J.S.Wang1
,
2)
,
M.L.Zhou2)
,
J.X.Zhang2)
,
Z.R.Nie2) T.Y.Zuo2) and G.J.Zhang2) 1) State Key Laboratory of Materials Chemistry and Applications
,
Peking University
,
Beijing 100871
,
China2) Schoolof Materials Science and Engineering
,
Beijing Polytechnic University
,
Beijing 100022
,
China
金属学报(英文版)
The valenceofelementyttrium of Y2 O3 Mocathode materialhasbeenstudied by usingther mal weight analysis, X ray diffraction analysis, Scanning electron microscopy and X rayphotoelectronspectrum . It hasbeen provedthatyttrium oxidecan bereduced by molybdenum carbide. Thereaction between powdered Y2 O3 and Mo2 Ccan happen at 1173 , and Y2 O3may bereduced to metallicyttrium . Afterthepowder mixtureof Y2 O3 and Mo2 Cwasheat treated at1873 K, Yttrium existsin two kinds of chemicalstate- yttrium of zero valence and yttrium ofthreevalences.
关键词:
valence
,
null
,
null
,
null
QIAO Lijie LIU Rui XIAO Jimei University of Science and Technology Beijing
,
Beijing
,
China
金属学报(英文版)
The effects of stress components on nucleation sites and propagation directions of stress cor- rosion cracks in brass were investigated with specimens under mode Ⅱ and mode Ⅲ loadings. The results indicated that under mode Ⅱ loading,stress corrosion cracks nucleated on the site with maximum normal stress component and propagated along the plane perpendieular to the maximum normal stress,under mode Ⅲ loading,the stress corrosion crack was not evident on the 45°plane due to the general corrosion in aqueous solution with high NH_4OH concentra- tion,while stress corroded in aqueous solution with low NH_4OH concentration, numerous cracks with spacings of 10—150μm were found on the 45°plane with maximum normal stress and no stress corrosion cracks was observed on the plane with maximum shear stress.
关键词:
stress corrosion cracking
,
null
,
null
,
null
Materials and Corrosion-Werkstoffe Und Korrosion
Carbon steels were pre-corroded in atmospheres containing certain pollutants such as sulfur dioxide or hydrogen sulfide or nitrogen dioxide for certain period of time. Then the pre-corroded samples were further exposed at two central test stations in the country to evaluate the influence of pre-corrosion on the behavior of long-term atmospheric corrosion of carbon steel by gravimetric measurement and rust examinations with FT-IR and XRD. The results showed that the corrosion rates of every kind of carbon steel at Jiangjin station were two times higher than that at Beijing station. The influence of different pre-corrosion conditions on the long-term atmospheric corrosion of carbon steel was analyzed. It followed that the pre-corrosion conditions made the long-term atmospheric corrosion performance of three kinds of carbon steels different, but the differences were small. Among the three pollutants, NO2 showed the strongest influence to the process. As the exposure time was going on, all the samples corroded slowly at Beijing and Jiangjin stations.
关键词:
pollution parameters;prediction;outdoor;rust
