[en] The casting of several chromium-molybdenum steels for steam and hydraulic turbines is discussed. Non-destructive testing of the castings is performed demonstrating the safety for use in nuclear technology. The effect of metallurgical parameters on steel casting quality, the heat treatment, and the effect of construction design on costs for fettling and repair weldings are considered. (Auth.)

[en] An UHV apparatus is described which allows energy analysis of low energy rare gas ions backscattered from surfaces in the energy range from 100 to 2000 eV and in a large range of scattering angles. Surface composition is measured by ion scattering and Auger electron spectroscopy. Surface structure of monocrystalline samples is evaluated by LEED. Examples of surface composition analysis and ion impact desorption are given. (author)

[en] Industrial needs in terms of multifunctional components are increasing. Many sectors are concerned, from the integrated direct nanoparticles production to the emerging combinations which include the metal matrix composites (MMC), ductile ceramics and ceramic matrix composites, polymer matrix composites (PMC) for bulk application and advanced surface coatings in the fields of automotive, aerospace, energy production and building applications. Moreover, domains with a planetary impact such as environmental issues, as well as aspects for instance health (toxicity) and hazard assessment (ignition and explosion severity) were also taken into account. Nanotechnologies play an important role in promoting innovation in design and realization of multifunctional products for the future, either by improving usual products or creating new functions and/or new products. Nevertheless, this huge evolution in terms of materials could only be promoted by increasing the social acceptance and by acting on the different main technological and economic challenges and developing safe oriented processes. Nowadays, a huge number of developments of nanoparticles are potentially industrial up-scalable. However, some doubts exist about the handling's safety of the current technologies. For these reasons, the main purpose was to develop a self-monitored automation in the production line coupling different techniques in order to simplify processes such as in-situ growth nanoparticles into a nanostructured matrix, over different substrates and/or the nanopowders synthesis, functionalization, dry or wet safe recovery system, granulation, consolidation in single-step, by monitoring at real time the processing parameters such as powder stoichiometry. With the aim of assuring the traceability of the product during the whole life, starting from the conception and including the R and D, the distribution and the use were also considered. The optimization in terms of processing, recovery and conditioning, permits to increase its versatility, thus leading to the increase of the added value to the production. This review put in evidence -by different examples- the progress achieved since the beginning of Nanosafe integrated initiative developed by CEA and its partners as well as promoting, firstly the safety at work place, and then extending to an integrated and controlled in-situ production by of Nanosafe-by-Design controlled processes.

[en] A specific method of pack-cementation has been developed in order to perform a CVD deposition of Fe-Al alloys on a martensitic steel at a temperature which respects its mechanical properties (< 750 deg. C). Dense, uniform and adhesive coatings can be deposited at temperatures between 650 and 750 deg. C without Fe₂Al₅ intermetallic phases thanks to a low pressure deposition and using a special cement containing Fe and Al. These coatings coated with an Al₂O₃ top layer drastically reduce the permeation rate of deuterium with regards to the uncoated substrate. (authors)

[en] Chromium carbide coatings were grown at 748 K in a hot wall CVD reactor fed by sublimation of bis(benzene)chromium, BBC (MOCVD) and by direct liquid injection using a BBC/toluene solution (DLICVD). The two types of coatings exhibit an amorphous structure and the same C content (22 at.%). DLICVD permits delivering higher mass flow rate of precursors and consequently the growth rate is 3 times higher and the thickness uniformity is better than using MOCVD. Chromium metal deposition has also been investigated by DLICVD in this hot wall reactor using BBC/toluene/additive as precursor. The purpose of the additive is to block carbide formation. Two additives have been studied: (i) hexachlorobenzene (C₆Cl₆) and (ii) thiophenol (C₆H₅SH). The ratio additive/BBC required for Cr metal deposition is a few percent. In this process, C₆Cl₆ is not decomposed and only traces of Cl (0.4 at.%) are found in the coatings. For a ratio C₆Cl₆/BBC ≥ 27% the growth of any coating is blocked. The gas phase containing C₆H₅SH is more reactive since the onset of deposition occurs approximately 50 K before the temperature of the chlorinated compound. Furthermore, a sulfur contamination of 3 at.% has been analyzed in the coatings revealing a partial decomposition of the additive. The results are detailed and discussed in relation with previous works. (authors)

[en] X-ray structural analyses of two monoclinic allotropes of cycloheptasulfur carried out at -110⁰C revealed almost identical chair-like molecular structures of approximate Csub(s) symmetry with bond distances between 199.5 and 218.2 pm, bond angles between 101.5 and 107.5⁰, and torsional angles between 0 and 109⁰. (orig.)

[en] SiC coatings have been grown by direct liquid injection of organo-silanes in a hot-wall chemical vapor deposition reactor (DLICVD). 1,3-disilabutane (DSB) and poly-sila-ethylene (PSE) were used as single-source precursors. Amorphous and stoichiometric SiC coatings were deposited under low pressure on various substrates in the temperature range of 923-1073 K. Thickness gradients due to the temperature profiles and the precursor depletion were observed along the reactor axis but the thickness uniformity could be improved as a function of the deposition conditions. Growth rates as high as 90 μm.h"-"1 were obtained using pure precursors. The injection of PSE solutions in toluene significantly reduces the deposition rate due to the decrease of the PSE mole fraction but allows a better control of the growth rates and the microstructure of coatings. They exhibit a smooth surface morphology and a very dense structure. The films grown using pure precursors exhibit an Si:C atomic ratio equal to 1:1 while those using toluene solutions are slightly C-rich (54 at.% C). The presence of solvent vapor in the CVD reactor becomes a source of carbon contamination at deposition temperatures equal to or higher than 1073 K. The influence of the growth conditions is discussed, in particular the presence of toluene vapor. (authors)

[en] In this work, chromium thin films were deposited using dcMS and HiPIMS technologies. To compare these technologies, we analyzed the ion flux and the Cr coating microstructure in the same plasma conditions. Ion flux was measured with a mass spectrometer in time-averaged for both discharge and time-resolved for HiPIMS discharge. Time-averaged measurements provided important information. First, the low energetic part of the ion energy distribution function (IEDF) was similar in dcMS and HiPIMS and second the high energetic component was more prominent in the HiPIMS discharge. Time-resolved measurements showed that the high energetic part of the ion flux reached the mass spectrometer faster than the lowest part. It is only after the pulse end that most of the thermalized ions arrived and then cooled the flux. The correlation of these results with microstructure analysis shows that energetic particles induced a higher film density and a smoother surface in HiPIMS compared to dcMS discharge. (authors)

[en] The emergence of novel technologies calls for the development of materials affording ever-higher performance levels. This goes hand in hand, in most cases, with the requirement to protect such materials against an extreme, aggressive environment, be it for applications in the nuclear industry, or in the aerospace and automotive sectors. The evolution undergone by deposition processes has helped make possible the development of nano-structured coatings, exhibiting remarkable properties, in terms of wear, corrosion, and high-temperature resistance, in exacting conditions. (authors)

[en] Direct liquid injection - metalorganic chemical vapor deposition (DLI-MOCVD) is the most advanced process dedicated to the internal protection of nuclear fuel cladding in accident conditions such as loss of coolant. It allows the deposition of an amorphous, glassy-like chromium carbide CrC_x coating which is resistant against high-temperature oxidation in air and steam. Since the above-mentioned material characterizations demonstrated that coatings possessed the appropriate protection properties, the DLI-MOCVD process was scaled-up. First, a joint development between experimental and numerical studies led to a deposition inside a 1 m long cladding segment with a coating of sufficiently large and uniform thickness. Optimized reactor parameters consist in a combination of low temperature (∼ 600 K) and low pressure (∼ 600 Pa) with a high vapor flow rate of reactive species in the reactor ensuring a short residence time. The second phase of the scale-up consisted in coating simultaneously three, then sixteen segments in a single run. 3D computational simulations of the deposition process assisted the development of specific flanges designed to distribute homogeneously the reactive vapor into the three or sixteen cladding tubes. Experimental conditions have been extrapolated from one to three and to sixteen cladding segments, resulting in the deposition of the CrC_x coating inside all segments with a relatively uniform partition. Overall, this paper demonstrates the feasibility of the deposition of CrC_x coating in a bundle of several, up to sixteen, nuclear fuel cladding segments of 1 m in length (ID 8 mm), in order to protect them during accident conditions. This 'batch demonstration' is a first step in the course of DLI-MOCVD technological transfer. Next step will be the deposition in a full-length cladding tube (4 m) that is already supported by numerical predictions. (authors)