Journal of Materials Science

, Volume 50, Issue 20, pp 6559–6566 | Cite as

Investigation on sol–gel Al2O3 and hybrid phosphate-alumina insulation coatings for FeSiAl soft magnetic composites

Original Paper


Alumina has been prepared by sol–gel method as the coating layer in the fabrication of FeSiAl soft magnetic composites (SMCs). Influence of the Al2O3 content on the magnetic properties of the SMCs has been studied, and optimized effective permeability (μ e = 116.3) and core loss (P cv = 331.2 mW cm−3) measured at 50 kHz, 100 mT was achieved with 0.8 wt% Al2O3. Hybrid phosphate-alumina coating has also been used to prepare the FeSiAl SMCs with a total addition of 0.8 wt%. Significantly improved performance of the SMCs can be achieved with the hybrid coating compared to single phosphate or alumina coating. The addition of 0.2 wt% H3PO4 and 0.6 wt% Al2O3 gives rise to the optimal magnetic properties (μ e = 123.4; P cv = 226.4 mW cm−3) of the FeSiAl SMCs. For the hybrid coating, the inner phosphate layer grown by direction reaction at the powder surfaces gives rise to excellent adhesion. Also, investigation on the thermal stability of the coatings indicates that the outer Al2O3 layer hinders the decomposition of the phosphate layer, leading to enhanced magnetic performance of the SMCs.


Al2O3 Coating Layer Effective Permeability Core Loss Hybrid Coating 



This work was supported by the Fundamental Research Funds for the Central Universities (2014QNA4007), Program for Innovative Research Team in University of Ministry of Education of China (IRT13R54), the Key Innovation Team of Magnetic Materials, and the Key Laboratory of Novel Materials for Information Technology of Zhejiang Province.

Compliance with Ethical Standard

Conflict of interest

The authors declare that they have no conflict of interest.


  1. 1.
    Aghaie-Khafri M, Mahmudi R (2005) The effect of preheating on the formability of an Al-Fe-Si alloy sheet. J Mater Process Technol 169:38–43CrossRefGoogle Scholar
  2. 2.
    Kasama AH, Bolfarini C, Kiminami CS, BottaFilho WJ (2007) Magnetic properties evaluation of spray formed and rolled Fe-6.5 wt% Si-1.0 wt% Al alloy. Mater Sci Eng A 449:375–377CrossRefGoogle Scholar
  3. 3.
    Kishimoto Y, Yamashita O, Makita K (2003) Magnetic properties of sintered sendust alloys using powders granulated by spray drying method. J Mater Sci 38:3479–3484. doi: 10.1023/A:1025157019440 CrossRefGoogle Scholar
  4. 4.
    Taghvaei AH, Ebrahimi A, Gheisari K, Janghorban K (2010) Analysis of the magnetic losses in iron-based soft magnetic composites with MgO insulation produced by sol-gel method. J Magn Magn Mater 322:3748–3754CrossRefGoogle Scholar
  5. 5.
    Pang YX, Hodgson SNB, Weglinski B, Gaworska D (2006) Investigations into sol-gel silica and silica hybrid coatings for dielectromagnetic soft magnetic composite applications. J Mater Sci 41:5926–5936. doi: 10.1007/s10853-006-0360-9 CrossRefGoogle Scholar
  6. 6.
    Iwanabe H, Lu B, McHenry ME, Laughlin DE (1999) Thermal stability of the nanocrystalline Fe-Co-Hf-B-Cu alloy. J Appl Phys 85:4424CrossRefGoogle Scholar
  7. 7.
    Yang JY, Wu JS, Zhang TJ, Chi K (1998) Multicomponent mechanical alloying of Fe-Cu-Nb-Si-B. J Alloy Compd 265:269–272CrossRefGoogle Scholar
  8. 8.
    Shokrollahi H, Janghorban K (2007) Effect of warm compaction on the magnetic and electrical properties of Fe-based soft magnetic composites. J Magn Magn Mater 313:182–186CrossRefGoogle Scholar
  9. 9.
    Taghvaei AH, Shokrollahi H, Janghorban K (2009) Properties of iron-based soft magnetic composite with iron phosphate-silane insulation coating. J Alloy Compd 481:681–686CrossRefGoogle Scholar
  10. 10.
    Wei X, Chen W, Mi Y (2015) Preparation of Fe-Si-Ni soft magnetic composites with excellent high-frequency properties. J Magn Magn Mater 381:116–119CrossRefGoogle Scholar
  11. 11.
    Wei D, Longtao J, Yaqin L, Jiabin S, Bingqing L, Gaohui W (2015) Effect of iron particle size and volume fraction on the magnetic properties of Fe/silicate glass soft magnetic composites. J Magn Magn Mater 378:232–238CrossRefGoogle Scholar
  12. 12.
    Donchul C, Moosung C, Jongryoul K (2014) Magnetic properties of Fe@FeSiAl oxide nanoparticles and magneto-dielectric properties of their composite sheets. IEEE Trans Magn 50:2007904Google Scholar
  13. 13.
    Yaghtin M, Taghvaei AH, Hashemi B, Janghorban K (2013) Effect of heat treatment on magnetic properties of iron-based soft magnetic composites with Al2O3 insulation coating produced by sol-gel method. J Alloy Compd 581:293–297CrossRefGoogle Scholar
  14. 14.
    Kabátová M, Dudrová E, Bruncková H (2013) The effect of calcination on morphology of phosphate coating and microstructure of sintered iron phosphated powder. Surf Interface Anal 45:1166–1173CrossRefGoogle Scholar
  15. 15.
    Aliouane N, Badeche T, Gagou Y, Nigrelli E, Saint-Gregoire P (2000) Synthesis and phase transitions of iron phosphate. Ferroelectrics 241:255–262CrossRefGoogle Scholar
  16. 16.
    Liu YP, Yi YD, Shao W, Shao YF (2013) Microstructure and magnetic properties of soft magnetic powder cores of amorphous and nanocrystalline alloys. J Magn Magn Mater 330:119–133CrossRefGoogle Scholar
  17. 17.
    Wu S, Sun AZ, Zhai FQ et al (2012) Annealing effects on magnetic properties of silicone-coated iron-based soft magnetic composites. J Magn Magn Mater 324:818–822CrossRefGoogle Scholar
  18. 18.
    Padmaja P, Anilkumar GM, Mukundan P, Aruldhas G, Warrier KGK (2001) Characterisation of stoichiometric sol-gel mullite by fourier transform infrared spectroscopy. Int J Inorg Mater 3:693–698CrossRefGoogle Scholar
  19. 19.
    Urlaub R, Posset U, Thull R (2000) FT-IR spectroscopic investigations on sol-gel-derived coatings from acid-modified titanium alkoxides. J Non-Cryst Solids 265:276–284CrossRefGoogle Scholar
  20. 20.
    Colthup N, Lawrence H, Wiberley SE (1964) Introduction to Infrared and Raman Spectroscopy, vol 2. Academic Press, New YorkGoogle Scholar
  21. 21.
    Monma H (1994) Electrolytic depositions of calcium phosphates on substrate. J Mater Sci 29:949–953. doi: 10.1007/BF00351415 CrossRefGoogle Scholar
  22. 22.
    Mounir F, Karima HN, Khaled BS, Mokhtar F (2012) Modeling Li-ion conductivity in LiLa(PO3)4 powder. Phys B 407:2593–2600CrossRefGoogle Scholar
  23. 23.
    Pu HT, Jiang FJ, Yang ZL (2006) Studies on preparation and chemical stability of reduced iron particles encapsulated with polysiloxane nano-films. Mater Lett 60:94–97CrossRefGoogle Scholar
  24. 24.
    Zhao NN, He CC, Liu JB et al (2014) Dependence of catalytic properties of Al/Fe2O3 thermites on morphology of Fe2O3 particles in combustion reactions. J Solid State Chem 219:67–73CrossRefGoogle Scholar
  25. 25.
    Gotić M, Dražić G, Musić S (2011) Hydrothermal synthesis of α-Fe2O3 nanorings with the help of divalent metal cations, Mn2+, Cu2+, Zn2+ and Ni2+. J Mol Struct 993:167–176CrossRefGoogle Scholar
  26. 26.
    Yilmaz S, Kutmen-Kalpakli Y, Yilmaz E (2009) Synthesis and characterization of boehmitic alumina coated graphite by sol-gel method. Ceram Int 35:2029–2034CrossRefGoogle Scholar
  27. 27.
    Rebeyrata S, Grosseau-Poussarda JL, Renaultb PO, Panicauda B, Dinhuta JF (2002) Structural characterisation of phosphated α-iron oxidised at 400 °C. Surf Coat Technol 161:144–149CrossRefGoogle Scholar
  28. 28.
    Suguma T, Kukocka LE, Carciello N, Warren JB (1988) Aspects of the adhesion and corrosion resistance of polyelectrolyte-chemisorbed zinc phosphate conversion coatings. J Mater Sci 23:101. doi: 10.1007/BF01174040 CrossRefGoogle Scholar
  29. 29.
    Meyer K (1997) Characterization of the structure of binary zinc ultraphosphate glasses by infrared and Raman spectroscopy. J Non-Cryst Solids 209:227–239CrossRefGoogle Scholar
  30. 30.
    Meyer K, Barz A, Stachel D (1995) Effects of atmospheric humidity on the infrared reflectivity of vitreous P2O5 and ultraphosphate glasses. J Non-Cryst Solids 191:71–78CrossRefGoogle Scholar
  31. 31.
    Chandradass J, Balasubramanian M (2006) Sol-gel processing of alumina fibres. J Mater Process Technol 173:275–280CrossRefGoogle Scholar

Copyright information

© Springer Science+Business Media New York 2015

Authors and Affiliations

  1. 1.School of Materials Science and Engineering, State Key Laboratory of Silicon Materials, Key Laboratory of Novel Materials for Information Technology of Zhejiang ProvinceZhejiang UniversityHangzhouChina

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