煅烧条件对介孔TiO_2空心球成形的影响及其结构与性能研究

以三聚氰胺甲醛(MF)微球为硬模板和十六烷基三甲基溴化铵(CTAB)为介孔导向剂,经溶胶-凝胶法和高温煅烧模板辅助法合成了具有介孔结构的TiO_2空心球。探讨了煅烧温度和煅烧时间的改变对介孔TiO_2空心球完整性形成的影响,采用扫描电镜(SEM)、透射电镜(TEM)、红外光谱(FT-IR)、氮气吸附-脱附(BET)、X射线衍射(XRD)、紫外-可见分光光度法等测试手段对成形完整的TiO_2空心球的表面形貌、结构、组分和光谱性质进行了表征。结果表明,在500℃的条件下煅烧3h能形成结构完整的锐钛矿型TiO_2空心球,具有完整的球形空腔、较高的比表面积,其粒径在700nm左右,形成介孔的壳层厚度在75nm左右。另外,介孔TiO_2空心球对亚甲基蓝在紫外光照射下有较高的光催化活性。     

氮-镨共掺杂TiO_2的制备及催化性能研究

为了提高TiO_2的光催化性能,采用溶胶凝胶法制备了N和稀土Pr共掺杂TiO_2光催化剂。用XRD、SEM和紫外-可见光分度计对样品进行表征,并考察了掺杂量、煅烧温度和晶型对TiO_2光催化性能的影响。研究发现N-Pr混合改性的TiO_2的催化活性均高于未改性的,5%的N和0.5%的Pr混合掺杂并经500℃锻烧后,样品为单一的锐钛矿相且粒径分布较窄,在模拟灯光照射下表现出较高的光催化活性和降解甲基橙溶液的能力,在80 min内使甲基橙溶液的降解率达到了99%。     

N-CQDs修饰介孔TiO2/RGO异构体的构建及光催化性能研究

以柠檬酸三铵为前驱体,构建了系列N-CQDs(N掺杂碳量子点)修饰介孔TiO_2/RGO(还原氧化石墨烯)异构体,并通过XRD、TEM、BET、BJH、XPS、PL、UV-Vis等测试手段系统表征其样品的微观结构以及谱学性能,通过使用模拟太阳光为光源测试其光催化性能。实验可知,所构建系列样品均为锐钛矿相TiO_2晶体结构,且显著形成了H2型介孔结构,均属于langmuir Ⅳ型孔径结构;柠檬酸三铵的引入以及RGO的异构化逐步地增加介孔TiO_2光催化体系比表面积,体系比表面积最高可达331.6 m~2/g;N-CQDs的修饰以及RGO的异构化,使介孔TiO_2光催化体系光生电子效率逐步地提升,同时体系光谱响应范围逐步地拓宽;所构建介孔TiO_2异构体均具有较强的可见光光催化性能,其中样品N-CQDs-MT/RGO-1.8的光催化活性最强,在模拟太阳光照射下,对甲基橙的降解率在10 min内可达到90%左右,1 h的降解率可达到99%。     

硅掺杂介孔TiO2材料的制备及可见光下降解甲基橙研究

采用溶胶-凝胶法合成了硅掺杂的介孔TiO2材料,用X射线衍射(XRD)、透射电子显微镜(TEM)、和N2吸附脱附等分析手段对产物结构和光学性能进行了表征.分别在紫外和可见光下对甲基橙进行了降解实验,结果表明:Si/TiO2介孔材料在紫外光和可见光下均有较高的催化活性,3%Si/TiO2为催化剂,初始pH=3,催化剂用量为2g/L的条件下,分别以紫外光和可见光为激发光源降解甲基橙,甲基橙在1.5h和4h内被完全降解.     

铁铕共掺杂的TiO_2空心微球的制备及光催化活性

通过溶胶-凝胶法制备铁铕共掺杂的TiO_2(Fe~(3+)-Eu~(3+)/TiO_2)空心微球,采用XRD、TEM、BET和XPS等对样品进行表征,以亚甲基蓝(MB)的光催化降解为目标反应,评价其光催化活性。结果表明:SiO_2微球表面均匀地包覆了1层TiO_2,超声有利于提高SiO_2@TiO_2复合微球间的分散性,同时也发现煅烧前对SiO_2@TiO_2复合微球进行研磨处理后所得的Fe~(3+)-Eu~(3+)/TiO_2空心微球部分塌陷,而未研磨和煅烧后研磨所得Fe~(3+)-Eu~(3+)/TiO_2空心微球完整性较好。XRD和BET分析表明,Fe~(3+)-Eu~(3+)/TiO_2空心微球为锐钛矿且具有良好的介孔结构,铁铕共掺杂在TiO_2空心微球中产生协同作用,使Fe3+-Eu3+/TiO2空心微球的粒径进一步减小,比表面积增大。当Fe~(3+)的掺杂量为1.0%、Eu~(3+)的掺杂量为0.5%时,Fe~(3+)-Eu~(3+)/TiO_2空心微球的光催化活性最高。     

氮掺杂改性TiO_2多孔薄膜光催化降解4-硝基苯酚

本文采用溶胶-凝胶法制备了N掺杂TiO_2光催化剂,并对N掺杂TiO_2进行了改性,分别以P25、N掺杂TiO_2、改性的N掺杂TiO_2为原料,通过逐步研磨、旋转涂膜以及高温煅烧制得三种多孔薄膜,并对其进行了表征。场发射扫描电子显微镜(FESEM)观察结果显示,煅烧后薄膜呈现显著的多孔结构。以4-硝基苯酚(4-NP)溶液为目标污染物,研究紫外光下TiO_2多孔薄膜的光催化性能,确定最佳降解条件,并研究了薄膜耐用性以及三种薄膜对4-NP的光催化性能的比较。结果表明,三种多孔薄膜中,改性N掺杂TiO_2多孔薄膜光催化性能最佳,10mg/L的4-NP溶液吸附30min,在pH=2条件下180min,降解率达到了90%以上,改性N掺杂TiO_2多孔薄膜单次降解180min,循环使用4次的降解率仍接近80%,显示了薄膜具有较好的可耐用性。     

稀土Dy掺杂对纳米TiO2相变及光催化性能的影响

采用溶胶-微波法制备了稀土元素Dy掺杂的纳米TiO_2复合粉体,采用XRD、拉曼、XPS等手段对样品进行了表征和分析,并以甲基橙的光催化降解为探针反应,探讨稀土Dy掺杂对纳米TiO_2的相变及光催化活性的影响。研究结果表明:稀土掺量为1.3%、经550℃煅烧后制备的样品光催化活性显著提高,对甲基橙的降解率为92%。与未掺杂纳米TiO_2相比,稀土Dy掺杂可以阻碍纳米TiO_2晶粒的生长,增大了比表面积;提高其热稳定性,抑制TiO_2锐钛矿相向金红石相转变;并使TiO_2产生晶格缺陷从而增加纳米TiO_2粉体表面羟基含量和表面氧空位,抑制了光生电子和空穴的复合,增强纳米TiO_2的光催化活性。     

Ce掺杂的有序大孔TiO_2制备及其光催化性能研究

以硝酸铈和异丙醇钛为铈源和钛源,利用溶胶-凝胶和胶晶模板技术合成了一种新型Ce掺杂的有序大孔TiO_2光催化材料,并用扫描电镜、透射电镜、X射线衍射、紫外-可见光谱、比表面积分析等手段对样品结构和形貌进行了表征。最后以甲基橙溶液为对象,在可见光条件下,考察了不同Ce掺杂量的大孔TiO_2材料的可见光催化性能。结果表明,Ce掺杂的大孔TiO_2材料在可见光条件下展现出良好的光催化性能和循环再生能力,当Ce/Ti摩尔比为0.3∶1时,光催化性能最佳,甲基橙降解率可达96%。     

Eu、Y掺杂TiO_2光催化剂的制备及光催化性能研究

以硝酸铕、硝酸钇、钛酸四丁酯为原料,采用溶胶-凝胶法分别制备了Eu、Y单掺杂及Eu、Y共掺杂TiO_2光催化剂,采用XRD、BET、XPS、UV-Vis对产物的结构和性能进行表征。以亚甲基蓝为目标产物,考察了制备光催化剂的光催化性能。结果表明:Eu、Y共掺杂TiO_2光催化剂比单掺杂的光催化活性高;在热处理温度600℃、掺杂摩尔分数为1.2%条件下,Eu、Y共掺杂TiO_2光催化剂对亚甲基蓝的降解率最高,可达90%左右,协同掺杂作用提高了TiO_2的光催化活性。     

N、S共掺杂TiO_2催化剂的制备及其光催化性能

以硫脲作为N、S源,尿素作为水解调节剂,水热合成了N/S-TiO_2催化剂。采用XRD、SEM、XPS等手段对产品进行了表征。产品分散后,以质量浓度为0.02g·L~(-1)的甲基橙水溶液为模拟污染物,采用UV-vis光谱,多点BET分析及光催化实验研究了所得产品的光催化活性效果。实验结果表明:S以+6价形式进入TiO_2晶格取代Ti形成Ti-O-S键,N通过取代晶格中的O形成O-Ti-N键而改变了TiO_2能带结构。当煅烧温度为500℃时,水热合成出的产品结晶度较高,粒径较小,约17nm左右。光催化活性实验结果表明:当紫外灯照射时间达到1.5h时,N/S-TiO_2催化剂降解甲基橙溶液基本完成,脱色率达到96%以上。     

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.……     

From Industry 4.0 to Research 4.0. Development of High Performance Fibers in the Light of Digitization

We associate a variety of innovations with the term ＂Industry 4.0＂. The pioneer of many 4.0 modifications forms the basisfor the trend towards the integrated di...     

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.……     

Roman iron and steel: A review

ABSTRACT

The production of ferrous metal increased during the Roman Late Republican period, Principate and Empire. The direct bloomery process was used to extract the metal from its ores using slag-tapping and slag-pit furnaces. The fuel was charcoal and an air blast was introduced by bellows-operated tuyères. Iron formed as a bloom, often as a spongy mass of metal, which contained impurities from the smelting process, including unreacted ore, fuel, slag and fragments from the furnace walls, while the metal was often inhomogeneous with varied carbon contents. Blooms were either smithed directly into bars or ingots or they were broken up, which also allowed the removal of gross impurities and a selection of pieces with similar properties to be made. These could then be forge-welded together and formed into characteristically shaped ingots. Making steel in the furnace seems to have been achieved: it depended on the ore and the furnace and conditions within it. Surface carburization was also carried out. Iron and steel were used extensively in construction and for tools and weapons. Fire welding was often used to add pieces of steel to make the edges of tools and weapons, which could be heat-treated by quenching to harden them.     

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.     

Synthesis of Alumina-Zirconia Nanocomposites by Solgel Process

Al₂O₃-ZrO₂ nanocomposites were developed starting with the solgel process. Composite alumina-zirconia nanopowders were synthesized from metallorganic precursors (Aluminium secondary butoxide and zirconium Iso propoxide) using the solgel process. The parameters affecting the synthesis—solvent, concentration of precursor, R/H ratio (i.e., dilution of water in solvent)—were varied as also the temperature and pH. BET and TEM were used to measure nanosize. Diffuse reflectance spectroscopy and also qualitative optical absorption led to identical particle size estimate. The variation of process parameters was used to study the effect and interdependence of process parameters. Artificial Neural Networks was used to rigorously analyze the process. Although this led to confirmation of interdependence of parameters, the presence of a single overwhelming solvent variable was also established. Then the optimal process was used to synthesize more nanopowder. To produce bulk nanocomposite the nanopowders were sintered by varying the temperature and time period. The sintered lithoids were probed with a vickers hardness tester to measure elastic modulus, hardness, and fracture toughness. The results showed high elastic modulus, modest hardness, and very high fracture toughness.