工艺因素对钛酸铝溶胶-凝胶转变过程的影响

以硝酸铝和钛酸丁酯为前驱体,用冰醋酸为螯合剂,采用溶胶-凝胶技术制备钛酸铝超细粉,系统研究了溶胶体系中冰醋酸用量、乙醇用量、pH值、水解温度等因素对溶胶-凝胶转变过程的影响,并探讨了其影响机理。同时,还对凝胶陈化时间对粉体性能的影响规律进行了讨论。研究表明,制备稳定溶胶的最佳工艺参数是:冰醋酸与钛酸丁酯的摩尔比以及乙醇与硝酸铝摩尔比分别为2.3∶1和22∶1、pH值为2、水解温度为30℃;凝胶陈化时间以36h为宜。     

SiO_2气凝胶的合成与孔结构表征

采用溶胶-凝胶法结合超临界流体干燥技术制备了SiO2气凝胶,系统地考察了醇硅比、水硅比、体系pH值等制备条件对SiO2气凝胶胶凝时间、孔径分布及孔型结构的影响.结果表明,水硅比对气凝胶的孔径分布和孔型具有较大的影响;水用量增加.胶凝时间延长,气凝胶的孔径分布逐渐变窄,孔型趋于一致.乙醇不参与溶胶-凝胶反应,只对TEOS有助溶和稀释的作用,因此乙醇用量增加,溶胶的胶凝时间延长,但对体系反应的影响相对较小,不会引起气凝胶孔结构的剧烈改变.在较小pH值或弱碱性范围内,pH值对孔形结构的影响也比较小,体系pH值增大,胶凝时间缩短,制得的气凝胶孔径分布较窄,孔型均一.当pH值大于8.5后,不利于气凝胶网络结构的形成和均匀分布,胶凝时间随pH值的增大而延长,制备的气凝胶孔径和孔型分布都比较大.     

SiO_2/ZrO_2复合溶胶稳定性的研究

以正硅酸乙酯(TEOS)、无水乙醇(EtOH)、水和氧氯化锆(ZrOCl2·8H2O)为原料,盐酸(HCl)为催化剂,四乙基溴化铵(TEAB)为添加剂,采用溶胶-凝胶工艺制备SiO2/ZrO2复合溶胶。正交试验和单因素综合分析了乙醇、氧氯化锆、TEAB、pH、水解反应温度对复合溶胶凝胶时间的影响。总结出了稳定性良好的SiO2/ZrO2复合溶胶的制备工艺及以上各因素对复合溶胶稳定性的影响趋势。结果表明:在室温、pH为0.7条件下,实验最优配比是:TEOS∶EtOH∶H2O∶ZrOCl2·8H2O∶TEAB=0.7∶40∶6∶0.3∶0.07;复合溶胶的凝胶时间随着乙醇、TEAB的增加而延长,随着氧氯化锆、水解反应温度的增加而缩短,随着pH的增加先延长后缩短。     

Al2O3气凝胶的制备技术研究

Al2O3气凝胶是一种新型、轻质的纳米多孔材料,具有许多独特的物理、化学性质和潜在的应用价值.综述了Al2O3气凝胶的超临界干燥及非超临界干燥制备方法以及各种制备参数(醇铝盐与水的比例、醇盐的类型、溶剂的类型、温度、乙醇的用量、由催化剂所决定的溶液的pH值、老化时间以及干燥过程)对Al2O3气凝胶性质的影响,并探讨了Al2O3气凝胶进一步研究的方向.     

反应条件对海藻酸钠/聚N-异丙基丙烯酰胺水凝胶温度及pH敏感性能的影响研究

以海藻酸钠(SA)和N-异丙基丙烯酰胺(NIPAM)为原料,采用水溶液聚合法制备了具有温度和pH值双重敏感性的海藻酸钠/聚(N-异丙基丙烯酰胺)水凝胶.在不同温度、不同pH值条件下,考察了单体浓度、交联剂用量、引发剂用量和反应温度对该凝胶溶胀度的影响,结果表明,凝胶有良好的温度和pH敏感性能,单体浓度、交联剂用量、引发剂用量和反应温度对凝胶的溶胀度均有较大影响.     

恩施矿区煤矸石中白炭黑的提取试验

以恩施矿区煤矸石为原料,经煅烧活化、碱熔和乙醇的作用,最后酸中和等工艺过程,制得非晶态、纳米白炭黑。考察了煤矸石煅烧活化温度、NaOH用量、碱熔时间、乙醇浓度和盐析pH值对白炭黑溶出率的影响,并利用X-射线粉末衍射仪、傅里叶红外光谱仪和扫描电子显微镜对煤矸石和白炭黑进行了表征。结果表明,当煤矸石煅烧活化温度为720℃、NaOH用量为煤矸石用量的40%、碱熔时间为2h、乙醇浓度为2mol/L和盐析pH值为9时,白炭黑的溶出率较好,达到90.1%。     

脂肪酸/SiO_2复合相变材料的制备及其对织构的影响因素

以SiO2为载体材料、以脂肪酸为相变材料、以无水酒精和去离子水为溶剂,用溶胶-凝胶法制备脂肪酸/SiO2复合相变材料,用SEM、LPSA、FT-IR、DSC等手段对其表征,研究了芯材种类、相变材料用量、无水酒精用量、去离子水用量、溶液pH值、超声波功率等因素对脂肪酸/SiO2复合相变材料织构的影响。结果表明,脂肪酸/SiO2复合相变材料织构受到芯材种类、相变材料用量、无水酒精用量和去离子水用量的影响较大,也与溶液pH值和超声波功率有关。其最佳工艺参数为:癸酸-棕榈酸为芯材、癸酸-棕榈酸与正硅酸乙酯的物质的量比为0.4、无水酒精与正硅酸乙酯的物质的量比为5、去离子水与正硅酸乙酯的物质的量比为9、溶液pH值4和超声波功率为200W。     

酸碱条件对水玻璃为源制备SiO2气凝胶的影响

以廉价的工业水玻璃为凝胶前躯体,柠檬酸为凝胶促进剂,使用溶胶-凝胶与CO2超临界干燥工艺制备了块状的SiO2气凝胶,并探讨了酸性和碱性条件对所制备SiO2气凝胶结构与性能的影响.实验结果表明:水玻璃在酸性条件(pH≈4)和碱性条件(pH≈10)下均可以制备出完整、无开裂的二氧化硅气凝胶块体样品,酸性和碱性环境对水凝胶和最终SiO2气凝胶结构和性能的影响较大.酸性条件下获得的水凝胶呈透明块体,而碱性条件下所得水凝胶为白色不透明体.与碱性条件下制备的SiO2气凝胶相比,酸性条件下所得气凝胶具有更高的比表面积、较大的密度以及尺寸较小的胶体粒子.     

采用Sol-gel法制备梯度复合热释电薄膜

以TaCl5和NbCl5为原料制备了乙醇钽和乙醇铌,对溶胶-凝胶法制备KTa1-xNbxO3薄膜的工艺过程、影响因素进行了研究,提出了优化的制备工艺,采用溶胶-凝胶法在Pt/Ti/SiO2/Si衬底上制备了组分梯度复合KTa1-xNbxO3热释电薄膜.     

纳米TiO2/SiO2复合催化剂的制备与表征

以钛酸四丁酯、正硅酸乙酯作为前驱体,冰醋酸作为水解抑制剂,用溶胶-凝胶法制备了纳米TiO2/SiO2复合物.讨论了加水量、稳定剂、催化剂、乙醇用量、反应温度等工艺因素对制备过程的影响.用X射线衍射、红外光谱、比表面积仪等测试手段对纳米TiO2/SiO2复合粒子进行了表征.结果表明,用溶胶-凝胶法制备TiO2/SO2复合光催化粒子,整个反应采用滴加方式;各反应组分用量为n(TEOS+TBOT) :n(EtOH) :n(HCl) :n(H2O)=1 :16 :0.06 :4,n(TBOT) :n(HAc)=1 :0.6;反应温度为室温.制备得到的纳米TiO2/SiO2复合粒子主要以锐钛矿型存在;SiO进入TiO2晶体结构中,两者以化学键相结合;TiO2/SiO2复合粒子的比表面积要比纯TiO2粒子的比表面积大得多,当xTi :xsi=3时,TiO2/SiO2复合粒子比表面积达389.11 m2/g.     

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 ...     

Effect of Oxide Assisted Metal Nanoparticles on Microstructure and Morphology of Gallium oxide Nanowires

Several researches have been reported about the characteristic of β-Ga2O3 nanowires which was synthesized on nickel oxide particle. But indeed, recent researches about synthesis of β-Ga2O3 nanowires on oxide-assisted transition metal are limited to nickel or cobalt oxide catalyst. In this work, Gallium oxide (β-Ga2O3 ) nanowires were synthesized by a simple thermal evaporation method from gallium powder in the range of 700 - 1000℃ using the iron, nickel, copper, cobalt and zinc oxide as a catalyst, respectively. The β-Ga2O3 nanowires with single crystalline without defects were successfully synthesized at the reaction temperature of 850, 900 and 950℃ in all the catalysts. But optimum experimental condition in synthesis of nanowires varied with the kind of catalyst. As increasing synthesis temperature,the morphology of gallium oxide nanowires changed from nanowires to nanorods, and its diameter increased. From these results, we could be proposed that the growth mechanism of β-Ga2O3 nanowires was changed with synthesis temperature of nanowires. Microstructure and morphology of Synthesized nanowire was characterized by HR-TEM, FE-SEM, EDX and XRD.     

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