Speaker
Sasa Novak
(Department for Nanostructured Materials)
Description
The main aim of the work has been to improve properties of the plasma-facing material for the divertor to resist high thermal loading during operation. Among the available materials we selected (carbide) particles reinforcement of tungsten, wherein the reinforcement should not chemically react with the matrix. In this respect, W2C particles offer the most attractive solution.
The paper will present two fabrication routes for W-W2C composites with the composition involving up to 10 vol. % W2C precursor. As a carbon precursor, graphene or phenolformaldehide resin was mixed with the tungsten powder. Mixtures were dry pressed and sintered in vacuum or in hydrogen atmosphere. The samples were characterized with respect of microstructure, where the main efforts were put on the identification of the newly formed W2C, and composites’ phase composition, charcaterized by XRD -Rietveld analysis.
It has been confirmed, that two-phase composites (W-W2C) can be prepared by both proposed techniques. As expected, the amount of W2C particles in W-matrix increases with increasing addition of the precursor. At the same time also the density is increasing from 87 % of theoretical density for the pure W to 96 % of theoretical density for the composites in which 10 vol. % of carbon precursors were added. Microstructural analyses revealed that the W2C particles are mostly located at the W-grain boundaries and hence they successfully prevent grain-growth that occurs during the sintering. The introduction of reinforcements into the W-matrix has not only changed the microstructure, but also the mechanical properties, such as increased hardness of the composites.
In continuation, high heat flux tests will be performed to estimate the behaviour of prepared composites in order to determine whether these composites are appropriate candidates for a plasma facing material in divertor.
Co-authors
Alajaz Ivekovic
(Department for Nanostructured Materials, Jožef Stefan Institute, Ljubljana, Slovenia)
Andreja Sestan
(Center for Electron Microscopy and Microanalysis, Jožef Stefan Institute, Ljubljana, Slovenia)
Janez Zavasnik
(Center for Electron Microscopy and Microanalysis, Jožef Stefan Institute, Ljubljana, Slovenia)
Matej Kocen
(Department for Nanostructured Materials, Jožef Stefan Institute, Ljubljana, Slovenia)
Petra Jenus
(Department for Nanostructured Materials, Jožef Stefan Institute, Ljubljana, Slovenia)
Sasa Novak
(Department for Nanostructured Materials, Jožef Stefan Institute, Ljubljana, Slovenia;Jožef Stefan International Postgraduate School, LJubljana, Slovenia)
