The correlation between the anticorrosivity and the intensity of the low energy-photoelectron emission of metal iron particles for magnetic recording media was studied and we found that particles with higher anticorrosivity showed lower intensity in photoelectron emission. Particles treated with cis-1, 2-cyclohexyl-dicarboxylic acid showed a higher threshold for photoelectron emission than those without treatment. This higher threshold was explained by the formation of a surface potential barrier on the outer layer of γ-Fe2O3 by the anionic species of the acid
Cracks occurred on the Al-diffused surface of specimens of type SUS 310S stainless steel during tension loading was observed by a plastic replica technique. The initiation of cracks depended on the Al concentration in the diffusion layer; the strain at which cracks initiated decreased and the number of cracks increased with increasing Al concentration. Cracks occurring at low strain grew with increasing crack opening displacement and a small increase in the number of cracks during tension loading. The fracture strength of the diffusion layer at strain in which cracks just initiated was estimated by the rule of mixtures, considered that the diffused material consisted of two layers of the diffusion layer and the substrate. The fracture strength increased with the increasing degree of order of the α2 phase in the diffusion layer. Energy accumulated in the diffusion layer during tension loading was calculated from a strain-stress curve as energy was released by crack formation. Energy decreased with the increasing degree of order of the diffusion layer. This phenomenon corresponded to the fracture behavior of the layer, that is, change in fracture surfaces from cleavage to intergranular fracture.
Continuous Ni-P alloy plating without any effluence of waste plating solution was studied using a plating cell divided into cathode and anode compartments with a cation exchange membrane and introducing a dimensionally stable anode. Nickel and hydrogen ions reduced in the plating reaction could be replenished by those invading through the membrane from the anode compartment. The replenishment rate of these ions, which depends on their concentration ratio in the anolyte, was maintained at a suitable value by the reasonable distribution of the anodic current to the nickel anode and a dimensionally stable anode. In addition to replenishment through membrane, the continuous addition of phosphorous acid to the catholyte resulted in the constant composition of the plating solution and thus the constant composition of deposited films.
We fabricated an electrochemical photo memory device using a Pt-TiO2-Pt microarray electrode coated with a polypyrrole film. The TiO2 microband electrode, positioned between two comb-shaped Pt electrodes, was an n-type semiconductor to oxidize the polypyrrole film under light irradiation. Because oxidation enhances the conductivity of polypyrrole, light irradiation is detected by the increase in the conductivity of polypyrrole between the two Pt comb electrodes. Enhanced conductivity remained even after light irradiation was terminated. This photo memory behavior was observed when the potential of the titanium oxide electrode was set to -0.3V vs. SCE.
Smooth and semibright to bright Pd-Ag alloy electrodeposits were obtained from an ammoniacal alkaline solution. Silver co-deposition took place under mass-transport-controlled conditions. The Pd-Ag alloy system conformed to the regular type of alloy deposition, one of the five types of alloy-plating processes classified by A. Brenner, and, in this plating bath, Ag, the less noble metal in the standard electrode potential, behaved as the more noble one, as was clearly shown by polarization behavior. To evaluate Pd-Ag alloy deposits from an applicational viewpoint, properties such as contact resistance, solderability, hardness, and corrosion resistance were compared with those of hard gold. In conclusion, Pd-Ag alloy plating is a useful substitute for hard gold in contact application.
Effects of additives on the deposition rate of autocatalytic tin plating were studied for the bath using TiCl3 as a reducing agent. The deposition rate was greatly increased by adding either Ca or Mg to the bath, while drastically decreased by Tl or Sb. Other additives examined, i.e. Zn, Ni, Sr, Mn, Ba, Fe, Al and Sn had no effects on the rate. It was also found desirable to add Ca and Mg as chlorides, iodides, bromides, sulfates, acetates and phosphinates for increasing the deposition rate, whereas not desirable, as nitrates.