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91.
设计了一种九元系α+β两相新型超高强钛合金。探讨了3种极端合金元素含量的新型钛合金经VAR熔炼+常规锻造+热轧制备14 mm棒材的工艺。研究了合金元素含量和热处理对该新型钛合金显微组织和力学性能的影响。结果表明,该合金在极端元素含量波动情况下具有不同的组织形貌特征;在室温下该材料具有1 200~1 700 MPa的抗拉强度和一般低于5%的延伸率,可以进行真空电子束焊接,但韧性较低;在600℃下具有一定的高温短时强度。根据以上特点,该新型钛合金有望被应用于有特种服役条件要求的场合。 相似文献
92.
Shaomin Liu Mingqiang Chen Lei Chu Zhonglian Yang Chuanhao Zhu Jun Wang Minggong Chen 《International Journal of Hydrogen Energy》2013
Hydrogen will be an important energy carrier in the future and hydrogen production has drawn a great deal of attention to its advantages in efficiency and environmental benefit. Catalytic steam reforming in this study was carried out in a fixed bed tubular reactor with sepiolite catalysts. Sepiolite catalysts modified with nickel (Ni) and molybdenum (Mo) were prepared using the precipitation method. Influential parameters such as temperature, catalyst, steam to carbon ratio (S/C), the feeding space velocity (WHSV), reforming length, and activity of catalyst were investigated and the yields of H2, CO, CH4, and CO2 were obtained. The result of this experiment shows that the acidified sepiolite catalyst with addition of the Ni and Mo greatly improves the activities of catalyst and effectively increases the yield of hydrogen. The favorable reaction condition is as follows: reaction temperature is 700–800 °C; S/C is 16–18; the feeding space velocity is 1.5–2.2 h−1, respectively. 相似文献
93.
94.
研究了纳米SiO2在偶联剂修饰后对质子交换膜的热稳定性及热降解动力学的影响。利用热重分析(TG-DTG)在氮气气氛中,升温速率分别为5℃、10℃和20℃的条件下,采用Kissinger、Flynn-Wal-l Ozawa、Friedman和Modified Coats-Redfem方法对膜SiO2改性后的非等温动力学数据进行了分析。TG-DTG曲线显示SiO2改性后质子交换膜分解率达到10%和15%时,最低热降解温度分别为392.4℃和429.5℃,比改性前分别提高26.8℃和57.7℃。改性后质子交换膜为一步法分解,分解的温度区间为405℃~550℃,热分解的表观活化能E和指前因子lnA分别为223.1 kJ/mol和31.63 min-1,分解过程属于一维扩散(D1)机理控制。 相似文献
95.
钟明强 《现代塑料加工应用》2008,20(6)
采用熔体流动速率测定仪,考察了ABSHGB(丙烯腈-丁二烯-苯乙烯共聚物-中空硼硅酸盐微球,后者简称中空微球)复合材料的流动性能。结果表明,试样熔体服从幂律定律;剪切黏度对温度的依赖性符合Arrhenius关系:ηa(剪切黏度)随着γa(剪切速率)的增加而下降,剪切变稀现象明显。还发现填充体系的剪切黏度随着填充体积分数的增大而非线性增大,且增幅下降。 相似文献
96.
S. Piril Ertem Emel Yilgor Cagla Kosak Garth L. Wilkes Mingqiang Zhang Iskender Yilgor 《Polymer》2012,53(21):4614-4622
Influence of soft segment molecular weight and hard segment content on the morphology, thermomechanical and tensile properties of homologous polyurethaneurea copolymers based on narrow molecular weight poly(propylene oxide)glycol (PPG) oligomers were investigated. A series of polyurethaneureas with hard segment contents of 12–45% by weight and PPG number average molecular weights <Mn> of 2000 to 11,800 g/mol were synthesized and characterized structurally by SAXS and mechanically by DMA and stress strain analysis. Bis(4-isocyanatocyclohexyl)methane and 2-methyl-1,5-diaminopentane were used as the diisocyanate and the chain extender respectively. All copolymers displayed microphase separation by SAXS and DMA. The critical entanglement molecular weight (Me) of PPG is reported to be around 7700 g/mol. Our mechanical results suggest that when copolymers possess similar hard segment contents and are compared to those based on soft segments with number average molecular weights (Mn) greater than Me, they generally displayed higher tensile strengths and particularly lower hysteresis and creep than those having soft segment molecular weights below Me. These results imply that soft segment entanglements in thermoplastic polyurethaneureas may provide a critical contribution to the tensile properties of these copolymers – particularly in the range where the soft segment content is dominant. 相似文献
97.
页岩气藏孔渗结构特征和渗流机理研究现状 总被引:1,自引:0,他引:1
页岩气因其储量大、分布广、清洁,被认为是替代常规能源的重要能源之一。此类气藏属于特低孔、特低渗且存在吸附解吸等特性的非常规气藏。与常规气藏相比,因其具有特殊的微观储存结构和复杂的渗流机理,导致一般无自然产能或低产。因此能否认清其储渗结构和渗流机理是制约页岩气藏有效开发的瓶颈之一。为此调研了页岩气孔渗特征、评价方法以及多尺度下的渗流产出机理发展现状,为下一步的页岩气藏动态分析,产能预测等研究提供理论支撑。 相似文献
98.
为解决烟条切割过程中因旋转式喇叭嘴与虎克式切刀干涉而造成烟支端面不整齐等问题,以ZJ119卷接机组烟条切割装置为对象,对烟条切割运动过程进行分析。通过研究喇叭嘴与切刀发生干涉的机理,建立烟条切割装置的等效运动学模型,并结合数值分析与Adams仿真计算3种喇叭嘴调整方法中喇叭嘴与切刀不产生干涉的最小间隙。结果表明:①在烟条切割过程中,切刀在切入与切出时刻与喇叭嘴在烟条轴线方向上存在位移差是产生干涉的主要原因;②单侧间隙调整、双侧间隙调整和前后排间隙调整3种方法中不发生干涉的最小间隙分别为0.63、0.69和0.51 mm。该方法可为提高烟条切割质量提供支持。 相似文献
99.
Jintao YangMinjie Wu Feng ChenZhengdong Fei Mingqiang Zhong 《The Journal of Supercritical Fluids》2011,56(2):201-207
Graphene oxide (GO) was prepared by oxidation of graphite using the Hummers method, and was modified by isocyanate to obtain dispersed GO sheets in dimethylformamide. Polystyrene (PS)/GO composites were prepared by solution blending, and their morphologies and properties were characterized. The addition of GO increased the glass transition temperature of the PS/GO composites. The storage modulus and thermal stability of the composites were also improved compared with PS. Foams of PS and PS/GO composites were prepared by supercritical carbon dioxide foaming. The composite foams exhibited slightly higher cell density and smaller cell size compared with the PS foam, indicating the GO sheets can act as heterogeneous nucleation agents. 相似文献
100.
In this study, spherical ordered mesoporous silica (s‐OMS) was applied as a new type of nucleating agent in polystyrene (PS) foaming with supercritical CO2 as a blowing agent. These s‐OMS particles were modified by the selective grafting of PS brushes on the outside surface, by which the mesoporous structure inside particles could be maintained. Transmission electron microscopy, X‐ray diffraction, thermogravimetric analysis, Fourier transform infrared spectroscopy, and Brunauer–Emmett–Teller surface area analysis were used to characterize the structure of the original and modified particles; these indicated that the PS brushes were grafted on the outside surface and the inside porous structure were maintained. PS/s‐OMS–PS composites were prepared by a solution blending method, and the s‐OMS–PS particles could have been well dispersed in the PS matrix because of the surface modification. Subsequently, PS and composite microcellular foams were prepared by a batch foaming process, and the morphology characterization on these foams showed that the s‐OMS particles exhibited an excellent heterogeneous effect on PS foaming. The heterogeneous effect became more significant when the foaming temperature or saturation pressure was low. © 2013 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 130: 4308–4317, 2013 相似文献