Integration of electrochemical capacitors with silicon-based electronics is a major challenge, limiting energy storage on a chip. We describe a wafer-scale process for manufacturing strongly adhering ...carbide-derived carbon films and interdigitated micro-supercapacitors with embedded titanium carbide current collectors, fully compatible with current microfabrication and silicon-based device technology. Capacitance of those films reaches 410 farads per cubic centimeter/200 millifarads per square centimeter in aqueous electrolyte and 170 farads per cubic centimeter/85 millifarads per square centimeter in organic electrolyte. We also demonstrate preparation of self-supported, mechanically stable, micrometer-thick porous carbon films with a Young's modulus of 14.5 gigapascals, with the possibility of further transfer onto flexible substrates. These materials are interesting for applications in structural energy storage, tribology, and gas separation.
The COVID-19 response required the cancellation of all but the most urgent surgical procedures. The number of cancelled surgical procedures owing to Covid-19, and the reintroduction of surgical ...acivirt, was modelled.
This was a modelling study using Hospital Episode Statistics data (2014-2019). Surgical procedures were grouped into four urgency classes. Expected numbers of surgical procedures performed between 1 March 2020 and 28 February 2021 were modelled. Procedure deficit was estimated using conservative assumptions and the gradual reintroduction of elective surgery from the 1 June 2020. Costs were calculated using NHS reference costs and are reported as millions or billions of euros. Estimates are reported with 95 per cent confidence intervals.
A total of 4 547 534 (95 per cent c.i. 3 318 195 to 6 250 771) patients with a pooled mean age of 53.5 years were expected to undergo surgery between 1 March 2020 and 28 February 2021. By 31 May 2020, 749 247 (513 564 to 1 077 448) surgical procedures had been cancelled. Assuming that elective surgery is reintroduced gradually, 2 328 193 (1 483 834 - 3 450 043) patients will be awaiting surgery by 28 February 2021. The cost of delayed procedures is €5.3 (3.1 to 8.0) billion. Safe delivery of surgery during the pandemic will require substantial extra resources costing €526.8 (449.3 to 633.9) million.
As a consequence of the Covid-19 pandemic, provision of elective surgery will be delayed and associated with increased healthcare costs.
•Evidence of absence texturing of HMS densified by Spark Plasma Sintering.•The elasticity tensor of Mn15Si26 is determined via EBSD-nanoindentation coupling.•Nanohardness and Young’s modulus ...of< 001 > orientations is higher than the< 100 > ones.•Anisotropy of the mechanicals properties of Mn15Si26 has been evidenced.•Good agreement between experimental results and Ab-initio calculation.
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The goal of this study is to investigate the mechanical and elastic characteristics of the Mn15Si26 compound via experimental nanoindentation measurements and ab-initio calculations. The mechanical properties such as Young’s modulus (E) and nanohardness are important inputs for improving the design and mechanical reliability of thermoelectric modules. The high-energy X-ray diffraction pattern of Mn15Si26 has been indexed with the Miller indices of a tetragonal crystalline structure whose cell parameters are the following: a = b = 5.535(3) Å and c = 65.552(4) Å. Nanoindentation measurements, with a Berkovich indenter tip have been performed on higher manganese silicide (HMS) compound mainly composed of Mn15Si26 grains. For the first time ever, it has been evidenced that both elastic modulus and nanohardness of the latter varied significantly depending on their crystallographic orientations provided by electron backscatter diffraction. Nanohardness and Young’s modulus along the< 001 > orientations are higher than the< 100 > ones. The nanohardness value of Mn15Si26 ranges from 16 GPa to 20 GPa and the Young’s modulus measured varies between 234 GPa and 300 GPa. The stiffness tensor (Sij= (Cij)−1) of Mn15Si26 has been deduced from these experimental measurements as well as calculated using Ab-initio calculations. The macroscopic elastic modulus (E, G, Β) and Poisson's coefficient have been examined and discussed and their 3D-representation has been plotted. The mechanical anisotropy hereby evidenced as the existence of anisotropy of the thermoelectric properties could be a significant factor for the mechanical reliability of thermoelectric modules which consisted of Mn15Si26 legs with a possible preferred crystallographic orientation induced during their fabrication.
Radio-frequency (RF) contacts—which are an example of electrical contacts—are commonly employed on accelerators and nuclear fusion experimental devices. RF contacts with a current load of 2 kA for ...steady-state operation were designed for application to the International Thermonuclear Experimental Reactor (ITER) device. In contrast to the typical working conditions of general commercial electrical contacts, those of RF contacts employed on fusion devices include high vacuum, high temperature, and neutron radiation. CuCrZr is currently of interest as a base material for the manufacture of louvers of RF contacts, which has excellent thermal and electrical properties and has low creep rate at 250 °C. In this study, a hard Au coating (Au-Ni) was electroplated on CuCrZr samples and the samples were then subjected to thermal aging treatment at 250 °C for 500 h in order to simulate the vacuum-commissioning process of the ITER. The effects of thermal aging on the hardness, elastic modulus, crystallite size, and compositions of the coating were investigated via microstructural and mechanical characterizations of the coating material. Metal atom migration in different coating layers during thermal aging was characterized and evaluated via scanning electron microscopy/energy dispersive X-ray spectroscopy observations of the cross-sectional surfaces, and the obtained results could be used to directly select the coating thickness for the final RF contact component. The contact resistance—an important parameter of the RF contact—was measured in a dedicated testbed built to simulate fusion reactor conditions between CuCrZr pins and stainless steel plates coated with Au-Ni and Rh, respectively.
•Au-Ni alloy coating was achieved through electroplating on CuCrZr substrate.•Au-Ni showed good thermal stability on grain coarsening and hardness decreasing.•Diffusion phenomenon of Au-Ni coating on CuCrZr substrate was characterized.•Electrical property of Au-Ni layer was evaluated on a dedicated vacuum testbed.
Radio-Frequency (RF) contacts are key components on the International Thermonuclear Experimental Reactor (ITER) Ion Cyclotron Resonance Heating (ICRH) antenna, and these components are facing big ...challenges such as 2 kA operation current load and intensive sliding under up to 250 °C in high vacuum. Stainless steel (SS) 316L and CuCrZr are most likely to be applied as base materials for the conductor and the RF contacts louvers. To evaluate the performance of the selected materials, their electrical and tribological behaviors have to be studied. A multifunctional tribometer which can mimic the ITER ICRH RF contacts' relevant working conditions was designed and built in CEA. The contact resistance (Rc) and coefficient of friction (CoF) of CuCrZr-316L pair were researched on this tribometer.
•A tribometer that can mimic ITER ICRH RF contact working conditions was developed.•The coefficient of friction and contact resistance can be measured simultaneously.•The load plates that supply the normal contact force can be adjusted without opening the vacuum vessel.•The performance of CuCrZr/316L material pair was evaluated for ITER RF contact application.
Ceramics long history in biomedical field is related to their high biocompatibility and mechanical properties. Precisely, for joint replacements, wear resistance is fundamental, so advanced ceramics ...as alumina and zirconia are preferred. Developments in ceramic additive manufacturing allow for dense ceramic parts with improved mechanical properties and shape accuracy.
This paper focuses on the tribological analysis of stereolithography-manufactured components for orthopaedics. Alumina, yttria-stabilised zirconia, 10 and 20 wt% zirconia toughened alumina (ZTA) samples were analysed. The effect of surface finishing, microstructure and microhardness on wear was considered.
Printing orientation does not significantly impact microhardness, wettability, and microporosity. However, some printing artefacts as the staircase effect were observed on spherical surfaces. Zirconia system presented high wear rates and friction coefficient, while alumina system showed more acceptable and stable values, with the formation of a self-mated tribofilm. ZTA composites presented the lowest wear volume and better mechanical and surface properties in general.
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Rhodium (Rh) coating on CuCrZr substrate is a promising material option for optical, structural and electrical applications on nuclear fusion reactors. For these applications, Rh coated CuCrZr ...components subject to long time of thermal ageing due to pre-treatment or normal operation condition. In this paper, both finite element method (FEM) and experimental method were applied to investigate the effects of thermal ageing on mechanical performance of Rh coating after 250 °C, 500 h baking in vacuum. Based on FEM analysis, thermal stresses which concentrate at Rh coating interface is the main source of cracking, and such stresses can be minimized efficiently by introducing a 0.5 μm Au interlayer into the coating layer structure. According to thermal ageing experiments, through-thickness cracking in the Rh coating due to thermal stress releasing and voids generated at the Rh bonding interface caused by Kirkendall effect were the main micro-structure changes in the coating system. The solid-solution hardening caused by significant Cu diffusion into Rh is the dominant factor that affected the Rh coating's hardness. The existing of large amount of cracks in the Rh coating and voids at the Rh coating interface deteriorated the adhesion performance of Rh on CuCrZr substrate by 30%.
•Applying of Au interlayer to decrease Rh coating's thermal stress was modeled.•Electroplated Rh showed good thermal stability in hardness and crystallite size.•Diffusion phenomenon at Rh/Cu interface impaired the Rh adhesion significantly.
The ITER Ion Cyclotron Resonance Heating (ICRH) system is designed to couple to the plasma 20 MW of RF power from two antennas in the 40–55 MHz frequency range during long pulses of up to 3600 s and ...under various plasma conditions with Edge Localized Modes. Radio-Frequency (RF) contacts are integrated within the ITER ICRH launcher in order to ensure the RF current continuity and ease the mechanical assembly by allowing the free thermal expansion of the Removable Vacuum Transmission Line coaxial conductors during RF operations or during 250 °C baking phases. A material study has been carried out to determine which materials and associated coatings are relevant for RF contacts application in ITER. In parallel, RF tests have been performed with a new prototype of Multi-Contact® LA-CUT/0,25/0 contacts made of silver-coated CuCrZr louvers. During these tests on a RF vacuum resonator, currents between 1.2 kA and 1.3 kA peak have been reached a few tens of times in steady-state conditions without any visible damage on the louvers. A final 62 MHz pulse ending in a 300 s flat top at 1.9 kA resulted in severe damage to the contact. In addition, a test bed which performs sliding test cycles has been built in order to reproduce the wear of the contact prototype after 30 000 sliding cycles on a 3 mm stroke at 175 °C under vacuum. The silver coating of the louvers is removed after approximately a hundred cycles whilst, to the contrary, damage to the CuCrZr louvers is relatively low.
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