Evaluation of corrosion resistance of titanium/stainless steel diffusion joints bonded by interlayers made of pure metals

Abstract

.The purpose of this study is to compare corrosion resistance of the joints between commercially pure titanium (Grade 2) and stainless steel (X5CrNi18-10) bonded by interlayers made of pure metals. Three different interlayers were used in the study, which were made of aluminium (Al 99.5), copper (Cu 99.99) and nickel (Ni 99.6). The diffusion bonding process has been employed to join those dissimilar materials. The microstructure of the joints were investigated using scanning electron microscopy equipped with an energy dispersive X-ray system (EDS). The phases of the reaction layers in the diffusion zone were identified by means of an X-ray diffraction (XRD).The structures of the joints varied importantly depending on the interlayer. The galvanic corrosion test was carried out in two solutions one in a 3,5% NaCl and second one in 1M Na2SO4 solution. The potentiodynamic polarization curves in a 3,5% NaCl solution show that the higher corrosion potential as well as a lower corrosion current were registered for the joints performed by nickel. The test carried out in 1M Na2SO4 solution show that that the lowest corrosion current was registered for the joints performed by copper and also all investigated samples have a tendency towards passivation.