scholarly journals Characterization of dispersion strengthened copper with 3wt%Al2O3 by mechanical alloying

2004 ◽  
Vol 36 (3) ◽  
pp. 205-211 ◽  
Author(s):  
Viseslava Rajkovic ◽  
Olivera Eric ◽  
Dusan Bozic ◽  
M. Mitkov ◽  
Endre Romhanji
Keyword(s):  
Mechanical Alloying ◽  
Structural Changes ◽  
Early Stage ◽  
Structure Refinement ◽  
Average Particle Size ◽  
Copper Matrix ◽  
Alumina Powder ◽  
Average Particle ◽  
Micro Hardness ◽  
Electrolytic Copper Powder

The copper matrix has been dispersion strengthened with 3wt.%Al2O3 by mechanical alloying. Commercial alumina powder with an average particle size of 0.75mm was used for alloying. The mechanical alloying process was performed in a planetary ball mill up to 20h in air. After milling all powders were treated in H2 at 4000C for 1h, and finally hot pressing was used for compaction (800oC, 3h, Ar). Structure observations revealed a lamellar structure (Al2O3 particles largely restricted to interlamellar planes between adjacent copper lamellae) accompanied also by structure refinement. These structural changes were mostly completed in the early stage of milling, and retained after compaction. Micro hardness was found to progressively increase with milling time. So, after 5h of milling the micro hardness of the Cu+3twt%Al2O3 compact was 1540MPa, i.e. 2.5 times greater than for the as-received electrolytic copper powder (638MPa) compacted under identical conditions, while after 20h of milling it was 2370 MPa. However after exposing the tested compact at 800oC up to 5h, the achieved hardening effect vanished.

scholarly journals Effect of Particle Size on Microstructure and Element Diffusion at the Interface of Tungsten Carbide/High Strength Steel Composites

Materials ◽  
2019 ◽  
Vol 12 (24) ◽  
pp. 4164 ◽  
Author(s):  
Hongmei Zhang ◽  
Hongnan Li ◽  
Ling Yan ◽  
Chao Wang ◽  
Fangfang Ai ◽  
...  
Keyword(s):  
Particle Size ◽  
Tungsten Carbide ◽  
High Strength Steel ◽  
Average Particle Size ◽  
High Strength ◽  
Average Particle ◽  
Micro Hardness ◽  
Vacuum Sintering ◽  
Element Diffusion ◽  
Average Grain Size

The microstructure and micro-hardness of tungsten carbide/high strength steel (WC/HSS) composites with different particle sizes were analyzed by optical microscopy (OM), scanning electron microscopy (SEM), ultra-high temperature laser confocal microscopy (UTLCM) and micro-hardness testing. The composites were prepared by cold pressing and vacuum sintering. The results show that WC density tends to increase as the average grain size of WC decreases and the micro-hardness of WC increases with the decrease of WC particle size. The micro-hardness of WC near the bonding interface is higher than that in other regions. When the particle size of WC powder particles is 200 nm, a transition layer with a certain width is formed at the interface between WC and HSS, and the combination between the two materials is metallurgical. The iron element in the HSS matrix diffuses into the WC structure in contact with it, resulting in a fusion layer of a certain width, and the composite interface is relatively well bonded. When the average particle size of WC powder is 200 nm, W, Fe and Co elements significantly diffuse in the transition zone at the interface. With the increase of WC particle size, the trend of element diffusion decreases.

scholarly journals Catalyst materials based on plasma-processed alumina nanopowder

2012 ◽  
Vol 77 (12) ◽  
pp. 1799-1806 ◽  
Author(s):  
Eriks Palcevskis ◽  
Lidija Kulikova ◽  
Vera Serga ◽  
Antons Cvetkovs ◽  
Svetlana Chornaja ◽  
...  
Keyword(s):  
Particle Size ◽  
Platinum Catalyst ◽  
Average Particle Size ◽  
Alumina Powder ◽  
Average Particle ◽  
Glycerol Oxidation ◽  
Plasma Technology ◽  
Oxidation By Molecular Oxygen ◽  
Prepared Material ◽  
Alumina Nanopowder

A platinum catalyst for glycerol oxidation by molecular oxygen has been developed applying the extractive-pyrolytic method and using, as a support, a fine alumina powder with an average particle size of 30-60 nm processed by plasma technology. The extractive-pyrolytic method (EPM) allows affixing small amounts of catalytic metals (1-5%) with the particle size ranging from several nanometers to several tens of nanometers onto the surface of the support. The prepared material - 4.8 wt. % platinum on nano-sized alumina - can be used as a catalyst for glycerol oxidation by oxygen with conversion up to 84%, in order to produce some organic acids (glyceric and lactic acid) with a selectivity of about 60%.

Formation of Fe3AlC Base Alloy by Mechanical Alloying and Vacuum Hot Pressing

2007 ◽  
Vol 534-536 ◽  
pp. 189-192 ◽  
Author(s):  
Kazuo Isonishi
Keyword(s):  
Mechanical Alloying ◽  
Hot Pressing ◽  
Base Alloy ◽  
Average Particle Size ◽  
Processing Route ◽  
Full Density ◽  
Second Phase ◽  
Average Particle ◽  
Vacuum Hot Pressing ◽  
Metallurgical Processing

Fabrication of Fe3AlC matrix in-situ composite, reinforced by a FeAl phase, was studied by using the powder metallurgical processing route. Especially, in order to disperse the second phase more finely, we chose the mechanical alloying process. We investigated the microstructural and mechanical properties of the consolidated material. After consolidation by vacuum hot pressing, the compact showed almost full density and consisted of a Fe3AlC matrix and FeAl second phase (average particle size was less than 1μm). The compact showed HV746, which was higher than that of the arc melted Fe3AlC monolithic material, HV650.

Microstructural and Magnetic Properties of Nanostructured Fe65Co35 Powders Prepared by Mechanical Alloying

2013 ◽  
Vol 829 ◽  
pp. 778-783 ◽  
Author(s):  
Mohsen Razi ◽  
Ali Ghasemi ◽  
Gholam Hossein Borhani
Keyword(s):  
Magnetic Properties ◽  
Mechanical Alloying ◽  
Milling Time ◽  
Cooling System ◽  
Average Particle Size ◽  
Weight Ratio ◽  
Lattice Parameter ◽  
Milling Process ◽  
Protective Atmosphere ◽  
Average Particle

Nanostructured Fe65Co35 alloy powders were fabricated by mechanical alloying in an attritor mill with different milling times. The milling process carried out in speed of 350 rpm, with 20:1 ball to powder weight ratio and under argon protective atmosphere. A continuous cooling system applied to avoid increasing temperature during the milling. The effect of milling time on structural and magnetic properties investigated by X-ray diffraction, scanning electron microscopy and vibration sample magnetometer. According to the obtained results, nanostructured Fe65Co35 solid solution powders resulted with an average particle size of 400 nm and crystallite size of 6.8 nm by milling for 20 hours. With increasing the milling time, the lattice parameter decreased and the lattice strain increased for Fe65Co35 powders. The maximum saturation magnetization with 1311 emu/cc value and the minimum coercivity with 22 Oe value occurs after milling for 15 hours.

scholarly journals Adsorption-Semiconductor Sensor Based on Nanosized SnO2 for Early Warning of Indoor Fires

2021 ◽  
Author(s):  
Nelli Maksymovych ◽  
Ludmila Oleksenko ◽  
George Fedorenko
Keyword(s):  
Tin Dioxide ◽  
Early Stage ◽  
Dynamic Properties ◽  
Sol Gel ◽  
Average Particle Size ◽  
High Sensitivity ◽  
Average Particle ◽  
Semiconductor Sensor ◽  
Wide Range

The paper is devoted for a solution of indoors fires prevention at early stage by determination of H2 (fire precursor gas) in air using a semiconductor sensor. A material based on Pt-containing nanosized tin dioxide with an average particle size of 10–11 nm obtained via a sol–gel method was created for a gas sensitive layer of the sensor. The developed sensor has high sensitivity to H2 micro concentration, a wide range of its detectable content in air, selectivity of H2 measuring in the presence of СО and СН4, good dynamic properties. The combination of these properties is very important for prevention of inflammations on their early stages before the open fires appearance. Economic benefit of the proposed sensor is due to a lower cost and higher reliability of the fire situation detection.

Fine Copper Powders Production

2021 ◽  
Vol 410 ◽  
pp. 418-424
Author(s):  
Natalia E. Agarova ◽  
Lyubov M. Yakovleva ◽  
Roman S. Voinkov ◽  
Konstantin L. Timofeev
Keyword(s):  
Average Particle Size ◽  
Chloride Ions ◽  
Average Particle ◽  
Air Classification ◽  
Operating Modes ◽  
Electrolytic Copper Powder ◽  
Copper Powders ◽  
Powder Particles ◽  
Fine Copper

The article is devoted to the description of a method for producing electrolytic copper powder with an average particle size of 3 to 10 μm. In order to increase the proportion of the finely dispersed fraction during the electrolysis process, the composition of the electrolyte was changed. In particular, the content of chloride ions was increased from 6 to 53 mg/dm3. After the growth of the powder in industrial baths, its subsequent drying and sieving on vibrating screens, samples were obtained with a fraction of 5 μm content in the range from 3 to 38 %. Additionally, air classification of powders was carried out at various speeds of the classifier rotor from 800 to 2000 rpm. Based on the results of the study, the optimal ranges of the specific surface area and the size of the initial powder particles before classification, as well as the composition of the electrolyte and the operating modes of the classifier, were determined.

Synthesis of Nanocrystalline Fe25Al57.5Ni17.5 by Mechanical Alloying

2012 ◽  
Vol 476-478 ◽  
pp. 1318-1321
Author(s):  
Qi Zhi Cao ◽  
Jing Zhang
Keyword(s):  
Thermal Analysis ◽  
Solid Solution ◽  
Differential Thermal Analysis ◽  
Mechanical Alloying ◽  
Ball Mill ◽  
Structural Changes ◽  
Early Stage ◽  
High Energy ◽  
X Ray Diffraction ◽  
X Ray

Nanostructured Fe25Al57.5Ni17.5intermetallics was prepared directly by mechanical alloying (MA) in a high-energy planetary ball-mill. The phase transformations and structural changes occurring in the studied material during mechanical alloying were investigated by X-ray diffraction (XRD). Thermal behavior of the milled powders was examined by differential thermal analysis (DTA). Disordered Al(Fe,Ni) solid solution was formed at the early stage. After 50 h of milling, Al(Fe,Ni) solid solution transformed into Al3Ni2，AlFe3，AlFe0.23Ni0.77 phase. The power annealed at temperature 500 results in forming of intermetallics AlFe3 and FeNi3 after 5h milling. The nanocrystalline intermetallic compound was obtained after 500h milling.

scholarly journals PREPARATION OF Cu MATRIX COMPOSITE REINFORCED WITH IN-SITU NANOSIZED Al2O3 PARTICLE POWDER FROM METAL NITRATES

2019 ◽  
Vol 25 (1) ◽  
pp. 41
Author(s):  
Hai Minh Le ◽  
Yen Ngoc Nguyen ◽  
Duong Tien Hoang Truong ◽  
Huy Duc Vu ◽  
Hai Hong Nguyen ◽  
...  
Keyword(s):  
Matrix Composite ◽  
Average Particle Size ◽  
Synthesis Method ◽  
Copper Matrix ◽  
Al2o3 Particle ◽  
Average Particle ◽  
X Ray ◽  
Metal Nitrates ◽  
Xrd Patterns

The objective of the present work is to investigate the feasibility of the synthesis of copper matrix composite reinforced with in-situ nanosized Al2O3 ¬particle powder via combustion synthesis method from metal nitrates followed by reducing process at high temperature. The starting nitrates Cu(NO3)2.3H2O and Al(NO3)3·9H2O composition corresponds to Cu-30%Al2O3. X-ray Diffraction (XRD) patterns of the obtained powders indicated the presence of the oxides CuO and CuAl2O4. The powder had the size of 75 ± 10 nm after deagglomerating by soft ball milling for 24h. After reducing in CO at 1000oC for 3h, the peaks of the oxides were no longer observed and were replaced by the peaks of Cu and -Al2O3. The morphology of the reduced powders observed by scanning electron microscopy (SEM) and energy dispersive x-ray (EDX) analysis showed a well distribution of the -Al2O3 particles within the Cu matrix with an average particle size of 40 nm.

scholarly journals The phase composition, structure and properties of high-temperature-based powders of the system iron-aluminum obtained by the technology of the reaction-mechanical alloying. Foundry production and metallurgy

2019 ◽  
pp. 133-141 ◽  
Author(s):  
F. G. Lovshenko ◽  
A. S. Fedosenko
Keyword(s):  
Phase Composition ◽  
Mechanical Alloying ◽  
Average Particle Size ◽  
Thermal Spraying ◽  
Average Particle ◽  
Structure And Properties ◽  
Prolonged Heating ◽  
Iron Aluminum ◽  
Properties Of Materials ◽  
Composition Structure

The regularities of the formation of powders based on the Fe-Al system, obtained by the method of mechanical alloying and intended for the deposition of thermal spraying coatings were established. The morphology, structure, phase composition and properties of materials are investigated. After mechanical synthesis, the powders have an average particle size of 30–100 µm, submicrocrystalline structures, and nonequilibrium phase composition. Annealing of powders causes to an increase in the hardness of particles up to 80%, the value of which is largely preserved after prolonged heating to 1170 K, which indicates the presence of heat-resistant materials.

scholarly journals Synthesis of submicronic α-alumina from local aluminum slags

2021 ◽  
pp. 53-53
Author(s):  
A. Benkhelif ◽  
M. Kolli ◽  
M. Hamidouche
Keyword(s):  
Particle Size ◽  
Extraction Efficiency ◽  
Average Particle Size ◽  
Alumina Powder ◽  
Average Particle ◽  
Ceramic Fibers ◽  
Transition Alumina ◽  
Future Studies ◽  
Refractory Ceramic ◽  
Precipitation Ph

In this study, a high valued product submicronic ?-alumina is successfully extracted from aluminum slags generated by the local aluminum industry. The extraction technique is based on the leaching of slags by H2SO4 followed by precipitation. The coarser aluminum-rich fractions of the slags are used in this study instead of the finer oxide-rich fractions that were commonly used in previous studies. The precipitation of the leached slags by NH4OH is controlled by zetameter in order to determine the optimal precipitation pH. Then, the obtained gel showing the higher precipitation rate and the finer particle size is calcined at 1200 ?C and characterized by XRF, XRD, FTIR, SEM, EDS and laser granulometry. Even without any pretreatment of slags, the XRF analysis reveals that a high purity and high extraction efficiency of 99.2% and 93.75% respectively can be achieved just at a leaching acid concentration of 15%. XRD spectrum shows that the produced alumina is a pure a-corundum, which is confirmed by FTIR spectrum showing only the Al-O bonds. The laser granulometry shows that the recovered powder exhibit a wide particle size distribution. It is between 50 nm and 20 ?m while the average particle size (d50) is about 400 nm. SEM observations reveal that the grains are in the form of submicronic whiskers. The above characteristics allow the obtained alumina powder in this study to be used in the usual applications of alumina such as refractory, ceramic fibers, abrasive, etc. The obtained powders may assume also applications as a thermally stable substitute for the commonly used transition alumina powders, which need further investigations in future studies.

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