Evaluation of the Tensile and Elastic Properties of W/Cu Coatings for its Application to the FGM DEMO Divertor Concept

ITER based conceptual design of EUDEMO divertor envisages W monoblocks as plasma-facing material joined to a CuCrZr cooling tube with a thick Cu-OHFC interlayer. Since divertor configuration will define the power exhaust capabilities of the reactor, additional concepts have been developed within the EUROfusion WPDIV project. The Functionally Graded Material (FGM) concept is one of the proposed alternatives

Evaluation of the Tensile and Elastic Properties of W/Cu Coatings for its Application to the FGM DEMO Divertor Concept

ITER based conceptual design of EUDEMO divertor envisages W monoblocks as plasma-facing material joined to a CuCrZr cooling tube with a thick Cu-OHFC interlayer. Since divertor configuration will define the power exhaust capabilities of the reactor, additional concepts have been developed within the EUROfusion WPDIV project. The Functionally Graded Material (FGM) concept is one of the proposed alternatives

Instagram, a Tool for Teaching your Students

Instagram is nowadays a popular social network, with over 1 million users worldwide on mobile devices (Clement, 2019), so it has become an essential application among young people. This makes Instagram an excellent channel to reach students, a mainly young audience

Processing of WC/W Composites for Extreme Environments by Colloidal Dispersion of Powders and SPS Sintering

Tungsten and tungsten carbide are materials with high thermomechanical response that are used or have been proposed for extreme environment applications such as first plasma face, or cutting tools. The high melting temperature and strong bonding energy of both materials force the use of powder metallurgical processes and non-conventional sintering routes to achieve dense parts. Consequently, a high dispersion and close contacts of the starting powders are required. In this paper tungsten and tungsten carbide powders are colloidally processed and mixed to achieve composite powders that are sintered later by Spark Plasma Sintering. Starting micrometric tungsten carbide and nanosized tungsten powders are dispersed in water at pH?3. By using a cationic dispersant, the surface charge of the nanosized W suspended in water reverses to positive, ensuring its attachment to the carbide surfaces and the good dispersion of the two phases when both slurries are mixed. Composite powders with volumetric rations of 50WC/50W, 80WC/20W and 90WC/10W as well as pure WC and W are sintered by SPS following the dimensional change of the specimens during the process. It has been proved that complete coverage of the micronic WC by the nanosized W powders, achieved with this colloidal approach, makes the tungsten govern the initial sintering stages. The derivative of the sintering curves is used to detect the solid state reactive sintering temperature of W2C. After sintering, XRD and SEM observations indicate that all the mixture compositions yield to ceramic materials with different W2C/WC ratios, depending on the initial compositions. Dispersion of the two phases is high and no remaining W is detected. Flexure tests at room temperature show that composite materials present a slightly lower fracture strength than pure WC

Processing of WC/W Composites for Extreme Environments by Colloidal Dispersion of Powders and SPS Sintering

Tungsten and tungsten carbide are materials with high thermomechanical response that are used or have been proposed for extreme environment applications such as first plasma face, or cutting tools. The high melting temperature and strong bonding energy of both materials force the use of powder metallurgical processes and non-conventional sintering routes to achieve dense parts. Consequently, a high dispersion and close contacts of the starting powders are required. In this paper tungsten and tungsten carbide powders are colloidally processed and mixed to achieve composite powders that are sintered later by Spark Plasma Sintering. Starting micrometric tungsten carbide and nanosized tungsten powders are dispersed in water at pH?3. By using a cationic dispersant, the surface charge of the nanosized W suspended in water reverses to positive, ensuring its attachment to the carbide surfaces and the good dispersion of the two phases when both slurries are mixed. Composite powders with volumetric rations of 50WC/50W, 80WC/20W and 90WC/10W as well as pure WC and W are sintered by SPS following the dimensional change of the specimens during the process. It has been proved that complete coverage of the micronic WC by the nanosized W powders, achieved with this colloidal approach, makes the tungsten govern the initial sintering stages. The derivative of the sintering curves is used to detect the solid state reactive sintering temperature of W2C. After sintering, XRD and SEM observations indicate that all the mixture compositions yield to ceramic materials with different W2C/WC ratios, depending on the initial compositions. Dispersion of the two phases is high and no remaining W is detected. Flexure tests at room temperature show that composite materials present a slightly lower fracture strength than pure WC

Monitorization of Varietal Aroma Composition Dynamics during Ripening in Intact Vitis vinifera L. Tempranillo Blanco Berries by Hyperspectral Imaging

The measurement of aromatic maturity during grape ripening provides very important information for determining the harvest date, particularly in white cultivars. However, there are currently no tools that allow this measurement to be carried out in a noninvasive and rapid way. For this reason, in the present work, we have studied the use of hyperspectral imaging (HSI)) to estimate the aromatic composition of Vitis vinifera L. Tempranillo Blanco berries during ripening. A total of 236 spectra in the VIS+short wave near-infrared (VIS+SW-NIR) range (400-1000 nm) of intact berries were acquired contactless under laboratory conditions. As gold standard values, a total of 20 volatile compounds were quantified by gas chromatography-mass spectrometry (GC-MS), and the concentration of total soluble solids (TSS) was measured by refractometry. Calibration, cross-validation, and prediction models were built using partial least squares (PLS). Values of R ≥ 0.70 were obtained for α-terpineol, p-cymene, β-damascenone, β-ionone, benzaldehyde, benzyl alcohol, hexanal, citral, linalool, 2-phenylethanol, octanoic acid, nonanoic acid, 2-hexenal, 2-hexen-1-ol, (Z)-3-hexen-1-ol, total C norisoprenoids, total C6 compounds, total positive compounds (i.e., the sum of all families except C6 compounds), total benzenoids, and total soluble solids (TSS). Therefore, it can be affirmed that HSI in the VIS + SW-NIR range could be a good tool to estimate the aromatic composition of Tempranillo Blanco grape berries in a contactless, fast, and nondestructive way.Financialsupportwas givenby the Ministerio de Ciencia,Innovación y Universidades under the project RTI2018-096549-B-I00.S.M.-S.-R.thanks Gobierno de La Rioja forher predoctoralcontract

Thermomechanical Characterisation of W-Eurofer 97 Brazed Joints

The preliminary conceptual design of both the blanket and the divertor of the future DEMO reactor envisages tungsten as plasma-facing material joined to Eurofer 97 steel as the structural element. Therefore, the development of new joining technologies to constitute these first wall components has become an essential task in the fusion community. In this regard, there is a lack of knowledge on the thermal stability and mechanical behaviour of these W-Eurofer 97 joints under the expected service temperatures, which will be situated around 400–600 °C. In this paper, successful diffusion brazing of Eurofer 97 steel with tungsten was achieved by using a copper interlayer. Its microstructure, hardness and flexural strength were investigated for different configurations and thermal histories in its predicted operating temperature range. Investigations on as-brazed specimens showed defect-free interfaces and a continuous metallic bond between W and Eurofer 97 was successfully accomplished; although the hardening of steel base material was detected after joining. Microstructure alterations were observed just at the W-Eurofer 97 interface, with the diffusion of Cu braze into the iron grain boundaries and the formation of a Fe-rich hard intermetallic layer, which was, in fact, the weakest part of the joint during thermo-mechanical testing. The flexural strength of the brazed specimens at room temperature was relatively low, with a strong dependence on the anisotropy of the W base material and little influence of the stress-relieving thermal treatment. However, testing at temperatures up to 600 °C showed high strength of the bonded specimens, with values as high as 470 MPa, comparable to those of the Eurofer 97 steel

Beneficial Effects of a WC Addition in FAST-Densified Tungsten

The particle reinforcement of fusion-relevant tungsten through the incorporation of tungsten sub-carbide W2C particles at the grain boundaries is demonstrated as an effective way of eliminating the harmful W oxide, enhancing densification and stabilising the composite's microstructure and flexural strength at room and high temperatures. The W2C particles are formed in situ during the sintering by carbon diffusion from WC nanoparticles added as a precursor to the W matrix. Even in an extremely fast sintering process using Field-Assisted Sintering Technology (FAST, 1900 °C, 5 min), the added WC completely transforms to W2C, resulting in a W–W2C composite. While at least 5 vol % of WC nanoparticles are needed to eliminate the oxide, approximately 10 vol % result in a W–W2C composite with favourable characteristics: high density, high flexural strength at RT (>1200 MPa) as well as at elevated temperatures, and high thermal conductivity, which remains above 100 W/mK up to 1000 °C

Beneficial Effects of a WC Addition in FAST-Densified Tungsten

The particle reinforcement of fusion-relevant tungsten through the incorporation of tungsten sub-carbide W2C particles at the grain boundaries is demonstrated as an effective way of eliminating the harmful W oxide, enhancing densification and stabilising the composite's microstructure and flexural strength at room and high temperatures. The W2C particles are formed in situ during the sintering by carbon diffusion from WC nanoparticles added as a precursor to the W matrix. Even in an extremely fast sintering process using Field-Assisted Sintering Technology (FAST, 1900 °C, 5 min), the added WC completely transforms to W2C, resulting in a W–W2C composite. While at least 5 vol % of WC nanoparticles are needed to eliminate the oxide, approximately 10 vol % result in a W–W2C composite with favourable characteristics: high density, high flexural strength at RT (>1200 MPa) as well as at elevated temperatures, and high thermal conductivity, which remains above 100 W/mK up to 1000 °C