Due to high Fe4N chemical stability, wear resistance, and Bs (saturation magnetic flux density), it shows promise as a magnetic recording medium. The many types of iron nitride, and their properties depend on their preparation. Iron nitrides were prepared by new PVD: electron shower. Nitriding increased with N2 gas pressure, and the Fe4N single phase was obtained at PN2=7×10-3 Torr. Bs was high……1.1T, but Hc (coercive force) low……30Oe. To increase Hc due to shape anisotropy, Fe film was prepared by oblique evaporation, and nitrided by electron shower bombardment in PN2=0.01Torr for 420s. The iron film changed to iron nitride film (Fe4N+Fe2-3N), Bs was 0.75T and Hc was 500Oe. Which made the film applicable in magnetic recording media.
We studied the expanding and reducing of cracks in thermal cycling such as heating and cooling for the ZrO2+8%Y2O3 layer built up from plasma spray on stainless steel and carbon steel, with the following Results 1) The ZrO2+8%Y2O3 layer showed self-repair in thermal cycling such as heating and cooling. 2) The ZrO2+8%Y2O3 layer sprayed on carbon steel had better self-repair than that sprayed on stainless steel, indicating that ZrO2+8%Y2O3 layer self-repair was influenced by a substrate's expansion coefficient. 3) Self-repair of the ZrO2+8%Y2O3 layer is the characteristic property of ZrO2+8%Y2O3 layer built up by spraying particles.
Modification of steel bolt coating layers was studied using two step Hot-Dipping. The sample was at first dipped into primary Zn melt, and successively into secondary Zn-7mass%Al melt. To clean the steel surface, and prevent it from oxidation, two fluxes, aqueous solution and molten salt, were used before the first dip. The formation and morphology of the coating layer were studied using SEM and EPMA. When the aqueous solution flux was used, an alloy layer consists of a palisade δ1 phase and granular (δ1+η) phases, and an ζ phase was formed on the steel surface after the dipping into primary Zn melt. In the sample pretreated with molten salt flux, δ1 phase grew thickly from the steel surface, and ζ phase grew successively, and minimal (δ1+η) phases were ovserved. The alloy layer thickness formed after dipping into secondary melt was controlled by the morphology of the alloy layer formed at the first dipping, i. e., if the alloy layer includes η phase, Fe4Al13-Znx phase, formed by the reaction with Zn-Al melt, is dispersed, resulting in spalling and dislodgment of the alloy layer during centrifugation. When the molten salt flux was used, uniform coating layer thickness more than 50μm was obtained in two step Hot-Dipping.
To determine the presence of chemical compounds, we applied AC voltage to a titanium dioxide surface chemical sensor and recorded conductivity, surface potential and phase difference of the input voltage-output current wave form. This multidimensional information enabled us to distinguish alcohols and benzenes with a single detector. We also found that selecting the suitable type of surface electrode enhances sensitivity of the sensor.
In order to understand codeposition in Mo-Ni alloy electroplating, we studied the environmental atomic scale structure around metallic cations in aqueous solutions for electroplating using anomalous X-ray scattering (AXS) and EXAFS. The size of complex ions in aqueous solutions was also estimated by applying small-angle X-ray scattering (SAXS), and the distribution of chemical species in solutions was obtained from multivariate analysis of visible absorption spectra. The results of AXS, EXAFS and SAXS indicate that a solution containing molybdate involves a isopoly-molybdate anion consisting of seven edge-shared MoO6 octahedra and a solution added nickel sulfate quite likely involves a heteropoly-molybdate anion formed by six edge-shared MoO6 octahedra surrounding a nickel. On the other hand, linkages of octahedra in the heteropoly anion are broken when citrate is added to the Mo-Ni solution. From the multivariate analysis of visible absorption spectra, we found that addod citric ions form new complexes with Mo as well as Ni in aqueous solutions. Thus, disconnection of relatively large complex appears to be essential for the codeposition process as Mo-Ni alloy, and citric ions also play an important role in this electroplating.
Several life tests were conducted for a newly developed oxygen-evolving anode of a thermally decomposed SiO2-IrO2 catalyst layer on a titanium substrate. The lifetime of a 20-overlap coated anode was 6 times longer than that of a 10-overlap coated anode. Over etching of the substrate was effective in surface conditioning. The effects of 11 organic additive agents on anode lifetime were studied separately compared to ethylene chlorohydrin, which was reported in detail elsewhere. No additives, including acetonitrile, butynediol, thiourea and phenolsulfonic acid shortened the lifetime beyond the durable limit for practical use.
The effects of periodically reversed electrolysis on the lifetime of IrO2-based anodes were studied. Periodic current reversal tended to shorten lifetimes. Increasing the cathodic period and cathodic current density of PR electrolysis decreased significantly lifetimes. The deterioration mechanism of the anode during PR electrolysis differed from that during continuous anodic electrolysis.