In Ag-La2O3 dispersion plating, where lanthanum oxide is regarded as a dispersed phase, silver ion in liquid medium is adsorbed on the colloidal oxide particles, which have negative charge. As the amount of lanthanum oxide in the medium increases, the co-deposition of the oxide in the deposition layer increases linearly. Oxide co-deposition also increases with increasing current density. It was found that the properties of the plated film depended on the amount of lanthanum oxide in the bath as well as the current density, lanthanum oxide was distributed uniformly on the deposition layer and smaller silver crystals were formed. The hardness and antiwear properties of the plated film were markedly improved over those of pure silver. The addition of triethylenetetramine and polyethyleneimine also improved the surface properties. With the co-deposition of lanthanum oxide particles, the oxide reacts with silver in the deposited layer and a reaction layer is formed, so that the binding energy on the 3d orbit of lanthanum is decreased.
A study on Si3N4-Ti interface behavior and the effect of the Ti reactive layers on the strength of the bond between the Si3N4 ceramic and the metal in active metal brazing was conduced by means of EPMA, SEM, XRD and tensile tests. The results show that the interface reactive layers of Si3N4-Ti consisted of TiN and Ti5Si3. When the Ti foil was thick and the temperature was high, a reactive layer of coarse grain of Ti5Si3 was formed and bond strength decreased.
The influence of the amount of silica added to dry-in-place chromate and of drying temperature were analysed by thermal analysis and mass analysis. The interaction between silica and chromium is estimated further. At temperatures of 80-200°C, two reaction were observed: dehydration condensation of the silanol group and polymerization of the chromate constituent. When silica was added, the polymerization enthalpy of the chromate constituent decreased. This was caused by a reduction in the chance of bonding between the ions of the chromate constituent due to the dilution effect of silica particles in dried coating. This demonstrates that polymerization of the chromate coating is obstructed by the addition of silica. Change in chromium fixation rate in aqueous solution is good agreement with the enthalpy and the polymerization behavior of chromate constituent. Silica in the coating forms coordination cross-linking, and the anions in the chromate constituent work as a bridging group in this case. Thus it is postulated that silica particles are combined with each other by the chromate constituent.
Aluminum foil of 99.99% purity was etched in an aqueous solution of hydrochloric acid, sulfuric acid and aluminum chloride by a 5-Hz AC signal at controlled anodic potential and cathodic potential. The effect of hydrochloric acid concentration and solution temperature on the characteristics of AC-etched aluminum foil were investigated. At a given cathodic potential, the anodic potential above which AC etching takes place and the anodic potential that gives the highest capacity, both shift toward the negative value, as hydrochloric acid concentration and solution temperature increase. At a given anodic potential, the cathodic potential that results in optimum etching, shifts toward the positive value, while the cathodic potential that gives the highest capacity, shifts toward the negative value as hydrochloric acid concentration and solution temperature increase.
Based on the adsorption data of krypton and n-butylbenzene vapor, the shape of the cylindrical pores on anodic alumina prepared in a H2SO4 aqueous solution was estimated to be anomalous, which had a narrow neck (d=84nm) and a somewhat wide body (122nm), and a length of 052μm The characteristic features of adsorption/desorption hysteresis for such cylindrical pores was also clarified