Kinetic model of induced codeposition of Ni-Mo alloys

The kinetic model of induced codeposition of nickel-molybdenum alloys from ammonium citrate solution was studied on rotating disk electrodes to predic t the behavior of the electrode-position. The molybdate (MoO42-) could be f irstly electrochemically reduced to MoO2, and subsequently undergoes a chem ical reduction with atomic hydrogen previously adsorbed on the inducing met al nickel to form molybdenum in alloys. The kinetic equations were derived, and the kinetic parameters were obtained from a comparison of experimental results and the kinetic equations. The electrochemical rate constants for discharge of nickel, molybdenum and water could been expressed as k(1)(E) = 1. 23 x 10(-9) C(Ni)exp( - 0.198FE/RT) mol/(dm(2).s), k(2)(E) = 3.28 x 10( -10) C(Mo)exp(- 0.208FE/RT) mol/(dm(2).s) and k(3)(E) = 1.27 x 10(-6)exp(- 0.062FE/RT) mol/(dm(2).s), where C-Ni and C-Mo are the concentrations of th e nickel ion and molybdate, respectively, and E is the applied potential vs . saturated calomel electrode (SCE). The codeposition process could be well simulated by this model.