M. Dias^a, N. Pinhão^a, R. Faustino^a, R.M.S. Martins^a,b, A.S. Ramos^c, M.T. Vieira^c, J.B. Correia^d, E. Camacho^b, F.M. Braz Fernandes^b, B. Nunes^e,f, A. Almeida^e, U.V. Mardolcar^g, E. Alves^a

^aInstituto de Plasmas e Fusão Nuclear, Instituto Superior Técnico, Universidade de Lisboa, Av. Rovisco Pais, 1049-001, Lisboa, Portugal

^bCENIMAT/I3N, Departamento de Ciência dos Materiais, Faculdade de Ciências e Tecnologia, FCT, Universidade NOVA de Lisboa, Quinta da Torre, 2829-516, Caparica, Portugal

^cCEMMPRE, Department of Mechanical Engineering, University of Coimbra, R. Luís Reis Santos, 3030-788, Coimbra, Portugal

^dLNEG, Laboratório Nacional de Energia e Geologia, Estrada do Paço do Lumiar, 1649-038, Lisboa, Portugal

^eCeFEMA, Center of Physics and Engineering of Advanced Materials, Instituto Superior Técnico, Universidade de Lisboa, Av. Rovisco Pais, 1049-001, Lisboa, Portugal

^fAtlântica, Escola Universitária de Ciências Empresariais, Saúde, Tecnologia e Engenharia, Fábrica da Pólvora de Barcarena, 2730-036, Barcarena, Portugal

^gDepartamento de Física, Instituto Superior Técnico, Av. Rovisco Pais, 1049-001, Lisboa, Portugal

The requirements for the divertor components of future fusion reactors are challenging and therefore a stimulus for the development of new materials. In this paper, WC-Cu composites are studied for use as thermal barrier between the plasma facing tungsten tiles and the copper-based heat sink of the divertor. Composite materials with 50% vol. WC were prepared by hot pressing and characterized in terms of microstructure, density, expansion coefficient, elastic modulus, Young's modulus and thermal diffusivity. The produced materials consisted of WC particles homogeneously dispersed in a Cu matrix with densifications between 88% and 98%. The sample with WC particles coated with Cu evidenced the highest densification. The thermal diffusivity was significantly lower than that of pure copper or tungsten. The sample with higher densification exhibits a low value of Young's modulus (however, it is higher compared to pure copper), and an average linear thermal expansion coefficient of 13.6 × 10⁻⁶ °C^-1 in a temperature range between 100 °C and 550 °C. To estimate the behaviour of this composite in actual conditions, a monoblock of the divertor in extreme conditions was modelled (Fig. 1). The results predict that while the use of WC-Cu interlayer leads to an increase of 190 °C on the temperature of the upper part of the monoblock when compared to a pure Cu interlayer, the composite will improve and reduce significantly the cold-state stress between this interlayer and the tungsten.

Fig. 1 - Geometry and mesh used for the FEM model. The geometry corresponds to a quarter part of a monoblock. The arrow indicates the position of the vertical axis.