Nanodispersed metal powders in high-energy condensed systems

2010 ◽  
Vol 5 (9-10) ◽  
pp. 565-582 ◽  
Author(s):  
S. G. Fedorov ◽  
Sh. L. Guseinov ◽  
P. A. Storozhenko
Keyword(s):  
High Energy ◽  
Metal Powders ◽  
Condensed Systems

High Energy Milling of WС-FeСr Cemented Carbide

2019 ◽  
Vol 799 ◽  
pp. 136-141
Author(s):  
Marek Tarraste ◽  
Jakob Kübarsepp ◽  
Kristjan Juhani ◽  
Märt Kolnes ◽  
Mart Viljus
Keyword(s):  
Particle Size ◽  
Ball Mill ◽  
Size Range ◽  
High Energy ◽  
Cemented Carbide ◽  
Cemented Carbides ◽  
Binder Phase ◽  
Metal Powders ◽  
Powder Mixtures ◽  
High Energy Milling

During production of cemented carbides hard and brittle tungsten carbide (WC) and ductile metal powders (mainly from Fe-group) are milled together. Complete milling results in a Gaussian distribution and narrow particle size range of the milled powder which promote the homogeneity and improve the properties of sintered composites. Cobalt, conventional metal employed in cemented carbides, possesses good comminution characteristics with WC powder. However, its toxicity and fluctuating price pushes researchers to find suitable alternatives and Fe-based alloys have shown most promising results. Cemented carbides with the Fe-Cr system as metal binder phase have potential to perform better than regular WC-Co composites in corrosive and oxidative environments. The goal of this paper was to prepare uniform cemented carbides powders with relatively high fraction of stainless Fe-Cr steel. To achieve a uniform powder mixture is a challenge at high ductile steel fraction. High energy milling (HEM) is a powerful technique for achieving (ultra) fine powder mixtures with narrow powder size range. HEM was carried out in a novel high energy ball mill RETSCH Emax. Milling in tumbling ball mill, which is the most widely used method, was employed for reference. Prepared powder mixtures were characterised in terms of particle size, size distribution and shape. In addition, powder mixtures were consolidated via spark plasma sintering to evaluate the effect of the milling method and the duration on the microstructure of final cemented carbide.

IGNITION, COMBUSTION, AND AGGLOMERATION OF HIGH-ENERGY MATERIALS BASED ON ALUMINUM AND BORON

2020 ◽  
Author(s):  
A. G. Korotkikh ◽  
◽  
V. A. Arkhipov ◽  
O. G. Glotov ◽  
I. V. Sorokin ◽  
...  
Keyword(s):  
Burning Rate ◽  
Ignition Time ◽  
Combustion Products ◽  
High Energy ◽  
Metal Powders ◽  
Energy Materials ◽  
Complete Replacement ◽  
Aluminum Powders ◽  
High Energy Materials ◽  
Condensed Combustion Products

The burning rate control of the high-energy materials (HEM) is mainly achieved by introducing the catalysts in composite solid propellant as well as by partial or complete replacement of ammonium perchlorate (AP) and ammonium nitrate by nitramines that change the equivalence ratio of formulation, or by varying the particle size of oxidizer and metal fuels. Promising metallic fuels are highly dispersed aluminum powders, which are characterized by different dispersity and passivation method, as well as bimetallic powders or mixtures of aluminum and other metals, their alloys, and metal powders with various coatings. In this study, the Al-based, Al/B-based, and Al/Fe-based HEM compositions have been used for comparative analysis of the ignition, combustion, and agglomeration characteristics. At the use of boron additive in the Al-based HEM, the ignition time is decreased by a factor of 1.2-1.4 and the burning rate is virtually unchanged as compared with that for the Al-based HEM. However, the agglomeration is significantly enhanced, which is manifested in the increase in the agglomerate particle content in condensed combustion products (CCP), increase in the agglomerate mean diameter, and increase in the unburned metal fraction in agglomerates.

Thermal Modeling of Electron Beam Additive Manufacturing Process: Powder Sintering Effects

2012 ◽  
Author(s):  
Ninggang Shen ◽  
Kevin Chou
Keyword(s):  
Electron Beam ◽  
Additive Manufacturing ◽  
High Energy ◽  
Maximum Temperature ◽  
Beam Diameter ◽  
Moving Heat Source ◽  
Metal Powders ◽  
Melt Pool ◽  
Metallic Parts ◽  
Melt Pool Size

In recently developed Additive Manufacturing (AM) technologies, high-energy sources have been used to fabricate metallic parts, in a layer by layer fashion, by sintering and/or melting metal powders. In particular, Electron Beam Additive Manufacturing (EBAM) utilizes a high-energy electron beam to melt and fuse metal powders to build solid parts. EBAM is one of a few AM technologies capable of making full-density metallic parts and has dramatically extended their applications. Heat transport is the center of the process physics in EBAM, involving a high-intensity, localized moving heat source and rapid self-cooling, and is critically correlated to the part quality and process efficiency. In this study, a finite element model was developed to simulate the transient heat transfer in a part during EBAM subject to a moving heat source with a Gaussian volumetric distribution. The developed model was first examined against literature data. The model was then used to evaluate the powder porosity and the beam size effects on the high temperature penetration volume (melt pool size). The major findings include the following. (1) For the powder layer case, the melt pool size is larger with a higher maximum temperature compared to a solid layer, indicating the importance of considering powders for the model accuracy. (2) With the increase of the porosity, temperatures are higher in the melt pool and the molten pool sizes increase in the depth, but decrease along the beam moving direction. Furthermore, both the heating and cooling rates are higher for a lower porosity level. (3) A larger electron-beam diameter will reduce the maximum temperature in the melt pool and temperature gradients could be much smaller, giving a lower cooling rate. However, for the tested electron beam-power level, the beam diameter around 0.4 mm could be an adequate choice.

Effect of Metal Additives (Co and Ni) on the Electrochemical Properties of Lithium/FeS2 Batteries

2007 ◽  
Vol 544-545 ◽  
pp. 973-976 ◽  
Author(s):  
Jae Won Choi ◽  
Gouri Cheruvally ◽  
Jou Hyeon Ahn ◽  
Ki Won Kim ◽  
Hyo Jun Ahn
Keyword(s):  
Room Temperature ◽  
Electronic Conductivity ◽  
High Energy ◽  
Metal Powders ◽  
Iron Disulfide ◽  
Iron Sulfur ◽  
Ethylene Glycol Dimethyl Ether ◽  
Metal Additives ◽  
Metallic Additive ◽  
Discharge Capacities

Iron, sulfur and transition metal powders were used as the starting materials to prepare iron disulfide (FeS2) cathode material at room temperature by high energy mechanical alloying. Modified FeS2 were also prepared by incorporation of transition metals like Co and Ni. Li/FeS2 cells with the prepared iron disulfides as cathodes were studied for discharge properties at room temperature using the 0.5M LiTFSI in tetra(ethylene glycol) dimethyl ether (TEGDME). The first discharge capacities of Li/composite FeS2 cell with 5 wt.% Co and 3 wt.% Ni were 571 and 844 mAh/g, respectively, compared to 389 mAh/g for the cell without any additive. The enhanced properties resulted from the better electronic conductivity of the material containing the metallic additive. The initial capacity and cyclic performance were improved when nickel and cobalt were added to prepare the modified iron disulfide.

scholarly journals The effect of ball milling on crystallite size

2020 ◽  
Vol 3 (1) ◽  
pp. 543-549
Author(s):  
Oguzhan Sahin ◽  
Veysel Erturun
Keyword(s):  
Crystallite Size ◽  
Ball Milling ◽  
High Energy ◽  
Metal Powders ◽  
X Ray Diffraction ◽  
Ceramic Powders ◽  
Sem Images ◽  
X Ray ◽  
Sic Ceramic ◽  
Energy Ball

Homogeneous mixing of Al, varying amounts of Cu, Mg and Zn metal powders and SiC ceramic powders and mechanical alloys of metal powders by using high energy ball milling were carried out in the Retsch MM400 model mixer device, which performs movement in a spex manner. After this process, X-ray diffraction (XRD) was applied to the powdered mixtures. With the data obtained from XRD graphics; The crystallite size was calculated using the Scherrer equation, and the lattice stresses were calculated using the Williamson-Hall equation and comparisons between these two data were made. It was observed that the amount of Cu by weight, both the crystallite size, did not make a notable change for this property. Then, powder mixtures were sintered in hot isostatic press in argon atmosphere, which is a shielding gas, and turned into samples. These samples were polished and scanning electron microscopy (SEM) images were taken.

Features of Structural-Phase Transformations during Oxidation of Metals with Bulk Submicrocrystalline Structure and Fine Metal Powders

2021 ◽  
Vol 887 ◽  
pp. 275-280
Author(s):  
A.V. Korshunov
Keyword(s):  
Phase Transformations ◽  
Critical Role ◽  
Structural Phase ◽  
High Energy ◽  
Structure Stability ◽  
Metal Powders ◽  
Thermally Induced ◽  
Energy Impact ◽  
Oxide Component ◽  
Structural Phase Transformations

The oxidation processes for compact and powdery samples of titanium, copper, and molybdenum with different volume structure and dispersivity were studied using thermal analysis, electron microscopy, and X-ray diffraction. It is established that producing of metals with a modified structure under conditions of high-energy impact (severe plastic deformation, electric explosion of a thin wire) in accordance with intermediate annealing leads to an increase in the content of oxygen in the form of solid solutions and oxides; the oxide component’s share, form and localization within the material depend on physicochemical properties of both metal and oxide . It is shown that the structural-phase transformations of the oxide component during heating of fine-grained metals and powders have a significant effect on the parameters of the oxidation process of such materials. The thermally induced effects in the oxygen-containing components might play a critical role for the structure stability during long-term use of such materials under cyclic thermomechanical impacts.

Laser Cladding Based Solid Freeform Fabrication and Direct Metal Deposition

2006 ◽  
Author(s):  
Huan Qi ◽  
Jyotirmoy Mazumder
Keyword(s):  
Laser Beam ◽  
Laser Cladding ◽  
Solid Freeform Fabrication ◽  
Three Dimensional ◽  
High Energy ◽  
Metal Deposition ◽  
Direct Metal Deposition ◽  
Effective Control ◽  
Metal Powders ◽  
Freeform Fabrication

Three-dimensional additive manufacturing or solid freeform fabrication (SFF) techniques, originated in the rapid fabrication of non-functional physical prototypes in polymers (Rapid Prototyping), have matured to the manufacture of functional prototypes, short-run production products, and now even advanced engineering designs. Laser-based material deposition or laser cladding has been used as a SFF technique, in which a laser beam is used as a precise high-energy thermal source to melt preplaced or pneumatically delivered metal powders and make solidified deposits on a substrate. By using laser cladding techniques, three-dimensional fully dense components can be built line-by-line and layer-by-layer directly from a CAD model with tailored material properties. Laser cladding is essentially a fusion and solidification (thermal) process, which involves complicated interactions between the laser beam, metal powders, the base material (substrate), and processing gases. Maintaining a stable and uniform melt pool during laser cladding is critical to produce dimensional accuracy and material integrity. An effective control of energy (laser power) spatial and temporal distributions in either an open-loop or closed-loop laser cladding process is essential to achieve the high quality results. This paper reviews, from a laser-material interaction point of view, various laser cladding based SFF processes, and particularly the direct metal deposition technique.

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