On sinterability of nanostructured W produced by high-energy ball milling

2007 ◽  
Vol 22 (5) ◽  
pp. 1200-1206 ◽  
Author(s):  
R. Malewar ◽  
K.S. Kumar ◽  
B.S. Murty ◽  
B. Sarma ◽  
S.K. Pabi
Keyword(s):  
Sintered Density ◽  
Sintering Temperature ◽  
High Energy ◽  
Deformation Bands ◽  
Dramatic Decrease ◽  
Powder Charge ◽  
Grinding Media ◽  
Energy Ball ◽  
High Level ◽  
First Time

The present investigation reports for the first time a dramatic decrease in the sintering temperature of elemental W from the conventional temperature of ≥2500 °C to the modest temperature range of 1700–1790 °C by making the W powder nanostructured through high-energy mechanical milling (MM) prior to sintering. The crystallite size of the initial W powder charge with a particle size of 3–4 μm could be brought down to 8 nm by MM for 5 h in WC grinding media. Further milling resulted in a high level of WC contamination, which apparently was due to work hardening and the grain refinement of W. A sintered density as high as 97.4% was achieved by sintering cold, isostatically pressed nanocrystalline (8 nm) W powder at 1790 °C for 900 min. The microstructure of the sintered rods showed the presence of deformation bands, but no cracks, within a large number of W grains. The mechanical properties, when compared with the hardness and elastic modulus, of the sintered nano-W specimen were somewhat superior to those reported for the conventional sintered W.

scholarly journals Structure and Deformation Behavior of Ti-SiC Composites Made by Mechanical Alloying and Spark Plasma Sintering

Materials ◽  
2019 ◽  
Vol 12 (8) ◽  
pp. 1276 ◽  
Author(s):  
Dariusz Garbiec ◽  
Volf Leshchynsky ◽  
Alberto Colella ◽  
Paolo Matteazzi ◽  
Piotr Siwak
Keyword(s):  
Mechanical Alloying ◽  
Spark Plasma Sintering ◽  
Indentation Size Effect ◽  
Sintering Temperature ◽  
High Energy ◽  
Indentation Size ◽  
X Ray ◽  
Plasma Sintering ◽  
Spark Plasma ◽  
Energy Ball

Combining high energy ball milling and spark plasma sintering is one of the most promising technologies in materials science. The mechanical alloying process enables the production of nanostructured composite powders that can be successfully spark plasma sintered in a very short time, while preserving the nanostructure and enhancing the mechanical properties of the composite. Composites with MAX phases are among the most promising materials. In this study, Ti/SiC composite powder was produced by high energy ball milling and then consolidated by spark plasma sintering. During both processes, Ti3SiC2, TiC and Ti5Si3 phases were formed. Scanning electron microscopy, energy-dispersive X-ray spectroscopy and X-ray diffraction study showed that the phase composition of the spark plasma sintered composites consists mainly of Ti3SiC2 and a mixture of TiC and Ti5Si3 phases which have a different indentation size effect. The influence of the sintering temperature on the Ti-SiC composite structure and properties is defined. The effect of the Ti3SiC2 MAX phase grain growth was found at a sintering temperature of 1400–1450 °C. The indentation size effect at the nanoscale for Ti3SiC2, TiC+Ti5Si3 and SiC-Ti phases is analyzed on the basis of the strain gradient plasticity theory and the equation constants were defined.

scholarly journals Magnetic Properties of SmCo5 + 10 wt% Fe Exchange-Coupled Nanocomposites Produced from Recycled SmCo5

Nanomaterials ◽  
2020 ◽  
Vol 10 (7) ◽  
pp. 1308 ◽  
Author(s):  
Arnab Chakraborty ◽  
Răzvan Hirian ◽  
Gregor Kapun ◽  
Viorel Pop
Keyword(s):  
Heat Treatment ◽  
Exchange Coupling ◽  
Permanent Magnets ◽  
High Energy ◽  
Raw Material ◽  
Energy Ball ◽  
Hydrogen Decrepitation ◽  
Energy Products ◽  
First Time ◽  
Recycled Material

Nanostructured alloy powders of SmCo5 + 10 wt% Fe obtained using recycled material were studied for the first time. The SmCo5 precursor was obtained from commercial magnets recycled by hydrogen decrepitation. The results were compared with identically processed samples obtained using virgin SmCo5 raw material. The samples were synthesized by dry high-energy ball-milling and subsequent heat treatment. Robust soft/hard exchange coupling was observed—with large coercivity, which is essential for commercial permanent magnets. The obtained energy products for the recycled material fall between 80% and 95% of those obtained when using virgin SmCo5, depending on milling and annealing times. These results further offer viability of recycling and sustainability in production. These powders and processes are therefore candidates for the next generation of specialized and nanostructured exchange-coupled bulk industrial magnets.

scholarly journals Effects of Milling Atmosphere and Increasing Sintering Temperature on the Magnetic Properties of Nanocrystalline Ni0.36Zn0.64Fe2O4

2015 ◽  
Vol 2015 ◽  
pp. 1-11 ◽  
Author(s):  
Abdollah Hajalilou ◽  
Mansor Hashim ◽  
Halimah Mohamed Kamari ◽  
Mohamad Taghi Masoudi
Keyword(s):  
Magnetic Properties ◽  
Sintering Temperature ◽  
Parallel Evolution ◽  
High Energy ◽  
High Energy Ball Mill ◽  
Zn Ferrite ◽  
Crystallite Sizes ◽  
Energy Ball ◽  
Xrd Patterns ◽  
Fesem Micrographs

Nanocrystalline Ni0.36Zn0.64Fe2O4was synthesized by milling a powder mixture of Zn, NiO, and Fe2O3in a high-energy ball mill for 30 h under three different atmospheres of air, argon, and oxygen. After sintering the 30 h milled samples at 500°C, the XRD patterns suggested the formation of a single phase of Ni-Zn ferrite. The XRD results indicated the average crystallite sizes to be 15, 14, and 16 nm, respectively, for the 30 h milled samples in air, argon, and oxygen atmospheres sintered at 500°C. From the FeSEM micrographs, the average grain sizes of the mentioned samples were 83, 75, and 105 nm, respectively, which grew to 284, 243, and 302 nm after sintering to 900°C. A density of all the samples increased while a porosity decreased by elevating sintering temperature. The parallel evolution of changes in magnetic properties, due to microstructural variations with changes in the milling atmosphere and sintering temperature in the rage of 500–900°C with 100°C increments, is also studied in this work.

Effect of Sintering Temperature on Microstructure and Mechanical Properties of WC-16TiC-xTaC-9Co Cemented Carbides

2012 ◽  
Vol 268-270 ◽  
pp. 340-343
Author(s):  
Chong Cai Zhang ◽  
Quan Wang
Keyword(s):  
Mechanical Properties ◽  
Grain Size ◽  
Sintering Temperature ◽  
Rupture Strength ◽  
High Energy ◽  
Cemented Carbides ◽  
Average Grain Size ◽  
Comprehensive Performance ◽  
Energy Ball ◽  
Average Size

In this paper, the WC-16TiC-xTaC-9Co and Co are mixed together preparing for WC, (W, Ti, Ta) C. By high-energy ball milling, the powder is cold isostatic pressed and vacuum sintered by 1410°C, 1430°Cand 1450°C.The physical properties and the micrographs of samples are detected. The main conclusions are as following: sintered samples have the best comprehensive performance at 1450°C, the density of the sample is 99.7% and the actual density is 10.91g/cm3. The hardness is 92.8 HRA and the transverse rupture strength (TRS) is 1100MPa. The grain size grows up obviously with the high temperature. The average grain size of WC is 0.7μm and the average size of (W, Ti, Ta)C is 3μm.

scholarly journals Combustion of Titanium–Carbon Black High-Energy Ball-Milled Mixtures in Nitrogen: Formation of Titanium Carbonitrides at Atmospheric Pressure

Materials ◽  
2020 ◽  
Vol 13 (8) ◽  
pp. 1810
Author(s):  
Michail A. Korchagin ◽  
Dina V. Dudina ◽  
Alexander I. Gavrilov ◽  
Boris B. Bokhonov ◽  
Natalia V. Bulina ◽  
...  
Keyword(s):  
Carbon Black ◽  
Atmospheric Pressure ◽  
Single Phase ◽  
High Energy ◽  
Nitrogen Atmosphere ◽  
Titanium Carbonitrides ◽  
Carbon Black Powder ◽  
High Temperature Synthesis ◽  
Energy Ball ◽  
First Time

In this work, titanium carbonitrides were synthesized by self-propagating high-temperature synthesis (SHS) in nitrogen. For the first time, the synthesis of titanium carbonitrides by combustion was realized in nitrogen at atmospheric pressure. The synthesis was carried out by subjecting high-energy ball-milled titanium–carbon black powder mixtures to combustion in a nitrogen atmosphere. The influence of the ball milling time on the phase composition of the products of SHS conducted in the Ti+0.3C reaction mixture was studied. It was found that the titanium–carbon black mixtures need to be milled for a certain period of time for the combustion synthesis to yield a single-phase carbonitride product.

Luminescent Properties of Eu3+-Doped BaGd2ZnO5 Phosphors for White LED

2012 ◽  
Vol 531-532 ◽  
pp. 22-26 ◽  
Author(s):  
Hyeon Mi Noh ◽  
Hyun Kyoung Yang ◽  
Byung Kee Moon ◽  
Byung Chun Choi ◽  
Jung Hyun Jeong ◽  
...  
Keyword(s):  
Sintering Temperature ◽  
Emission Spectra ◽  
Luminescent Properties ◽  
High Energy ◽  
White Led ◽  
Photoluminescence Properties ◽  
X Ray Diffraction ◽  
Sem Images ◽  
Milling Method ◽  
Energy Ball

BaGd2ZnO5:Eu3+ phosphors were synthesized at sintering temperatures of 800, 900, 1000, 1100 and 1200 °C by high-energy ball milling method. The crystallinity, surface morphology and photoluminescence properties of phosphors were investigated by using X-ray diffraction (XRD), field-emission scanning electron microscopy (FE-SEM) and luminescence spectrophotometry, respectively. The XRD results indicate that the crystallinity of the powder was improved and the powder shows a orthorhombic structure as the sintering temperature increased. The emission spectra of BaGd2ZnO5phosphors excited at 280 nm exhibit a series of shaped peaks assigned to the5D0→7FJ(J=0, 1, 2, 3) transitions, and luminescence intensity was increased with increasing sintering temperature. The FE-SEM images indicate that the size and shape of particles are regular.

Influence of Grinding Media Size and Sintering Time in the Processing of AISI D2 Tool Steel by High-Energy Milling

2017 ◽  
Vol 899 ◽  
pp. 511-516
Author(s):  
Selauco Vurobi Jr. ◽  
Marcio Ferreira Hupalo ◽  
Ricardo Sanson Namur ◽  
Thiago Augustin Lucas Fernandes ◽  
Osvaldo Mitsuyuki Cintho
Keyword(s):  
Sintering Temperature ◽  
Cold Work ◽  
High Energy ◽  
High Wear Resistance ◽  
Tool Steels ◽  
High Energy Milling ◽  
Sintering Time ◽  
Grinding Media ◽  
Aisi D2 ◽  
Microstructure Of The Material

Tool steels are fundamental in the current production processes, as they are used in dies and molds, essential for the transformation of raw materials into the final product. The tool steels for cold work have a low hot hardness, so their use is limited to temperatures below 200° C. The D-X series of tool steels, high carbon and high chromium, have a high wear resistance and is much used in the manufacture of dies and molds. Despite the high hardness, these steels have a microstructure with coarse carbides, which affects the hardness of the material. An alternative to the processing tool steels is the high-energy milling and subsequent powder metallurgy, in order to refine the microstructure of the material. This work aimed to study the influence of the size of the grinding media in the refining of the microstructure of AISI D2 by high-energy milling and the microstructural changes with the increase in sintering temperature. The results indicated that grinding media of smaller diameters had higher efficiency in high-energy milling due to smaller mean particle size obtained by grinding and subsequent final reduction in the average size of carbides. The sintering time had a direct influence on the microstructure of the material, higher sintering times led to formation of lower bainite, after cooling from sintering temperature.

The Influence of the Sintering Temperature on the Wear Testing for Some Steels Samples Obtained by Powder Metallurgy

2014 ◽  
Vol 216 ◽  
pp. 216-221 ◽  
Author(s):  
Bebe Adrian Olei ◽  
Iulian Ştefan ◽  
Nicoleta Popescu
Keyword(s):  
Powder Metallurgy ◽  
Ball Mill ◽  
Sintering Temperature ◽  
Wear Behavior ◽  
High Energy ◽  
Wear Testing ◽  
Iron Powders ◽  
High Energy Ball Mill ◽  
Energy Ball

The objective of this research is to observe the influence of the sintering temperature on the wear testing for some steel samples elaborated by powder metallurgy technology. For obtaining the steels there were used iron powders and graphite powders. The powders were homogenized in a high energy ball mill Pulverisette 6, cold compacted and then sintered in a furnace. The sintering parameters are: the sintering temperature, T = (1050, 1100, 1150)°C and the maintaining time, t = 60 minutes. The influence of the sintering parameters on the samples wear behavior is studied using both a tribometer and a profilometer.

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