The purpose of this study is to investigate the effect of several additives on the ionic conductivity of polyethylene oxide (PEO). The fabrication and characterization of sodium carboxymethylcellulose (CMC-Na) composite PEO solid electrolytes with sodium bis(fluorosulfonyl)imide (NaFSI) as sodium salt were investigated. The prepared PEO electrolyte films were subjected to AC impedance measurements to measure their resistance, and the ionic conductivity was calculated from the results. The ionic conductivity was significantly enhanced by the addition of NaFSI, reaching a maximum of 8.66×10^-5 S/cm, but the ionic conductivity decreased after a certain concentration. This may be due to the fact that the ionic conductivity increases with increasing concentration due to the increase in carrier ions, but above a certain concentration, the glass transition temperature increases due to the increase in complexes. Interfacial electrochemical reactions between PEO and cemented carbide were Co dissolution and WC oxidation.

In die-sinking electrical discharge machining (EDM), pulsed discharges are repeatedly generated between the electrode and workpiece, whereby small discharge craters are repeatedly formed on the workpiece as machining progresses. The machining speed is low in this process because all removed parts are discharged as debris. High-speed EDM was previously attempted using a water-based machining fluid with a high-current discharge of approximately 1000 A with a water-based machining fluid. However, this method is impractical because of electrode wear, low machining accuracy, and high roughness of the machining surface. As another countermeasure, a scooping EDM method that uses a frame electrode was proposed. The machining speed is high because the removed part is processed as mass, not as debris. However, this method is only applied to zinc alloys because the frame electrode disappears with electrode wear. In this study, we propose bottom cutting EDM using a thin-plate electrode, which is theoretically resistant to electrode wear. Highly rigid stainless steel and phosphoric bronze were selected as electrodes to bend the thin-plate electrodes in the horizontal direction. However, using both electrodes is difficult because of the substantial electrode wear and unstable discharge state. Therefore, we devised a hybrid electrode in which a thin copper plate is attached to the tips of both thin-plate electrodes, further determining the attachment method and considering the conditions for stable EDM.

X-ray astronomical telescopes with higher angular resolution are required for future astronomical missions. To achieve a high spatial resolution below 10 arcseconds, high figure accuracy is required for the Wolter mirror, which serves as the focusing element. In this study, we aimed to improve the figure accuracy of Ni-electroformed mirrors by achieving uniform film thickness during electrodeposition. An electrodeposition simulation using the finite element method (FEM) was developed to predict thickness distributions. The simulation reveals that placing shields around the mirror is an effective method to suppress current concentration at the edges. We experimentally confirm that this approach improves the uniformity of the thickness distribution in the electrodeposited film, leading to an increase in the figure accuracy of the Wolter mirror.

In electrical discharge machining, various discharge current waveforms such as square, sawtooth, and sine waveforms have been used by various researchers, and machining speed and tool electrode wear change depending on the waveform. In this study, thermo-fluid analysis in single-pulse discharge was conducted using square and sawtooth waveforms in which the current increases with time, and the effects of discharge current waveforms on the formation of discharge craters were verified. The analysis results showed that, for the sawtooth waveform with increasing current with time, a large recoil pressure owing to the material evaporation was generated at the end of the discharge when the discharge current became large, and the outward velocity at the molten region of the discharge crater became large. Furthermore, single-pulse discharge experiments showed that the sawtooth waveform resulted in a larger removal volume. In addition, in the sawtooth waveform, the pulse duration was varied to investigate when removal tends to occur during the discharge. The removal volume became significantly larger at the end of the discharge. The reason for this is thought to be that the recoil pressure increases at the end of the discharge when the discharge current becomes large, and the molten area is easily removed as indicated by the analysis results.

Surface smoothing of mold steels with planar shape can be performed efficiently by large-area electron beam (EB) irradiation. However, it is difficult to smooth side wall and bottom surfaces in hole shape by the EB irradiation, since the EB tends to concentrate on entrance edge or upper inside wall of hole. The bottom surface of high aspect ratio hole could be smoothed by the EB irradiation under magnetic field control. On the other hand, smoothing of side wall surface in hole shape, and appropriate magnetic field for guiding the EB to the side wall surface have not been clarified yet. In this study, smoothing of side wall surface in hole shape by the EB irradiation was proposed. Experimental results indicate that whole area of side wall surface in hole shape can be uniformly smoothed by the EB irradiation under appropriate magnetic force lines distributions and magnetic flux density.