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《功能材料》2017,(11)
以KNO_3为氧化剂,经5%~15%(质量分数)KOH常温浸渍,在N_2-水蒸气混合气氛下进行控制热分解制备均匀超微孔活性炭。试验选用正交试验法,选择活化温度、活化时间、KOH浸渍浓度、浸渍时间等参数为影响因素,以碘吸附值为考察指标,得到最佳水平组合,活化温度900℃,活化时间1h,KOH浓度15%,浸渍时间24h。对活性炭表征结果如下:最佳样品碘吸附值达840 mg/g。BET比表面积为725cm~2/g,中值孔径为0.489nm,其中微孔容积占总孔容的70.8%,氢气最大吸附量达76.85cm3/g。该样品以超微孔为主,超微孔孔径主要分布在0.45~0.52nm之间,孔分布比较集中,可用于混合气体分离。 相似文献
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《功能材料》2016,(3)
以生物质玉米芯为原料,采用氢氧化钾活化的方法制备了一系列具有高比表面积的活性炭。制备的样品通过热重和氮气吸脱附进行表征,并对样品进行了储氢性能测试。结果表明,碱碳比和活化温度对活性炭的比表面积和总孔容有很大影响,并且随碱碳比和活化温度的升高,活性炭中的微孔比例逐渐减小。储氢测试结果表明,碱碳比为4,活化温度为850℃时,样品的储氢性能最好(-196℃、0.1 MPa下为3.21%,4.0 MPa下为5.80%)。分析活性炭储氢量与微孔孔容的关系可知,吸附氢气最有效孔径随气体压力的变化而变化。0.1 MPa下,孔径为1.5~2nm的孔最有利于氢气吸附,而更高压力下(4.0 MPa),孔径为0.85~1.5nm的孔型更有利于氢气吸附。 相似文献
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《化工新型材料》2016,(8)
以毛豆秸秆、茄子秸秆为原料,KOH为活化剂制备活性炭。采用正交实验对活性炭的制备工艺进行了优化,并研究了该活性炭对正己烷蒸气的吸附、解吸特性。实验结果表明:毛豆秸秆活性炭吸附性能优于茄子秸秆活性炭;毛豆秸秆活性炭最佳制备条件为炭化温度450℃、碱炭质量比为1、活化时间90min、活化温度750℃,此条件下对正己烷蒸气的吸附率为60.44%;茄子秸秆活性炭的最佳制备条件为炭化温度450℃、碱炭质量比为5、活化时间60min、活化温度650℃,此条件下对正己烷蒸气的吸附率为55.60%;二者的吸附率均达到较高水平;随实验次数增加,2种活性炭对正己烷的解吸率升高,而吸附率降低。 相似文献
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太西无烟煤制备微孔活性炭的试验研究 总被引:6,自引:5,他引:6
研究了在硝酸盐与含钾化合物两种添加剂作用下用太西无烟煤制备微孔活性炭的试验条件。其制备工艺为经粉磨的原料煤和添加剂混捏挤条,然后炭化和活化。在试验中利用正交试验法,选定两种添加剂比例、炭化升温速度、活化温度、活化时间作为考查的四个因素,微孔孔容作为考查指标,得出了最佳水平组合:添加剂硝酸盐与含钾化合物的质量比为2:1,炭化升温速度5℃/min,活化温度920℃,活化时间3.5h。用氮气吸附法对活性炭产品进行分析,并用BET法、D-R方程和密度函数理论(DFT)表征了活性炭产品的比表面、总孔容、微孔孔容和孔径分布等性能指标。并对添加质量分数为6%的添加剂和无添加剂,其余因素取最佳水平值制得的活性炭产品用DFT法进行了孔径分布分析。结果表明,相同条件下添加质量分数为6%的添加剂制得的活性炭在微孔孔容和总孔容方面都有较大的提高:微孔孔容从0.1847mL/g提高到0.3299mL/g,总孔容从0.2186mL/g提高到0.5128mL/g。 相似文献
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以云南曲靖褐煤、陕西神府烟煤和山西大同烟煤与有机添加剂的混合物为原料,经过挤出成型、炭化、水蒸气活化得到蜂窝状活性炭,采用N2吸附、压力试验、热天平等测试手段对得到的样品进行了分析表征。结果显示,煤种和活化程度显著影响蜂窝状活性炭孔结构、着火温度和机械强度,以大同煤为原料制备的蜂窝状活性炭具有高的比表面积(884m2/g)、着火温度(535℃)和机械强度(>13MPa)。煤基蜂窝状活性炭的机械强度随大孔容积的增加呈下降趋势。煤基蜂窝状活性炭的着火点与其中的挥发份含量成反比关系,而与灰分含量无关。 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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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 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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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