scholarly journals Achieving high strength and ductility in ODS-W alloy by employing oxide@W core-shell nanopowder as precursor

2021 ◽  
Vol 12 (1) ◽  
Author(s):  
Zhi Dong ◽  
Zongqing Ma ◽  
Liming Yu ◽  
Yongchang Liu
Keyword(s):  
High Temperature ◽  
Metal Matrix ◽  
High Performance ◽  
High Energy ◽  
Core Shell ◽  
Microstructural Stability ◽  
Oxide Particles ◽  
Ods Alloy ◽  
Prepared Alloy ◽  
Strength And Ductility

AbstractWith excellent creep resistance, good high-temperature microstructural stability and good irradiation resistance, oxide dispersion strengthened (ODS) alloys are a class of important alloys that are promising for high-temperature applications. However, plagued by a nerve-wracking fact that the oxide particles tend to aggregate at grain boundary of metal matrix, their improvement effect on the mechanical properties of metal matrix tends to be limited. In this work, we employ a unique in-house synthesized oxide@W core-shell nanopowder as precursor to prepare W-based ODS alloy. After low-temperature sintering and high-energy-rate forging, high-density oxide nanoparticles are dispersed homogeneously within W grains in the prepared alloy, accompanying with the intergranular oxide particles completely disappearing. As a result, our prepared alloy achieves a great enhancement of strength and ductility at room temperature. Our strategy using core-shell powder as precursor to prepare high-performance ODS alloy has potential to be applied to other dispersion-strengthened alloy systems.

Effect of Improved ThO2 Particle Dispersion in Nickel on High-Temperature Strength

1970 ◽  
Vol 28 ◽  
pp. 444-445
Author(s):  
E. R. Kimmel ◽  
H. L. Anthony ◽  
W. Scheithauer
Keyword(s):  
High Temperature ◽  
Metal Matrix ◽  
Oxide Particle ◽  
Oxide Phase ◽  
Dislocation Motion ◽  
Particle Dispersion ◽  
High Temperature Strength ◽  
Strengthening Effect ◽  
Oxide Particles ◽  
The Stability

The strengthening effect at high temperature produced by a dispersed oxide phase in a metal matrix is seemingly dependent on at least two major contributors: oxide particle size and spatial distribution, and stability of the worked microstructure. These two are strongly interrelated. The stability of the microstructure is produced by polygonization of the worked structure forming low angle cell boundaries which become anchored by the dispersed oxide particles. The effect of the particles on strength is therefore twofold, in that they stabilize the worked microstructure and also hinder dislocation motion during loading.

Scalable construction of heteroatom-doped and hierarchical core–shell MnO2 nanoflakes on mesoporous carbon for high performance supercapacitor devices

2020 ◽  
Vol 7 (2) ◽  
pp. 411-420
Author(s):  
Xue Bai ◽  
Dianxue Cao ◽  
Hongyu Zhang
Keyword(s):  
Mesoporous Carbon ◽  
High Performance ◽  
High Energy ◽  
Cycling Stability ◽  
Core Shell ◽  
Power Densities ◽  
Shell Composite ◽  
Asymmetric Device

Combining interfacial methods and mesoporous carbon channels, an asymmetric device, using N,S-codoped mesoporous carbon and a MnO2@MC-30 core shell composite, is assembled with high energy, power densities and outstanding cycling stability.

Influence of Distinct Manufacturing Processes on the Microstructure of Ni-Based Metal Matrix Composites Submitted to Long Thermal Exposure

2019 ◽  
Vol 809 ◽  
pp. 79-86
Author(s):  
Georges Lemos ◽  
Márcio C. Fredel ◽  
Florian Pyczak ◽  
Ulrich Tetzlaff
Keyword(s):  
Metal Matrix Composites ◽  
High Temperatures ◽  
Metal Matrix ◽  
Thermal Exposure ◽  
High Energy ◽  
Matrix Composites ◽  
Microstructural Stability ◽  
Aerospace Applications ◽  
Plasma Sintering ◽  
Energy Processes

Metal Matrix Composites (MMCs) are known for their remarkable properties, by combining materials from different classes. Ni-based MMCs are a promising group of heat-resistant materials, targeting aerospace applications. A discontinuously reinforced Inconel X-750/TiC 15 vol.% MMC was proposed for use in lighter, creep resistant turbine elements, with the aim to endure service temperatures up to 1073 K (800 °C). However, their microstructural stability at high temperatures for long periods of time remained to be further investigated. To address this need, specimens were produced by both conventional hot pressing and spark plasma sintering, using powders milled by low and high energy processes, followed by long isothermal aging. The treatments were conducted at 973 and 1073 K, for times between 50 and 1000 hours. The resulting samples were investigated with XRD and EDS techniques for phase analysis. In addition, measurements of hardness were made to monitor changes in mechanical behavior. It was found that, for each different manufacturing process, the amount, distribution and size of γ’ and other precipitates notably vary during the overaging process. Consequently, the amount of elements kept in solid solution also shifted with time. Furthermore, the study shows how distinct initial microstructures, resulting from diverse fabrication processes, differently impact the microstructural stability over long times of exposure to high temperatures.

THERMODYNAMIC AND KINETIC ANALYSES OF SYNTHESIZING ZrB2@Al(OH)3–Y(OH)3 CORE–SHELL COMPOSITE PARTICLES

2007 ◽  
Vol 14 (01) ◽  
pp. 117-122 ◽  
Author(s):  
JIEGUANG SONG ◽  
LIANMENG ZHANG ◽  
JUNGUO LI ◽  
JIANRONG SONG
Keyword(s):  
High Temperature ◽  
High Performance ◽  
Solubility Product ◽  
Ceramic Materials ◽  
Precipitation Method ◽  
Composite Particles ◽  
Core Shell ◽  
High Temperature Strength ◽  
Co Precipitation ◽  
Shell Composite

ZrB 2 has some excellent performances, but it is easily oxidized at high temperatures to impact the high-temperature strength, which restricts its applied range. To protect from the oxidization and improve the strength of ZrB 2 at high temperature, the surface of ZrB 2 particles is coated with the Al ( OH )3– Y ( OH )3 shell to synthesize ZrB 2@ Al ( OH )3– Y ( OH )3 core–shell composite particles. Through the thermodynamic and kinetic analyses of the heterogeneous nucleation and homogeneous nucleation, the concentration product of precursor ion ( Y 3+ or Al 3+) and OH - (Qi) must be greater than the solubility product (K sp ), respectively; the conditions of Y 3+ and Al 3+ are reached to produce Al ( OH )3– Y ( OH )3 shell on the ZrB 2 surface between the Y 3+ line and the AlO 2- line. Through TEM and XRD analyses, ZrB 2@ Al ( OH )3– Y ( OH )3 core–shell composite particles are successfully synthesized by the co-precipitation method, the shell layer quality is better at pH = 9, which established the foundation for preparing high-performance YAG / ZrB 2 and Al 2 O 3– YAG / ZrB 2 multiphase ceramic materials.

Addressing Matrix Acidizing Stimulation Challenges in Depleted, High-Temperature, and Acid-Sensitive Sandstone Formations with a High-Performance Acid System

2021 ◽  
Author(s):  
Rao Shafin Khan ◽  
Nestor Molero ◽  
Philippe Enkababian ◽  
Aizaz Khalid ◽  
Malik Anzar Afzal ◽  
...  
Keyword(s):  
High Temperature ◽  
Organic Acid ◽  
High Performance ◽  
Clay Content ◽  
High Energy ◽  
Acid System ◽  
Matrix Acidizing ◽  
Well Production ◽  
Production Trend ◽  
Sandstone Reservoirs

Abstract Acid stimulation in high-temperature sandstone reservoirs with high clay content can lead to undesired results due to secondary and tertiary reactions between treatment fluids and reservoir clays. Although there have been significant advancements in treating clastic formations over the years, high bottomhole temperature (BHT) coupled with high clay content of up to 35% and subhydrostatic conditions still presents a major challenge. A stimulation workflow to address these challenges was adapted to treat and successfully enhance well production in sandstone reservoirs in southern Pakistan. Candidate wells were selected for acidizing treatments based on declining production trend and identification of significant damage skin. X-ray diffraction tests on core samples indicated presence of acid-sensitive clays and calcite. Due to the risk of precipitation from secondary and tertiary reactions, conventional hydrochloric and hydrofluoric acid treatments were not viable options. Core flow testing was conducted to assess the efficiency of alternative acid systems at the reservoir conditions with BHT above 320°F, validating the selection of a high-performance sandstone acid system that was designed to handle undissolved clays in the critical matrix by helping to bind the clays to the pore surfaces, thus preventing them from migrating and plugging the pore throat during flowback. The matrix stimulation campaign included vertical and deviated dry gas wells, completed with 3 1/2-in. to 4 1/2-in. production tubing and 7-in. liner, with perforated intervals averaging 20 ft. Prior to the main acid treatment, high-pressure rotary jetting across the target intervals was conducted by pumping organic acid via coiled tubing. This wellbore conditioning technique allowed maximizing the acid performance by delivering 360° high-energy fluid to clear the perforations of scale and improve injectivity. The main treatment consisted of an organic acid preflush and a high-performance sandstone acid system as the main fluid, followed by a brine post-flush. Throughout the treatment, nitrogen was added to all fluids to facilitate fluid flowback under subhydrostatic conditions. The wells treated using this matrix stimulation engineered workflow yielded sustained production gains from 3 MMscf/D to 3.5 MMscf/D, exceeding expectations by more than 50% and achieving payback periods less than 20 days. The success of the treatment was largely due to the carefully designed stimulation workflow and its flawless execution. Acidizing high-temperature sandstone reservoirs with 30 to 35% clay content is uncommon. The experience gained in southern Pakistan validates the high-performance sandstone acid system as a reliable option for matrix acidizing in hot, acid-sensitive sandstone reservoirs. It also provides a detailed engineering workflow for candidate selection, treatment design, and job execution and evaluation, which can easily be adapted to regions facing similar challenges.

SYNTHESIS AND CHARACTERIZATION OF Si3N4@Al(OH)3–Y(OH)3 CORE-SHELL COMPOSITE PARTIC3LES

2008 ◽  
Vol 15 (05) ◽  
pp. 581-585 ◽  
Author(s):  
JIE-GUANG SONG ◽  
GANG-CHANG JI ◽  
SHI-BIN LI ◽  
LIAN-MENG ZHANG
Keyword(s):  
High Temperature ◽  
High Performance ◽  
Ceramic Materials ◽  
Composite Particles ◽  
Core Shell ◽  
High Temperature Strength ◽  
Bet Analysis ◽  
Co Precipitation ◽  
Shell Composite

Silicon nitride ( Si 3 N 4) has attracted substantial interest because of its extreme chemical and physical properties, but the sintering densification of Si 3 N 4 is difficult, and it is easily oxidized in the high-temperature air to impact high-temperature strength, which restricts its applied range. In order to decrease the oxidization and improve the strength of Si 3 N 4 at high temperature, the surface of Si 3 N 4 is coated with Al ( OH )3 and Y ( OH )3 to synthesis Si 3 N 4@ Al ( OH )3– Y ( OH )3 core-shell composite particles. Through TEM, XRD, and BET analysis, when pH is about 9, Si 3 N 4@ Al ( OH )3– Y ( OH )3 core-shell composite particles are successfully synthesized by co-precipitation methods. Coating layer is about 200 nm, which is compaction and conformability. Dispersion of coated Si 3 N 4 with Al ( OH )3 and Y ( OH )3 particles are very good. Synthesis of Si 3 N 4@ Al ( OH )3– Y ( OH )3 core-shell composite powder will lay the foundation for preparing high-performance YAG/Si 3 N 4 multiphase ceramic materials.

scholarly journals Hierarchical porous graphitic carbon for high-performance supercapacitors at high temperature

RSC Advances ◽  
2017 ◽  
Vol 7 (55) ◽  
pp. 34488-34496 ◽  
Author(s):  
Chong Chen ◽  
Dengfeng Yu ◽  
Gongyuan Zhao ◽  
Lei Sun ◽  
Yinyong Sun ◽  
...  
Keyword(s):  
High Temperature ◽  
Energy Density ◽  
Power Density ◽  
High Performance ◽  
High Energy ◽  
Porous Graphitic Carbon ◽  
Graphitic Carbon ◽  
Cycle Life ◽  
High Energy Density ◽  
Hierarchical Porous

Developing supercapacitors with high energy density without sacrificing the power density and cycle life has attracted enormous attention.

A synergistic vertical graphene skeleton and S–C shell to construct high-performance TiNb2O7-based core/shell arrays

2018 ◽  
Vol 6 (41) ◽  
pp. 20195-20204 ◽  
Author(s):  
Shenghui Shen ◽  
Weihao Guo ◽  
Dong Xie ◽  
Yadong Wang ◽  
Shengjue Deng ◽  
...  
Keyword(s):  
High Temperature ◽  
High Temperatures ◽  
High Performance ◽  
High Rate ◽  
Core Shell ◽  
Rate Performance ◽  
Binder Free ◽  
High Rate Performance ◽  
Method Show

Binder-free VG/TiNb2O7@S–C electrodes prepared via a powerful solvothermal-electrodeposition (ST-ED) method show good high-rate performance (241 mA h g−1/70 °C at 160C) and long high-temperature lifespan (>5000 cycles) at medium–high temperatures.

High Temperature Silicon Carbide Power Modules for High Performance Systems

2011 ◽  
Vol 2011 (HITEN) ◽  
pp. 000159-000166 ◽  
Author(s):  
J. Hornberger ◽  
B. McPherson ◽  
J. Bourne ◽  
R. Shaw ◽  
E. Cilio ◽  
...  
Keyword(s):  
Silicon Carbide ◽  
High Temperature ◽  
High Speed ◽  
High Performance ◽  
High Reliability ◽  
Extreme Environment ◽  
High Energy ◽  
Energy Applications ◽  
Power Modules ◽  
Reliability Systems

The demands of modern high-performance power electronics systems are rapidly surpassing the power density, efficiency, and reliability limitations defined by the intrinsic properties of silicon-based semiconductors. The advantages of silicon carbide (SiC) are well known, including high temperature operation, high voltage blocking capability, high speed switching, and high energy efficiency. In this discussion, APEI, Inc. presents two newly developed high performance SiC power modules for extreme environment systems and applications. These power modules are rated to 1200V, are operational at currents greater than 100A, can perform at temperatures in excess of 250 °C, and are designed to house various SiC devices, including MOSFETs, JFETs, or BJTs. One newly developed module is designed for high performance, ultra-high reliability systems such as aircraft and spacecraft, and features a hermetically sealed package with a ring seal technology capable of sustaining temperatures in excess of 400°C. The second module is designed for high performance commercial and industrial systems such as hybrid electric vehicles or renewable energy applications, implements a novel ultra-low parasitic packaging approach that enables high switching frequencies in excess of 100 kHz, and weighs in at just over 130 grams (offering ~5× mass reduction and ~3× size reduction in comparison with industry standard power brick packaging technology). It is configurable as either a half or full bridge converter. In this discussion, APEI, Inc. introduces these products and presents practical testing of each.

Aromatic Polyurea for High Temperature High Energy Density Capacitors

2008 ◽  
Vol 1134 ◽  
Author(s):  
Yong Wang ◽  
Xin Zhou ◽  
Minren Lin ◽  
Sheng-Guo David Lu ◽  
Jun-Hong Lin ◽  
...  
Keyword(s):  
High Temperature ◽  
Energy Density ◽  
High Performance ◽  
High Efficiency ◽  
Breakdown Strength ◽  
Dielectric Material ◽  
Weibull Model ◽  
High Energy ◽  
High Energy Density ◽  
Low Dissipation

AbstractWe investigate aromatic polyureas which can be fabricated in the form of thin films through CVD. It was found that the polymer possesses a flat dielectric response (k∼ 4.2 and loss <1%)) to more than 200°C. The frequency-independent dielectric properties in the investigated frequency range(1kHz∼1MHz), low conductance, low dissipation factor (∼0.005), high breakdown strength (>800MV/m), high energy density (>12J/cm3) and high efficiency suggest this polymer can be a good candidate material for high temperature energy storage capacitors. Breakdown strength was analyzed with Weibull model over a broad temperature range (25°C ∼180°C). Experimental results indicate that aromatic polyurea is more like a nonpolar linear dielectric material because of its highly cross-linked structures. The experiment results further show that this polymer maintains its high performance even at high temperatures.

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