Microstructures and Electrical Conductivity of Cu-Ca Alloys for High Efficiency Induction Motors

2004 ◽  
Vol 449-452 ◽  
pp. 685-688 ◽  
Author(s):  
Keun Yong Sohn ◽  
Dong Woo Suh ◽  
Sang Yong Lee
Keyword(s):  
Electrical Conductivity ◽  
Grain Size ◽  
Thermomechanical Treatment ◽  
High Purity ◽  
High Efficiency ◽  
Induction Motors ◽  
Processing Condition ◽  
Molten Copper ◽  
Subsequent Heating ◽  
Semi Solid

The microstructures and electrical conductivity of newly developed Cu-Ca alloys for semi-solid forming have been investigated. High purity calcium was added to molten copper up to 1.4% by weight and mold-cast into a rod. Thermomechanical treatment (TMT) has been carried out to evaluate the variation in electrical conductivity and microstructures of Cu-Ca alloys. The electrical conductivity of copper was reduced linearly with the concentration of calcium by , where k is a constant having the values ranging from 16.7 to 20, depending on the processing condition. The introduction of prestrain significantly reduced the grain size during subsequent heating by recrystallization, influencing the electrical conductivity of Cu-Ca alloys.

Zum Kornwachstum beim reinen und dotierten polykristallinen Selen / Grain Growth of Pure and Doped Poly crystalline Selenium

1971 ◽  
Vol 26 (7) ◽  
pp. 1198-1201
Author(s):  
C. Weyrich
Keyword(s):  
Electrical Conductivity ◽  
Grain Size ◽  
Grain Growth ◽  
Annealing Time ◽  
High Purity ◽  
The Mean ◽  
Grain Surface ◽  
Polycrystalline Form ◽  
Grain Diameter

Abstract Grain Growth of Pure and Doped Poly crystalline Selenium Samples of vitreous high-purity selenium as well as vitreous chlorine-and thallium-doped selenium have been brought into the polycrystalline form by annealing. The dependence of grain size on annealing time tu was measured. In high-purity selenium and in chlorine-doped selenium the mean grain diameter increases essentially ~ tu1/2 , in thallium-doped selenium ~ tu1/2 , as is expected from the laws of grain growth. The proportionality between electrical conductivity and specific grain surface reported by other authors could not be verified.

scholarly journals Unconventional Microstructures in Tool Steel Obtained by Semi-Solid Processing and Subsequent Heat Treatment

2014 ◽  
Vol 217-218 ◽  
pp. 235-240 ◽  
Author(s):  
David Aišman ◽  
Bohuslav Mašek ◽  
Štěpán Jeníček
Keyword(s):  
Mechanical Properties ◽  
Heat Treatment ◽  
Grain Size ◽  
Thermomechanical Treatment ◽  
Tool Steel ◽  
Microstructure Evolution ◽  
Heat Treating ◽  
Subsequent Heat Treatment ◽  
Wide Range ◽  
Semi Solid

Mechanical properties of all metals depend predominantly on the type and morphology of their microstructure. Microstructure attributes can be altered by various heat treating and thermomechanical treatment procedures. One of the advanced techniques profoundly affecting the microstructure evolution is semi-solid processing. It can produce unconventional microstructures even in conventional steel types. Moreover, subsequent heat treatment can also deliver a wide range of microstructures and correspondingly varied mechanical properties. In the present experimental programme, the X210Cr12 ledeburitic tool steel was studied. Its initial annealed microstructure consisted of ferritic matrix, chromium carbides and globular cementite particles. The semi-solid processed structure, on the other hand, contained polyhedral austenite grains embedded in carbide-austenite network. The austenite volume fraction exceeded 95 %. This microstructure was then altered by subsequent heat treatment or thermomechanical treatment. The experimental programme comprised three stages. At the first stage, the effects of the rate of cooling from the semi-solid region to the ambient temperature on the nature and morphology of the ledeburitic network and the austenitic grain size were explored. The second stage was aimed at the impact of tensile and compressive deformation applied after transition through semi-solid state on the microstructure evolution and, in particular, on grain size. Once suitable processing conditions and parameters were identified, the treatment led to a recrystallized austenitic microstructure with an average grain size of less than 3 μm. As high volume fractions of austenite were obtained, the third stage involved exploring the effects of thermal exposure. The stability of austenite and the decomposition of austenite into other microstructure constituents were mapped. Metallographic observation revealed a resulting wide range of microstructures from fine pearlite to martensite, depending on the heat treating schedule.

scholarly journals Synthesis, microstructure, and properties of high purity Mo2TiAlC2 ceramics fabricated by spark plasma sintering

2020 ◽  
Vol 9 (6) ◽  
pp. 759-768
Author(s):  
Yunhui Niu ◽  
Shuai Fu ◽  
Kuibao Zhang ◽  
Bo Dai ◽  
Haibin Zhang ◽  
...  
Keyword(s):  
Grain Size ◽  
Flexural Strength ◽  
Spark Plasma Sintering ◽  
Layered Structure ◽  
High Purity ◽  
High Fracture Toughness ◽  
Temperature Range ◽  
Microstructure And Properties ◽  
Plasma Sintering ◽  
Spark Plasma

AbstractThe synthesis, microstructure, and properties of high purity dense bulk Mo2TiAlC2 ceramics were studied. High purity Mo2TiAlC2 powder was synthesized at 1873 K starting from Mo, Ti, Al, and graphite powders with a molar ratio of 2:1:1.25:2. The synthesis mechanism of Mo2TiAlC2 was explored by analyzing the compositions of samples sintered at different temperatures. It was found that the Mo2TiAlC2 phase was formed from the reaction among Mo3Al2C, Mo2C, TiC, and C. Dense Mo2TiAlC2 bulk sample was prepared by spark plasma sintering (SPS) at 1673 K under a pressure of 40 MPa. The relative density of the dense sample was 98.3%. The mean grain size was 3.5 μm in length and 1.5 μm in width. The typical layered structure could be clearly observed. The electrical conductivity of Mo2TiAlC2 ceramic measured at the temperature range of 2–300 K decreased from 0.95 × 106 to 0.77 × 106 Ω–1·m–1. Thermal conductivity measured at the temperature range of 300–1273 K decreased from 8.0 to 6.4 W·(m·K)–1. The thermal expansion coefficient (TEC) of Mo2TiAlC2 measured at the temperature of 350–1100 K was calculated as 9.0 × 10–6 K–1. Additionally, the layered structure and fine grain size benefited for excellent mechanical properties of low intrinsic Vickers hardness of 5.2 GPa, high flexural strength of 407.9 MPa, high fracture toughness of 6.5 MPa·m1/2, and high compressive strength of 1079 MPa. Even at the indentation load of 300 N, the residual flexural strength could hold 84% of the value of undamaged one, indicating remarkable damage tolerance. Furthermore, it was confirmed that Mo2TiAlC2 ceramic had a good oxidation resistance below 1200 K in the air.

A Strategy for Preparing High-efficiency and Economical Catalytic Electrodes toward Overall Water Splitting

Nanoscale ◽  
2021 ◽  
Author(s):  
Dongxue Yao ◽  
Lingling Gu ◽  
Bin Zuo ◽  
Shuo Weng ◽  
Shengwei Deng ◽  
...  
Keyword(s):  
Hydrogen Production ◽  
Water Splitting ◽  
Production Technology ◽  
High Purity ◽  
High Efficiency ◽  
Energy Development ◽  
Overall Water Splitting ◽  
Important Field ◽  
High Purity Hydrogen

The technology of electrolyzing water to prepare high-purity hydrogen is an important field in today's energy development. However, how to prepare efficient, stable, and inexpensive hydrogen production technology from electrolyzed...

scholarly journals Investigation of Polyol Process for the Synthesis of Highly Pure BiFeO3 Ovoid-Like Shape Nanostructured Powders

Nanomaterials ◽  
2019 ◽  
Vol 10 (1) ◽  
pp. 26 ◽  
Author(s):  
Manel Missaoui ◽  
Sandrine Coste ◽  
Maud Barré ◽  
Anthony Rousseau ◽  
Yaovi Gagou ◽  
...  
Keyword(s):  
Grain Size ◽  
Magnetic Properties ◽  
High Purity ◽  
Average Crystallite Size ◽  
Polyol Process ◽  
Pure Bifeo3 ◽  
Optimum Parameters ◽  
Mössbauer Measurements ◽  
Synthesis Protocol ◽  
Nanostructured Powders

Exclusive and unprecedented interest was accorded in this paper to the synthesis of BiFeO3 nanopowders by the polyol process. The synthesis protocol was explored and adjusted to control the purity and the grain size of the final product. The optimum parameters were carefully established and an average crystallite size of about 40 nm was obtained. XRD and Mössbauer measurements proved the high purity of the synthesized nanostructurated powders and confirmed the persistence of the rhombohedral R3c symmetry. The first studies on the magnetic properties show a noticeable widening of the hysteresis loop despite the remaining cycloidal magnetic structure, promoting the enhancement of the ferromagnetic order and consequently the magnetoelectric coupling compared to micrometric size powders.

Effect of Li on Mechanical Properties and Electrical Conductivity of the Al–Zn–Cu–Mg Based Alloys

2021 ◽  
Vol 21 (9) ◽  
pp. 4897-4901
Author(s):  
Hyo-Sang Yoo ◽  
Yong-Ho Kim ◽  
Hyeon-Taek Son
Keyword(s):  
Mechanical Properties ◽  
Electrical Conductivity ◽  
Grain Size ◽  
Tensile Strength ◽  
Spherical Particles ◽  
Al Alloy ◽  
High Angle ◽  
Average Grain Size ◽  
Strength Improvement ◽  
Li Content

In this study, changes in the microstructure, mechanical properties, and electrical conductivity of cast and extruded Al–Zn–Cu–Mg based alloys with the addition of Li (0, 0.5 and 1.0 wt.%) were investigated. The Al–Zn–Cu–Mg–xLi alloys were cast and homogenized at 570 °C for 4 hours. The billets were hot extruded into rod that were 12 mm in diameter with a reduction ratio of 38:1 at 550 °C. As the amount of Li added increased from 0 to 1.0 wt.%, the average grain size of the extruded Al alloy increased from 259.2 to 383.0 µm, and the high-angle grain boundaries (HGBs) fraction decreased from 64.0 to 52.1%. As the Li content increased from 0 to 1.0 wt.%, the elongation was not significantly different from 27.8 to 27.4% and the ultimate tensile strength (UTS) was improved from 146.7 to 160.6 MPa. As Li was added, spherical particles bonded to each other, forming an irregular particles. It is thought that these irregular particles contribute to the strength improvement.

Constructing oxygen vacancy-enriched Fe2O3@NiO heterojunctions for highly efficient electrocatalytic alkaline water splitting

CrystEngComm ◽  
2021 ◽  
Author(s):  
Yan Sang ◽  
Xi Cao ◽  
Gaofei Ding ◽  
Zixuan Guo ◽  
Yingying Xue ◽  
...  
Keyword(s):  
Oxygen Vacancy ◽  
Water Splitting ◽  
Oxygen Evolution ◽  
High Purity ◽  
Oxygen Evolution Reaction ◽  
High Efficiency ◽  
Low Cost ◽  
Dual Function ◽  
Alkaline Water ◽  
High Purity Hydrogen

Electrolysis of water to produce high-purity hydrogen is a very promising method. The development of green, high-efficiency, long-lasting and low-cost dual function electrocatalysts for oxygen evolution reaction (OER) and hydrogen...

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