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991.
Masamitsu Watanabe Etsuko Toyoda Toshihiro Ichino Yasuhiro Higashi 《Corrosion Science》2007,49(2):766-780
Copper plates were exposed under sheltered outdoor conditions for up to one year, starting in September 2001 in Musashino City, Tokyo, a suburban area. Following various periods of exposure, the patinas on the plates were characterized to investigate their evolution by using X-ray fluorescence analysis, X-ray diffraction, field emission scanning electron microscopy, and glow discharge optical emission spectroscopy. The difference in the roles of sulfur and chlorine in the early stages of copper patination were identified by analyzing the depth profiles of these two elements. Sulfur was found on top of the patina as cupric sulfates such as posnjakite (Cu4SO4(OH)6 · H2O) or brochantite (Cu4SO4(OH)6). Brochantite appeared only after 12 months of exposure. In contrast, chlorine was found on the surface after only one month of exposure. It gradually penetrated the patina as the exposure period lengthened, forming copper chloride complexes. Chloride ions accumulated at the patina/copper interface, forming nantokite (CuCl), which promoted corrosion. 相似文献
992.
993.
Michael Wrle Hans-Joachim Muhr Holger Meyer zu Altenschildesche Reinhard Nesper 《Journal of Alloys and Compounds》1997,260(1-2):80-87
Ca15(CBN)6(C2)2O contains CBN4− anions as well as C2− units and isolated O2− anions. The compound is obtained by heating a stoichiometric mixture of CaO, C and BN with an excess of Ca in sealed niobium ampoules to 1270 K. It crystallizes in the space group Ia
d with a = 1656.84(9) pm. Preparation, crystal structure, NMR and IR-spectroscopic properties are discussed. 相似文献
994.
第十一届中国国际模展模具评定评述专家组 《电加工与模具》2006,(3):12-23
通过对第十一届中国国际模具技术和设备展览会中模具加工技术以及关键设备、刀具、测量仪器、模具的C如/CAE/CAM技术等的水平评述,介绍了现代模具制造技术的现状、特点和发展趋势。 相似文献
995.
The thermal degradation of foamed polymethyl methacrylate (PMMA) patterns in the expendable pat-tern casting process has been
studied. Various physical transitions that may occur during the degradation of PMMA have been determined using scanning electron
microscopy, differential scanning calorimetry, and thermogravimetric analysis, and the effects of polymer density on the degradation
characteristics have been investigated. The results indicate that, when exposed to elevated temperatures, the polymer beads
collapse at about 140 to 200 °. The collapsed beads melt at 260 ° and begin to volatilize. Peak volatilization temperatures
are on the order of 370 °. The end temperature for volatilization is between 420 and 430 °. The initial density of the polymer
does not have a significant effect on the transition tem-peratures associated with degradation. 相似文献
996.
采用Sol-gel法合成了系列纳米材料La0.68Pb0.32Fe1-xMnxO3(x=0.0,0.1,0.2,0.4,0.6),研究了Mn掺杂对材料的导电特性和气敏特性的影响。研究表明:合成的系列纳米材料均具有正交钙钛矿结构,Mn的掺杂对材料La0.68Pb0.32FeO3的结构没有影响,且对材料粒径的影响较小;随Mn元素含量的增加,La0.68Pb0.32Fe-xMnxO3纳米粉体对丙酮的气敏性均迅速降低;Mn掺杂同时导致电阻率减小,这是由于形成Mn^3+-O^2--Mn^4+双交换作用键的缘故。 相似文献
997.
This communication reports into the effects of flow, fluid composition and the effectiveness of imidazoline inhibitors on the evolution and distribution of corrosion products on 1018 C-steel exposed to CO2 corrosion. Focused ion beam technique was used to measure the thickness of the corrosion product layer (CPL), in contrast to the conventional techniques used to observe the cross-section of specimens. Morphological analysis using scanning electron microscopy revealed topographical variations on the surface with the change in the multiphase environment. The CPL was found to be more porous in nature with the presence of oil in the multiphase environment. Electrochemical impedance spectroscopy was also used in the present study to measure the corrosion rates and was subsequently correlated to the CPL evolution for 1018 C-steel in multiphase environment. 相似文献
998.
999.
介绍国内外不锈钢生产的发展应用状况,认为建立不锈钢生产基地是迈向“钢铁强国”的坚实步代,重点介绍了宝钢集团一钢公司不锈钢工程。 相似文献
1000.
Gallium activity in the B2 phase regions of both binary Co–Ga and ternary Co–Ga–Sb systems was measured by EMF method with stabilized zirconia solid electrolyte The temperature range was 1073–1273 K and Sb concentrations were 1, 2 and 3 mol fractions. Ga activity at 1173 and 1273 K increases sharply in Ga rich region and the addition of Sb to the CoGa phase increases Ga activity. Activity change corresponds to the lattice parameter change with Sb addition to the CoGa phase. 相似文献