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Zhang P.,Hefei University of Technology | Zhang P.,Anhui Province Key Laboratory of Rare Earth Permanent Magnet Materials | Liu J.,Hefei University of Technology | Xu G.,Hefei University of Technology | And 4 more authors.
Surface and Coatings Technology | Year: 2015

An Al coating was achieved on NdFeB substrate via plasma assisted physical vapor deposition method. The coatings were treated with trivalent chromium passivation and were characterized by a scanning electron microscope equipped with an energy dispersive spectrometer. The adhesive strength between the coatings and NdFeB substrates was evaluated by tensile test. The coatings achieve much higher adhesive strength (25.7MPa) than that of Al coating without plasma assistance. The anticorrosive property of the coatings was studied by electrochemical impedance spectroscopy, neutral salt spray and potentiodynamic polarization curve tests. The corrosion current density of the passivated Al coated NdFeB specimens is 0.2205μA·cm-2, which is two orders of magnitude lower than that of bare NdFeB substrates. Also, the NSS and EIS tests confirm the excellent anticorrosive properties of the Al coated NdFeB specimens with plasma assisted physical vapor deposition method. © 2015 Elsevier B.V. Source


Zhang P.,Hefei University of Technology | Zhang P.,Earth Panda Advance Magnetic Material Co. | Zhang P.,Anhui Province Key Laboratory of Rare Earth Permanent Magnet Materials | Zhang P.,State Key Laboratory of Rare Earth Permanent Magnet Materials | And 10 more authors.
Applied Surface Science | Year: 2016

Zinc coated NdFeB specimens were prepared with different pretreating technologies, such as polishing, pickling (50 s), sandblasting and combined technology of sandblasting and pickling (5 s). Morphologies of the NdFeB substrates pretreated with different technologies were observed with a scanning electron microscope equipped with an energy dispersive spectrometer and an atomic force microscope. The tensile test was performed to measure the adhesive strength between Zn coating and NdFeB substrate. The self-corrosion behavior of the NdFeB specimen was characterized by potentiodynamic polarization curve. The anticorrosion properties of Zn coated NdFeB specimens were characterized by neutral salt spray tests. The pretreating technologies possess obvious impact on the adhesive strength and anticorrosion property of Zn coated NdFeB specimens. Combined pretreating technology of sandblasting and pickling (5 s) achieves the highest adhesive strength (25.56 MPa) and excellent anticorrosion property (average corrosion current density of 21 μA/cm2) in the four pretreating technologies. The impacting mechanisms of the pretreating technology on the adhesive strength and anticorrosion properties are deeply discussed. © 2015 Published by Elsevier B.V. Source

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