scholarly journals Моноокись кремния, карбонизированная фторуглеродом, как композитный материал для анодов литий-ионных аккумуляторов

2021 ◽  
Vol 91 (9) ◽  
pp. 1381
Author(s):  
Д.А. Ложкина ◽  
Е.В. Астрова ◽  
А.И. Лихачев ◽  
А.В. Парфеньева ◽  
А.М. Румянцев ◽  
...  
Keyword(s):  
High Speed ◽  
Annealing Temperature ◽  
Solid Phase ◽  
Coulombic Efficiency ◽  
Silicon Monoxide ◽  
Sharp Drop ◽  
Optimal Annealing Temperature ◽  
The Matrix ◽  
Current Densities ◽  
Initial Coulombic Efficiency

Dispersed composite materials based on silicon monoxide and carbon (SiO/C) were obtained as a result of heat treatment of a powder mixture consisting of 40 wt% SiO and 60 wt% CF0.8. Annealing was carried out in an argon atmosphere at temperatures 1000 − 1250°C. Using electron microscopy and Raman scattering, it was found that at Т>=1100°C, silicon carbide appears in the solid-phase product, including in the form of cubic nanowhiskers. Based on the data on the weight loss of the reaction mixture, the composition of the resulting products was calculated as a function of the annealing temperature. Anodes made of composites obtained at temperatures above 1100°C demonstrate a sharp drop in capacitance and Columbic efficiency. It is shown that the observed changes are caused not so much by the formation of SiC as by an increase in the oxygen content in the matrix surrounding the silicon precipitates, which were formed as a result of disproportionation of SiO. It was found that the optimal annealing temperature, which provides the highest values of capacity, the initial coulombic efficiency and the ability to operate at high speed current densities is Т =1150°С.

scholarly journals Study of the Origin of the Unexpected Pearlite during the Cooling Stage of Two Cast High-Speed Steels

2011 ◽  
Vol 172-174 ◽  
pp. 803-808 ◽  
Author(s):  
Jérôme Tchoufang Tchuindjang ◽  
Jacqueline Lecomte-Beckers
Keyword(s):  
Retained Austenite ◽  
High Speed ◽  
Solid Phase ◽  
Casting Process ◽  
Eutectic Phase ◽  
Chemical Compositions ◽  
Spin Casting ◽  
Eutectic Carbides ◽  
Similar Chemical ◽  
The Matrix

Two HSS grades (A and B) belonging to the complex system Fe-Cr-C-Si-X, where X is a strong carbide-forming element such as V, Mb or W, were studied. Samples in the as-received conditions came from an industrial spin casting process, with a varying cooling rate during processing. Chemical compositions of both alloys were closed to each other and were chosen to enhance their hardenability and to avoid less resistant phases such as pearlite and ferrite. Differential Thermal Analysis was performed on both alloys, in order to increase their crystallization behaviour. Light microscopy and SEM associated with EDS analyses were done to characterize the microstructure of both alloys in the as-received conditions and after DTA trials. The matrix of both HSS grades was composed of eutectic carbides, martensite and retained austenite, these phases exhibiting similar chemical compositions in both alloys. Unexpected pearlite was found in the as-cast HSS alloy B without W, this grade containing more Mo, more V and less Cr than the HSS grade A. It appeared from DTA tests that pearlite found in the alloy B arose more from the destabilisation of the Cr-rich retained austenite associated with the plate-like M2C carbide, than from the matrix itself. In fact, pearlite zones located in the vicinity of M2C are due to related isothermal solid phase transformations form the previous austenitic eutectic phase that is enriched with Cr and Mo.

scholarly journals Influence of Cu on the Improvement of Magnetic Properties and Structure of L10 FePt Nanoparticles

Nanomaterials ◽  
2021 ◽  
Vol 11 (5) ◽  
pp. 1097
Author(s):  
Luran Zhang ◽  
Xinchen Du ◽  
Hongjie Lu ◽  
Dandan Gao ◽  
Huan Liu ◽  
...  
Keyword(s):  
Magnetic Properties ◽  
Annealing Temperature ◽  
Reduction Method ◽  
Solid Phase ◽  
Average Particle Size ◽  
Fept Nanoparticles ◽  
Average Particle ◽  
Phase Reduction ◽  
Different Temperatures ◽  
One Step

L10 ordered FePt and FePtCu nanoparticles (NPs) with a good dispersion were successfully fabricated by a simple, green, one-step solid-phase reduction method. Fe (acac)3, Pt (acac)2, and CuO as the precursors were dispersed in NaCl and annealed at different temperatures with an H2-containing atmosphere. As the annealing temperature increased, the chemical order parameter (S), average particle size (D), coercivity (Hc), and saturation magnetization (Ms) of FePt and FePtCu NPs increased and the size distribution range of the particles became wider. The ordered degree, D, Hc, and Ms of FePt NPs were greatly improved by adding 5% Cu. The highest S, D, Hc, and Ms were obtained when FePtCu NPs annealed at 750 °C, which were 0.91, 4.87 nm, 12,200 Oe, and 23.38 emu/g, respectively. The structure and magnetic properties of FePt and FePtCu NPs at different annealing temperatures were investigated and the formation mechanism of FePt and FePtCu NPs were discussed in detail.

scholarly journals Energetic-Materials-Driven Synthesis of Graphene-Encapsulated Tin Oxide Nanoparticles for Sodium-Ion Batteries

Materials ◽  
2021 ◽  
Vol 14 (10) ◽  
pp. 2550
Author(s):  
Yingchun Wang ◽  
Jinxu Liu ◽  
Min Yang ◽  
Lijuan Hou ◽  
Tingting Xu ◽  
...  
Keyword(s):  
Tin Oxide ◽  
Energetic Materials ◽  
High Speed ◽  
Coulombic Efficiency ◽  
Sno2 Nanoparticles ◽  
Direct Synthesis ◽  
Exothermic Reaction ◽  
Rate Capability ◽  
Rapid Expansion ◽  
Core Shell

By evenly mixing polytetrafluoroethylene-silicon energetic materials (PTFE-Si EMs) with tin oxide (SnO2) particles, we demonstrate a direct synthesis of graphene-encapsulated SnO2 (Gr-SnO2) nanoparticles through the self-propagated exothermic reaction of the EMs. The highly exothermic reaction of the PTFE-Si EMs released a huge amount of heat that induced an instantaneous temperature rise at the reaction zone, and the rapid expansion of the gaseous SiF4 product provided a high-speed gas flow for dispersing the molten particles into finer nanoscale particles. Furthermore, the reaction of the PTFE-NPs with Si resulted in a simultaneous synthesis of graphene that encapsulated the SnO2 nanoparticles in order to form the core-shell nanostructure. As sodium storage material, the graphene-encapsulated SnO2 nanoparticles exhibit a good cycling performance, superior rate capability, and a high initial Coulombic efficiency of 85.3%. This proves the effectiveness of our approach for the scalable synthesis of core-shell-structured graphene-encapsulated nanomaterials.

A Universal Strategy toward the Precise Regulation of Initial Coulombic Efficiency of Li‐Rich Mn‐Based Cathode Materials

2021 ◽  
pp. 2103173
Author(s):  
Weibin Guo ◽  
Chenying Zhang ◽  
Yinggan Zhang ◽  
Liang Lin ◽  
Wei He ◽  
...  
Keyword(s):  
Cathode Materials ◽  
Coulombic Efficiency ◽  
Initial Coulombic Efficiency

Optimization of thermal conductivity in composites loaded with the solid-solid phase-change materials

2018 ◽  
Vol 25 (6) ◽  
pp. 1157-1165
Author(s):  
Taoufik Mnasri ◽  
Adel Abbessi ◽  
Rached Ben Younes ◽  
Atef Mazioud
Keyword(s):  
Thermal Conductivity ◽  
Phase Change ◽  
Phase Change Materials ◽  
Solid Phase ◽  
Spherical Inclusions ◽  
First Case ◽  
The Matrix ◽  
Composite Conductivity ◽  
First Time

AbstractThis work focuses on identifying the thermal conductivity of composites loaded with phase-change materials (PCMs). Three configurations are studied: (1) the PCMs are divided into identical spherical inclusions arranged in one plane, (2) the PCMs are inserted into the matrix as a plate on the level of the same plane of arrangement, and (3) the PCMs are divided into identical spherical inclusions arranged periodically in the whole matrix. The percentage PCM/matrix is fixed for all cases. A comparison among the various situations is made for the first time, thus providing a new idea on how to insert PCMs into composite matrices. The results show that the composite conductivity is the most important consideration in the first case, precisely when the arrangement plane is parallel with the flux and diagonal to the entry face. In the present work, we are interested in exploring the solid-solid PCMs. The PCM polyurethane and a wood matrix are particularly studied.

Optical Waveguide Formation by Ion Implantation of Ti or Ag

1988 ◽  
Vol 100 ◽  
Author(s):  
D. B. Poker ◽  
D. K. Thomas
Keyword(s):  
Ion Implantation ◽  
Concentration Profile ◽  
Optical Waveguides ◽  
Annealing Temperature ◽  
Solid Phase ◽  
Effective Means ◽  
Complete Removal ◽  
Solid Phase Epitaxy ◽  
Annealing Temperatures ◽  
Residual Damage

ABSTRACTIon implantation of Ti into LINbO3 has been shown to be an effective means of producing optical waveguides, while maintaining better control over the resulting concentration profile of the dopant than can be achieved by in-diffusion. While undoped, amorphous LiNbO3 can be regrown by solid-phase epitaxy at 400°C with a regrowth velocity of 250 Å/min, the higher concentrations of Ti required to form a waveguide (∼10%) slow the regrowth considerably, so that temperatures approaching 800°C are used. Complete removal of residual damage requires annealing temperatures of 1000°C, not significantly lower than those used with in-diffusion. Solid phase epitaxy of Agimplanted LiNbO3, however, occurs at much lower temperatures. The regrowth is completed at 400°C, and annealing of all residual damage occurs at or below 800°C. Furthermore, the regrowth rate is independent of Ag concentration up to the highest dose implanted to date, 1 × 1017 Ag/cm2. The usefulness of Ag implantation for the formation of optical waveguides is limited, however, by the higher mobility of Ag at the annealing temperature, compared to Ti.

Sign in / Sign up

Export Citation Format

Share Document