ULTRASONIC CAVITATION EROSION-CORROSION BEHAVIOR OF NiTi CLADDINGS WITH Ni AND Cu INTERLAYER

The NiTi claddings by tungsten inert gas (TIG) with Ni and Cu interlayer were manufactured to resist the cavitation erosion-corrosion (CEC). The cavitation test, the open circuit potential and the potentiodynamic polarization measurements were used to study the synergistic effect among cavitation erosion (CE) and corrosion for the NiTi claddings. After the CEC test for 11h, the cumulative mass loss of 304 stainless steel is 5 and 1.15 times that of NiTi-Ni-TIG cladding and NiTi-Cu-TIG cladding, respectively. In NiTi-Cu-TIG cladding, the galvanic corrosion between the Cu-Ti intermetallics and the B2 phase causes the anodic dissolution of the Cu-Ti intermetallics, and results in the B2 phase losing support and spalling off during the CEC test. In contrast, NiTi-Ni-TIG cladding can be used against the CEC because of its uniform microstructure, no Cu-rich area and the effect of corrosion on CE of NiTi-Ni-TIG cladding is small.