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快速制备含镍SiO2气凝胶材料的研究与表征 总被引:2,自引:0,他引:2
以正硅酸乙酯(TEOS),硝酸镍为原料,HF为催化剂,通过sol-gel法,经CO2超临界流体干燥,可快速制备含镍的SiO2气凝胶;HF的加入大大加速了溶胶-凝胶反应速度.气凝胶密度在20~200mg/cm3范围内连续可调,镍含量的浓度可在1%~30%范围内控.运用IR、XRF、XRD、TEM等方法对样品进行结构表征.研究结果表明,掺杂物以非晶态形式成功掺人SiO2气凝胶中,经673K热处理5h,后SiO2气凝胶载体的微结构未被破坏. 相似文献
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通过正硅酸乙酯在碱性条件下水解生成的SiO2粒子改性酚醛泡沫。利用SEM和TEM对泡沫体进行了观察,同时测试了不同正硅酸乙酯添加量对泡沫冲击强度和压缩强度的影响,并通过热失重分析了改性酚醛泡沫的热稳定性。结果表明:正硅酸乙酯水解生成的SiO2和泡沫体有良好的亲和性,大部分SiO2晶粒尺寸在1μm左右,当正硅酸乙酯的添加量为2%时,泡沫有较好的压缩强度和冲击强度,比纯酚醛泡沫分别提高了40%和63%。同时泡沫的热稳定性有了一定的提升。 相似文献
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通过液相法制备棒状SiO2颗粒,研究正硅酸乙酯的浓度和聚乙烯吡咯烷酮的相对分子质量对棒状SiO2颗粒的影响,利用液相沉积法在最优化条件下制备的棒状SiO2颗粒表面均匀包覆TiO2,制备棒状SiO2-TiO2核壳结构粒子,并采用X射线衍射、透射电镜和傅里叶红外光谱等手段对棒状SiO2-TiO2核壳粒子进行表征。结果表明,随着聚乙烯吡咯烷酮相对分子质量的增大,SiO2颗粒由大头针状转变为棒状,随着正硅酸乙酯浓度的增大,棒状SiO2颗粒的长径比变大并出现类球状颗粒;棒状SiO2表面包覆的TiO2为针状,晶型为锐钛矿,包覆厚度为80 nm左右。 相似文献
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为提高铝粉的耐腐蚀性,研究了片状铝粉原料的表面预处理方法,以达到有效除去表面脂肪酸的目的,以正硅酸乙酯为原料,利用溶胶-凝胶法(Sol-Gel)在表面预处理后的铝粉表面包覆一层SiO2薄膜,以达到增加铝粉耐腐蚀性的目的。将包覆完的铝粉置于一定浓度的盐酸溶液中,以相同时间内的析氢量作为评价标准,通过正交试验的极差分析与方差分析优选出最佳的包覆条件。结果显示:铝粉耐腐蚀性的因素影响大小为正硅酸乙酯添加量>温度>时间>H2O添加量>催化剂添加量;包覆15 g铝粉的最佳工艺条件为温度55℃,反应时间6 h,TEOS添加量12 g,H2O添加量16 g,NH3·H2O添加量1 g;采用最佳方案制备的包覆型铝粉具有较好的耐腐蚀性能。 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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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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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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Zusammenfassung Bei der Gestaltung von Ernteprozessen — beispielsweise des Prozesses Mähdrusch, Körnertransport und -abnahme — als transportverbundene Fließarbeitsverfahren mit mindestens zwei verschiedenen Arbeitsmitteln gibt es einen großen Optimierungsspielraum. Solche Prozesse sind mehrstufige Bedienungsprozesse mit gemischter Anordnung der Bedienungseinrichtungen. Außerdem besitzen sie stark ausgeprägte räumliche Aspekte. Es wird vor allem gezeigt, welche Merkmale solcher Prozesse in Simulationsmodellen abgebildet sein müssen, welche Zielgrößen in Abhängigkeit von welchen Einflußgrößen unter Berücksichtigung welcher Prozeßbedingungen ermittelt werden sollten und wie der Bewertungsprozeß zur Ermittlung der gewünschten Informationen gestaltet werden muß. 相似文献
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C. Qihong W. Zhan‐Wen J. Yi J. Yehua L. Fei F. Hanguang 《Materialwissenschaft und Werkstofftechnik》2014,45(7):582-590
In the present study a high‐boron high speed steel (HSS) roll material was designed. Many expensive alloy elements have been substituted by cheap boron alloy, and high‐boron high speed steel roll has been manufactured by centrifugal casting method. The microstructures, mechanical properties and wear resistance of centrifugal casting high‐boron high speed steel roll have been investigated by optical microscopy (OM), scanning electron microscopy (SEM), and X‐ray diffraction (XRD) analysis, hardness test, impact test and wear test. The results indicated that the solidification microstructures of high‐boron high speed steel roll consisted of M2(B,C), (W,Mo)2(B,C), M3(B,C), M23(B,C)6 type borocarbides and martensite, a small amount of retained austenite. Borocarbides were continuously distributed over the grain boundary. After quenching from 1050 °C, local broken network appeared in partial borocarbides, and fine secondary borocarbide precipitated from the matrix. After tempering from 525 °C, the amount of precipitated borocarbide increased significantly. After heat treatment, the hardness of high‐boron high speed steel roll excelled 60 HRC, and its impact toughness excelled 8.0 J/cm2. The single groove steel rolling amount of high‐boron high speed steel rolls increases by 500% than that of bainite cast iron roll, when the rolls are used in K1 mill housing of bar mill. 相似文献
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The end of over unit products of more than Chinese firms have passed the quality grade certification for liquor products. These products involve distilled spirits beer wine yellow wine fruit syrup wine others cover over % of the national top-branded liquor products.…… 《中国标准化(英文版)》2008,25(1):30
The end of 2007, over 200 unit products of more than 80 Chinese firms have passed the quality grade certification for liquor products. These products involve distilled spirits, beer, wine, yellow wine, fruit syrup wine and others, and cover over 80% of the national top-branded liquor products.…… 相似文献
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Surface characterization and microstructure studies are performed on chemical vapor deposited (CVD) tungsten coating. There is about 2 μm thickness diffusion layer of tungsten in the molybdenum substrate. The thermal shock test shows tungsten coating has good adhesion with molybdenum substrate, but the elements of oxygen and carbon in the tungsten coating have the bad affection to the adhesion. The result of high-temperature diffusion experiment is the diffusion rate from molybdenum substrate to tungsten coating is faster. 相似文献