Complexities in predicting erosion corrosion

CrN/NbN coatings deposited by HIPIMS: A preliminary study of erosion–corrosion performance

“…The lower mass loss at +300 mV can be attributed to the protective nature of the passive layers of chromium (Cr) and niobium (Nb) formed in the electrochemical potential range of -300 mV and +350 mV [23]. Transport of the reacting species and corrosion reaction rates in the flowing fluid are higher [24] which can lead to the rapid reformation/repair of any passive layer being removed providing a cushioning effect to the incoming particles thereby reducing the total mass loss. These results are consistent with other studies where researchers have found that passive layer removal under solids-free impingement [24 -25] and for conditions with suspended particles [26] depends on a critical value of velocity.…”

Flow Accelerated Corrosion in Nuclear Power Plants

“…Also, orifices and valves promote turbulence close to the wall in the downstream pipe and thus enhance the rate of mass transfer at the wall [5]. These mechanisms have been identified as the governing factors responsible for FAC as explained by Chen et al [6].…”

Mass Transfer Equation and Hydrodynamic Effects in Erosion-Corrosion

“…However, flow velocity is not sufficient to accurately predict damage, since erosion-corrosion frequently occurs in a turbulent region where the direction of flow changes, such as in a pipe bend, an elbow and or tee pipe fittings. Several papers have reported that the Sherwood number, a dimensionless number used in mass transfer operations, is useful as the mass transfer coefficient in the concentration boundary layer (Sydberger et al 1982;Poulson, 1983Poulson, , 1993Poulson, , 1999Wharton, 2004). Poulson reported that the Sherwood number in many flow conditions can be estimated through electrochemical measurements (Poulson, 1983).…”