Cold-Sprayed Al Coating for Corrosion Protection of Sintered NdFeB

A protective Al coating was achieved on the sintered NdFeB magnet by cold spray. The sprayed Al particles generate plastic deformation and hang together. The thickness of the coating is about 170 mu m. The corrosion currents of Al coating and NdFeB without immersion tested by potentiodynamic polarization in 3.5 wt.% NaCl solutions are 1.350 x 10(-6) and 4.361 x 10(-6) A/cm(2), respectively. X-ray photoelectron spectrometry results confirm that the oxide film is Al2O3 and the corrosion process can be derived into two different stages. The Al coating can provide long-term protection for NdFeB effectively.