The aim of the present work is to evaluate the activation energy (Ea) at different cathodic overpotentials (η) by potentiodynamic tests which were carried out at different temperatures of Ni-based, NiCr-m, and NiCr-p porous electrodes, during the alkaline electrolysis processes. On the other hand, the electrochemical stability of the electrodes was evaluated by cyclic voltammetry after 1000 cycles of operation and by potentiostatic tests after 10 h at −1.5 V vs. SCE. The electrodes were sintered with a heating rate of 25 °C/min up to a temperature of 1000 °C (Ni-based and NiCr-m) and 1200 °C (NiCr-p) for 60 min. The results showed that the Ea value was lower for the Ni-based system at equilibrium; however, the NiCr-p electrode had a better performance due to higher negative apparent Ea values as a function of η (dEa/dη). The cyclic voltammetry tests suggest that the NiCr-p electrode improves its activity by about 71% in its long-term operation in comparison with Ni-based and NiCr-m. A similar behavior was observed in the potentiostatic test which showed a higher cathodic current density associated with a charge transfer process after 10 h. The higher stability of the NiCr-p is attributed to a homogeneous Cr distribution in the nickel matrix.
High-temperature surface oxidation kinetics were determined for low-carbon steel using a Joule heating device on hollow cylindrical specimens. The growth of the oxide layer was measured in situ between 800 and 1050 C under isothermal oxidation conditions and in an air laboratory atmosphere ( = 20.3% and humidity = 42%). Through a laser and infrared measuring system, the expansion and temperature were measured continuously. From the data acquired, the oxidation kinetic parameters were obtained at different temperatures with a parabolic-type growth model to estimate the rate of oxide layer generation. The convergence degree of the data fitted with the oxidation model was acceptable and appropriately correlated with the experimental data. Finally, comparisons were made between the estimated kinetic parameters and those reported in the literature, observing that the activation energy values obtained are in the range of the reported values.