首页 | 本学科首页   官方微博 | 高级检索  
相似文献
 共查询到20条相似文献,搜索用时 62 毫秒
1.
络合法合成Sb掺杂SnO2(ATO)纳米粉体   总被引:2,自引:0,他引:2  
采用非均相成核法,在晶种上以络合法均匀生长Sn,Sb混合金属氢氧化物,合成了纳米ATO导电粉体.以粉体电阻、粉体粒径为指标进行实验,得到了最佳络合剂.系统研究了合成条件如掺杂浓度,反应温度、pH值、配体/Sb比等对最终粉体导电性能的影响.以TG—DTA、XRD、TEM等手段研究了晶粒生长过程.结果表明粉体为四方金红石型结构,平均粒径为10nm左右,粉体的团聚很少.  相似文献   

2.
以九水硝酸铁、六水硝酸镍、水溶性肼类燃料为原料,添加金属离子络合剂、分散剂等为辅助剂,利用溶液燃烧合成法制备了纳米NiFe2O4粉体。利用XRD、TEM、SEM等测试方法对产物进行了表征,并研究了不同燃料、络合剂用量、分散剂用量、煅烧温度对粉体粒径和形貌的影响。实验结果表明,在以水溶性肼为燃料、络合剂2g、分散剂2g、煅烧温度800℃、煅烧时间2h时,可获得粒径均匀的纳米NiFe2O4粉体。所得产物的粒径范围为40~80nm,结构膨松,分散性良好。  相似文献   

3.
选用平均粒径约为50~100μm的碳化硅颗粒作为基料,以水合联氨为还原剂、氨水为络合剂,利用非均相成核法制备铜包覆碳化硅复合粉体材料,在温度为83℃时得到了分散效果较好的复合粉体,采用XRD、SEM、EDS对复合粉体进行了表征,结果表明,制备的铜微晶粒径为100nm左右,碳化硅颗粒表面的铜包覆层均匀、连续.  相似文献   

4.
功率超声作用下纳米氧化铜粉体的制备   总被引:6,自引:0,他引:6  
李光  冯伟骏  李喜孟  宋美丽 《材料导报》2003,17(Z1):44-45,49
用Cu(NH3)6(OH)2在功率超声作用下分解制备了纳米CuO粉体.用X射线衍射和透射电镜进行表征,结果表明,所得纳米CuO粉体平均粒径为24nm,尺寸分布范围较窄.  相似文献   

5.
为研究络合剂对纳米铜粉体的制备及其催化性能的影响,分别以柠檬酸、葡萄糖为络合剂,采用溶胶-凝胶法制备纳米铜.考察了两种络合剂对制备过程以及产物结构的影响,通过催化苯氧化合成苯酚的反应考察制得的纳米铜粉的催化性能.研究表明:葡萄糖为络合剂制得的纳米铜(G-Cu)平均粒径较小(30 nm),比表面积为5.203 m2/g,在催化苯制苯酚反应时,具有较高的苯转化率(50.30%),但对苯酚的选择性较差;而柠檬酸为络合剂制得的纳米铜(C-Cu)平均粒径为55 nm,比表面积19.517 m2/g,催化苯转化率为21.95%,选择性为38.46%.此外,通过对溶胶凝胶法制备机理分析可知,在形成的胶体结构中,柠檬酸和葡萄糖中的羧基和羟基分别与铜离子进行配位.  相似文献   

6.
化学沉淀法制备电极用纳米β-Ni(OH)_2粉体材料   总被引:2,自引:0,他引:2  
通过化学沉淀法成功制备了电极用纳米B-氢氧化镍粉体。用TEM及XRD时样品进行分析,结果表明,所得产物为球形或椭球形,粒径在2~20nm之间,平均粒径为10nm左右,晶型为β型的纳米晶粒。实验得出了制备纳米氢氧化镍粉体的温度、氨水浓度与pH值的最佳参数。  相似文献   

7.
分别以硝酸铜水溶液和乙醇溶液为原料、氢氧化钠为沉淀剂,采用直接沉淀法制备了纳米CuO.通过TEM、XRD和XPS技术对比分析了乙醇对纳米CuO粒径及晶型的影响,并对比测试了制得的两种纳米CuO室温脱硫性能.实验结果表明:乙醇为分散剂制得的纳米CuO主要是球形,其平均粒径约为7nm,水为分散剂制得的样品中出现了大量棒形纳米CuO,尺寸约为8 nm×36 nm,说明溶剂极性影响纳米材料的粒径和晶型的形成;球形纳米CuO室温脱除H2S的活性时间是棒形纳米CuO的近两倍,表明纳米粒子的结构是影响脱硫性能的重要因素.  相似文献   

8.
室温固相合成前体法制备纳米CuO粉体   总被引:11,自引:1,他引:10  
以Cu(NO3)2·3H2O和NH4HCO3为原料,利用室温固相反应首先制备出对H2O2分解具有极高催化活性的纳米级混合碱式铜盐粉体,然后经230℃焙烧2h得纳米CuO粉体,并借助XRD、SEM、FT IR、TEM、TGA和DTA等手段对产物的结构、大小、形貌及相关性质进行了表征。结果表明获得了外貌呈球形、大小均匀、无团聚、平均粒径为28nm的纳米CuO粉体。  相似文献   

9.
为了解决乙醇钽、醋酸锶、硝酸铋在乙二醇中的溶解问题,分别以醋酸、乙醇胺、吡啶、甘露醇作为络合剂,对比研究了4种络合剂对溶液稳定性和粉体物相的影响,利用X射线衍射、透射电镜和热重-差热仪分析了粉体的相组成、微观形态和热分解历程,结果表明,以乙醇胺作为络合剂,通过化学溶液分解(CSD)法可以获得稳定的SBT溶液;稳定的SBT溶液经干燥,300℃焙烧30min和800℃煅烧1h,可获得粒径约为100nm的钙钛矿相SBT粉体。  相似文献   

10.
彭秧锡  陈启元  刘士军  张海波 《功能材料》2006,37(12):1995-1996
以CuSO4·5H2O与NaOH为反应物, 在乙二醇中机械化学法直接合成了纳米CuO粉体.用扫描电镜(SEM)、透射电镜(TEM)和X射线衍射(XRD)对产物进行了表征.结果表明,产物CuO颗粒大小比较均匀,平均粒径30nm左右.对于反应机理,认为是固-固反应中放出的大量的热,使Cu(OH)2直接转化为CuO粒子.该方法具有合成工艺简单、产率高等特点.  相似文献   

11.
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.  相似文献   

12.
13.
A four-ball tester was used to evaluate the anti-wear performance of three kinds of organomolybdemun compounds in the engine oils, i. e., molybdenum dialkyldithiophosphate (MoDDP), molybdenum dialkyldithiocarbamate ( MoDTC), and sulphur and phosphorus freeorganomolybdeum (Molybdate). The results indicate that a low concentration of MoDDP doesn' t improve the anti-wear properties of the commercial engine oils, but a high concentration of MoDDP can obviously improve the anti-wear properties and the load-carrying capacity of the engine oils. MoDTC doesn' t improve the antiwear properties of the engine oils, but worsens the anti-wear properties of the oils. Signifi can timprove ment of frictional and wear characteristics is obtained with Molybdate added in the commercial engine oils and the formulated oils.  相似文献   

14.
Standards are the basis for production enterprises to organize production, ex-factory inspection, trade (delivery) and technical exchanges, product certification, quality arbitration and supervision.……  相似文献   

15.
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.  相似文献   

16.
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...  相似文献   

17.
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.……  相似文献   

18.
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.  相似文献   

19.
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.  相似文献   

20.
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.  相似文献   

设为首页 | 免责声明 | 关于勤云 | 加入收藏

Copyright©北京勤云科技发展有限公司  京ICP备09084417号