Corrosion behaviour of sintered NdFeB deposited with an aluminium coating

A protective, pure Al coating was deposited by direct current (DC) magnetron sputtering onto sintered NdFeB magnets. Separated, single phases of sintered NdFeB (the Nd-rich phase, the B-rich phase and the matrix phase) were prepared by arc melting for open circuit potential (OCP) tests. The corrosion process of the sintered NdFeB magnets coated with Al (Al/NdFeB) was studied experimentally. It was found that the corrosion process can be divided into three different stages. The Al coating cannot provide complete sacrificial protection for the sintered NdFeB magnets.

Research highlights
► Al coating was deposited on sintered NdFeB by DC magnetron sputtering.
► Nd-rich, B-rich and matrix phases were prepared by arc melting separately.
► Nd-rich phase was the most electrochemically active phase.
► Al coating cannot provide complete sacrificial protection for NdFeB.
► Corrosion process of Al/NdFeB can be divided into three different stages.