scholarly journals Annealing-Induced Changes in the Microstructure and Mechanical Response of a Cu Nanofoam Processed by Dealloying

Metals ◽  
2020 ◽  
Vol 10 (9) ◽  
pp. 1128
Author(s):  
Péter Jenei ◽  
Csilla Kádár ◽  
Gigap Han ◽  
Pham Tran Hung ◽  
Heeman Choe ◽  
...  
Keyword(s):  
Heat Treatment ◽  
Mechanical Response ◽  
Bulk Material ◽  
Lithium Ion ◽  
Large Change ◽  
Oxide Content ◽  
Hardness Testing ◽  
Initial State ◽  
Induced Changes ◽  
Ligament Size

Cu nanoporous foams are promising candidates for use as an anode material for advanced lithium ion batteries. In this study, Cu nanofoam was processed from pack-cemented bulk material via dealloying. In the as-processed Cu nanofoam, the average ligament size was ~105 nm. The hardness in this initial state was ~2 MPa, and numerous cracks were observed in the indentation pattern obtained after hardness testing, thus indicating the low mechanical strength of the material. Annealing for 6 h under an Ar atmosphere at 400 °C was shown to result in crystalline coarsening and a reduction in the probability of twin faulting in the ligaments. Simultaneously, the junctions of the ligaments became stronger and hence more difficult to crack. This study demonstrates that moderate heat treatment under Ar can improve the resistance against crack propagation in Cu nanofoam without a large change in the ligament size and the surface oxide content, which can thus influence the electrochemical performance of the material in battery applications.

Structure, Magnetic Properties and Magnetic Impedance of Fast Quenched Ribbons of Alloys Based on FINEMET in the Initial State and After Heat Treatment

2020 ◽  
Vol 121 (10) ◽  
pp. 961-967
Author(s):  
E. A. Stepanova ◽  
S. O. Volchkov ◽  
V. A. Lukshina ◽  
D. A. Shishkin ◽  
D. M. Khudyakova ◽  
...  
Keyword(s):  
Heat Treatment ◽  
Magnetic Properties ◽  
Initial State ◽  
Magnetic Impedance

scholarly journals Atomic Layer Deposition of Ni-Co-O Thin-Film Electrodes for Solid-State LIBs and the Influence of Chemical Composition on Overcapacity

Nanomaterials ◽  
2021 ◽  
Vol 11 (4) ◽  
pp. 907
Author(s):  
Yury Koshtyal ◽  
Ilya Mitrofanov ◽  
Denis Nazarov ◽  
Oleg Medvedev ◽  
Artem Kim ◽  
...  
Keyword(s):  
Chemical Composition ◽  
Atomic Layer Deposition ◽  
Nickel Oxide ◽  
Cobalt Oxide ◽  
Lithium Ion ◽  
Atomic Layer ◽  
Metallic Nickel ◽  
Uniform Density ◽  
Oxide Content ◽  
Layer Deposition

Nanostructured metal oxides (MOs) demonstrate good electrochemical properties and are regarded as promising anode materials for high-performance lithium-ion batteries (LIBs). The capacity of nickel-cobalt oxides-based materials is among the highest for binary transition metals oxide (TMOs). In the present paper, we report the investigation of Ni-Co-O (NCO) thin films obtained by atomic layer deposition (ALD) using nickel and cobalt metallocenes in a combination with oxygen plasma. The formation of NCO films with different ratios of Ni and Co was provided by ALD cycles leading to the formation of nickel oxide (a) and cobalt oxide (b) in one supercycle (linear combination of a and b cycles). The film thickness was set by the number of supercycles. The synthesized films had a uniform chemical composition over the depth with an admixture of metallic nickel and carbon up to 4 at.%. All samples were characterized by a single NixCo1-xO phase with a cubic face-centered lattice and a uniform density. The surface of the NCO films was uniform, with rare inclusions of nanoparticles 15–30 nm in diameter. The growth rates of all films on steel were higher than those on silicon substrates, and this difference increased with increasing cobalt concentration in the films. In this paper, we propose a method for processing cyclic voltammetry curves for revealing the influence of individual components (nickel oxide, cobalt oxide and solid electrolyte interface—SEI) on the electrochemical capacity. The initial capacity of NCO films was augmented with an increase of nickel oxide content.

scholarly journals Mechanical response of aluminum 7075 with heat treatment and exfoliation corrosion

2021 ◽  
Author(s):  
Mohammad Yaseen Kittur ◽  
M.I. Kittur ◽  
Avala Raji Reddy ◽  
Maughal Ahmed Ali Baig ◽  
Ridwan ◽  
...  
Keyword(s):  
Heat Treatment ◽  
Mechanical Response ◽  
Exfoliation Corrosion ◽  
Aluminum 7075

Effects of heat treatment and SOC on fire behaviors of lithium-ion batteries pack

2018 ◽  
Vol 136 (6) ◽  
pp. 2429-2437 ◽  
Author(s):  
Mingyi Chen ◽  
Ouyang Dongxu ◽  
Shuchao Cao ◽  
Jiahao Liu ◽  
Zhi Wang ◽  
...  
Keyword(s):  
Heat Treatment ◽  
Lithium Ion Batteries ◽  
Lithium Ion

Influence of Laser Heat Treatment on Fracture Strength of Ceramic Thin Film

2012 ◽  
Vol 566 ◽  
pp. 145-149
Author(s):  
Hirotaka Tanabe ◽  
Keiji Ogawa ◽  
Yui Izumi ◽  
Tohru Takamatsu ◽  
Heisaburo Nakagawa ◽  
...  
Keyword(s):  
Thin Films ◽  
Heat Treatment ◽  
Fracture Strength ◽  
Strength Loss ◽  
Substrate Material ◽  
Laser Quenching ◽  
Ceramic Thin Films ◽  
Film Hardness ◽  
Induced Changes ◽  
Substrate Hardness

In our previous study, it has been shown that improvement of the adhesive strength and substrate hardness of ceramic coated steels without compromising the film hardness can be achieved by applying laser quenching. In the present research, in order to demonstrate further development of this method, the fracture strength of laser-irradiated ceramic thin films (CrAlN, TiAlN and CrN) was investigated by sphere indentation testing. To prevent heat-induced changes in the substrate hardness, a cemented carbide WC-Co rather than steel was used as substrate material. While the fracture strength of each film decreased significantly through furnace heat treatment, it remained almost unchanged in case of the laser irradiated films. Laser quenching has been shown to effectively reduce the fracture strength loss of the ceramic thin films in coated steels.

scholarly journals Balanced networks under spike-time dependent plasticity

2021 ◽  
Vol 17 (5) ◽  
pp. e1008958
Author(s):  
Alan Eric Akil ◽  
Robert Rosenbaum ◽  
Krešimir Josić
Keyword(s):  
Spike Timing ◽  
Recurrent Networks ◽  
Spike Time ◽  
Weight Changes ◽  
Initial State ◽  
Dependent Plasticity ◽  
Plausible Mechanism ◽  
Spike Time Dependent Plasticity ◽  
Induced Changes ◽  
Balanced Networks

The dynamics of local cortical networks are irregular, but correlated. Dynamic excitatory–inhibitory balance is a plausible mechanism that generates such irregular activity, but it remains unclear how balance is achieved and maintained in plastic neural networks. In particular, it is not fully understood how plasticity induced changes in the network affect balance, and in turn, how correlated, balanced activity impacts learning. How do the dynamics of balanced networks change under different plasticity rules? How does correlated spiking activity in recurrent networks change the evolution of weights, their eventual magnitude, and structure across the network? To address these questions, we develop a theory of spike–timing dependent plasticity in balanced networks. We show that balance can be attained and maintained under plasticity–induced weight changes. We find that correlations in the input mildly affect the evolution of synaptic weights. Under certain plasticity rules, we find an emergence of correlations between firing rates and synaptic weights. Under these rules, synaptic weights converge to a stable manifold in weight space with their final configuration dependent on the initial state of the network. Lastly, we show that our framework can also describe the dynamics of plastic balanced networks when subsets of neurons receive targeted optogenetic input.

scholarly journals Influence of the energy electron beam exposure regimes on the structure and mechanical properties of composite coatings

2020 ◽  
pp. 23-27
Author(s):  
T.A. Krylova ◽  
◽  
Y.A. Chumakov ◽  
Keyword(s):  
Mechanical Properties ◽  
Heat Treatment ◽  
Wear Resistance ◽  
Electron Beam ◽  
Structural Changes ◽  
Composite Coatings ◽  
Initial State ◽  
Austenitic Structure ◽  
Solid Carbide ◽  
Soft Ferrite

The effect of heat treatment on the structure and properties of composite coatings based on chromium carbide with titanium carbide fabricated by non-vacuum electron beam cladding without has been studied. It was shown that tempering leads to a decrease in microhardness and wear resistance, which is associated with the decomposition of the austenitic structure with the formation of a soft ferrite-carbide structure. The post heat treatment tempering was showed to decrease of microhardness and wear resistance, which leads to the decomposition of the austenitic structure with the formation of a soft ferrite-carbide structure. The bulk quenching of coatings after tempering leads to an increase in microhardness comparable to the values of microhardness in the initial state after electron beam cladding, due to the formation of high hard martensite. The wear resistance of composite coatings after tempering is lower than after cladding due to brittle martensite, which is not able to hold solid carbide particles. The composite coatings obtained at the optimal processing conditions have a combination of improved properties and do not require additional heat treatment, resulting in structural changes, causing a decrease in mechanical properties.

scholarly journals 475 Heat Treatments Reduce Irradiation-induced Changes in Phenylpropanoid Metabolism in Grapefruit

HortScience ◽  
1999 ◽  
Vol 34 (3) ◽  
pp. 527A-527
Author(s):  
R.E. McDonald ◽  
W.R. Miller ◽  
T.G. McCollum
Keyword(s):  
Heat Treatment ◽  
Fold Increase ◽  
Heat Treatments ◽  
Maximum Activity ◽  
Phenylpropanoid Metabolism ◽  
Total Phenols ◽  
Citrus Paradisi ◽  
Pal Activity ◽  
Canopy Position ◽  
Induced Changes

Irradiation is being evaluated as a quarantine treatment of grapefruit (Citrus paradisi, Macf.), but it can cause damage to the fruit. We wanted to determine if pre-irradiation heat treatments would improve fruit tolerance to irradiation as they improve tolerance to low-temperature injury. `Marsh' grapefruit were harvested from interior and exterior canopy positions and irradiated at 0 or 1.0 kGy at a dose rate of 0.148 kGy·min-1 before storage for 4 weeks at 10 °C. Following storage, pitting of flavedo tissue was the most evident condition defect noted as a result of irradiation. Pitting was noted on 15% and 27% of irradiated interior and exterior canopy fruit, respectively, whereas there was no pitting on non-irradiated fruit. Temperature conditioning before irradiation decreased the susceptibility of fruit to damage. Pitting was 26%, 19%, and 17% when fruit were held 2 h at 20 (ambient), 38 or 42 °C, respectively. There was a marked increase in phenylalanine ammonia-lyase (PAL) activity following irradiation. Maximum activity (≈18-fold increase) was attained 24 h after irradiation. Irradiation-induced PAL activity was reduced significantly by temperature conditioning at 38 or 42 °C. Exterior canopy fruit flavedo contained higher levels of total phenols, including flavanols and coumarins, compared with interior canopy fruit. The deposition of lignin was not related to canopy position. Neither irradiation nor heat treatment had an effect on total phenols or lignin deposition. It seems that irradiation causes a stress condition in the fruit, which leads to pitting of peel tissue. Heat treatment before irradiation reduced the damaging effects of irradiation.

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