Improvement of the magnetic properties of SrFe12O19 ceramics by tailored sintering with SiO2 addition

Guzmán-Mínguez, Jesús C.; Vicente-Arche, Luis M.; Granados-Miralles, Cecilia; Fernández, J.F.; Quesada, A.

doi:10.1016/j.jallcom.2020.157890

Cited by 20 publications

(10 citation statements)

References 26 publications

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“…It usually requires two heating steps: first, the SrFe 12 O 19 powder is prepared by heating a mixture of strontium carbonate and iron oxide at 1100°C for 2 h 33 . In the second step, the prepared powders are sintered at 1300°C for 4 h 34 . Figure 4 includes the values of energy and time consumption of a tubular furnace (GSL‐1500X, MTI Corporation) for both conventional processes as measured with a power analyzer (PPA1500, Newtons4th Ltd.) directly connected to the furnace during the heating cycles.…”

Section: Resultsmentioning

confidence: 99%

“…The conventional preparation of SrFe 12 O 19 magnets is an energetically intensive process. It usually requires two heating steps: first, the SrFe 12 O 19 powder is prepared by heating a mixture of strontium carbonate and iron oxide at 1100 • C for 2 h. 33 In the second step, the prepared powders are sintered at 1300 • C for 4 h. 34 Figure 4 includes the values of energy and time consumption of a tubular furnace (GSL-1500X, MTI Corporation) for both conventional processes as measured with a power analyzer (PPA1500, Newtons4th Ltd.) directly connected to the furnace during the heating cycles. The resulting energy consumption value, as determined by integrating the power consumed by the furnace for the entire synthesis + sintering cycle, was 3 × 10 8 J.…”

Section: Energy Consumption Analysesmentioning

confidence: 99%

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Touch‐free reactive flash sintering of dense strontium hexaferrite permanent magnet

et al. 2023

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This work presents an extension of the touch‐free flash sintering technique. In the proposed technique, chemical reaction and sintering occur in a single step, without the use of electrodes, in the presence of electric and magnetic fields. We show that a dense, single‐phase strontium hexaferrite magnet can be produced from a mixture of commercial carbonates and oxides powders in a single step in a little more than a minute. This new technique implies significant reduction in energy and time consumption (primarily because of ultrafast processing) relative to conventional sintering.This article is protected by copyright. All rights reserved

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Section: Resultsmentioning

confidence: 99%

Section: Energy Consumption Analysesmentioning

confidence: 99%

Touch‐free reactive flash sintering of dense strontium hexaferrite permanent magnet

et al. 2023

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“…A promising development for low-temperature applications was doping ferrites with B 2 O 3 , affecting the temperature coefficient of coercivity, which, unexpectedly, switched sign, enhancing the effect of the temperature on the magnetic properties (Figure 11) [80]. Guzmán-Mínguez et al improved the magnetic performance of strontium ferrite sintered magnets using silica by tuning sintering parameters [81].…”

Section: Non-ree-based Pmsmentioning

confidence: 99%

The Future of Permanent-Magnet-Based Electric Motors: How Will Rare Earths Affect Electrification?

Podmiljšak,

Saje,

Jenuš

et al. 2024

Materials

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In this review article, we focus on the relationship between permanent magnets and the electric motor, as this relationship has not been covered in a review paper before. With the increasing focus on battery research, other parts of the electric system have been neglected. To make electrification a smooth transition, as has been promised by governing bodies, we need to understand and improve the electric motor and its main component, the magnet. Today’s review papers cover only the engineering perspective of the electric motor or the material-science perspective of the magnetic material, but not both together, which is a crucial part of understanding the needs of electric-motor design and the possibilities that a magnet can give them. We review the road that leads to today’s state-of-the-art in electric motors and magnet design and give possible future roads to tackle the obstacles ahead and reach the goals of a fully electric transportation system. With new technologies now available, like additive manufacturing and artificial intelligence, electric motor designers have not yet exploited the possibilities the new freedom of design brings. New out-of-the-box designs will have to emerge to realize the full potential of the new technology. We also focus on the rare-earth crisis and how future price fluctuations can be avoided. Recycling plays a huge role in this, and developing a self-sustained circular economy will be critical, but the road to it is still very steep, as ongoing projects show.

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“…Thus, the BH max values obtained after consolidation of BaM and SrM powders is generally far below the theoretical maximum of 45 kJ m −3 predicted for these compounds [17]. Different strategies are pursued to retain H c after sintering, such as fine-tuning the thermal cycles in order to maximize the density while minimizing the temperature [66][67][68], or including different additives to hinder grain growth [69][70][71].…”

Section: General Aspects On Consolidation and Typical Problems Encoun...mentioning

confidence: 99%

“…The densification of final stages is not at all unwanted, as the remanence of a magnet increases linearly with the density, so the optimal sintering method should ensure a trade-off between a controlled grain growth and a good densification. In a quest for the suppression of grain growth during final stages of sintering without hampering densification, various sintering additives have been used, SiO 2 being one of the most widely explored [57, 71,94,[97][98][99][100]. In 1985, Kools concluded that the highest H c were obtained for SiO 2 concentrations within the range 0.36-1.44 wt% and he put forward a mechanism for the grain growth impediment [97,98].…”

Section: Conventional Sinteringmentioning

confidence: 99%

On the potential of hard ferrite ceramics for permanent magnet technology—a review on sintering strategies

Granados-Miralles

Jenuš

2021

J. Phys. D: Appl. Phys.

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A plethora of modern technologies rely on permanent magnets for their operation, including many related to the transition towards a sustainable future, such as wind turbines or electric vehicles. Despite the overwhelming superiority of magnets based on rare-earth elements in terms of the magnetic performance, the harmful environmental impact of the mining of these raw materials, their uneven distribution on Earth and various political conflicts among countries leave no option but seeking for rare-earth-free alternatives. The family of the hexagonal ferrites or hexaferrites, and in particular the barium and strontium M-type ferrites (BaFe12O19 and SrFe12O19), are strong candidates for a partial rare-earth magnets substitution, and they are indeed successfully implemented in multiple applications. The manufacturing of hexaferrites into dense pieces (i.e. magnets) meeting the requirements of the specific application (e.g. magnetic and mechanical properties, shape) is not always straightforward, which has in many cases hampered the actual substitution at the industrial level. Here, past and on-going research on hexaferrites sintering is reviewed with a historical perspective, focusing on the challenges encountered and the solutions explored, and correlating the sintering approaches with the magnetic performance of the resulting ceramic magnet.

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Improvement of the magnetic properties of SrFe12O19 ceramics by tailored sintering with SiO2 addition

Cited by 20 publications

References 26 publications

Touch‐free reactive flash sintering of dense strontium hexaferrite permanent magnet

Touch‐free reactive flash sintering of dense strontium hexaferrite permanent magnet

The Future of Permanent-Magnet-Based Electric Motors: How Will Rare Earths Affect Electrification?

On the potential of hard ferrite ceramics for permanent magnet technology—a review on sintering strategies

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