Surface Optimization of Commercial Porous Ti Substrates by EPD of Titanium Nitride

In this work, the infiltration of TiN powders by electrophoretic deposition (EPD) in aqueous media was considered as alternative method to reduce the size craters and the roughness of commercial porous Ti substrates. Ti substrates can be used as suitable supports for the deposition of dense hydrogen separation TiNx-based membranes by physical vapor deposition (PVD) techniques. The influence of various EPD deposition parameters on surface morphology and roughness of TiN-infiltrated substrates were investigated in order to optimize their surface properties. The results suggest that a multi-step EPD procedure is an effective technique for reducing substrate surface defects of commercial porous Ti substrates which could then be successfully used as proper supports for the deposition of dense and defect-free TiNx layers, also aligning the thermal mismatch between the active layer and the porous substrate

Experimental assessment and predictive model of the performance of Ti-based nanofluids

The need for innovative propulsion technologies (e.g., fuel cells) in the mobility sector is posing a higher-than-ever burden on thermal management. When low operative temperature shall be ensured, dissipation of a significant amount of heat is requested, together with limited temperature variation of the coolant; mobile applications also yield limitations in terms of space available for cooling subsystems. Nanofluids have recently become one of the most promising solutions to replace conventional coolants. However, the prediction of their effectiveness in terms of heat-transfer enhancement and required pumping power still appears a challenge, being limited by the lack of a general methodology that assesses them simultaneously in various flow regimes. To this end, an experiment was developed to compare a conventional coolant (ethylene glycol/water) and a TiO2-based nanofluid (1% particle loading), focusing on heat transfer and pressure loss. The experimental dataset was used as an input for a physical model based on two independent figures of merit, aiming at an a priori evaluation of the potential simultaneous gain in heat transfer and parasitic power. The model showed conditions of combined gain specifically for the laminar flow regime, whereas turbulent flows proved inherently associated to higher pumping power; overall, criteria are presented to evaluate nanofluid performance as compared to that of conventional coolants. The model is generally applicable to the design of cooling systems and emphasizes laminar flow regime as promising in conjunction with the use of nanofluids, proposing indices for a quantitative a priori evaluation and leading to an advancement with respect to an a posteriori assessment of their performance

Electrochemical behavior of diphenyl disulfide and thiophenol on glassy carbon and gold electrodes in aprotic media

The investigation of the electrochemical reduction processes of C6H5SSC6H5 and C6H5SH in CH3CN using cyclic voltammetry indicates a different behavior on GC and Au electrodes. On GC surface adsorption phenomena are absent, the electrochemical reduction process is irreversible and diffusion controlled. For both the starting molecules the same species, C6H5S-, is formed upon reduction. The Edegrees values of the reduction processes were determined by convolution method and the standard free energy of the S-S bond of C6H5SSC6H5 estimated. On Au surface instead, a self-assembled monolayer of C6H5SAuads originated after the S-S or S-H bond breaking can be observed by simply dipping the electrode in solution of C6H5SSC6H5 and C6H5SH, respectively. The properties of the SAM were investigated by electrochemical reduction of the adsorbed thiolates. On Au electrode the reduction processes involve C6H5SAuads, and give rise to desorbed C6H5S-. A neutral radical is obtained by. electrochemical oxidation of thiolate anion. It reacts rapidly with the electrode surface to give the S-Au bond again

Chromium (VI) Galvanic Bath: Chemical Treatments and Possible Recycling Ways of the Obtained Sludges

Galvanic processes, that increase corrosion resistance properties and improve wear qualities of metal materials, are based on metal plating baths and rinsewaters. They generate effluents with a metal concentration varying with the installed process. Traditional systems reduce the toxicity of wastewater by aggregating disposed aqueous solutions of various concentrations, followed by treatment with chemicals to coagulate, flocculate, and settle out solid wastes for off-site disposal. In this paper the efficiency of different precipitating agents was evaluated in order to obtain a Cr (III) sludge.There are several treatment routes proposed in the literature to avoid dumping, or in other words, recycle the wastes. Recent increase in the cost of landfill disposal and decrease in number of disposal sites have led to consideration of alternative routes and treatments. For this reason, the screening results of scientific activity conducted on a laboratory scale on the possibility to both inertize and valorize the obtained galvanic sludge in the traditional ceramic filed (glasses, bricks, tiles, pigments and glazes) were reported with particular emphasis on the possible problems and the possible ways to solve them

Synthesis, Magnetic, Spectroscopic and Electrochemical Studies of Mixed Pyrimidine-2-thiolate/triphenylphosphine Rhenium(V) and Rhenium (III) Complexes.

Equimolar amounts of trans-[ReOX2(OEt)(PPh3)2] (XCl, Br, I) precursors and potentially bidentate N,S-donor pyrimidine-2(1H)-thione (pymSH) react in refluxing acetone to give mononuclear octahedral paramagnetic trans-[ReIIIX2(pymS)(PPh3)2](XCl, Br, I) species. Starting from a metal–ligand molar ratio of 1:3, in the presence of N(C2H5)3 as deprotonating agent inrefluxing ethanol, the same reaction proceeds stepwise, affording octahedral [ReO(pymS)3] or [ReO(pymS)3] and pentagonalbipyramidal[Re(pymS)3PPh3] complexes as a function of the reaction time. The compounds were characterized by elementalanalysis, magnetic susceptibility, UV–Vis–NIR, IR and 1H NMR spectroscopy and by cyclovoltammetric measurements.Reaction pathways and physico-chemical properties of the complexes are discussed

Chemical-Physical characterization of the Au-C6H5SSCH3 SAM through the electrochemical study of the surface

The Au-C6H5SSCH3 SAM bahaviour has been studied through linear voltammetry