A novel self-repairing hydrophobic composite coating for anti-corrosion protection of sintered Nd-Fe-B

In this paper, a corrosion-resistant glutamic acid (Glu)-Cu-Nano-Al 2 O 3 composite coating with both hydrophobicity and self-healing characteristics was electrodeposited on the sintered Nd-Fe-B surface. The influence of the amount of Nano-Al 2 O 3 added in the acidic Cu 2+ -glutamate (Glu 2− ) solution on the performance of the composite coating was studied, the results show that Nano-Al 2 O 3 inclusion can make the surface of the composite coating appear papillary particles and make the composite coating hydrophobic. By analyzing the products of the composite coating after corrosion in 3.5% NaCl solution, it is shown that the codeposition copper dihydroglutamate (CuGlu 2 H 2 ) and Glu particles in the composite coating are released and dissolved in the solution with pH = 6.5 after copper corrosion, and then complexed with Cu 2+ produced by corrosion to form an insoluble copper glutamate (CuGlu) passive film, which was deposited on the corroded coating to achieve self-repairing function and prevent further corrosion. The hydrophobicity and self-repairing function of the composite coating ensure that the sintered Nd-Fe-B has excellent corrosion resistance.