Structure and protective effect of AlN/Al multilayered coatings on NdFeB by magnetron sputtering

• The AlN/Al multilayered coatings were deposited on NdFeB by DC magnetron sputtering.
• The multilayered coatings with λ = 20 nm have an excellent corrosion resistance and scratch resistance.
• The multilayered coatings with a thickness of 2 μm have a good protection to NdFeB.

In order to improve corrosion resistance and scratch resistance of NdFeB magnet, AlN/Al multilayered coatings were deposited on the surface of the magnet by magnetron sputtering. During deposition, the modulation periods were made at λ = 10 nm, λ = 20 nm, λ = 40 nm and λ = 100 nm, respectively. Al and AlN are well crystallized in the multilayered coatings. The coatings become dense and smooth with the decrease of the modulation period. For the modulation period of 20 nm, AlN/Al multilayered coatings have the excellent scratch resistance and corrosion resistance. In addition, the multilayered coatings with thickness of 2 μm can achieve a similar corrosion resistance and better scratch resistance compared with Al monolayer with a thickness of 5 μm.