Introduction. General objectives of the project
The materials that we have in view are Carbon (C), Beryllium (Be) and Tungsten (W). They are materials of interest for the nuclear applications, mainly for fusion technology. Nevertheless, due to induced cancerous pathologies of Be, the work with this material is precluded. Instead, Al and Mg are normally used as substitutes for Be, given that many of their chemical and physical properties are closed to that of Be. In the present work, these metals will be used as Be substitutes by the Romanian team.
The general objective of the project is to obtain particulates and powders of the above materials, with fine control of their properties (size, surface chemistry, structure) and their transformation by using innovative plasma and laser methods in order to insure safer maneuverability with respect to nuclear safety issues. The general objective incorporates a series of particular objectives, as follows:
- The investigation of laser ablation for fabrication of nano/microparticles of Al, Mg and W in gas and liquid phase;
- Fabrication of composites consisting of carbon or hydrogenated carbon matrix incorporating Al, Mg, tungsten particles by combined MS/PECVD and the characterization of the obtained material;
- Plasma transformation of powders and composites in order to change their surface properties, and if possible the particles size. Study of processes of particle destruction by laser and plasma means.
Concepts and methodology
In order to reach the project objectives we propose innovative experimental approaches combined with an intensive effort of material characterization, as follows:
- Experiments of ablation of Al, Mg, and W in liquids with various chemistries will be performed. The laser beam will be focused on Al, Mg, or W targets immersed in liquid media, which leads to material expulsion in the liquid phase. The produced material will be extracted from the liquid phase and characterized from the point of view of particulates size, morphology, structure and chemical composition. The effect of laser pulse characteristics (wavelength, duration, fluence) and chemical nature of the liquid on particle properties will be determined.
- Al, Mg, W particles incorporated in a carbon matrix will be obtained via a novel concept of sequential MS/PECVD deposition. An experimental setup will be designed in which a MS plasma deposition source and a PECVD source will be operated independently on the same deposition chamber. Particles of controlled size will be incorporated in the carbon matrix by periodical exposing, for defined periods of times, the substrate to the two separated plasma deposition sources.
- For plasma treatment of powders and particulates, two types of experiments are foreseen. In one of them a fluidization method is proposed, in which a plasma jet will be used to spread out and circulate the powder in plasma, insuring the intimate contact of each particle with plasma species. This method will be checked for being used with micro-sized powders, aiming to oxidizing, nitriding or reducing the powders. The treated powder will be investigated as concerning the change in morphology and surface chemistry and the effect of experimental conditions (plasma power, type of gas, temperature) will be assessed. In another type of experiments, particulates incorporated in the carbon matrix of composite layers will be revealed by plasma etching of the carbon matrix. Investigation of oxidizing, nitriding, reducing the composite layers and the core particulates by the etching process will be performed.
Work programme, work planning, deliverables
The activities in the three subtopics are planned according to the existent knowledge and equipments. As follows:
Year 1: Setting up and demonstration of the feasibility of making particles by laser irradiation of metallic targets in liquids and by time controlled sequential codeposition of materials with magnetron sputtering and plasma enhanced chemical vapor deposition.
Milestones/Deliverables: Functional setups for particles and composites production by laser and respectively sequential plasma deposition / Scientific report;
Year 2: Characterization of the laser and plasma processes of particle synthesis and of the obtained material properties (particles morphology, structure, size, chemical state).
Milestones/Deliverables: Scientific and technical data describing the processes leading to synthesis of particles with controlled properties / Scientific report;
Year 3: Setting up of experiments for plasma and laser modification of particles in view of their chemical, morphological, and possible size transformations);
Milestones / Deliverables: Scientific and technical describing the processes leading to transformation of particles by plasma and laser processes / Conclusive final report on results, with the outlining of the perspectives with respect to the nuclear and other domains.
Contribution of partners
The Romanian partners will contribute with the fabrication of nanosized particles, establishment and characterization of the processes, material characterization by SEM, AFM, XRD and EDS.
The French partners will contribute with micro-sized powder supplying, Specific Surface Area characterization, particles size distribution experiments and powder mobilization experiments.
Both partners will insure an intense exchange of researchers performed by short visits of the senior staff and scientific stages for the young researchers.
| Teams composition |
Romanian team:
Dr. Gheorghe Dinescu
Dr. Maria Dinescu
Dr. Acsente Tomy
Dr.
Nicu Doinel Scarisoreanu, young researcher
Dr. Flavius Stokker Cherengi, young researcher
Antoniu Moldovan, young researcher
Eusebiu Rosini Ionita,
PhD student
Maximilian Teodorescu, PhD student, young researcher
Veronica Satulu, PhD student, young researcher
Stancu Cristian, PhD student, young researcher
Stoica Daniel, PhD student, young researcher |
CEA team:
Dr. Christian Grisolia
Dr Alexandre Semerok |
THE RESULTS OF THE LAPART PROJECT WERE PRESENTED IN THE FRAME OF THE FOLLOWING JOINT CEA-IFA SYMPOSIUS:
