Figure 4 shows the Tafel polarization curves of the
140 MXC and 530 AS coatings. To observe the
e!ect of substrate resistance against corrosion, 140
MXC and 530 AS coatings were deposited onto
two substrates (SAE 1045 and 4340 steel). For these coatings, an improvement in the resistance
corrosion for both substrates was observed, that is,
the corrosion potential values are more positive and
present lower corrosion resistance values. "ese
observations are consistent with the chemical
composition, given that the presence of niobium
and chromium, even in small quantities, improves
corrosion resistance [15]. "e 530 AS coating was
also deposited onto the two substrates. In this case,
corrosion resistance showed improvement when
applied over the 1045 substrate, but when applied
over a SAE 4340 steel substrate, no improvement
in the electrochemical behavior was observed; thus,