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Projects / Programmes source: ARIS

W- and WC-based composites for high thermally loaded parts in the fusion demonstration power plant DEMO

Research activity

Code Science Field Subfield
2.04.02  Engineering sciences and technologies  Materials science and technology  Metallic materials 

Code Science Field
T152  Technological sciences  Composite materials 

Code Science Field
2.05  Engineering and Technology  Materials engineering 
Keywords
composite; tungsten; tungsten carbide; fusion energy; divertor; high-heat-flux
Evaluation (rules)
source: COBISS
Researchers (7)
no. Code Name and surname Research area Role Period No. of publicationsNo. of publications
1.  35645  PhD Jaka Burja  Materials science and technology  Researcher  2017 - 2019  325 
2.  17286  Darko Eterović    Technical associate  2019 
3.  33403  PhD Petra Jenuš Belec  Materials science and technology  Researcher  2017 - 2019  157 
4.  39530  Matej Kocen  Materials science and technology  Researcher  2017 - 2019  58 
5.  26457  PhD Andraž Kocjan  Materials science and technology  Researcher  2017 - 2019  320 
6.  04292  PhD Saša Novak Krmpotič  Materials science and technology  Head  2017 - 2019  669 
7.  32177  PhD Borut Žužek  Materials science and technology  Researcher  2017 - 2019  456 
Organisations (2)
no. Code Research organisation City Registration number No. of publicationsNo. of publications
1.  0106  Jožef Stefan Institute  Ljubljana  5051606000  91,415 
2.  0206  Institute of Metals and Technology  Ljubljana  5051622000  6,069 
Abstract
The progress in the development of fusion power plants is closely linked to the availability of suitable materials for structural parts that are exposed to extreme conditions in the reactor chamber, i.e. neutrons, very high temperatures and heat fluxes, thermal shock, erosion, etc., and at the same time they have to meet requirements for the high thermal conductivity, low neutron-activation, etc. Consequently, designers of the first demonstration fusion power plant, DEMO, pay great attention to the selection of appropriate materials and improvement of those who constitute limitations for optimum operation of the power plant. Research and development in Europe are taking place within the framework of the fusion program EUROfusion, which sets guidelines for coordinated research and in which the applicant of this proposal with her group is also involved. For the most thermally loaded part of a fusion reactor – the divertor, in which the proposed operational temperature is in the range of approx. 800-1400 ° C, tungsten was selected as a candidate material. However, pure tungsten has two major drawbacks: at lower temperatures, it becomes brittle, while over approx. 1000 ° C strength significantly decreases due to the recrystallization and exaggerated grain growth. Therefore, the working group "High-Heat-Flux-Materials" within the EUROfusion project focuses the research primarily on the development of tungsten based composites. Our group addresses the first deficiency through the addition of long SiC fibers with a tungsten core (SiCf/W composite). This topic is not included in the present proposal, but it represents its background. The second weakness of tungsten, a drastic deterioration in strength at high temperatures, is solved by improving the properties of the matrix. Here, the main goal is to limit the growth of tungsten grains in the working temperature range, while the other properties (e.g., heat conductivity, toughness, low activation) must not be significantly affected. Within the proposed project we will explore two options: a) dispersion strengthening of tungsten with small W2Cparticles formed during the sintering by reaction of W with the present precursor and b) replacement of WC-based cemented carbide with low-activation binder phase. In the first part of the project, we will prepare samples of the composite W-W2C with precursors (graphene, phenol formaldehyde resins, WC nanoparticles) for which we already confirmed the capability of forming W2C particles at the tungsten grain boundaries. The optimal additive and sintering process will be determined based on the analysis of phase composition and properties. In the second part, we will first select the appropriate low-activation alloy (LAA), which will be used as a binder phase in the WC-LAA composite. We will check the possibility of the preparation and use of high-entropy alloys, for which the composition will be determined by thermodynamic calculations. In both of the proposed configurations the selection of the most suitable option will be based on the structure, phase composition and the mechanical properties at room temperature. Further selection will include the testing of mechanical properties and thermal conductivity in the range from room temperature to 1000 ° C. Final selection of the material for the matrix in the SiC/W-based composite will be based on the high-heat-flux test. The proposed project will be conducted in close collaboration and under the coordination of the EUROfusion program, which co-finances part of the research, provides strong scientific background and support as well as the guidelines for research work. Moreover, postgraduate studies and practical training for the Ph.D. students involved in the project is enabled within the framework of the Fusion Education program.
Significance for science
Development of structural materials based on tungsten composites for application in contact with hot plasma shifts the limit capacity of the materials and enables operation of devices at higher heat loads and high thermal shocks. The knowledge attained within this project will contribute to the development of materials also for other applications at extreme conditions.
Significance for the country
Development and construction of the fusion devices ITER and DEMO in Europe has indirect benefit for the European economy via new employment, collaboration of companies in production of construction parts as well as in construction works.
Most important scientific results Interim report, final report
Most important socioeconomically and culturally relevant results Interim report, final report
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