COMPUTER MODELING THE DIFFUSION OF NI IN NIO AT HIGH-TEMPERATURES

A computer model was developed to simulate the diffusion of Ni through both the grain boundaries and lattice in NiO at high temperatures, us ing a random walk method. The grain boundary network was defined by th e shape and size of oxide grains and by the grain boundary character d istribution (GBCD). These were derived from the experimental data for NiO grown at 1073 K on (100) and (111) faces of Ni single crystal. The simulation shows that GBCD strongly affected the Ni diffusion and the resultant oxidation rate. For GBCD, specific for (100)Ni substrate, t he influence of NiO grain size on the oxidation rate was also tested. The NiO growth parameters obtained during the simulation were verified by comparing them with the experimental oxidation kinetics. (C) 1997 Elsevier Science Ltd.