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本文首次系统地研究了Na2O—B2O3—Ta2O5。三元新系统的红外光谱,分析了B2O3、Ta2O5含量的变化对玻璃结构的影响。结果表明:随着Na2O/B2O3比值的减小,结构中:[BO4]四面体减小,[BO3]三角体增加。随着Ta2O5含量的增加,[BO4]四面体的数量增多,非桥氧的数量减少,表明Ta5+可以连结非桥氧,形成网络。 相似文献
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Al2O3/(Ag72Cu28)97Ti3/Ti-6Al-4V界面反应 总被引:1,自引:0,他引:1
《机械工程学报》2002,38(2):31-34
在1.8 ks、1
073~1 173 K条件下对Al2O3/(Ag72Cu28)97Ti3/Ti-6Al-4V进行了钎焊试验.通过扫描电镜、波谱、能谱和X射线衍射对界面反应产物进行了测试,确定了界面结构,并讨论了这些反应产物形成的可能性.结果表明,温度小于1
123 K的界面结构为Al2O3/Cu2Ti4O/Cu4Ti3+Cu固溶体/Ag-Cu共晶 + 富Ag相;温度1 173
K的界面结构为Al2O3/Cu3TiO5 + CuAl2O4/Cu4Ti3/富Ag相+ Cu4Ti3. 相似文献
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本文系统地研究了,SiO2-BaO-La2O3-RmOn系统玻璃的光吸收。通过选用不同硅硼比值及引入适宜的Nb2O5含量获得了紫外区透过率好,抗析晶性能好的玻璃。 相似文献
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Al2O3/Cu-Ti-Zr/Nb钎焊研究 总被引:5,自引:0,他引:5
使用Cu-Ti-Zr钎料对Al2O3/Nb进行了钎焊试验。通过扫描电镜、能谱、X射线衍射分析了界面形貌、元素分布,并对反应相进行了判定。Cu70Ti25Zr5钎料在1293K、10min条件下界面产生了3种新相Cu2Ti4O、Ti固溶体、CuTi,界面结构为Al2O3/Cu2Ti4O/Ti固溶体/CuTi/Cu固溶体+CuTi。采用拉剪试验评定了强度,结果证实1293K、10min,使用Cu70Ti25Zr5钎料的接头强度最高达到162MPa,增加或减少Ti的质量分数以及改变保温时间都会使接头抗剪强度下降。 相似文献
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本文研究了在B2O3-La2O3-BaO-Nb2O5四元系统中当B2O3含量分别为25、30、35wt%时,该系统的玻璃生成范围和它们的光性、密度等变化规律。结果表明,随着B2O3含量的增加,系统的玻璃生成范围向贫Nb2O5边界扩充,富Nb2O5边表现收缩。工作中得出了该系统分别以SiO2代B2O3、Al2O3代BaO后的析晶、折射率、色散及密度等性质的变化规律。最后应用该系统研制定型了713/538玻璃。 相似文献
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J. Campa-Molina† O. Blanco† A. Correa-Gomez M. Czank‡ & A. G. Castellanos-Guzman 《Journal of microscopy》2002,208(3):201-211
The domain structures of Zn3B7O13Cl, Zn3B7O13Br and Zn3B7O13I boracite single crystals were studied by means of polarized light in conjunction with electron microscopy. Single crystals of the three compositions were grown by chemical transport reactions in closed quartz ampoules, at a temperature of 900 °C and were examined by polarizing optical microscopy (PLM), scanning electron microscopy (SEM) and transmission electron microscopy (TEM). For both PLM and SEM, the same as‐grown samples were used without having to resort to metallization of the crystal faces. For TEM the single crystals were crushed and mounted on holey carbon films. Comparative electron microscope images were useful for revealing the domain structure of these ferroelectric/ferroelastic materials previously observed between the crossed polars of an optical microscope. X‐ray diffraction analysis of the pulverized crystals was performed for this triad of halogen boracites containing zinc as a common metal. 相似文献
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An Al86 Mn3 Be11 alloy cast into copper mould was subjected to metallographic investigation. The as-cast microstructure consisted of a quasicrystalline icosahedral phase (i-phase), Be4 AlMn phase and, occasionally, a hexagonal phase. Al-rich solid solution represented the dominant phase. The chemical compositions of phases were determined using AES. The composition of the Be4 AlMn slightly deviated from the stoichiometric composition, whereas the composition of the i-phase was approximately Al52 Mn18 Be30 , containing an appreciable amount of Be. The average composition of the hexagonal phase was Al66 Mn21 Be13 . Deep etching and particle extraction provided a deep insight into the three-dimensional morphology of the i-phase and the hexagonal phase, whereas Be4 AlMn was slightly attacked by the etchant. The i-phase was present predominantly in the form of dendrites and a rodlike eutectic phase. The hexagonal phase was primarily in the form of hexagonal platelets, whereas Be4 AlMn was rather irregular in shape. The morphology of the i-phase can be explained by predominant growth in 3-fold directions and the lowest energy of the 5-fold planes, leading to the faceting and adopting a pentagonal dodecahedron shape. The brightnesses of phases in the backscattered electron images were rationalized by determining their backscattering coefficients. TEM investigation showed considerable phason strain in the i-phase, and the polycrystalline nature of the Be4 AlMn phase. 相似文献
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C.J. Klenke 《Tribology International》1990,23(1)
A recent investigation suggests that selected oxides perform well as additives in molybdenum disulphide (MoS2) because of their ability to soften at asperity contacts with the result that the solid lubricant can attain and retain a preferred tribological orientation.This research determined the effectiveness of boric oxide (B2O3), when used as an additive in MoS2, for substrate temperatures ranging from 21°C to 316°C. This range was used to allow the asperity contact temperature to vary below and above the softening point of B2O3. It was found that a moderate friction coefficient and high wear, which is attributed to the additive acting abrasively, occurred when the asperity contact temperature was well below the softening point of the oxide. When the asperity contact temperature neared the softening point of the oxide, the friction coefficient increased dramatically and wear volume was reduced. It is postulated that B2O3 acted adhesively at the interface resulting in a higher coefficient of friction, and wear decreased due to an attainment of a preferred orientation by the MoS2. For asperity contact temperatures significantly above the softening point of B2O3, the friction coefficient returned to about the same value as for temperatures below the softening point. It is speculated that wear continued to increase moderately because of localized melting of the B2O3, permitting the MoS2 to be removed from the interface. These observations support a hypothesis that an additive, such as boric oxide, can soften as the asperity contact temperature approaches the softening point temperature of the additive so that the overall tribological conditions may be improved resulting in reduced interfacial wear. Significant changes in temperature, load or sliding velocity would, of course, dramatically alter the wear characteristics observed at the interface. 相似文献
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