铈掺杂白云母复合粉体的制备及其减摩抗磨机理

采用机械力固相化学反应法制备了稀土铈掺杂白云母(Muscovite,MC)的复合粉体(Ce-MC),表征了粉体的微观形貌、晶体结构、元素组成和粒径分布。利用四球摩擦磨损试验机考察比较了MC和Ce-MC作为润滑脂添加剂的摩擦学性能,对磨损表面进行了SEM、EDS和XPS分析,并探讨了Ce-MC的减摩抗磨机理。结果表明:CeMC复合粉体中铈化合物包覆在白云母粉体表面,主要物相为CeO_2;Ce-MC和MC作为添加剂均能提高锂基润滑脂的减摩抗磨性能,且Ce-MC复合粉体的摩擦学性能优于MC单体;Ce-MC优良的摩擦学性能与其磨损表面Ce-MC的物理吸附膜和主要成分为Fe_2O_3、SiO_2的化学反应膜有关。     

添加剂Ni-B非晶合金纳米微粒的制备及其摩擦学性能

非晶合金纳米粒子具有许多特殊功能,但摩擦领域尚未见其应用报道.采用液相还原法制备了Ni-B非晶合金纳米微粒,利用四球摩擦磨损试验机考察了Ni-B非晶合金纳米微粒作为润滑脂添加剂的摩擦学行为,并用扫描电子显微镜(SEM)和能量散射谱(EDS)等对钢球摩擦表面进行了分析.结果表明:所制备的Ni-B非晶合金纳米微粒平均粒径约30 nm,表面被氧化;作为润滑油添加剂能够明显提高基础油的减摩抗磨能力,尤其当浓度为1.0%时,磨斑直径从0.54 mm降至0.38 mm.其抗磨减摩机理为:Ni-B非晶态合金纳米微粒在摩擦过程中沉积并发生摩擦化学反应,生成由氧化镍、氧化硼、铁氧化合物及有机吸附物组成的具有良好摩擦学性能的润滑防护膜,从而改善了基础脂的摩擦学性能.     

表面修饰硼酸钾作为船用气缸润滑油添加剂的高温摩擦学性能EI北大核心

以月桂酸钠和十六烷基三甲基溴化铵为复配型修饰剂,采用等离子体辅助球磨法制备表面修饰硼酸钾润滑添加剂,通过扫描电镜(SEM)、傅里叶变换红外光谱仪(FT-IR)及同步热分析仪(DSC-TG)对添加剂进行表征分析,研究其在低碱值船用气缸油中的高温摩擦学性能,并讨论其减摩自修复机制。结果表明:在等离子体热效应和钢球机械研磨的耦合作用下,等离子体辅助球磨10 h的硼酸钾粉体和修饰剂被微区熔融并快速细化,获得的一次颗粒平均粒径在100~300 nm之间。通过修饰剂中离子对的化学作用,硼酸钾粉体表面吸附并化学键合—CH_(2),—CH_(3)有机分子基团,实现粉体的亲油化改性,并保障在FEOCY 54低碱值船用气缸油中的分散性。在摩擦过程中,硼酸钾微粒在电荷作用下不断吸附沉积到摩擦表面,在金属接触区域形成滚动润滑及抗磨沉积膜,同时摩擦表面与硼酸钾粉体发生摩擦化学反应生成Fe_(2)O_(3),Fe_(3)O_(4),B_(2)O_(3)极具减摩抗磨作用的边界润滑膜,明显提高船用气缸油的高温摩擦学性能。     

十二烷基硫醇修饰CuS纳米颗粒的制备及其摩擦学性能

为了考察表面修饰CuS纳米颗粒作为润滑脂添加剂的摩擦润滑性能,采用十二烷基硫醇对CuS纳米微粒进行表面修饰。用X射线衍射分析修饰CuS微粒的物相,用透射电镜及FTIR分析其表面形貌和成分,采用摩擦磨损试验评价了修饰CuS纳米微粒在锂基润滑脂中的摩擦性能。结果表明:十二烷基硫醇修饰CuS纳米微粒的粒径只有几个纳米,作为添加剂在锂润滑脂中具有良好的减摩性能,但抗磨性能较差;修饰CuS在摩擦过程中发生了摩擦化学反应,生成了FeS,从而有效地降低了摩擦系数,但增大了磨损。     

表面修饰硼酸钾作为船用气缸润滑油添加剂的高温摩擦学性能

以月桂酸钠和十六烷基三甲基溴化铵为复配型修饰剂,采用等离子体辅助球磨法制备表面修饰硼酸钾润滑添加剂,通过扫描电镜(SEM)、傅里叶变换红外光谱仪(FT-IR)及同步热分析仪(DSC-TG)对添加剂进行表征分析,研究其在低碱值船用气缸油中的高温摩擦学性能,并讨论其减摩自修复机制。结果表明：在等离子体热效应和钢球机械研磨的耦合作用下,等离子体辅助球磨10 h的硼酸钾粉体和修饰剂被微区熔融并快速细化,获得的一次颗粒平均粒径在100～300 nm之间。通过修饰剂中离子对的化学作用,硼酸钾粉体表面吸附并化学键合—CH₂,—CH₃有机分子基团,实现粉体的亲油化改性,并保障在FEOCY 54低碱值船用气缸油中的分散性。在摩擦过程中,硼酸钾微粒在电荷作用下不断吸附沉积到摩擦表面,在金属接触区域形成滚动润滑及抗磨沉积膜,同时摩擦表面与硼酸钾粉体发生摩擦化学反应生成Fe₂O₃,Fe₃O₄,B₂O₃极具减摩抗磨作用的边界润滑膜,明显提...     

Graphene/SiO2纳米复合材料作为水基润滑添加剂的摩擦学性能

以石墨烯和正硅酸乙酯为原料用溶胶-凝胶法制备了Graphene/SiO₂纳米复合材料，用球盘式摩擦磨损试验机评价其作为水基润滑添加剂在不同载荷和浓度下的摩擦学性能。用扫描电镜(SEM)、X射线光电子能谱(XPS)等手段表征了摩擦副的表面形貌和元素特征。结果表明：在15N载荷工况下，Graphene/SiO₂纳米复合材料作为添加剂在超纯水中含量为0.2%(质量分数)时具有最佳的摩擦学性能，比超纯水的摩擦系数降低了17.9%，钢球磨损率降低了61.7%。基于磨损表面分析提出的润滑机制为：在摩擦过程中，Graphene/SiO₂纳米复合材料在磨损表面生成的物理吸附膜、Graphene的层状剪切作用以及SiO₂在磨损表面的修复作用和滚珠轴承作用，使超纯水的摩擦学性能提高。     

超声液相剥离制备二维MoS_(2)作为润滑脂添加剂的摩擦学研究EI北大核心

通过超声液相剥离法制备不同片径的二硫化钼纳米片,并将其作为添加剂应用到锂基润滑脂。通过电子显微镜、拉曼光谱、X射线衍射仪和热重分析仪对所制二硫化钼纳米片的形貌、组成和结构进行表征;利用四球摩擦磨损试验机考察二硫化钼锂基润滑脂摩擦学性能,通过扫描电子显微镜和X射线光电子能谱分析MoS_(2)润滑脂润滑下钢球的磨损表面形貌,初步探究MoS_(2)的润滑机理。结果表明:二硫化钼纳米片表现出优异的抗磨减摩性能,当添加片径为80 nm,添加量为1.0%(质量分数)时,锂基润滑脂摩擦学性能最佳,最大无卡咬负荷和烧结负荷相较于基础脂分别提升了55.4%和61.2%,摩擦因数最高减小了23.15%,磨斑直径最高减小了21.13%。其摩擦学性能的提高主要与形成了Fe的各类氧化物、FeOOH、MoS_(2)和相关有机物构成的摩擦保护膜有关。     

表面修饰的纳米硼酸镁的制备及其摩擦学研究

为开发可作为硫化烯烃替代物的润滑油添加剂,制备了一种表面修饰的纳米硼酸镁粒子(T-MgBN),采用ICP-AES、XRD和TEM对其结构进行了表征.结果表明:制备的T-MgBN为无定型、平均粒径为50 nm的纳米粒子,且表面吸附了表面修饰剂.利用四球摩擦磨损试验机对在一种新型调油工艺下调制的T-MgBN试油摩擦学性能进行了评价,并和硫化异丁烯(T321)的摩擦学性能进行了比较.采用SEM及XPS对钢球磨损表面形貌和元素状态进行了分析.结果表明:T-MgBN在矿物油中具有优异的抗磨、减摩件能.随着剪切力的增大,T-MgBN在摩擦副表面吸附、沉积形成了一层保护膜,并且和表面吸附的表面活性剂以及摩擦副发生了摩擦化学反应生成了B_2O_3、BN、Fe_2O_3和FeB等物质.     

硅酸盐粉末作为润滑脂添加剂的摩擦磨损特性及绝缘性能研究

天然硅酸盐矿物可用作润滑添加剂,对其摩擦磨损性能进行深入研究很有意义。针对2种常见的层状硅酸盐蛇纹石和滑石,利用X射线衍射(XRD)分析2种亚微米粉末的组分,利用MFT-R4000摩擦磨损试验机考察两者作为润滑脂添加剂的摩擦学性质,通过扫描电子显微镜(SEM)分析了摩擦过程后磨损表面的形貌,利用电学仪器测定不同浓度润滑脂的击穿电压以及体积电阻率。XRD结果显示蛇纹石粉末的纯度高,而滑石粉中含有少量杂质。2种粉末在摩擦试验中均表现出良好的减摩抗磨性能。而相比于蛇纹石,滑石粉末在润滑脂中所起到的绝缘性能更优。     

液态硼酸钙纳米粒子的制备及摩擦学性能研究

制备了一种液态的硼酸钙（CBNL）纳米粒子,采用激光粒度分析（LPA）和红外光谱（FT-IR）等对其结构进行了表征,利用四球摩擦磨损试验机对CBNL在矿物基础油中的摩擦学性能进行了评价,并采用三位轮廓仪和XPS对钢球磨损表面形貌和元素状态进行了分析,结果表明：制备的硼酸钙为半峰宽20nm、平均粒径18nm的纳米粒子,在矿物油中具有优异的摩擦学性能;在摩擦过程中,纳米粒子能被金属表面吸附、沉积并发生了摩擦化学反应,形成了一层含有B2O3、CaO、Fe2O3和FeB等物质的保护膜。     

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