In recent years the saving of labor for train maintenance is strongly demanded, andtrain rubber (natural rubber) hoses have to be used in service for longer time andlonger distance. In order to examine the degradation properties, the evaluation of trainrubber hoses were carried out. As the results the explosive pressure and tensile strengthhad little relations with served distances of train, but the elongation at break, maximumloss factor tan δmax, temperature of tan δmax T α and spin-spin relaxation time had somerelations with them.

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The effects of HCO₃^- Cl^- and SO₄^2- on corrosion behavior of copper as a candidatematerial for overpacking for geological disposal of high level radioactive wastes arestudied at 303K in dissolved oxygen (DO)-controlled, ground water-simulating aqueoussolutions by using a cyclic polarization curve method. Two types of polarization curvewere determined Type A in which free corrosion proceeds in the active dissolutionmode, and Type P in which passivation takes place in a potential domain characterizedby a potential that corresponds to Eb, the potential at which the passivated film isbroken. Polarization dependence on DO was also determined when only HCO₃-ispresent, a type P curve results for DO‹0.5ppm; when DO›15ppm, however, a Type P results for HCO₃^-10ppm; when either Cl^- or SO₄^2- coexists with HCO₃^-, HCO₃^-promotes passivation while Cl^- and SO₄^2- promote active dissolution. The constantpotential test shows that the passivated film of copper is easily broken if Cl^- is present.

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