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This work investigates the influence of process parameters on microstructure, adhesion of layers to the substrate and wear resistance of Ni/MoS2 micro- and nanocrystalline composite layers. Pure nickel coatings were also fabricated and tested for comparison. The layers were deposited by electrochemical reduction on pure A2 aluminum and on PA6 alloy. The layers were produced at a current density of 3 A/dm2 and a mixing speed of 400 rpm. The bath composition was also modified by the addition of saccharin and the disperse phase of molybdenum disulfide in the bath (2.5 and 5 g/l). Materials prepared in this way underwent structural investigations (using scanning electron microscopy and optical microscopy), a scratch test and tribological tests (using a ball-on-disc method). The results of the tests allowed to determine the dependence of the structure and properties of the produced coatings on the production parameters. The composition of the electrolyte affects the size of crystallites as well as the morphology and topography of the surface. The scratch test confirmed the good adhesion of the nickel and composite layers to the substrate. The best lubricating properties were shown by nanocrystalline coatings. The too high content of molybdenum disulfide in the bath caused an undesirable increase in the coefficient of friction.

International audience; Radon is one of the main potential sources of background radiation for any rare event experiments like neutrinoless double beta decay or dark matter experiments. The Radon Trapping Facility (RTF) installed in 2004 at the Modane Underground Laboratory (LSM) has been running for nine years providing radon-purified air at a level of 10 mBq m−3 for several experiments. The radon suppression principle is based on a radon physical adsorption using cooled compressed air at −55 °C pumped through a column filled with the K48 activated charcoal. After disassembling of the RTF, the 2.6 m high charcoal column has been divided into several layers in order to study with different techniques the dynamic adsorption coefficient (the K-factor) as a function of the depth and the radon spatial trapping profile by measuring the 210Pb activity. It has been demonstrated that after almost a decade of running, the K-factor of the activated charcoal remains constant except for the first few cm of the column. Furthermore, it has been demonstrated that the mass activity of 210Pb as a function of the depth of the charcoal column exhibits an exponential decay profile. The radon mean retention time τ R of (47.6 ± 1.2) days and the radon mean free path of (28.9 ± 0.4) cm have been derived and found to be consistent at 1σ with the ones obtained from the K-factor study, i.e. from a total independent measurement. The radon suppression factor of the RTF of has been also estimated with a value consistent at 2σ with the suppression factor measured during the RTF operation. Thus, this study has proven the capacity of the RTF to purify the LSM air from radon by more than three orders of magnitude during nine years of operation.

A new RNAA procedure was developed for simultaneous determination of low levels of I and Mn in biological materials. The procedure is based on sample decomposition by alkaline-oxidative fusion in a mixture of Na2O2 + NaOH at 900°C followed by extraction of elementary iodine by chloroform. Subsequently, Mn is separated either by precipitation of hydrated MnO2 or by extraction of the Mn-diethyldithiocarbamate complex in chloroform. The accuracy of the RNAA procedure developed was proven by analysis of several low-level biological reference materials. Detection limits of I and Mn achievable in both institutes and the degree of interference for the Mn determination due to 56Fe(n,p)56Mn reaction with fast neutrons are discussed.

Rad iochemical neutron activation procedures using liquid -liquid extraction with tetraphenylarsonium chloride in chloroform from 1M HCl and solid extraction with ALIQUAT 336 incorporated in a polyacrylonitrile binding matrix from 0.1M HCl were developed for ac curate determination of rhenium in biological and environmental samples at the sub -ng . g –1 level. Concentrations of Re in the range of 0.1 to 2.4 ng . g –1 were determined in several botanical reference materials (RM), while in a RM of road dust a value of ~10 ng . g –1 was found. Significantly elevated values of Re, up to 90 ng . g –1 were found in seaweed (brown algae). Results for Re in the brown algae Fucus vesiculosus in which elevated 99 Tc values had previously been determined suggested possible competition bet ween Re and Tc in the accumulation process.

This study is concerned with the modification of titanium surface by plasma electrolytic oxidation (PEO) and hydrothermal treatment. The samples were oxidized in an electrolytic solution that contained calcium β-glycerophosphate and calcium acetate. Then, the specimens were hydrothermally heated at a temperature of 220 °C for 4 h using an autoclave. The chemical composition of the surface layers was examined by XPS. The morphology of the surface was observed by SEM-EDS. The crystalline phases were identified by XRD. The corrosion resistance was determined by the electrochemical methods in a simulated body fluid (SBF) at a temperature of 37 °C after various times of exposure in SBF. The oxide layers formed by PEO were porous, highly crystalline and enriched with Ca and P. After hydrothermal treatment, hydroxyapatite crystals precipitated on the surface. The results of electrochemical examinations show that the surface modification by PEO and hydrothermal treatment decreases the corrosion resistance of titanium.

The paper presents the results of examinations of the corrosion resistance of titanium after its being subjected to the surface modification by the alkali- and heat-treatments. The material examined was commercially pure titanium (grade 2). The samples were soaked in an aqueous 10M NaOH solution at 60 degrees C for 24 h and subsequently heated at 500, 600, or 700 degrees C for 1 h. The chemical composition of the surface layers was determined by X-ray photoelectron spectroscopy and secondary ion mass spectroscopy. The phases present in the layers were identified by XRD. The corrosion resistance was evaluated by electrochemical methods (Stern's method, potentiodynamic method, and impedance spectroscopy) at a temperature of 37 degrees C after short- and long-time exposures. The 13 h exposure was aimed to allow the corrosion potential to stabilize. The aim of the long-term exposures was to examine how the corrosion resistance of the modified samples changes during the exposure. Under the conditions prevailing during the experiments, the highest corrosion resistance was achieved with the samples heated at a temperature of 700 degrees C.