共查询到20条相似文献,搜索用时 62 毫秒
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采用38g/L的草酸溶液为电解液,制备了孔洞规则有序,孔径和厚度均一可控的氧化铝模板,并研究了阳极氧化工艺对阳极氧化铝膜形貌的影响。实验结果表明,采用38g/L的草酸溶液作为电解液,经两步法阳极氧化可制得孔径均一,排列规则的多孔阳极氧化铝膜。随着氧化电流密度的升高,氧化膜孔径逐渐增大。电流密度过大,反应放热严重,氧化铝膜孔径均匀性,孔洞形状规则性和有序性都下降。在恒电流密度条件下,氧化膜厚度随着氧化时问的延长呈线性增长,但对氧化铝膜孔径影响较小。 相似文献
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采用电沉积的方法,以减薄阻挡层后的铝基多孔阳极氧化铝(AAO)为模板,制备了银纳米线。采用场发射扫描电镜(FESEM)和X射线衍射(XRD)等检测手段对产物的形貌和结构进行了表征。实验结果表明,所得的银纳米线具有面心立方结构,长度超过4μm,平均直径60nm左右。将所制备的银纳米线制成电极,电化学性能测试表明,银纳米线具有良好的可逆性和较高的比电容,当电流密度为5mA/cm2时,单电极比容量达到1110F/g。机理分析表明,一维结构的Ag纳米线对于提高电化学电容器的综合性能具有重要意义。 相似文献
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交流电沉积制备SnO2纳米线及其电沉积条件研究 总被引:5,自引:0,他引:5
采用阳极氧化的方法制备了孔径为30~50nm多孔阳极氧化铝(AAO)模板,用交流(AC)电沉积法在氧化铝模板孔洞内沉积金属锡,然后在空气中750℃加热含锡的模板10h,热氧化制备了直径在30~50nm SnO2纳米线.用扫描电子显微镜,透射电子显微镜,X射线衍射仪对所制备的SnO2纳米线进行了表征,表明所制备的纳米线为多晶结构.并通过改变交流电沉积过程中的电压,频率和热氧化时间来考察不同沉积条件对沉积结果的影响,发现采用交流沉积制备金属纳米线的过程中,频率和电压是影响沉积结果的关键因素. 相似文献
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通过溶胶填充模板法制备了Li4Ti5O12纳米线阵列,采用SEM、EDS、XRD对纳米线形貌和组成进行了表征.实验结果表明:以孔径为100nm阳极氧化铝模板(AAO),于-0.1MPa负压环境中填充0.8 mol/L Li4Ti5O12溶胶,80℃干燥,900℃空气气氛中焙烧20h,重复填充-干燥-焙烧四次,得到平均直径为70nm尖晶石结构的Li4Ti5O12纳米线阵列.其直径和长度分别由模板的孔径、厚度,溶胶浓度和填充次数控制,晶体结构取决于焙烧时间和温度.并在实验基础上,分析了纳米线形成机理. 相似文献
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《International journal for numerical methods in engineering》2018,113(9):1488-1506
In this paper, we present a new method for inserting several triangulated surfaces into an existing tetrahedral mesh generated by the meccano method. The result is a conformal mesh where each inserted surface is approximated by a set of faces of the final tetrahedral mesh. First, the tetrahedral mesh is refined around the inserted surfaces to capture their geometric features. Second, each immersed surface is approximated by a set of faces from the tetrahedral mesh. Third, following a novel approach, the nodes of the approximated surfaces are mapped to the corresponding immersed surface. Fourth, we untangle and smooth the mesh by optimizing a regularized shape distortion measure for tetrahedral elements in which we move all the nodes of the mesh, restricting the movement of the edge and surface nodes along the corresponding entity they belong to. The refining process allows approximating the immersed surface for any initial meccano tetrahedral mesh. Moreover, the proposed projection method avoids computational expensive geometric projections. Finally, the applied simultaneous untangling and smoothing process delivers a high‐quality mesh and ensures that the immersed surfaces are interpolated. Several examples are presented to assess the properties of the proposed method. 相似文献
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Steffen Müller-Probandt 《材料科学与工程:中英文B版...》2018,(4):161-177
We associate a variety of innovations with the term "Industry 4.0". The pioneer of many 4.0 modifications forms the basisfor the trend towards the integrated di... 相似文献
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Janet Lang 《Materials and Manufacturing Processes》2017,32(7-8):857-866
ABSTRACTThe production of ferrous metal increased during the Roman Late Republican period, Principate and Empire. The direct bloomery process was used to extract the metal from its ores using slag-tapping and slag-pit furnaces. The fuel was charcoal and an air blast was introduced by bellows-operated tuyères. Iron formed as a bloom, often as a spongy mass of metal, which contained impurities from the smelting process, including unreacted ore, fuel, slag and fragments from the furnace walls, while the metal was often inhomogeneous with varied carbon contents. Blooms were either smithed directly into bars or ingots or they were broken up, which also allowed the removal of gross impurities and a selection of pieces with similar properties to be made. These could then be forge-welded together and formed into characteristically shaped ingots. Making steel in the furnace seems to have been achieved: it depended on the ore and the furnace and conditions within it. Surface carburization was also carried out. Iron and steel were used extensively in construction and for tools and weapons. Fire welding was often used to add pieces of steel to make the edges of tools and weapons, which could be heat-treated by quenching to harden them. 相似文献
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A four-ball tester was used to evaluate the anti-wear performance of three kinds of organomolybdemun compounds in the engine oils, i. e., molybdenum dialkyldithiophosphate (MoDDP), molybdenum dialkyldithiocarbamate ( MoDTC), and sulphur and phosphorus freeorganomolybdeum (Molybdate). The results indicate that a low concentration of MoDDP doesn' t improve the anti-wear properties of the commercial engine oils, but a high concentration of MoDDP can obviously improve the anti-wear properties and the load-carrying capacity of the engine oils. MoDTC doesn' t improve the antiwear properties of the engine oils, but worsens the anti-wear properties of the oils. Signifi can timprove ment of frictional and wear characteristics is obtained with Molybdate added in the commercial engine oils and the formulated oils. 相似文献
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Standards are the basis for production enterprises to organize production ex-factory inspection trade 《中国标准化(英文版)》2008,25(1):24-25
Standards are the basis for production enterprises to organize production, ex-factory inspection, trade (delivery) and technical exchanges, product certification, quality arbitration and supervision.…… 相似文献
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A flow calorimeter for enthalpy increment measurements on condensed gases is presented. A better knowledge of the properties of the liquefied natural gas is needed, and therefore a liquid loop has been designed for our flow calorimeter. The fluid loop in the calorimeter is designed in order to avoid the two-phase region, since two phases would give compositional disturbances in the measurements. The avoidance of the two-phase region is made possible by increasing the pressure of the test fluid after the measurement section, then heating the fluid at super-critical pressure past the critical point. Finally, the fluid is throttled to the low-pressure gas state at the inlet condition of the compressor that circulates the fluid. To perform the pressure increase, a new cryogenic pump has been designed. To evaluate the new equipment, measurements were taken on liquid ethane over the temperature range 146–256 K at pressure between 0.9 and 5.1 MPa. 相似文献
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S. K. Malhotra Paramanand Singh A. Thirunavukkarasu 《Materials and Manufacturing Processes》2006,21(7):652-657
Al2O3-ZrO2 nanocomposites were developed starting with the solgel process. Composite alumina-zirconia nanopowders were synthesized from metallorganic precursors (Aluminium secondary butoxide and zirconium Iso propoxide) using the solgel process. The parameters affecting the synthesis—solvent, concentration of precursor, R/H ratio (i.e., dilution of water in solvent)—were varied as also the temperature and pH. BET and TEM were used to measure nanosize. Diffuse reflectance spectroscopy and also qualitative optical absorption led to identical particle size estimate. The variation of process parameters was used to study the effect and interdependence of process parameters. Artificial Neural Networks was used to rigorously analyze the process. Although this led to confirmation of interdependence of parameters, the presence of a single overwhelming solvent variable was also established. Then the optimal process was used to synthesize more nanopowder. To produce bulk nanocomposite the nanopowders were sintered by varying the temperature and time period. The sintered lithoids were probed with a vickers hardness tester to measure elastic modulus, hardness, and fracture toughness. The results showed high elastic modulus, modest hardness, and very high fracture toughness. 相似文献
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On November 30, 2007, the China Association for Standardization (CAS) held a press conference at Beijing Diaoyutai State Guest House. Leaders from the China Household Electric Appliance Research Institute, the China Household Electric Appliance Association, and the China Consumers' Association attended and made speeches.…… 相似文献
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Friction Stir Processing Strategies for Uniform Distribution of Reinforcement in a Surface Composite
Vipin Sharma Yashpal Gupta Ujjwal Prakash 《Materials and Manufacturing Processes》2016,31(10):1384-1392
Friction stir processing (FSP) is an important technique for preparing surface composites. Fabricating defect-free surface composites with uniform particle distribution by FSP is a challenging task. In this study, silicon carbide particles reinforced AA5083 alloy surface composites was fabricated using different FSP strategies including variation in process parameters, dual-tool processing and tool offset overlapping. Material flow of the processed material with reinforcement particles demonstrated that the distribution of particles was influenced by the stirring action of the probe as well as the extrusion of the plasticized material due to the movement of the tool. Process parameters, particularly rotational speed, showed a dominant influence on the distribution of silicon carbide particles. 相似文献