Corrosion Behavior of Air Plasma Sprayed Alloy 625 on Nickel Foam Substrate

Alloy 625 possesses excellent corrosion properties, particularly in saline, sulfuric acid and high temperature environments. However, it is an expensive alloy, and building large assemblies from alloy 625 can be very expensive. In the interest of cost savings, alloy 625 can be deposited on the surface of less expensive materials using Air Plasma Spraying (APS) technique. The coated material can attain the excellent corrosion resistance similar to wrought alloy 625 at lower cost. The microstructure of the APS alloy 625 is much different than the wrought alloy due to the layered type structure with the presence of additional oxides and unmelted particles. This study examines changes in the reduction potential of the APS deposited alloy 625 compared to the wrought material, which is important for galvanic corrosion. It also examines the corrosion potential measurements of the alloy 625 coating compared to the wrought material. These experiments will be carried out to understand the effect of oxides and coating layers interface on the corrosion of the deposited material.