高可见光活性磁性催化剂ZnO/ZnFe_2O_4/石墨烯的制备与表征

以硝酸锌和硫酸亚铁为原料,采用水热法一步合成了ZnO/ZnFe_2O_4纳米颗粒,再通过水合肼还原氧化石墨烯合成了ZnO/ZnFe_2O_4/石墨烯磁性催化剂。采用X射线衍射(XRD),场发射扫描电子显微镜(FESEM),透射电子显微镜(TEM),傅立叶变换红外光谱仪(FT-IR)等仪器对催化剂的结构进行了表征。以亚甲基蓝作为目标降解物,考察了不同石墨烯掺量的磁性催化剂在可见光照射下的光催化性能。结果表明,当石墨烯掺量为3%时,磁性催化剂的活性最优,可见光照射60min后亚甲基蓝溶液的降解率高达98%。磁性催化剂稳定性良好,且由于ZnFe_2O_4的存在,磁性催化剂可通过外部磁场进行回收。     

热氧化烧结条件对树枝状ZnFe_2O_4结构及光催化制氢性能的影响

通过电沉积和热氧化的方法制备了树枝状结构ZnFe_2O_4,研究了热氧化烧结条件对结构和光催化性能的影响。利用SEM、XRD表征样品的形貌和组成,利用紫外可见漫反射分析样品的光吸收性能,利用光催化制氢测试评价样品的光催化性能。结果表明烧结温度升高,树枝状结构氧化物可进一步生长,但是温度过高,枝状结构发生断裂。烧结温度为200℃时,光催化产氢速率为43.5μmol/(h·g),烧结温度为350和450℃时,光催化产氢速率分别为70.5、75.5μmol/(h·g)。烧结气氛不仅影响样品的树枝状结构,并且高纯氮气条件下样品中既有ZnFe_2O_4又有Fe Zn8.87以及Zn O相,其光催化产氢速率明显低于空气气氛烧结得到的样品的光催化产氢速率。     

ZnFe_2O_4纳米粒子-石墨烯复合材料制备和超级电容器性能

为提高ZnFe_2O_4的电化学性能,采用一步溶剂热法合成ZnFe_2O_4纳米粒子-石墨烯复合材料,对其进行X射线衍射、扫描电子显微镜、透射电子显微镜表征和电化学性能分析。结果表明:该方法可防止二维层状结构石墨烯团聚,把ZnFe_2O_4颗粒粒径控制在纳米级且均匀地附着到石墨烯片层上;复合材料呈现二维层状结构,比表面积达到180 m~2/g,有效增加活性位点数量;当电流密度为1 A/g时,复合材料电极的比电容达到180.9 F/g,电化学性能优于纯ZnFe_2O_4电极。     

复合改性活性炭的表征及其吸附模拟烟气中SO_2的研究

为了研究单一金属盐和复合金属盐改性活性炭材料对SO_2吸附性能的影响,以活性炭(activated carbon,AC)为载体,通过水热法制备ZnO/AC复合材料、Fe_2O_3/AC复合材料、ZnFe_2O_4/AC复合材料以及空白AC材料。采用场发射扫描电镜(SEM)、X射线能谱仪(EDS)、X射线衍射仪(XRD)、傅立叶变换红外光谱仪(FTIR)、物理吸附仪(BET)及X射线光电子能谱分析仪(XPS)对复合材料结构及化学组分进行表征,并且在常温条件下考察活性炭复合改性前后对模拟烟气中SO_2的吸附性能。结果表明,复合改性后活性炭材料成功负载金属氧化物活性组分,比表面积孔容减小,孔径增大并且对SO_2的去除效率显著提高。通过AC、ZnFe_2O_4以及4种复合材料脱硫效率的比较发现,负载ZnFe_2O_4的活性炭材料的脱硫效率最高,其比表面积和孔容分别为435.9m~2/g、0.37cm~3/g,脱硫性能试验中样品的击穿时间为136.0min,硫容达到168.3mg/g。     

合成条件对纳米锌铁氧体形貌与性能的影响

采用多元醇法制备ZnFe_2O_4纳米颗粒,研究回流时间、升温速率和回流温度对产物尺寸、形貌和磁性能的影响。通过X射线衍射仪(XRD),透射电子显微镜(TEM),傅里叶红外光谱和振动样品磁强计对样品的结构、形貌和磁性能进行表征。结果表明:制备的ZnFe_2O_4纳米颗粒分散性较好,尺寸较均一。随着回流时间的延长和回流温度的升高,ZnFe_2O_4颗粒粒径增大。回流温度为270℃时,制备的ZnFe_2O_4饱和磁化强度为35.09A·m~2/kg,剩磁较小,矫顽力为4.2kA/m,表现出亚铁磁性。     

铈镧复合氧化物对ZnVCrO陶瓷显微结构及压敏性能的影响

采用混合氧化物工艺经850℃、4h烧结制备了铈镧复合氧化物掺杂的ZnVCrO基压敏陶瓷,综合应用XRD、SEM、EDS和伏安电学特性测试等方法研究了铈镧复合氧化物掺杂在0%~0.6%(质量分数)范围内对显微结构和压敏性能的影响。结果显示,所有样品以ZnO为主晶相,以Zn_3(VO_4)_2、ZnCr_2O_4为第二相,含掺杂样品中还形成Ce(La)VO_4固溶体,其含量随掺杂量增加而升高。铈镧复合氧化物对烧结影响不大,但其含量大于等于0.4%(质量分数)时可大幅提高ZnVO基压敏陶瓷显微组织的均匀性。0.4%(质量分数)铈镧复合氧化物掺杂样品压敏性能最优:非线性系数为24.7,压敏电压为1 029V/mm,漏电流为92μA/cm~2。     

氧化物添加剂对 Si_2N_2O 粉末生成的影响

氮氧化硅(Si_2N_2O)难于直接从 Si_3N_4和 SiO_2中制取。因此加入少量氧化物添加剂,如 Al_2O_3、Y_2O_3或MgO 于 Si_3N_4和 SiO_2中,在1150～1800℃的温度范围内,对 Si_2N_2O 生成反应的动力学进行了研究。应用 X 射线衍射确定了反应产物。实验结果表明,氧化物添加剂导致液相形成,从而降低了反应的活化能,大大加速了 Si_2N_2O 的生成。生成反应可描述如下:Si_3N_4(c)+SiO_2((?))→2Si_2N_2O(c)Si_3N_4在液相中的溶解是控制性步骤。Si_2N_2O 生成动力学与 Si_3N_4在液相中溶解量的大小有关,与 Si_3N_4的晶型种类无关。Y_2O_3或 MgO 比 Al_2O_3添加剂更有利于 Si_2N_2O 的生成。     

静电纺丝法制备的Co0.6Ni0.3Cu0.1Fe2O4和Co0.6Ni0.3Zn0.1Fe2O4纳米纤维的结构及磁性能

采用静电纺丝技术制备出表面光滑、直径均匀的Co_(0.6)Ni_(0.3)Cu_(0.1)Fe_2O_4/PVP和Co_(0.6)Ni_(0.3)Zn_(0.1)Fe_2O_4/PVP纳米纤维前驱丝,经500~900℃煅烧后得到Co_(0.6)Ni_(0.3)Cu_(0.1)Fe_2O_4和Co_(0.6)Ni_(0.3)Zn_(0.1)Fe_2O_4纳米纤维。用TG-DSC、XRD、SEM及VSM现代测试分析手段对Co_(0.6)Ni_(0.3)Cu_(0.1)Fe_2O_4和Co_(0.6)Ni_(0.3)Zn_(0.1)Fe_2O_4纳米纤维的结构、形貌及磁学性能进行测试表征。结果表明:在空气气氛中经500~900℃煅烧后可得到纯尖晶石相、结晶度良好的纳米纤维或短纤维;当温度为700℃时,Co_(0.6)Ni_(0.3)Cu_(0.1)Fe_2O_4和Co_(0.6)Ni_(0.3)Zn_(0.1)Fe_2O_4纳米纤维的形貌细长而光滑且直径相对均匀,大约为80nm;此时Co_(0.6)Ni_(0.3)Cu_(0.1)Fe_2O_4纳米纤维则保有较高的剩磁比(M_r/M_s)及矫顽力,分别为0.56和1 088.87Oe。在500℃、600℃、700℃、800℃、900℃煅烧后,Co_(0.6)Ni_(0.3)Zn_(0.1)Fe_2O_4纳米纤维的饱和磁化强度分别比Co_(0.6)Ni_(0.3)Cu_(0.1)Fe_2O_4纳米纤维增大了14.5%、7%、16%、10.7%、8%,而矫顽力则分别降低了38%、51%、50%、46%、46.7%。两种纳米纤维的饱和磁化强度及矫顽力存在差异,为CoNi铁氧体在电磁方面的应用提供了很好的参考。     

(1-x)Zn_(0.97)Cu_(0.03)Zr(Nb_(0.93)Ta_(0.07))_2O_8-xTiO_2陶瓷微波介电性能研究

以分析纯ZnO、CuO、ZrO_2、Nb_2O_5、Ta_2O_5以及TiO_2为原料,采用传统固相法制备(1-x)Zn_(0.97)Cu_(0.03)Zr(Nb_(0.93)Ta_(0.07))_2O_8-xTiO_2(x=0,0.4,0.45,0.5,0.55,0.575,0.6)微波介质陶瓷。研究了TiO_2对Zn_(0.97)Cu_(0.03)Zr(Nb_(0.93)Ta_(0.07))_2O_8陶瓷的晶体结构、烧结特性、显微形貌以及微波介电性能的影响。结果表明,随着TiO_2含量的增加,(1-x)Zn_(0.97)Cu_(0.03)Zr(Nb_(0.93)Ta_(0.07))_2O_8-xTiO_2陶瓷的晶体结构发生改变,烧结温度明显降低,介电常数逐渐增加,谐振频率温度系数可调节至近零。当x=0.575,陶瓷可在1 070℃保温4h烧结并获得最佳的微波介电性能,介电常数εr=36.25,品质因数Q×f=53 109GHz,频率温度系数τ_f=-6.24×10~(-6)/℃。     

MxOy-Al2O3复合氧化物在生物质油催化裂化中的催化性能

采用共沉淀法制备复合氧化物MxOy-Al2O3(MxOy=CeO_2,ZrO_2,SiO_2,TiO_2)催化剂,同时用XRD、SEM、TPD和FT-IR等对复合氧化物的晶相结构、酸种类、酸量以及热稳定性等进行了表征。结果表明,复合氧化物MxOy-Al2O3对生物质油具有较好的催化裂化的反应活性,其中ZrO_2-Al_2O_3有较好的裂化反应活性和选择性,裂化反应产物分布中相对分子量小于100的占70.72%;SiO2-Al2O3表现出较好的脱氧率,裂解油中含氧率为17.72%,比原料油下降了24.29%,而CeO_2-Al_2O_3催化剂具有较好的抗结焦能力。     

Insertion of triangulated surfaces into a meccano tetrahedral discretization by means of mesh refinement and optimization procedures

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.     

Certification Institutions Expected to Update and Transfer Information on Present Standards

Standards are the basis for production enterprises to organize production, ex-factory inspection, trade (delivery) and technical exchanges, product certification, quality arbitration and supervision.……     

Flow calorimeter for enthalpy increment measurements on condensed gases

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.     

Refrigerators Enter a New Era of Health Preservation Frestech initiates the establishment of China's first standard for household sterilization refrigerators

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.……     

Optimum-Simulation von Ernteprozessen

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.     

A study of centrifugal cast high boron high speed steel

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.     

Thixotropy of Systems with Shear Thinning and Plastic Flow Behavior

The definition of the thixotropy is a decrease in viscosity with time in shear and a subsequent recovery of viscosity after the shear deformation is removed.We ...     

Brainstorming for ISO Strategy 2016-2020

正Responding to ISO’s appeal for survey for the to-be-developed ISO Strategy Plan for 2016-2020,SAC hosted a special workshop over the needs and comments of various fi elds on June 8 in Beijing.The workshop was attended by ISO President-elect and Ansteel General Manager Zhang Xiaogang,SAC Vice-Administrator Yu Xinli,and 30 experts from     

CNAS Passes APLAC's PTP Review

正The review group of Asia Pacific Laboratory Accreditation Cooperation(APLAC)carried out a 4-day peer review of the proficiency testing provider(PTP)for China National Accreditation Service for Conformity Assessment(CNAS)from July 28 to 31,2014.CNAS passed the PTP review with excellent performance.Two senior peer reviewers of APLAC made a comprehensive,rigorous and detailed review of CNAS’s PTP accreditation activities,and made the on-spot inspection of the review groups in Shanghai and Shenzhen respectively.