphoric acid-activated carbons from Prosopis wood for toxic metals removal from wastewater may be developed by in situ modification of their characteristics operating under flowing air. [Copyright &y& Elsevier]

The nanotribological properties of magnetron sputtered sulfur deficient MoSx (x=1.3) coatings were investigated by oscillating lateral force microscopy (LFM) in ambient air of 50% relative humidity (RH) and 23 °C. The formation of a transfer film on the Si3N4 cantilever tip originated from the MoSx coating is found. The effect of that transfer film on the adhesive and frictional force between the MoSx coating and the cantilever tip, is reported for this nanoscale friction tests. Wear of the MoSx coatings was found on sliding against a Si3N4 cantilever tip. The sliding behavior of MoSx coatings in oscillating nano- and macro-sliding tests performed at different oscillation frequency is discussed. [Copyright &y& Elsevier]

The wear of materials in sliding contacts is considered as resulting from an energy dissipation due to friction between the contacting first bodies. Up to now, no standard procedure in tribology is available to relate that dissipated energy with wear losses for different sliding wear tests and conditions. In this paper, a procedure is proposed to correlate the volumetric wear loss of one first body with the dissipated energy for unidirectional and bidirectional ball-on-flat tests. The model can be useful to predict the service lifetime of components from a limited number of laboratory tests. The validity and limitation of the wear loss versus dissipated energy model is illustrated for hard coatings like TiN and (Ti, Al)N, and multilayered (Ti, Al)N/TiN coatings. The effect of the applied normal load and the relative humidity (RH) of the ambient air on the wear rate for these different coatings are shown as well. A mild oxidational wear model is used to describe the material loss on these coatings in sliding contacts. [Copyright &y& Elsevier]

Abrasive wear behaviour of WC-Co and Fe/Cu-based nanostructured coatings has been investigated under dry and slurry conditions in this study. The retention of nanostructured coating constituents was confirmed together with the formation of various metallic and ceramic phases. Abrasive wear rate of nanostructured WC-Co coating was one order lower than that of micro-structured coatings in both conditions. Relatively higher abrasion wear resistance of such coatings compare to reference metallic material was because of comparatively smaller debris formation. These debris roll in between the moving surfaces and thus limit the wear of coating materials. Another aspect of higher abrasive wear resistance is homogeneous distribution of hard (WC and Al 2 O 3) particles within relatively soft matrix (Co and FeCu) as revealed by SEM investigation. • Nanostructured coatings were successfully deposited from engineered nanosized powders using high thermal spraying. • Abrasive wear rate of nanostructured WC-based coating is one order of magnitude lower than that of micro-structured coating. • Different coating groups (WC-based or Fe/Cu-based) show different degradation mechanism during abrasion. [ABSTRACT FROM AUTHOR]