Cold-Sprayed aluminum coatings for magnesium aircraft components

A corrosion-resistant barrier coating of Al was applied to ZE41A-T5 Mg using cold spray to evaluate the corrosion resistance and mechanical properties of the coating. Al coatings were applied to 100 by 150 by 64 mm plates of cast ZE41A-T5 Mg by cold spray. The corrosion resistance of the coatings was evaluated by electrochemical polarization, open circuit galvanic coupling, and accelerated salt-spray corrosion testing. Each sample was masked with two coats of an organic maskant. The cold-spray Al coating was exposed by removing 27.9 mm ² of the maskant. Polarization was performed with a potentiostat in a Greene cell with two graphite counter electrodes and a saturated calomel reference electrode (SCE) placed in a Luggin probe. A decrease in current of two orders of magnitude was observed when comparing the commercially-pure Al-coated Mg to bare Mg. The Al coatings did not provide adequate barrier protection for coatings with thicknesses >0.254 to 0.381 mm.