Alloy 625 possesses excellent corrosion properties, in room temperature and particularly in saline,
sulfuric acid and high temperature environments. Alloy 625 coating can be deposited on the surface of
materials using Air Plasma Spraying (APS) technique to provide surface protection against corrosion. It
is assumed that the coating can attain the excellent corrosion resistance similar to wrought alloy 625. It
is therefore important to understand the corrosion behavior of APS sprayed alloy 625 as free standing
sample. The microstructure of the APS alloy 625 is different than the wrought alloy due to the layered
type structure with the presence of porosity and additional oxides and unmelted particles. All of these
parameters can alter the corrosion property of APS deposited alloy 625. This study compares corrosion
behavior of APS deposited alloy 625 with wrought alloy 625. Both open circuit potential and polarization
measurements were used to evaluate corrosion properties of both materials. The corrosion resistivity of
the APS alloy 625 and wrought alloy 625 were compared to the ones obtained from cold rolled steel for
the reason of comparison. While wrought alloy 625 exhibited better corrosion resistivity compared to
APS sprayed one, coating has shown outstanding corrosion resistivity compared to steel.
Key words: air plasma spraying, alloy 625, corrosion, open circuit potential, potentiodynamic
polarization.