以甲醛作还原剂制备超细铜粉

以甲醛作还原剂制备超细铜粉刘志杰，赵斌，张宗涛，胡黎明（华东理工大学化学系，上海２００２３７）（华东理工大学国家超细粉末工程研究中心）超细铜粉已得到广泛应用，不同粒径的铜粉有不同的用途：应用于电学领域的铜粉大部分是微米级铜粉［１］；纳米级铜超微粒子分...     

超细铜粉表面磷化及其抗氧化性能研究

本文采用液相化学还原法制备了粒径约 50 nm和 1 μm的超细铜粉 ,分别进行类似钢铁器件的表面防腐蚀处理—磷化处理 ,在铜颗粒的表面形成一层磷化膜 ,显著提高了铜粉的抗氧化性能。得到了在空气中能稳定存在的纳米级铜粉 ,其氧化温度高于 2 2 0℃。并将微米级粉末的氧化温度提高约 1 0 0℃。     

溶液还原法制备球形超细镍粉

超细镍粉由于表面活性高、导电性和导热性好而被广泛应用于化学催化剂、烧结活化剂、导电浆料门等方面．目前，制备超细镍粉的方法主要有问：真空蒸馏冷凝法、机械粉碎法、电解法、羰基镍热分解法、浆化氢还原法和溶液还原法等．在这些方法中，溶液还原法的工艺简单，所得粉末纯度高，颗粒尺寸小且分布均匀[3]．法国的Figlarz等[4]用弱有机还原剂乙二醇还原粒径小干0．1μm的Ni（OH）2。超细粉末，引入AgNO3。作为成核剂后，制得了粒径＜1μm的超细镍粉，但这种方法需长时间高温回流反应，对原料要求苛刻，且采用有机分散介质成本较高，…     

超细核壳铜-银双金属粉末的抗氧化性能研究

本文采用液相化学还原法分别制备了粒径均为50 nm和 1 μm的超细铜粉末，采用置换反应法制备得到了与原铜粉粒径和形貌大致相同的核壳铜-银双金属粉末，用热重仪和XRD衍射仪分别测定了铜－银双金属粉末的热重曲线和XRD图谱，研究了粉末的抗氧化性能。并用透射电子显微镜和X射线荧光光谱仪对粉末的形貌和组成进行了测定。     

环氧树脂导电胶用铜粉抗氧化性

根据铜本身具有的性质,选用γ-氨丙基甲基二乙氧基硅烷（KH-902）对铜粉进行改性,并采用FT-IR、超景深显微镜、TG、SEM及EDS技术对改性铜粉及铜粉导电胶进行表征。 结果表明,添加硅烷偶联剂KH-902可以有效改善铜粉的易氧化的问题,当添加量为3%时,不仅可以明显改善铜粉导电胶在高温固化下抗氧化性能,而且铜粉在环氧树脂胶体体系中能够均匀分散,且铜粉与铜粉之间的搭接紧密,具有良好的导电性能,体积电阻率仅1.31×10-2 Ω·cm。     

离子色谱法测定铜粉中的卤素离子

用离子色谱法测定了铜粉中卤素的含量. 采用酸溶法溶解固体铜粉样品以提取其中的卤化物, 然后分别除去过量的铜离子和硫酸根离子, 排除干扰, 以达到进样要求. 优化了溶解酸、 H2O2及其用量、淋洗液及流速等实验条件. 该方法加标平均回收率为97.4%～102.1%, 可用于实际铜粉样品的测定.     

溶胶-凝胶法合成β-SiC超细粉末

引言目前文献报道的溶胶法合成β-SiC超细粉末多以TEOS(Si(OC_2H_5)_4)和/或PTES(C_6H_5Si(OC_2H_5)_3)等有机硅和碳的化合物为原料,经溶胶-凝胶过程制SiC先驱体,然后在惰性气氛中热解合成.由于所用原料价格较贵,制备出的SiC粉末成本高,难以实现工业化生产.本文旨在探讨采用廉价硅源来制备β-SiC超细粉末的可行性,以加速我国SiC高技术材料的研究和应用.     

超细镍粉复合材料的微波电磁特性研究

以蒸馏水为溶剂,利用快捷、温和的液相还原法制备超细镍粉,将得到的超细镍粉作为填料制备了复合材料,考察了复合材料的电磁屏蔽和吸波性能．结果表明,超细镍粉质量分数为80％的树脂基复合材料在130MHz～1．5GHz测试频段范围内的电磁屏蔽性能高于45dB;而厚度为2mm的超细镍粉／石蜡复合材料在7GHz附近的反射率可达-27dB．     

氧化石墨烯/超细银粒子复合物的制备及其光电性能

超细银粉在太阳能电池正面电极领域有广阔的应用前景,其粒径分布、分散性、表面态与其性能息息相关。 本文通过在液相还原法合成超细银粉的后期引入氧化石墨烯(GO),利用溶液状态下二者相对活性的表面的相互作用获得了性能优良的银粉。 通过X射线衍射(XRD)、拉曼光谱(Raman)和扫描电子显微镜(SEM)等手段对所得复合超细银粉进行结构及形貌表征,结果显示该法获得的银粉分散性较好、尺寸分布较窄。 进而,利用紫外-可见光谱探讨了GO与银粒子之间的相互作用。 而且研究发现:固定硝酸银溶液的浓度,随着GO含量的增加,银粉的导电性能先升高后降低,当GO的质量分数为2.5%时,导电性能更好。 这为超细银粉在实际中的应用提供重要数据和有益参考。     

超声波法制备超细铜粉

在40k Hz超声波作用下,使用以Na BH4作为还原剂的化学还原法制备具有粒径约300 nm~500 nm、产率约为80~90%的超细铜粉,其具有反应温度低反应速率快的优点。最佳制备条件为Cu SO4溶液初始浓度为20 g/L、Na BH4的加入量为1.5 g/L、p H值为11.5、反应温度20~30℃;反应时间20~25 min。通过XPS、XRD、SEM对超细铜粉表面进行检测发现分析表明所制备的超细铜粉呈类球状,其表面有少量Cu2O和Cu(OH)2存在。     

利用手持技术改进测定乙醇分子结构实验

利用压强传感器代替排水集气法,改进测定乙醇分子结构实验的仪器装置,并探索最佳反应条件。另外,设计两个空白实验,结合压强变化曲线对实验误差进行相关讨论。     

光谱仪测试范围的扩展

由于石化行业的生产需要，其材质的使用具有多样性和广泛性，经常会出现顾客委托的测试样品的一个或几个元素跨越光谱仪现有测试程序测量范围的情况。本法通过对光谱仪测试原理的认识，根据光谱仪的测试能力及标样的采集，实现了一个或几个元素测量范围的扩展，并对其测量的影响因素进行了研究。     

Neutral diterpenoids of oleoresins of five species of conifers of Transcarpathia

The compositions of the neutral diterpenoids of the oleoresins of five species of conifers growing in the Transcarpathia have been studied. It has been found that the oleoresins ofAbies alba M.,Larix decidua M., andPicea excelsa L. contain more than 50% of neutral diterpenoids. The group and qualitative compositions of the oxygen-containing diterpenoids have been determined. In the oleoresins ofAbies alba,Picea excelsa, andPicea abies tertiary alcohols — cis-abienol and isocembrol — predominate, while inLarix decidua the main component is the hydroxy ester larixyl acetate. Primary alcohols related to the resin acids have been found in all the oleoresins investigated. Features of the distribution of diterpenoids according to the species of conifers have been revealed. The results obtained are necessary for the chemotaxonomy of conifers of the family Pinceae.Novosibirsk Institute of Organic Chemistry, Siberian Branch, Academy of Sciences of the USSR. Translated from Khimiya Prirodynkh Soedinenii, No. 6, pp. 812–816, November–December, 1988.     

Dichroism of absorption and polarization of phosphorescence of molecules of the closed form of nitrobenzospirothiopyran

The spectral-polarization characteristics of absorption and phosphorescence of molecules of the initial form of nitro-substituted indolinospirobenzothiopyran were studied in oriented polyethylene films and in solutions with different polarity. An oscillator model of the electron transitions responsible for the formation of absorption and luminescence spectra was suggested. It was established that the principal differences in the spectral and photophysical properties of the compound studied and its oxygen-containing analog are associated with the fact that the electronegativity of the S atom is lower than that of the O atom. Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 6, pp. 1143–1146, June, 1997.     

Influence of viscosity of medium on processes of oxygen quenching of excited states of mesoporphyrin

The oxygen quenching rate constants for singlet and triplet excited states of the dimethyl ester of mesoporphyrin IX increase with decreasing viscosity of the medium and reach a maximum at a viscosity of approximately 0.4 mPa·sec, after which the rate constants begin to decrease. The drop in rate constant with increasing fluidity of the medium may be related to a nonequilibrium character of the elementary act in the interaction of the reactants in the solvent cage. In viscous media such as isopropyl alcohol, isobutyl alcohol, and isoamyl alcohol, the reaction radius is greater than the sum of the radii of the reacting particles. The long-range character of these processes is due to the relatively weak dependence of the quenching probability on distance.Translated from Teoreticheskaya i Éksperimental'naya Khimiya, Vol. 25, No. 2, pp. 161–167, March–April, 1989.     

Determination of heats of detonation and influence of components of composite explosives on heats of detonation of high explosives

The heats of detonation of 20 simple high explosives and explosive mixtures were determined by means of an adiabatic detonation calorimeter designed by the authors. The results indicated that the performance of the instrument was reliable and the experimental data were very accurate. For explosive mixtures, there was a linear accumulative relationship between the heats of detonation of the explosive mixture and its components. Accordingly, the heats of detonation of explosive mixtures could be calculated directly from the heats of detonation of simple explosives and the characteristic heats of other components. The experiments showed that the gold or brass shell of the cylindrical charge could be substituted by a thick-walled porcelain shell, which had the advantage of cheapness.

     

物质分配系数的测定实验改进

实验教学目的是从解决实际问题出发,以实验技术训练和实验设计思想培养为目标。介绍了将单一的物质分配系数测定实验改进为综合实验,提高了实验效果及实验资源利用率。     

Calculation of enthalpies of hydrogenation of hydrocarbons

Sets of hydrogen molecule equivalents have been developed which permit the calculation of hydrogenation of different types of carbon-carbon bonds from ab initio total energies (3-21G and 6-31G* basis sets, and, to a more limited extent, for MP2/6-31G* data) of reactants and products. The calculated enthalpies of hydrogenation are in good agreement with experiment for unstrained molecules, with average errors on the order of 2 kcal/mol. The 6-31G* equivalents allow the enthalpies for strained molecules to be calculated accurately, but the 3-21G equivalents do not. The equivalents for both basis sets have been tested by calculating the enthalpies of hydrogenation of carbon-carbon bonds in nitrogen- and oxygen-containing organic molecules, free radicals, and classical carbocations. The results are in good agreement with experiment in most cases.     

非那雄胺合成工艺改进

非那雄胺能抑制5α-还原酶的活性,明显降低二氢睾酮水平,是一种治疗良性前列腺增生的有效药品。该合成工艺以甾烯酮酸为原料,将其与氯化亚砜反应,无须分离即与叔丁胺反应得17β-酰胺化合物,再氧化开环,环合,氢化,脱氢合成了非那雄胺。经元素分析、IR、1HNMR、13CNMR、MS分析表征了其结构。该法无须使用昂贵的2,2-二吡啶二硫化物和剧毒药品苯亚硒酸酐,且以乙酸铵代替氨气,降低了对设备的要求和腐蚀,更适用于工业生产。