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Article
Synthesis and Magnetic Hysteresis Properties of an Aluminum-Doped Isotropic Hard-Magnetic Fe–Cr–Co Powder Alloy
Abstract—Hard-magnetic Fe–30 Cr–20 Co alloys doped with 1 wt % of aluminum have been obtained. The two different aluminum sources used were elemental aluminum powder and an iron‒chromium‒aluminum alloying composi...
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Article
Maximum Gas Pressure in Pores
An analytical expression for estimating the maximum gas pressure within a closed pore is derived. The Lamé solution for the stress–strain state of the material around a spherical pore in an infinite medium is ...
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Article
Influence of Heat Treatment on the Structure, Phase Composition and Properties of Deformable Hard-Magnetic Fe–30Cr–20Co–2Mo Powder Alloy
The structure, phase composition, mechanical and magnetic properties of deformable hard magnetic Fe–30Cr–20Co–2Mo alloy obtained by sintering (1400°C, 240 min) of elemental powder compacts. The effect of quenc...
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Article
Properties of the Fe–30Cr–20Co–Mo Hard Magnetic Powder Alloy with Increased Porosity
The effect of the sintering medium (vacuum and argon) on the structural and magnetic characteristics of magnetically hard alloy Fe–30Cr–20Co–Mo with increased porosity (about 4%) has been studied. The material...
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Article
Calculation of the Internal Pressure in a Cylindrical Pore
This paper presents a method to calculate the internal pressure in a cylindrical pore occurring in the material of a powder metallurgy product. The pore pressure is determined by the displacements of the exter...
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Article
Strength and Permeability of a Porous Material Based on Submicron Titanium Carbide Powder
A highly porous material based on submicron titanium carbide powder has been prepared using a pore former. General mechanisms underlying the formation of the pore structure of the material have been identified...
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Article
Passivation of Compact Samples of Nickel Nanopowders and Modes of Their Interaction with Air
It was experimentally shown for the first time that compact samples of pyrophoric nickel nanopowders can be passivated in air for 3–5 s. The passivation of the samples was confirmed by the absence of noticeabl...
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Article
Effect of the Charge Mixing Time on the Magnetic Hysteretic Properties of a Hard Magnetic Powder Fe–30% Cr–8% Co Alloy
The elemental map** of a hard magnetic powder Fe–30Cr–8Co alloy prepared at different charge mixing times allows us to find that a homogeneous distribution of the components is reached upon mixing for 60 min...
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Article
Effect of the Density of Iron Nanopowders on the Parameters of Their Ignition during Heating in Air
The ignition of iron nanopowders of bulk density and those compacted to a relative density of 0.3–0.5 during heating in air has been studied. The ignition temperature of the compacted samples is independent of...
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Article
Synthesis of Hard-Magnetic Material of the Fe–Cr–Co System Made of a Spherical Powder
Abstract—A short-cut method of synthesis of a hard-magnetic material made of a spherical powder of the 25Cr–15Co–Al–Nb alloy obtained by spraying a melt with a stream of gas was proposed. It was established exper...
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Article
Synthesis of Nanostructured Island Alumina Coatings on the Surface of Macropores of Hierarchically Porous Nickel
Nanostructured island coatings composed of the low-temperature alumina modification were synthesized on the surface of macropores of hierarchically porous permeable monolithic nickel. The primary structural el...
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Article
Using Nickel Nanopowders with Different Morphologies for Fabrication of Highly Porous Nickel Materials
We study the effects that the morphology of nickel nanopowders obtained by chemical metallurgy, nickel formate thermal decomposition, and wire electrical explosion has on the properties of porous samples fabri...
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Article
Creation of Highly Porous Material with a Hierarchical Structure by Sintering of Nickel Nanopowder Using Ammonium Bicarbonate as Space Holder
The possibility of obtaining permeable highly porous materials based on nanopowders of nickel using ammonium bicarbonate as a space holder is shown. In the fabrication of porous samples, a sintering-evaporatio...
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Article
Hierarchically Structured, Highly Porous Nickel Synthesized in Sintering–Evaporation Process from a Metal Nanopowder and a Space Holder
Permeable (~70% porosity) nickel with a pronounced hierarchical structure was synthesized by powder metallurgy methods in sintering–evaporation process from a nickel nanopowder and an ammonium bicarbonate micr...
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Article
Synthesis of Nickel Nanoparticles with Controlled Pyrophoricity and Average Size
The nickel formate decomposition in an argon flow at 209°C with subsequent treatment of the obtained nanopowder in a hydrogen flow for a given time was shown to enable one to control the pyrophoricity and aver...
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Article
Effect of Production Conditions on the Size of Copper Nanoparticles and the Modes of Ignition and Combustion of a Copper Nanopowder in Air
Copper nanoparticles were produced by a chemical metallurgical method and by the thermal decomposition of copper citrate and formate. It was shown that the copper nanopowder obtained from copper citrate is not...
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Article
Synthesis of Nickel Nanopowders under Dynamic Conditions
In this paper, the synthesis of nickel nanopowders by the chemicometallurgical method under dynamic conditions, when the composition of the gas medium is changed in the process of synthesis (argon is changed f...
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Article
Phase Composition of Powder Hard Magnetic Fe–30Cr–(8–24)Co Alloys Sintered under Different Temperature Conditions
It has been shown that for magnetic materials with a low and moderate cobalt content (8–16%), a reduced sintering temperature (up to 1150°C) can be used to produce dense compacts with practically no nonmagneti...
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Article
Tuning the Properties of Refractory Carbide Nanopowders
Two methods for transition metal carbide nanopowder production such as plasma chemical synthesis and high-energy ball milling are considered. The control of the chemical, phase, and dispersed composition of ca...
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Article
Effect of Pressing Parameters on the Structure of Porous Materials Based on Cobalt and Nickel Powders
Porous materials with a bulk porosity of more than 68% were synthesized by powder metallurgy methods from a cobalt–nickel mixture. The effect of the ratio of nickel and cobalt powders used in the synthesis of ...
