The reaction distribution inside a polymer electrolyte fuel cell（PEFC）is important for the cell performance and durability, and needs to be elucidated. Visualization of the oxygen partial pressure（p（O₂））was conducted at the surface of a gas diffusion layer（GDL）under the single-serpentine flow channel and the ribs inside a see-through cell during the operation. A luminescent porphyrin dye was used to visualize p（O₂）at the temperature of 80 ℃ and the relative humidity of 53%. The oxygen utilization（Uo₂）was changed from 0% to 80% by changing the current density. p（O₂）under the ribs was lower than that under the flow channel, and the difference in p（O₂）became larger with increasing Uo₂. A small difference in configuration of an MEA in the cell was found to influence the p（O₂）pattern. This technique is expected to be used as a powerful tool for the cell and MEA designs.

To elucidate the mechanisms of the low friction coefficient of CVD diamond films, a series of pin-on-plate type friction tests was conducted in ambient air and in argon. Both pin and plate specimens were coated with CVD diamond. Their surfaces were polished after deposition. Results of the test show a low coefficient of friction in air and show a decreasing tendency with increasing applied load. However, the coefficient of friction fluctuated unstably at higher loads in argon. More wear debris was generated than by the test in air. Moreover, Raman spectroscopic analysis revealed that the wear debris has a form resembling that of hard diamond-like carbon（DLC）. In the experiments to replace the air in friction chamber with argon of different levels of purity, a low coefficient of friction was maintained for a long time with low-purity gas. These results demonstrate that a small amount of oxygen is necessary to convert the diamond to soft graphite-like material by frictional heat. In the absence of oxygen, abrasion powder is regarded as rapidly cooled. Diamond is converted into a material such as a hard DLC, which causes a high coefficient of friction.

Voltammetric technique using an ammonia buffer solution（0.5 mol/dm³ NH₄OH＋0.5 mol/dm³ NH₄Cl）was applied to ascertain the corrosion products formed on tin plating on pure copper or brass and to clarify the products' formation processes. The main corrosion products formed on tin plating in air were found to be SnO and SnO₂･nH₂O. Results further showed that SnO was formed in air at 180 ℃, although SnO₂･nH₂O was formed at 80 ℃ with high relative humidity of 90%. Copper/tin alloy layers in tin plating on copper grew with increased heating time. Analytical results show that the SnO film thickness on tin plating was lower than that on tin sheets. Moreover, characteristic behavior was shown for tin plating on brass in which Zn diffused rapidly to the surface under high-humidity conditions. The diffused Zn was oxidized to ZnO. However, the SnO amounts on tin plating on brass were lower than on pure copper.