热处理对铁掺杂TiO2锐钛矿-金红石相变的影响

采用溶胶-凝胶法制备了纯TiO_2和不同浓度Fe掺杂TiO_2纳米粉末,并对各样品进行了350℃、500℃、650℃的热处理。通过SEM、XRD、EDS、XPS等测试方法对其表面形貌、晶体结构及成分组成进行了表征,研究了热处理温度对Fe掺杂TiO_2相变的影响。实验结果表明:纯TiO_2与Fe-TiO_2在350℃、500℃时均为单一的锐钛矿,650℃时大部分转变为金红石;热处理温度升高有利于锐钛矿向金红石的转变;Fe掺杂后以+3价的形式存在,Fe离子掺杂能够明显减小TiO_2的晶粒尺寸,高浓度的Fe掺杂对锐钛矿-金红石相变有微弱的促进作用。     

直流电弧等离子体法制备TiO2纳米超细粉

采用直流电弧等离子体法直接制备了晶态的TiO2纳米超细粉,粉体中的晶粒既有锐钛矿结构,也有金红石结构;既有单晶结构的TiO2,也有多晶结构的TiO2.当热处理温度低于600℃时,粉体颗粒的长大较为缓慢,粒径在20nm以下;温度高于700℃时,颗粒迅速长大,锐钛矿向金红石结构的转变明显;当温度达到800℃时,样品转变为单晶结构的金红石型TiO2,颗粒大小在40-120nm之间.     

用低温水热法制备可控形貌金红石型纳米TiO2

以四氯化钛为反应前驱体,用低温水热法制备纯金红石相纳米TiO_2,研究了反应温度和反应时间对TiO_2微结构和形貌的影响。X-射线衍射分析表明,所有产物均为纯金红石型纳米TiO_2,晶粒尺寸范围4.0-11.5 nm。红外光谱和热重分析表明,产物TiO_2存在表面羟基和表面水。TEM分析表明,反应温度为60-80℃的TiO_2样品呈梭形,且彼此聚集呈束状,但反应温度高于120℃时呈粒状,且粒径增加。随着反应时间(4-40 h)的延长,TiO_2呈棒状、梭状及颗粒状。     

TiO2/CdS复合光催化剂的制备及结构研究

以钛酸四丁脂为原料、乙醇为溶剂、醋酸为水解抑制剂,采用溶胶-凝胶法制备CdS纳米颗粒改性TiO2光催化剂凝胶.系统地研究了干凝胶的热行为,在不同热处理温度下二氧化钛的晶体结构和二氧化钛热处理温度与晶粒度之间的关系.研究表明,670℃/3h焙烧后,TiO2由锐钛矿结构全部转变为金红石结构;当CdS的掺入量大于6%(mol)时,670℃/3h焙烧后,有CdTiO3新物相生成;CdS的掺入抑制了锐钛矿TiO2晶粒的长大和锐钛矿结构向金红石结构的转变.     

Sm-TiO_2光催化剂的制备及可见光下降解亚甲基蓝的研究

采用溶胶-凝胶法制备了稀土钐掺杂的纳米TiO_2光催化剂(Sm-TiO_2),通过XRD、XPS、UV-Vis-DRS、PL、Nano-sizer纳米粒度分析仪等对Sm-TiO_2样品进行表征和分析,以亚甲基蓝(MB)作为目标降解物,考察了不同掺杂浓度样品对MB的光催化降解效果。结果表明,Sm的替代掺杂引起的晶格畸变促进了金红石相的形成,但晶界及表面的Sm物种抑制了TiO_2从锐钛矿相向金红石相转变,细化了晶粒。适量的Sm掺杂使TiO_2的吸收光谱阈值红移,有效降低了光生电子-空穴对复合率,提高了TiO_2光催化活性。当pH值=2、掺杂量n(Sm)∶n(Ti)=0.006、热处理温度为500℃时,Sm-TiO_2样品在普通日光灯下光催化降解MB的活性最高,其一级表观速率常数较相同条件下纯TiO_2提高了约4倍。     

纳米TiO2粉晶的晶粒长大动力学及相转位动力学

用溶液胶－凝胶法制备了ＴｉＯ２纳米粉晶。对干凝胶做了ＤＴＡ、ＴＧ等热分析。利用ＸＲＤ微结构数据对粉晶长大行为及其相转位进行了分析了研究。结果表明,当热处理温度低于５００℃时,粉末粒径增长缓慢,而热处理温度高于５００℃时,粉末生长上变理论计算了晶粒长大激活能及相转位活化能,研究表明,高温区粒子生长激活能比低温区（５００℃以上）高出几倍,与粗晶粒相比,ＴｉＯ２的锐钛矿向金红石相转变的活化能要低得多。     

B与S共掺杂锐钛矿相TiO_2的制备与性能研究

以钛酸四丁酯、硫脲和硼酸为原料,采用溶胶-水热法制备了B-S-TiO_2光催化剂。通过TG-DTA、XRD、FT-IR、UV-Vis、PL等手段对样品进行表征和分析,研究了不同热处理温度对共掺杂B-S-TiO_2光催化剂晶体特性的影响。以亚甲基蓝(MB)作为目标降解物,研究了不同热处理温度下系列样品在可见光激发下的光催化性能。结果表明,B和S的共掺可以抑制样品由锐钛矿相向金红石相的转变,限制晶粒的生长,拓宽TiO_2的光谱响应范围至可见光区,减小了光生电子-空穴对的复合几率。当n(B)∶n(TiO_2)=1∶25,n(S)∶n(TiO_2)=1∶50,热处理温度为450℃时,B-S-TiO_2样品在发光范围为可见光的普通日光灯下5h内对亚甲基蓝的降解率达92.52%,显著高于同等实验条件下P25的降解率(60.74%)。     

热处理对溶胶-凝胶TiO2薄膜的晶相转变和性能影响

以钛酸丁酯（TPOT）为有机醇盐前驱体，采用溶胶－凝胶技术制备了TiO2溶胶。为测量方便起见，分别制备了凝胶粉体和薄膜，并对样品进行了不同温度的热处理。X射线衍射（XRD）、椭偏仪和紫外－可见光谱（UV－vis)的测量表明：随热处理温度的升高，TiO2的结构由非晶到锐钛矿再到金红石相转变，400℃为锐钛矿相，600℃开始出现金红石相，800℃完全转变为金红石相；晶粒尺寸随热处理温度的升高而逐渐增大，锐钛矿结构的晶粒尺寸范围是2.5-5.5nm，金红石结构的晶粒尺寸范围是5.9-6.8nm；TiO2薄膜的折射率随热处理温度的升高而增大，同时薄膜厚度降低；禁带宽度随热处理温度的升高而增大，同时薄膜厚度降低；禁带宽度随热处理温度升高而变窄，锐钛矿结构的禁带宽度为3.45eV，而金红石结构的禁带宽度为3.30eV。     

磁控气化回收SnO_2陶瓷电极的技术研究

本文提出一种高效回收SnO2陶瓷电极的技术,采用磁控气化回收的方法将SnO2电极制成复合纳米粉末,实现废电极的回收再利用。借助BET(比表面积)、XRD(X射线衍射)和SEM(扫描电子显微镜)等技术对粉末进行表征,结果表明,所回收制备的SnO2复合粉末颗粒形貌呈类球形,平均粒径dBET在100 nm左右。XRD结果表明,未经热处理的粉末晶粒结构为四方金红石型SnO2结构,其中存在极少量SnO,经900℃热处理后,只存在单一四方金红石型SnO2结构。     

不同形貌的TiO_2微球可控合成与机理研究

在盐酸溶液体系中,以TiCl4为原料,采用水热法制备分形结构金红石TiO_2微球。通过对水热温度、反应物配比、加入NaCl等水热条件的考察,讨论了不同水热条件对TiO_2晶型和形貌的影响。利用扫描电子显微镜(SEM)和X射线衍射仪(XRD)对不同形貌的TiO_2微球样品进行表征。SEM分析表明水热合成TiO_2微球的形貌和大小可控,XRD表明合成的TiO_2微球均为金红石型,最后提出了金红石型TiO_2微球的合成机理。     

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.     

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.     

新闻(英文)

正China and Greece Sign the Standardization Cooperation Agreement Witnessed by Chinese Premier Li Keqiang and Greek Prime Minister Antonis Samaras,AQSIQ Minister Zhi Shuping and ELOT Chairman and Executive Director Angelos Tolkas signed the SAC-ELOT Standardization Cooperation Agreement.The Agreement is one of the critical cooperation documents signed during Li Keqiang’s visit in Greece,encouraging China and Greece to