Characterization and precipitation mechanism of α-calcium sulfate hemihydrate growing out of FGD gypsum in salt solution

Alpha-calcium sulfate hemihydrate (α-HH) has been prepared from flue gas desulfurization (FGD) gypsum with salt solution method under atmospheric pressure. X-ray diffraction (XRD), thermogravimetry and differential scanning calorimetry (TG-DSC), optical micrograph, X-ray photoelectron spectroscopy (XPS), energy dispersive spectrometry (EDS), and scanning electron microscopy (SEM) have been employed to characterize the α-HH crystals, based on which the formation and growth mechanisms of the α-HH crystals have been discussed. The results show that FGD gypsum can be successfully transformed into high purity α-HH in salt solution under mild conditions, and that a dissolution-recrystallization route is most probably adopted by this transition. The growth of α-HH crystals in salt solution demonstrates a preferred direction along [001] and results in a bundle-of-sheets or bundle-of-raphide texture. The characteristics revealed in this study can help to understand and control the growth of the α-HH crystal from solution. Supported by the National High-Tech Research & Development Program of China (Grant No. 2006AA06Z385), New Century Excellent Talents in University (Grant No. NCET-04-0549), and the Project of Science and Technology Plan of Zhejiang Province (Grant No. 2007C23055)     

Synthesis and Enhanced Electrochemical Activity of Ag-Pt Bimetallic Nanoparticles Decorated MWCNTs/PANI Nanocomposites

Ag-Pt bimetallic nanoparticles decorated on MWCNTs/PANI nanocomposites have been synthesized by in-situ chemical oxidative polymerization and chemical co-reduction method. The Fourier transform infrared(FT-IR) spectroscopy, X-ray diffraction(XRD), ultraviolet-visible(UV-vis) absorption spectroscopy, scanning electron microscopy(SEM) and transmission electron microscopy(TEM) were used to characterize the morphology and structure of the nanocomposites. It can be observed that the PANI was uniformly grown along the MWCNTs to form MWCNsT/PANI fiber-like nanocomposites with diameter about 60 nm, and the Ag-Pt binary nanoparticles were decorated onto MWCNTs/PANI with particle sizes around 6.8 nm. Cyclic voltammetry(CV) and electrochemical impedance spectroscopy(EIS) were used to characterize the electrochemical performance of the prepared electrode. The results demonstrated that the obtained MWCNTs/PANI/Ag-Pt electrode displayed a good electrochemical activity and fast electron transport, which has potential applications in biosensors and supercapacitors.     

Synthesis and coloring properties of Cd(S1-xSex)pigments by precipitate-hydrothermal method

Cd(S1-xSex) pigments (red to yellow) were synthesized by precipitate-hydrothermal method.The structure,morphology and hue of the powder were characterized by X-ray diffractometry (XRD),scanning electron microscopy (SEM),energy dispersive X-ray spectroscopy (EDAX) and CIE chromaticity.The optimum synthesis conditions were obtained and reaction mechanism was further analyzed as well.The results show that molar ratio of S to Se,pH value and hydrothermal reaction conditions have great effects on the hues of the pigments.Pigments with vivid hues are obtained under the conditions that pH value is about 13.0,hydrothermal reaction condition is at 140 ℃ for 4 h or at 160 ℃ for 6 h.The reaction mechanism is that Se2- of Cd(S1-xSex)substitutes S2- of CdS and then forms a continuous solid solution.     

Passivation Mechanism of 316L Stainless Steel in Oxidizing Acid Solution

The compositions and the chemical valence states of elements of 316L stainless steel passive film formed in the oxidizing acid solution were studied by X-ray Photoelectron Spectroscopic (XPS) analysis. The electrochemical polarization curve was measured. The passivation process in the oxidizing acid solution was studied by AC impedance technology. The results indicated that the stable compounds layer was formed on the surface of the sample and the adsorption was the main step in the nitrite solution during passivation process. The catalysis passivation mechanism was put forward according to the experimental results. During passivation process, the water molecule was adsorbed on the surface of the sample at first in the oxidizing acid solution. The oxidizer in the solution played a role as catalyst. The oxide and hydroxide, which could be changed each other and finally formed stable passive film, were generated from adsorbing intermediate under the catalytic action. The mathematical models for predicting the steady polarization curve and the AC impedance spectra at certain conditions have been obtained. The passivation mechanism of 316L stainless steel in the oxidizing acid solution can be interpreted by the catalysis passivation mechanism.     

Pd/Pt双金属胶体的制备

以聚乙烯吡咯烷酮(PVP)为保护剂,甲醇为还原剂,V(醇)∶V(水)=1∶1的混合溶液为溶剂,制备了铂、钯单金属胶体和钯/铂双金属胶体,并用透射电镜进行了表征。结果表明,所制得的钯胶体和铂胶体颗粒粒径分别为(3.11±0.83)nm和(3.41±0.46)nm。钯/铂双金属胶体平均粒径大小在2.5~3.5 nm之间,其粒径的标准偏差为0.6~0.9 nm。双金属胶体会形成以铂原子在中心聚集,而钯原子在表面富集的结构模型。     

铜铅/钢双金属复合材料组织和粘结强度分析

采用双金属复合材料加工工艺制备铜铅/钢双金属复合材料,对复合材料金相组织、合金成分和界面处相组成进行分析,测定铜铅型轴瓦双金属复合材料的粘结强度。结果表明,专用钢背材料和铜铅合金复合,复合材料粘结强度σ为150 MPa;用08Al钢作钢背,复合材料粘结强度为85 MPa。不同钢背材料对双金属粘结强度产生不同影响,双金属界面金相组织观察和二次电子像结合能谱分析表明,铅均匀分布,未产生偏析现象,Fe原子和Cu原子互扩散而提高了双金属粘结强度。     

低热膨胀磷酸盐陶瓷材料Ca1—xBaxZr4（PO4）6的合成

Ca1-xBaxZr4(PO4)6（0≤X≤1．0,简称CBZP）属于NZP族磷酸盐陶瓷材料,它是新的一类低热膨胀陶瓷材料。本文采用共沉淀法合成了CBZP超细粉体,研究了共沉淀法反应机理和粉体分散性并对粉体进行了热重－差热分析及X射线衍射分析。实验结果表明,反应过程的pH应控制在7－11之间,共沉淀物用乙醇进行分散后,可得到粒径为1.6-1.8μm、分布均匀、无硬团聚体的CBZP超细粉体;煅烧后所得到的超细粉体具有确定的晶型。     

微/纳米ZnO的水热合成及其光学性质

以醋酸锌和氢氧化钠为原料,在低温下联用沉淀法和水热法合成了未掺杂的ZnO,考察了pH和温度等条件对ZnO晶体的影响,通过X射线衍射仪(XRD)、扫描电镜(SEM)、荧光光谱仪(PL)对产物进行了表征。结果表明:沉淀法制得的前躯体在低温下水热反应6h后可以生成晶型较好的六方晶系ZnO晶体。当反应条件变化时,ZnO呈现为微/纳米级的多种形态。130℃下制备的ZnO在380～700nm之间存在多条荧光发射峰,而且发光强度随着pH的增加而增大。     

1,3-丙二胺缩邻香兰素Ni-Gd配合物的合成及表征

文章用乙酸镍和1,3-丙二胺缩邻香兰素得到的配体(H2L),以及硝酸钆在无水甲醇体系中合成Ni-Gd配合物。用红外光谱对邻香兰素、1,3-丙二胺缩邻香兰素(H2L)、[LNi].H2O金属配合物和Ni-Gd配合物进行了表征,并用荧光光谱仪对异核双金属配合物做荧光性能表征。结果表明:金属元素成功的配合到Schiff碱上,成功地合成了1,3-丙二胺缩邻香兰素Ni-Gd配合物。     

Ru-Ir双金属催化剂制备及其催化氯代硝基苯加氢反应的研究

采用浸渍法制备了系列负载型Ru-Ir双金属催化剂,用于催化对氯硝基苯的选择加氢。系统考察了不同制备方法和制备条件对催化剂性能的影响。实验结果表明,以-γA l2O3为载体,用异丙醇共浸渍钌和铱,氢压为4.0 MPa,温度180℃,用氢气还原18 h制备的双金属Ru-Ir催化剂（nRu∶nIr=4∶1,担载量为2.0%）具有较好的催化性能。该催化剂用于对氯硝基苯加氢还原反应中,在反应温度60℃,氢气压力为2.0 MPa,底物与催化剂的摩尔比为1 000∶1条件下,反应1 h,转化率可达90.4%,目标产物对氯苯胺的选择性达99.5%。     

溶剂热法合成单质铜纳米晶

在表面活性剂PVP的辅助下采用溶剂热法成功地合成出了单质铜的纳米晶.同时,通过XRD、SEM手段对其进行探讨和研究,结果表明反应时间和表面活性剂(PVP)的浓度对样品的形貌起到了至关重要的作用.最后,我们推导出了它可能形成的机理.     

水玻璃溶液胶凝过程中硅酸聚合度的测定及分析

本文通过对各种水玻璃溶液透光率的测定,依雷莱(Rayleigh)公式推算出水玻璃溶液胶凝过程中硅酸平均聚合度的变化,比较分析了不同条件下硅酸胶粒性态上的差异,认为硅酸胶粒在偏碱性(pH=8)介质中与在偏酸性(pH=6)介质中相比具有更伸展的体型和较均匀的聚合速度.     

反应介质对沉淀法合成CaF_2粉体结构的影响

以硝酸钙、氟化钾为原料,二次去离子水、无水乙醇为介质,采用直接沉淀法制备出不同粒径的氟化钙纳米粉体,利用XRD、FE-SEM对制备的CaF2纳米粉体进行了分析,研究了不同的介质条件对CaF2纳米粉体的形貌和粒径的影响。结果表明,两种介质条件下均能生成氟化钙纳米颗粒。以去离子水为介质时,得到平均颗粒粒径在50nm左右的纳米粉体,生成的粉体分散性好。以无水乙醇为介质时,生成的粉体粒径在20nm左右,分布均匀。     

Synthesis and coloring properties of Cd（S1-xSex） pigments by precipitate-hydrothermal method

Cd（S1-xSex） pigments （red to yellow） were synthesized by precipitate-hydrothermal method. The structure, morphology and hue of the powder were characterized by X-ray diffractometry （XRD）, scanning electron microscopy （SEM）, energy dispersive X-ray spectroscopy （EDAX） and CIE chromaticity. The optimum synthesis conditions were obtained and reaction mechanism was further analyzed as well. The results show that molar ratio of S to Se, pH value and hydrothermal reaction conditions have great effects on the hues of the pigments. Pigments with vivid hues are obtained under the conditions that pH value is about 13.0, hydrothermal reaction condition is at 140 ℃ for 4 h or at 160 ℃ for 6 h. The reaction mechanism is that Se^2- of Cd（S1-xSex） substitutes S^2- of CdS and then forms a continuous solid solution.     

丙烯腈-丝朊蛋白接枝共聚反应的研究

介绍了丝朊蛋白与丙烯腈接枝共聚的工艺条件,接枝效率及其共聚物组成的测定方法和接枝共聚物的部分性能。用红外光谱、Ｘ－射线衍射对接枝共聚物进行了分析。     

XPS study of the corrosion resisting composite alloying layer obtained by double glow plasma with the brush plating Ni interlayer

The Ni-Cr-Mo-Cu multi-element surface alloying with the electric brush plating Ni interlayer on the low carbon steel substrate has been investigated. By the electrochemical method in 3.5% (mass fraction) NaC1 solution, the corrosion resistance of the composite alloying layer and single alloying layer is determined. The experimental results show that the corrosion resistance of the composite alloying layer is obviously better than that of the single alloying layer. The structure and composition of passive films formed on the two kinds of alloyed layers after electrochemical tests in 3.5% NaC1 solution have been studied using X-ray photoelectron spectroscopy (XPS). It is concluded that the double glow plasma surface alloying of low carbon steel with the electric brush plating Ni interlayer is an appropriate technique to enhance the corrosion resistance compared with the single double glow surface alloying.     

超声波化学法制备尖晶石型纳米铁酸镍

在超声波辐射下用前驱体法合成纳米尖晶石型铁酸镍.对硝酸镍、硝酸铁以及脲的水溶液进行超声波辐射得到前驱体,在950°C下灼烧15 h得到粒径约为15 nm的NiFe2O4颗粒.用X射线衍射、透射电子显微镜以及红外光谱表征,结果表明,用超声波化学法合成的产物确为纳米铁酸镍.     

Existing form and action mechanism of minor scandium and zirconium in Al-Cu-Mg alloy

In order to investigate the existing form and action mechanism of minor scandium (Sc) and zirconium (Zr) in Al-Cu-Mg alloy, microstructures of Al-4Cu-1Mg-Sc-Zr alloy under different conditions, including states of as-cast, homogenized, hot-rolled, as-solution and natural aged, were observed by scanning electron microscopy (SEM), X-ray diffractometry (XRD) and transmission electron microscopy (TEM). It is revealed that Sc and Zr are completely dissolved into the supersaturated solid solution in as-cast ingot...     

FeS<Subscript>2</Subscript> (pyrite) electrodeposition thin films and study of growth mechanism

With the development of semiconductor solar cells, much attention has been focused on the low-cost, high-performance photovoltaic materials for solar cell fabrications. Sul-fide compounds[1,2], due to their desirable optical properties, were widely used in pre-paring solar cells. Although the Cd-based II-VI compounds solar cell, such as CdS, CdTe, etc.[3,4], processes a higher conversion efficiency than the sulfide-based solar cell does. The iron pyrite (FeS2) characteristic of suitable ba…     

离心铸造复合铸铁轧辊复合层凝固过程的数值模拟

本文根据离心铸造大型复合轧辊的生产工艺,建立了复合层凝固过程数学模型,开发了同时求解金属型和复合层温度场的有限元程序.研究了复合层的凝固过程和传热特点,并用微机红外测温系统对复合层内表面温度进行了实测,计算值与实测结果比较一致.