W-Diamond/Cu-Diamond nanostructured composites for fusion devices
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1125-R07-08
W-Diamond/Cu-Diamond nanostructured composites for fusion devices D. Nunes1,3, V. Livramento2, J.B. Correia2, R. Mateus1, P.A. Carvalho1,3, N. Shohoji2, H. Fernandes1, C. Silva1, E. Alves4, K. Hanada5, E.Osawa6 1
Associação Euratom/IST, Instituto de Plasmas e Fusão Nuclear, Instituto Superior Técnico, Av. Rovisco Pais, 1049-001 Lisboa, Portugal 2
LNEG, Departamento de Materiais e Tecnologias de Produção, Estrada do Paço do Lumiar, 1649-038 Lisboa, Portugal 3
ICEMS, Departamento de Engenharia de Materiais, Instituto Superior Técnico, Av. Rovisco Pais, 1049-001 Lisboa, Portugal 4
ITN, Instituto Tecnológico e Nuclear, Estrada Nacional 10, 2686-953 Sacavém, Portugal
5
National Institute of Advanced Industrial Science and Technology (AIST), 1-2-1 Namiki, Tsukuba, Ibaraki 305-8564, Japan 6
NanoCarbon Research Institute, Shinshu University, 386-8567 Ueda-shi Tokida 3-15-1, Nagano, Japan
ABSTRACT A novel material design for nuclear fusion reactors is proposed based on Cu-Diamond and WDiamond nanocomposites. The proposed design involves the production of W/W-Diamond/CuDiamond/Cu functionally graded material. W, W-Diamond, Cu-Diamond and Cu nanostructured composite powders were produced independently by mechanical alloying and subsequently consolidated/welded through spark plasma sintering. Modulation of processing parameters allowed controlling the extent of unfavourable conversion of Diamond into tungsten carbide, as well as to overcome the Diamond intrinsically difficult bonding to copper. Microstructural features and microhardness of the as-produced materials are presented. INTRODUCTION The high melting point of tungsten and its high threshold for sputtering, together with low activation and low tritium inventory, render this material suitable for plasma facing components [1]. Copper alloys have been selected as first wall heat sinks due to favorable thermal conductivity and radiation resistance [1]. However, the demand for operation temperatures above the range proposed for ITER first wall (< 300 °C) poses extra challenges to both types of materials, especially on what thermal conductivity and microstructural stability are concerned [1].
The extremely high thermal conductivity of diamond turns its dispersions into excellent candidates for thermal management applications. Additionally, particle dispersions can be used as reinforcement for increased strength and microstructure thermal stabilization. As a result, Wdiamond composites are promising for first wall materials. Furthermore, Cu-Diamond composites are expected to present enhanced thermal conductivity [2], microstructural stability [3] and lower thermal expansion mismatch with W-based materials than copper alloys. Bonding between pure W, the two types of composites and pure Cu will allow producing functionally graded W/W-Diamond/Cu-Diamond/Cu material, where the pure W surface is exposed to the harsh fusion plasma and W-Diamond represents a higher thermal conductivity transition towards the Cu-Diamond and Cu heat sinks. Two fundamental challen
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