Stopping corrosion nickel

Nickel is deposited at a current density of 75 A/m. Calculate the limiting current if the reduction occurs at a concentration overpotential of—150 mV. Calculate the corrosion potential, corrosion current, and protection current needed to stop corrosion for cadmium in a corrosive deaerated medium. Additional information ... 

RNi acquires durability toward corrosion from acetylacetone (AA) (CH3—CO—CH2—CO—CH3) by modification (J0). Table XXI shows the amount of corroded nickel in the reaction system from the catalyst when the hydrogenation of A A (10 ml) with RNi or MRNi (400 mg) was carried out at 65 C under 100 kg/cm2 of initial hydrogen pressure and was stopped at the point where 1 mol of hydrogen had been consumed. The durability of... 

The pressure to stop the Ni corrosion cell is much less than the pressure to stop the iron corrosion ceU. Iron is more thermodynamically active with standard potential of -0.44 V vs. SHE when compared with nickel with standard electrode potential ofe° = -0.250V vs. SHE. 

The question one has to put is that, if this is the case, would copper then continue to deposit and nickel completely dissolve from the deposit However, snbseqnent analysis showed that copper emichment at the surface slowed down nntil the copper content reached about 80%, after which the reaction virtually stopped (Roy and Landolt, 1995 Bradley e/a/., 1996). The galvanic corrosion is controlled by copper mass transfer through the hquid phase at the beginning, showing a linear growth of the Cu-rich layer (Roy and Landolt, 1995). Since the reaction stops due to surface emichment of copper, the growth is inhibited quite suddenly when the thickness of the layer reaches about lOiun (Roy and Landolt, 1995 Bradley et al, 1996). 

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