A superhydrophobic multilayer coating
with excellent corrosion
resistance has been fabricated on an AZ61 magnesium alloy through
electroless plating and hydrothermal treatment. The surface morphologies,
chemical characteristics, wettabilities, and corrosion resistance
of the multilayer coating were characterized and discussed. The results
show that the electroless Ni–P coating on the magnesium alloy
exhibits a nodular structure with micropores and lower corrosion resistance.
However, a dense Ni
3
(NO
3
)
2
(OH)
4
layer, a porous Ni
3
(NO
3
)
2
(OH)
4
nanostructure layer, and a stearic absorbing layer
are grown on the surface of the Ni–P coating with superhydrophobic
characters and higher corrosion resistance after hydrothermal treatment.
Furthermore, the water contact angle and corrosion resistance of the
multilayer coating showed a trend of first increasing and then decreasing
as the hydrothermal reaction time increases. The optimum hydrothermal
reaction time is 15 h, and the multilayer coating prepared under this
condition has the highest corrosion resistance and the highest contact
angle. In addition, the protection mechanism of the multilayer coating
is discussed, and the formation of the dense Ni
3
(NO
3
)
2
(OH)
4
layer and the stearic absorbing
layer effectively improved the corrosion resistance of the multilayer
coating.