Samarium-cobalt Alloys Research Articles

Selective preparation of samarium phosphates from transition metal mixed solution by two-step precipitation

ABSTRACT Samarium-cobalt alloys are used as materials for powerful magnets with relatively high Curie temperatures. Samarium is a valuable and expensive material because it is one of a group of rare earth elements. In order to utilize this rare earth resource in a sustainable society, it is necessary to recover, reuse, and recycle rare earth elements. With this in mind, a new process for recovering neodymium phosphate from neodymium-iron mixed aqueous solutions has recently been reported, avoiding the difficulties reported with conventional methods. Given that rare earth phosphates are a major component of rare earth ores, this new process was proposed to recover them as phosphates. In this method, neodymium phosphate was selectively precipitated from a neodymium-iron mixture in a two-step process with an adjusted pH value. In this study, we attempted to selectively precipitate samarium phosphate from a mixed solution of transition metals using this two-step precipitation method. The advantage of this method is that the samarium compound can be separated from other metal salts without the use of high temperatures or special equipment. Optimal conditions were determined by evaluating the precipitates by molar ratio, color hue, UV-visible reflectance spectra, X-ray diffraction, and infrared spectroscopy of the precipitates obtained. In Step 1, the pH was adjusted using sodium hydroxide to remove cobalt, iron, and copper hydroxides other than samarium. In Step 2, after adding phosphoric acid, the pH was adjusted so that a precipitate of samarium phosphate was formed.

DETERMINATION OF THE REPULSIVE FORCE OF A THICK HIGH-COERCIVE PERMANENT MAGNETS IN THE AXIAL BEARING OF A VERTICAL PUMP

The article considers the possibility of applying a standard method for calculating the repulsive force for a thick high-coercive permanent magnets from samarium-cobalt alloy in a magnetic system. The results of the research allowed us to introduce correction coefficients in the method of calculating the repulsive force in a magnetic system with such magnets, depending on the air gap between of them. It is shown that the repulsive forces of the North poles of permanent magnets differ from the repulsive forces of the South poles. The research was carried out with magnets manufactured by different enterprises. When calculating the repulsive force, the average value of the repulsive force between the North and South poles of magnets is found.

Recovery of Samarium and Cobalt from Sm–Co Magnet Waste Using a Phosphonium Ionic Liquid Cyphos IL 104

Due to outstanding thermal stability and corrosion resistance, samarium–cobalt alloy is being used in rare earth magnet. So, this permanent magnet waste can be a potential source for rare earth metal samarium and critical metal cobalt. Recovery and reuse of Sm, Co from Sm–Co magnet waste can reduce the burden on primary resources and environmental issues related to primary resources. In this work, a hydrometallurgical method for recovery of samarium and cobalt from Sm–Co magnet waste has been developed using an ionic liquid Cyphos IL 104. The optimum separation condition for cobalt and samarium has been determined by varying the concentration of HCl, NaCl, and mixture of HCl and NaCl in the leach liquor. The McCabe–Thiele plot is constructed using 0.075 mol/L Cyphos IL 104. Three counter-current stages at A:O ratio of 1:1.5 are needed for complete extraction of cobalt into the ionic liquid phase leaving samarium in the raffinate. Precipitation stripping of cobalt from the loaded organic is carried out using oxalic acid and the cobalt oxalate, thus formed, is calcined at 450 °C to form Co3O4. The raffinate obtained from the counter-current extraction contains 2.02 g/L Sm and 0.02 mg/L Co. Sm2O3 from raffinate is produced by precipitation of samarium with oxalic acid followed by calcination of samarium oxalate at 800 °C. Both the oxide products are confirmed by XRD.

Overcoming mechanical fragility in Sm-Co permanent magnet materials

Samarium-cobalt alloys are used in some of the strongest permanent magnets, particularly for applications between about 200 and 550°C, but the utilization of these materials is restricted by their brittleness. Improving their mechanical resilience would allow them to be used more widely and, in some cases, substitute for neodymium-based magnet alloys which are subject to supply-chain risks. We have engineered a series of novel microstructures with bi-modal grain size distributions to achieve unprecedented combinations of mechanical and magnetic properties. Improvements up to 73% are obtained in the flexural strength of Sm2(CoFeCuZr)17 sintered magnets, with negligible impact on the magnetic properties. Our mechanically-robust, high-performance Sm-Co magnets are made without changing the chemical compositions of the materials or their heat treatment procedures, making them highly compatible with existing manufacturing processes.

Wetting behavior and mechanism of glass coatings on samarium–cobalt alloys in the heating process

The wetting behavior of glass coatings on samarium-cobalt alloys with different roughness at elevated temperatures in air was investigated by a sessile drop method. The wetting properties were analyzed through several parameters, including apparent contact angle, height and diameter of a glass cylinder on the samarium-cobalt alloy, determined by using a high temperature microscope. The morphology evolution of the glass coating was observed by using a scanning electron microscope. The results show that the glass cylinder contracts initially, and then swells followed by wetting and spreading on the samarium-cobalt alloy substrate. This process is explained by the role of air and the increase of capillary number. The dependence of apparent contact angle on surface roughness is related to interface reaction. It is concluded that the surface roughness firstly increases the contact angle, but then promotes wetting due to the wetting transition changing from the Cassie−Baxter state to the Wenzel state in the non-reactive wetting range. The surface roughness hinders the spreading of the glass melt due to the interface reaction between glass and samarium-cobalt alloys in the reactive wetting range.

Magnetic properties of thin films of samarium-cobalt alloy prepared by magnetron sputtering

We examine the magnetic properties of samarium-cobalt thin films on quartz and Si(111) substrates grown by dc magnetron sputtering. Both films are deposited on Cr buffer layer and subsequently a capping layer of Cr was also deposited. Secondary ion mass spectroscopy results reveal that Cr diffused in to Sm-Co layer.This lead to local change in magnetocrystalline anisotropy. As the result of this we observed the two coercive behaviors in magnetization of thin film.

Iron Oxide Shell as the Oxidation-Resistant Layer in SmCo5@Fe2O3 Core–Shell Magnetic Nanoparticles

This paper presents a synthesis of magnetic nanoparticles of samarium cobalt alloys and the use of iron oxide as a coating layer to prevent the rapid oxidation of as-made Sm-Co nanoparticles. The colloidal nanoparticles of Sm-Co alloys were made in octyl ether using samarium acetylacetonate and dicobalt octacarbonyl as precursors in a mixture of 1,2-hexadecanediol, oleic acid, and trioctylphosphine oxide (TOPO). Such Sm-Co nanoparticle could be readily oxidized by air and formed a CoO antiferromagnetic layer. Exchange biasing was observed for the surface oxidized nanoparticles. In situ thermal decomposition of iron pentacarbonyl was used to create iron oxide shells on the Sm-Co nanoparticles. The iron oxide shell could prevent Sm-Co nanoparticles from rapid oxidation upon the exposure to air at ambient conditions.

サマリウム・コバルト合金スクラップからのサマリウムの回収

サマリウム・コバルト合金スクラップからのサマリウムの回収

Rapidly Solidified Neodymium-Iron-Boron Magnets

Permanent magnets have long occupied an important position in technology. Among the multitude of products using permanent magnets are televisions, telephones, computers, videocassette recorders, audio systems, household appliances, and perhaps surprisingly to many consumers, automobiles. Figure 1 illustrates the numerous magnet applications in a modern passenger vehicle. These applications include an array of dc electric motors such as the starter, heater and air conditioner blower, windshield wiper, window lift, door lock, and fuel pump motors. A fully equipped car can have more than 30 dc electric motors. Other uses include actuators, gauges, and sensors. In all these examples higher performance magnetic materials may afford the advantages of increased operating efficiency and reduction in size and weight.One performance index or figure of merit for a permanent magnet is the energy product (BH)max, the maximum product of magnetic induction B and applied field H in the second quadrant of the B-H hysteresis curve. The so-called theoretical (BH)max, the highest energy product realizable in principle, is simply given by (4πMs)2/4, where Ms is the saturation magnetization. Progress in the development of technologically significant hard magnets has been monitored generally by improvements in (BH)max. For many years three types of materials were of commercial importance, namely, alnico, ferrite, and samarium-cobalt alloys based on either the SmCo5 or Sm2Co17 intermetallic compounds. Of these the Sm-Co magnets offer the largest energy products, on the order of 20 MGOe.

Individual properties of samarium-cobalt alloy powder particles and their interactions

Individual properties of samarium-cobalt alloy powder particles and their interactions

Electromagnetic Containerless Reaction of Samarium with Cobalt for the Formation of Samarium-Cobalt Alloys

The electromagnetic levitation technique has been used to obtain nearly stoichiometric SmCo5, with the reaction temperature controlled by a gas jet. The results of several experiments carried out at a 450 kHz, 25 kw RF power levitation facility using different reaction times and cooling rates are presented. It is shown that reaction rates achieved with the levitation technique are larger than the expected diffusion rate in the system liquid samarium-solid cobalt. It is also shown that substantial mixing occurs in the RF-levitated melt.

Magnetic properties of mischmetal-(Co, Cu,Fe,Mg) alloys

To relieve the dependence for critical and strategic minerals through conservation and substitution the Bureau of Mines, U. S. Department of the Interior, investigated alloys containing mischmetal (MM), cobalt, copper, magnesium, and iron for use in permanent magnets in place of the scarce samarium-cobalt alloys. The magnetic properties of selected MM-Co-Cu-Mg and MM-Co-Cu-Fe-Mg alloys were evaluated. Magnets were fabricated by powder metallurgy that consisted of arc-melting the metals, crushing and grinding the resultant alloy, aligning and compacting the powder, and sintering the green compacts. Magnetic values of <inf xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">M</inf> H <inf xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">c</inf> = 4.7 kOe, <inf xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">B</inf> H <inf xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">c</inf> = 4,070 Oe, B <inf xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">r</inf> = 6,810 G, and (BH) <inf xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">max</inf> = 10.0 MGOe were obtained with an MM-Co alloy containing 36.0 ±.5 wt-pct mischmetal. By substituting part of the cobalt with copper and magnesium, the value for <inf xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">M</inf> H <inf xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">c</inf> was increased to 29.0 kOe and that for <inf xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">B</inf> H <inf xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">c</inf> to 5,890 Oe. The intrinsic coercivity value exceeded that of Sm-Co alloy, <inf xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">M</inf> H <inf xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">c</inf> = 27.4 kOe, which was obtained in our laboratory. The addition of iron to MM-Co-Cu-Mg alloys resulted in an increase of B <inf xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">r</inf> to 6,900 G and ((BH) <inf xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">max</inf> to 10.3 MGOe. Copper and magnesium contents of these alloys were optimized to obtain maximum value of <inf xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">M</inf> H <inf xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">c</inf> .

The constitution of copper-hardened samarium-cobalt permanent magnets

A study has been made of the constitution of copper-hardened samarium-cobalt alloys lying between SmCo 5 and Sm 2Co 17 and containing up to 20 at.% copper. It is found that copper exerts a strong influence; the 2:17 phase is repressed in favour of the 1:5 phase with the peritectic line changing to a eutectic trough. The solvus line of the 1:5 phase is displaced towards the 2:17 phase in the composition range studied. SmCu 5 and the 1:5 phase are mutually soluble above the latter's eutectoid transformation temperature, which falls as the copper level increases. Finally, the cobalt solid solution comes into direct equilibrium with a wide range of composition of the 1:5 phase in the ternary alloys (in the region of 800°C).

Coercive force of new Cu-substituted samarium cobalt alloys

It was found that sintered alloys having a composition of approximately z=8 in Sm(Co0.85Fe0.05Cu0.10)z exhibit a high coercive force on the order of 10 kOe, for 5–10-μm average grain size. Magnetization and demagnetization curves showed that the coercive force is controlled by a nucleation process. Attempts were made to achieve a high density without serious grain growth by means of high-pressure isostatic compaction and hot pressing, resulting in 96% of the density and 7-μm average grain size. With this approach, Br=10.3kG, IHc=10.2 kOe, and a maximum energy product of 22.0 MG Oe were achieved.

Elastic constant increases upon crystallization of a sputter-deposited amorphous alloy

A 0.2-in.-thick amorphous samarium-cobalt alloy (Sm2Co17) was prepared by sputter deposition. Increases in shear and bulk moduli were measured before and after crystallization with an ultrasonic technique. The shear modulus increased 45% and the bulk modulus increased 7% upon crystallization. Density increases were less than 2%. The increases were in accord with theoretical predictions.