Characterization and corrosion behavior of intermetallic coated stainless steels with ESD

Stainless steels have a wide range of uses in various sectors of the industry (such as chemistry, petro-chemical industry, paper industry, nuclear engineering) due to their better corrosion resistance at high temperatures. Besides this it is also used the medical field as an implant material owing to its high corrosion resistance. In addition surface coating processes are carried out to improve superior properties of stainless steels. These coating processes are applied to steel surfaces by boronizing, nitriding, thermal spray coating, physical vapor deposition, chemical vapor deposition, electro-spark deposition processes. One of the most promising methods in this regard is the electro-spark deposition (ESD) coating technique. Basically ESD is a micro-welding process that allows electrode material to be welded (deposited) to the surface of a metallic substrate using high-frequency and high current electric currents. In this study, FeAl and NiAl intermetallics were coated on AISI 304 and AISI 316L stainless steels using ESD technique. First of all for ESD coating was determined appropriate experimental parameters Secondly microstructures and phases formed on the coated surfaces were characterized by X-ray diffraction (XRD) and scanning electron microscopy (SEM). After that the surface hardness of the obtained layers were measured by the microhardness method. Finally corrosion properties of intermetallic coated stainless steels were determined using electrochemical methods and compared with each other. As a result, both the hardness values and corrosion resistances of both stainless steels have increased with intermetallic coatings.