Rare Metals

, Volume 38, Issue 3, pp 238–244 | Cite as

Temperature stability of SmCo (2:17) magnets modified by Ni–Cr two-layer coating

  • Saira Bibi
  • Jing-Min WangEmail author
  • M. Faisal Rathore
  • Cheng-Bao Jiang


The oxidation resistance behavior of SmCo (2:17)-type high-temperature magnets modified with Ni–Cr two-layer coating was studied. The study depicts the mass gain kinetics and magnetic properties of uncoated and Ni–Cr-modified magnets oxidized at high temperature (500 °C) in air for 200 h. The oxidation test results illustrate that the mass gain of uncoated magnet is 6.95 mg·cm−2 which is more than that (0.08 mg·cm−2) of coated magnet after 200 h. For the magnetic properties concerned, there is a great loss for uncoated magnet, while for coated magnet, magnetic properties do not change much. The study of uncoated magnet through X-ray diffraction (XRD) and electron probe microanalysis (EPMA) shows that the invasion of oxygen at high temperature leads to the loss of magnetic properties by changing the microstructure of magnet.


SmCo (2:17) magnets Surface modification High temperature stability Ni–Cr coating 



This work was financially supported by the National Science Foundation of China (No. 51471016) and the Natural Science Foundation of Beijing (No. 2151002).


  1. [1]
    Tang W, Zhang Y, Hadjipanayis GC. Microstructure and magnetic properties of Sm(CobalFexCu0.128Zr0.02)7.0 magnets with Fe substitution. J Magn Magn Mater. 2000;221(3):268.CrossRefGoogle Scholar
  2. [2]
    Guo ZH, Li W. Room-and high-temperature magnetic properties of Sm(CobalFexCu0.088Zr0.025)7.5 (x = 0–0.30) sintered magnets. Acta Metall Sin. 2002;38(8):866.Google Scholar
  3. [3]
    Richard TF, Rubertus CS. Air force applications of advanced magnetic materials. In: Proceeding of Materials Research Society Spring Conference, Vol 57. San Francisco; 1999. 481.Google Scholar
  4. [4]
    Richard TF, Rubertus CS. Applications of high temperature magnetic materials. IEEE Trans Magn. 2000;36(5):3373.CrossRefGoogle Scholar
  5. [5]
    Rong CB, Zhang HW, Zhang J, Du XB, Zhang SY, Shen BG. Micromagnetic simulation of the coercivity mechanism in Sm(Co, Fe, Cu, Zr)z magnets. J Appl Phys. 2004;95(3):1351.CrossRefGoogle Scholar
  6. [6]
    Yi JH, Peng YD. Review of research on 2:17 type SmCo rare earth permanent magnets. Rare Met Mater Eng. 2004;33(4):337.Google Scholar
  7. [7]
    An SZ, Jiang CB. Recent progress in high temperature permanent magnetic materials. Rare Met. 2013;32(5):431.CrossRefGoogle Scholar
  8. [8]
    Liu LL, Jiang CB. The improved oxidation resistance of Si-doped SmCo7 nanocrystalline magnet. Appl Phys Lett. 2011;98(25):252504.CrossRefGoogle Scholar
  9. [9]
    Liu LL, Tingyan J, Jiang CB. High-temperature resistance and magnetic properties of Si-doped Sm2Co17-type magnets at 500 °C. J Magn Magn Mater. 2012;324(14):2310.CrossRefGoogle Scholar
  10. [10]
    Guo ZH, Pan W, Li W. Sm(Co, Fe, Cu, Zr)z sintered magnets with a maximum operating of 500 C. J Magn Magn Mater. 2006;303(2):396.CrossRefGoogle Scholar
  11. [11]
    Liu JF, Zhang Y, Dimitrov D, Hadjipanayis GC. Microstructure and high magnetic properties of Sm(CoCuFeZr)z (z = 6.7–9.1) permanent magnets. J Appl Phys. 1999;85(5):2800.CrossRefGoogle Scholar
  12. [12]
    Chen CH, Walmer MS, Walmer MH, Liu S, Kuhl GE. Thermal stability of Sm-TM high temperature magnets at 300–550 °C. IEEE Trans Magn. 2000;36(5):3291.CrossRefGoogle Scholar
  13. [13]
    Chen CH, Walmer MH, Kottcamp EH, Gong W. Surface reaction and Sm depletion at 550 °C. IEEE Trans Magn. 2001;37(4):2531.CrossRefGoogle Scholar
  14. [14]
    Wang X, Peng X, Zhao H, Guo ZH, Li W, Wang F. High temperature oxidation and its induced coercivity loss of a 2:17 type SmCo-based magnet. J Appl Phys. 2015;117(9):093902.CrossRefGoogle Scholar
  15. [15]
    Liu LL, Jiang CB. Oxidation resistance and magnetic properties of SmCo7-xSix permanent magnetic alloys. J Supercond Novel Magn. 2012;25(1):131.CrossRefGoogle Scholar
  16. [16]
    Saunders SRJ, Nicholls JR. Coatings and surface treatments for high temperature oxidation resistance. Mater Sci Technol. 1989;5(8):780.CrossRefGoogle Scholar
  17. [17]
    Chen CH, Walmer MH, Liu S. Thermal stability and the effectiveness of coatings for SmCo 2:17 high-temperature magnets at temperatures up to 550 °C. IEEE Trans Magn. 2004;40(4):2928.CrossRefGoogle Scholar
  18. [18]
    Chen CH, Huang MQ, John EF, Monnette G, Middleton J, Higgins A, Liu S. Effect of surface modification on mechanical properties and thermal stability of SmCo high temperature magnetic materials. Surf Coat Tech. 2006;201(6):3430.CrossRefGoogle Scholar
  19. [19]
    Wang QY, Zheng L, An SZ, Zhang T, Jiang CB. Thermal stability of surface modified Sm2Co17-type high temperature magnets. J Magn Magn Mater. 2013;331:245.CrossRefGoogle Scholar
  20. [20]
    Pragnell WM, Evans HE, Williams AJ. Oxidation protection of Sm2Co17-based alloys. J Alloy Compd. 2012;517(15):92.CrossRefGoogle Scholar
  21. [21]
    Pragnell WM, Evans HE, Williams AJ. The oxidation morphology of SmCo alloys. J Alloy Compd. 2009;487(1–2):69.CrossRefGoogle Scholar
  22. [22]
    Dong Z, Peng X, Guo ZH, Li W, Wang F. The effect of a surface Cr film on the oxidation of SmCo-based magnetic alloy at 700 °C. Corros Sci. 2013;77:113.CrossRefGoogle Scholar
  23. [23]
    Li JJ, Li AH, Zhu MG, Pan W, Li W. Study on corrosion behaviors of sintered Nd–Fe–B magnets in different environment conditions. J Appl Phys. 2011;109:07A744.CrossRefGoogle Scholar
  24. [24]
    Liu JF, Walmer MH. Thermal stability and performance data of SmCo 2:17 high-temperature magnets on PPM focusing structures. IEEE Trans Electron Devices. 2005;52(5):899.CrossRefGoogle Scholar
  25. [25]
    Kardelky S, Gebert A, Gutfleisch O, Hoffmann V, Schultz L. Prediction of the oxidation behavior of Sm-Co based magnets. J Magn Magn Mater. 2005;290–291(2):1226.CrossRefGoogle Scholar
  26. [26]
    Kardelky S, Gebert A, Gutfleisch O, Handstein A, Wyss U, Schultz L. Corrosion behavior of Sm-Co-based permanent magnets in oxidizing environments. IEEE Trans Magn. 2004;40(4):2931.CrossRefGoogle Scholar
  27. [27]
    Yang Z, Peng X, Feng Q, Guo Z, Li W, Wang F. The mechanism of high temperature oxidation of a SmCo-based magnetic alloy. Corros Sci. 2012;61:72.CrossRefGoogle Scholar
  28. [28]
    Zhao H, Peng X, Yang Z, Guo ZH, Li W, Wang F. Effect of a thin Cr2O3 film on oxidation at 600 °C of a Sm(CobalFe0.22Cu0.08Zr0.02)7.5 alloy. Surf Coat Tech. 2013;226(15):22.CrossRefGoogle Scholar
  29. [29]
    Chen CH, Huang M, Higgins A, Lee D, Liu S. Improved mechanical properties and thermal stability of Sm-Co high temperature magnets resulting from surface modifications. J Iron Steel Res Int. 2006;13(8):112.CrossRefGoogle Scholar
  30. [30]
    Tian JJ, Zhang SG, Que XH. Effects of oxygen and carbon on the magnetic properties and microstructure of Sm2Co17 permanent magnets. Rare Met. 2007;26(4):299.CrossRefGoogle Scholar
  31. [31]
    Zheng J, Lin M, Xia Q. A preparation method and effects of Al–Cr coating on NdFeB sintered magnets. J Magn Magn Mater. 2012;324(22):3966.CrossRefGoogle Scholar

Copyright information

© The Nonferrous Metals Society of China and Springer-Verlag GmbH Germany, part of Springer Nature 2018

Authors and Affiliations

  1. 1.School of Materials Science and EngineeringBeihang UniversityBeijingChina
  2. 2.National Center of PhysicsQuaid-e-Azam UniversityIslamabadPakistan

Personalised recommendations