Magnetic Properties Hard-Soft SmCo₅-FeNi and SmCo₅-FeCo Composites Prepared by Electroless Coating Technique

M. Lamichanne, B. K. Rai, S. R. Mishra, V. V. Nguyen, J. P. Liu

Department of Physics, The University of Memphis, USA.
Department of Physics, The University of Texas, Arlington, USA.

DOI: 10.4236/ojcm.2012.24014                

Abstract

Composites of SmCo₅-FeNi and SmCo₅-FeCo, hard-soft magnetic materials, have been synthesized via electroless plating of magnetically hard SmCo₅ powder particles with magnetically soft FeNi and FeCo, respectively. The influence of coating thickness of soft magnetic layers on the structure and magnetic properties of the composite has been studied. Overall FeNi coating was found to be less dense compared to FeCo for the same plating duration. Structurally the coat ing was found to be nodular in morphology. These coating have dramatic effect on the overall magnetic property of the composite. As compared to FeNi coated SmCo₅ composite, two-fold increase in the saturation magnetization has been observed upon coating SmCo₅ (M_s~28 emu/g) with FeCo to a value 56 emu/g. The coercivity of composite powder was found to decrease with increasing the coating layer thickness. The absence of exchange spring behavior in the hard-soft composite is attributed to magnetically soft layer thickness exceeding the theoretical length limit for exchange-spring coupling.

Keywords

Electroless Plating; Hard-Soft Composites; Exchange Spring

Conflicts of Interest

The authors declare no conflicts of interest.

References

[1]	J. F. Herbst, “R2Fe14B materials: Intrinsic properties and technological aspects,” Rev. Mod. Phys. Vol. 63, Issue 4, 199, pp. 819-898.
[2]	K. H. J. Buschow, “New developments in hard magnetic materials,” Rep. Prog. Phys. Vol. 54, No. 9, 1991, pp. 1123. doi:10.1088/0034-4885/54/9/001
[3]	J. M. D. Coey, “Industrial applications of permanent magnetism,” Phys. Scripta, Vol. 66, Issue T66, 1996, p.60. doi:10.1088/0031-8949/1996/T66/008
[4]	E. F. Kneller and R. Hawig, The Exchange-Spring Magnet: A New material principle for permanent magnets,” IEEE Trans. Magn. Vol. 27, 1991, pp. 3588-3600. doi:10.1109/20.102931
[5]	V. Patel, M. El-Hilo, K. O'Grady, and R. W. Chantrell, “Nucleation fields in an exchange spring hard magnet,” J. Phys. D: Appl. Phys. Vol. 26, No. 9, 1993, pp. 1453. doi:10.1088/0022-3727/26/9/018
[6]	R. Coehoorn, D. B. Mooji, and C. D. de Waard, “Meltspun permanent magnet materials containing Fe3B as the main phase,” J. Magn. Magn. Mater. Vol. 80, Issue 1, 1989, pp.101-104. doi:10.1016/0304-8853(89)90333-8
[7]	J. Ding, P. G. McCormick, and R. Street, “Remanence enhancement in mechanically alloyed isotropic Sm7Fe93-nitride,” J. Magn. Magn. Mater. Vol. 124, Issue 1-2, 1993, pp.1-4. doi:10.1016/0304-8853(93)90060-F
[8]	J. M. D. Coey, “Permanent magnetism,” Solid State Commun. Vol. 102, Issue 2-3, 1997, pp. 101-105. doi:10.1016/S0038-1098(96)00712-0
[9]	D. Lee, S. Bauser, A. Higgins, C. Chen, S. Liu, M. Q. Huang, Y. G. Peng, and D. E. Laughlin, “Bulk anisotropic composite rare earth magnets,” J. Appl. Phys. Vol. 99, 2006, pp. 08B516.
[10]	J. Wecker, M. Katter, and L. Schultz, “Mechanically alloyed Sm‐Co materials,” J. Appl. Phys. Vol. 69, Issue. 8, 1991, pp. 6058-6060. doi:10.1063/1.347769
[11]	S. K. Chen, J. L. Tsai, and T. S. Chin, “Nanocomposite Sm2Co17/Co permanent magnets by mechanical alloying,” J. Appl. Phys. Vol. 79, Issue 8, 1996, pp.5964-5966. doi:10.1063/1.362121
[12]	K. H. J. Buschow, D. B. De Mooij, and R. Coehoorn, “Metastable ferromagnetic materials for permanent magnets,” J. Less Common Metals, Vol. 145, 1988, pp.601-611. doi:10.1016/0022-5088(88)90318-9
[13]	S. Liu, A. Higgins, E. Shin, S. Bauser, C. Chen, D. Lee, Y. Shen, Y. He, and M. Q. Huang, “Enhancing Magnetic Properties of Bulk Anisotropic Nd–Fe–B/?-Fe Composite Magnets by Applying Powder Coating Technologies,” IEEE Trans. Magn. Vol. 42, No. 10, 2006, pp. 2912-2914. doi:10.1109/TMAG.2006.879905
[14]	Z. Chen, A. Ng, J. Yi, and X. Chen, “Multi-layered electroless Ni–P coatings on powder-sintered Nd–Fe–B permanent magnet,” J. Magn. Magn. Mater. Vol. 302, Issue 1, 2006, pp. 216-222.
[15]	P. Mitchell, “Corrosion protection of NdFeB magnets,” IEEE Trans. Magn. Vol. 26, Issue 5, 1990, p. 1933. doi:10.1109/20.104575
[16]	C. W. Cheng, F. T. Cheng, and H. C. Man, “Improvement of protective coating on Nd–Fe–B magnet by pulse nickel plating,” J. Appl. Phys. Vol. 83, No. 11, 1998, pp. 6417-6419. doi:10.1063/1.367921
[17]	Q. Zheng, Y. Zhang, M. J. Bonder, and G. C. Hadjipanayis, “Fabrication of Sm–Co/Co (Fe) composites by electroless Co and Co–Fe plating,” J. Appl. Phys. Vol. 93, Issue 10, 2003, pp. 6498-6410. doi:10.1063/1.1558246
[18]	Y. K. Takahashi, T. Ohkubo, and K. Hono, “Microstructure and magnetic properties of SmCo5 thin films deposited on Cu and Pt underlayers,” J. Appl. Phys. Vol. 100, Issue 5, 2006, pp. 053913-053915. doi:10.1063/1.2266247
[19]	M. F. de Campos and F. J. Gomes Landgra, “Determination of Intrinsic Magnetic Parameters of SmCo5 Phase in Sintered Samples,” Mater. Sci. Forum, Vol. 498-499, 2005, pp.129-123. doi:10.4028/www.scientific.net/MSF.498-499.129
[20]	T. Inoue, K. Goto, and T. Sakurai. “Magnetic Domains of Single-Domain Particles of SmCo5 Observed by the Colloid-SEM Method,” Jap. J. Appl. Phys. Vol. 22, 1983, pp. L695-L697. doi:10.1143/JJAP.22.L695
[21]	Y. Wang, Y. Li, C. Rong, and J. P. Liu, “Sm–Co hard magnetic nanoparticles prepared by surfactant-assisted ball milling,” Nanotechnology Vol. 18, No. 46, 2007, pp. 465701. doi:10.1088/0957-4484/18/46/465701
[22]	V. M. Chakka, B. Altuncevahir, Z. Q. Jin, Y. Li, and J. P. Liu, “Magnetic nanoparticles produced by surfactant-assisted ball milling,” J. Appl. Phys. Vol. 99, Issie 8, 2006, pp. 08E912.
[23]	N. Akdogan, G. Hadjipanayis, and D. J. Sellmyer, “Anisotropic Sm-(Co,Fe) nanoparticles by surfactant-assisted ball milling,” J. Appl. Phys. Vol. 105, Issue 7, 2009, pp. 07A710-07A712.
[24]	Y. Hou, Z. Xu, S. Peng, and C. Rong, J. P. Liu, and S. Sun, “A Facile Synthesis of SmCo5 Magnets from Core/Shell Co/Sm2O3 Nanoparticles,” Adv. Mater. Vol. 19, 2007, pp. 3349-3352. doi:10.1002/adma.200700891