The B-H loop of ferrite becomes narrower with a decrease in the excitation frequency. However, even at frequencies lower than 1 kHz, the B-H loop exhibits a certain minimum width, which is referred to as the (DC) hysteresis loop, and its area corresponds to the hysteresis loss. The dynamic magnetic loss is obtained by subtracting the hysteresis loss from the B-H loop area measured at a frequency above 1–10 kHz. The temperature characteristics of the hysteresis and dynamic magnetic losses are determined to be experimentally different, which suggests that the mechanism for the generation of dynamic magnetic loss is not exactly the same as that for the hysteresis loss. The dynamic magnetic loss is expressed using the dynamic magnetic loss parameter, which is a function of B and its time derivative, dB/dt. The dynamic magnetic loss parameter is measured under excitation with a rectangular waveform voltage. A ferrite core of TDK PC47 was used and the maximum magnetic flux density Bm, was set to 350 mT. The measured dynamic magnetic loss parameter was experimentally verified to be one of the intrinsic characteristics of ferrite and was also validated for cases of excitation with sinusoidal waveform voltages.

An impedance bridge using an inductor in parallel with the cell is proposed for accurate measurement of kinetic parameters of fast electrode processes. The theory and method of analysis are given in detail. Its applicability was proved up to at least 50 kc, and possibly at higher frequencies. The kinetic parameters obtained by this method for the electrode reaction Cd2++2e=Cd(Hg) in m Na2SO4 at the D. M. E. were α=0.17, and k°=0.064 cm/sec (25°C).

The effect of heat treatment on tensile and low cycle fatigue properties of the oxygen-free copper for electric power equipment was investigated. The heat treatment at 850 °C for 20 min, which corresponds to the vacuum brazing process, caused the grain growth and relaxation of strain by recrystallization, and thus, the residual stress in the oxygen-free copper was reduced. The tensile strength and 0.2% proof stress were decreased, and elongation was increased by the heat treatment accompanying recrystallization. The plastic strain in the heat-treated specimen was increased compared with that in the untreated specimen under the same stress amplitude condition, and thus, the low cycle fatigue life of the oxygen-free copper was degraded by the heat treatment. Striation was observed in the crack initiation area of the fractured surface in the case of the stress amplitude less than 100 MPa regardless of the presence of the heat treatment. With an increase in the stress amplitude, the river pattern and the quasicleavage fracture were mainly observed in the fracture surfaces of the untreated specimens, and they were observed with striations in the fracture surfaces of the heat-treated ones. The result of the electron backscattered diffraction (EBSD) analysis showed that the grain reference orientation deviation (GROD) map was confirmed to be effective to investigate the fatigue damage degree in the grain by low cycle fatigue. In addition, the EBSD analysis revealed that the grains were deformed, and the GROD value reached approximately 28° in the fractured areas of heat-treated specimens after the low cycle fatigue test.

In this study, the effect of surface treatment of Al with alkaline (pH 10.5 and pH 12.4) and acidic (pH 3.7) electrolyzed water was investigated on bonding strength of solid phase diffusion bonded Al. Aluminum hydroxide and hydroxyl groups were appeared on the surface of Al which was treated with alkaline electrolyzed water of pH 12.4 at 323 K for 2700 s. It was found that such treatment is similar to the one with NaOH aqueous solution at 323 K for 30 s. For bonding strength, shear strength of the bonded Al specimens treated with electrolyzed water of pH 12.4 at 293 K for 3 s and 30 s were higher than that of the untreated specimen.