The properties of chromium oxide coatings on NdFeB magnets by magnetron sputtering with ion beam assisted deposition

The coatings of Cr2O3 were deposited on sintered NdFeB magnets by direct current (DC) pulse magnetron sputtering with and without ion beam at different 02 pressures. The coatings were compact and had a thickness of 1.8-2.2 gm. The coatings achieved a hardness up to 29 GPa and a wear rate of 1.78 x 10(-7) mm(3)/Nm when ion-beam-assisted-deposition (IBAD) was used. Excellent anti-corrosion properties were obtained in the coating prepared by IBAD while the good magnetic properties of NdFeB substrate were retained. Electrochemical measurements revealed that the corrosion current density of the sample decreased from 4.66 x 10(-6) A/cm(2) (bare NdFeB) to 2.87 x 10(-7) A/cm(2) when O-2 flux was 17 sccm during IBAD process. (C) 2016 Elsevier Ltd. All rights reserved.