电沉积法制备低碳钢超疏水表面及其耐蚀性能

电沉积法制备超疏水表面优势明显,但施加电压较高。采用一步快速电沉积法在低碳钢表面制备超疏水膜,测试了超疏水膜的接触角、形貌,通过动电位极化曲线研究了超疏水膜在3.5%NaCl溶液中的耐蚀性能,优选了超疏水膜的制备工艺。结果表明:超疏水膜最佳制备工艺条件为电解液组成0.20mol/L硬脂酸+0.1%HCl,电沉积电压8V,电沉积时间16h;最优工艺所制备的超疏水膜接触角达到了153°,在3.5%NaCl溶液中的缓蚀效率高达99.1%。     

基于阳极氧化技术制备超疏水表面及其在金属防护中的应用

为提高钛的防腐蚀性能,通过阳极氧化+硬脂酸修饰的方法在钛基体上制备超疏水表面.采用扫描电子显微镜(SEM)、X射线衍射仪(XRD)和傅里叶变换红外光谱仪(FTIR)研究了试样的表面形貌和化学成分,通过电化学阻抗测试(EIS)和浸泡试验测定了超疏水表面在3.5％NaCl溶液中的耐腐蚀性和稳定性.结果表明:当钛基体表面具有...     

镁合金超疏水环氧复合涂层的制备与性能EI北大核心CSCD

传统的超疏水表面的制备过程比较复杂,机械稳定性差,这严重制约了超疏水表面的实际应用。采用“黏合剂+纳米粒子”的方法,在镁合金表面制备一种无氟、持久稳定的超疏水环氧复合涂层。接触角测试结果表明,复合涂层的接触角最高可达160.2°,且在3.5%(质量分数)NaCl溶液中浸泡30天后,接触角仍然高达103°;EIS结果表明,在5个加速老化循环周期后,复合涂层的|Z|_(0.01 Hz)仍高于10^(9)Ω·cm^(2),展现出优异的耐盐雾性能和耐蚀性能;摩擦磨损实验结果显示,在19.6 N的载荷下机械摩擦8 h后,复合涂层的|Z|_(0.01 Hz)高达1.84×10^(9)Ω·cm^(2)。通过“空气垫”的屏障作用,复合涂层能够为镁合金提供高效且持久的腐蚀防护,“黏合剂+纳米粒子”策略为超疏水涂层的制备提供了新的思路。     

溶液浓度和非溶剂比例对PVC膜形貌和疏水性能的影响

目的 研究溶液质量分数和非溶剂体积分数对PVC薄膜表面形貌和疏水性能的影响,以获得具有超疏水表面的PVC薄膜。方法 以四氢呋喃为良溶剂、乙醇为非溶剂,利用非溶剂诱导相分离的原理,采用旋涂法在玻璃基底上制备超疏水的聚氯乙烯（PVC）涂膜;通过对PVC样品的疏水性、表面形貌、结晶性能和热性能进行分析,探究溶液质量分数以及非溶剂的体积分数对PVC样品性能的影响。结果扫描电镜和接触角测试表明,添加一定体积分数的乙醇使得所制备的PVC样品形成了多孔膜层以及纳米级聚合物球粒,从而提高了PVC样品的疏水性。XRD测试结果表明,添加乙醇并不会改变PVC样品的无定形结构。结论 PVC溶液质量分数对所制备PVC样品的疏水性能和表面结构没有明显影响,乙醇体积分数为30%～40%时,可形成表面水接触角大于150°的超疏水表面。     

超疏水铝表面的一步法电化学制备及其耐蚀性能研究

金属材料的表面超疏水改性可以显著改善其耐腐蚀性能.为了制备超疏水铝合金表面,结合化学刻蚀与电化学氧化技术,采用一步法在铝表面构筑超疏水结构,研究了其中盐酸含量和氧化时间对铝电极表面结构和性能的影响.采用接触角测试仪表征了铝表面的疏水性能,利用扫描电镜和能谱仪分析了铝表面的微观形貌和化学组成.采用电化学阻抗谱和电化学噪声技术评价了改性铝电极在3.5％NaCl溶液中的耐蚀性能.结果表明:当盐酸浓度为0.015 mol/L,电压为2 V,氧化时间为20 min时,可在纯铝上制备得到接触角为155.8°、滚动角为3.1°的超疏水表面.电化学阻抗测试结果表明,电荷转移电阻由121 Ω·cm2增大至1 941 Ω·cm2,超疏水铝表面的保护效率高达93.8％.电化学噪声测试表明,铝电极表面的超疏水改性能够显著地减弱其在3.5％NaCl溶液中的局部腐蚀强度.     

表面铝含量对Q235钢电化学腐蚀性能的影响

用粉末渗铝技术在Q235钢表面上制备了不同铝含量的渗铝层,通过阳极极化曲线测试了渗铝试样在35 g/L NaCl溶液中的电化学腐蚀性能.试验结果表明:不论铝含量如何,Q235钢在35 g/L NaCl溶液中的阳极极化曲线上均表现为活化溶解,未出现钝化.试样的耐腐蚀能力随Q235钢表面铝含量的增加而增强;当表面铝含量低到2.6%(质量分数)时,即使表面未形成连续的渗铝层,其耐蚀性能仍高于不含铝试样;当表面铝含量为51.2%时,其耐蚀性能低于1Cr18Ni9Ti不锈钢,这与有关文献报道的含铝钢的耐蚀性能高于1Cr18Ni9Ti不锈钢的不同.     

铝合金表面超疏水涂层的火焰喷雾热解法制备及其耐蚀性能

采用火焰喷雾热解与表面修饰相结合的方法在铝合金表面制备了具有一定耐蚀性能的超疏水表面。以六甲基二硅氧烷溶液为前驱液,通过火焰喷雾热解方法,首先在铝合金表面沉积SiO2纳米颗粒构建粗糙结构,再以氟硅烷溶液进行表面修饰,获得了具有154.9°静态接触角,滚动角<2°的超疏水表面。通过电化学测试,对比了构筑超疏水表面前后的铝合金样品的耐蚀性能。结果表明沉积层与低表面能物质协同作用,通过对腐蚀性离子的有效隔离,提高了铝合金基体的耐蚀性能。     

可见光宽波带减反超疏玻璃的制备工艺及结构探讨

高透射率和自洁净复合功能化是光伏玻璃研究热点。利用光伏玻璃原片，以乙二胺四乙酸二钠(EDTA-2Na)和乙二胺四乙酸四钠(EDTA-4Na)混合溶液为刻蚀液，通过水热刻蚀，再经十二烷基三乙氧基硅烷(DTES)疏水修饰，成功得到具有可见光宽波带(380～780 nm)减反超疏玻璃。探究了水热温度、反应时间、络合物混合比例、络合物添加量对膜层结构和光学性能的影响，以及疏水剂涂覆工艺和预处理时间对表面润湿性的影响。在160℃、8 h,刻蚀液中络合物为EDTA-2Na(40%,体积分数)与EDTA-4Na(60%,体积分数)、EDTA-nNa (0.34 mol/L)总添加量为4%(体积分数)时，所得玻璃的可见光380～780 nm各个波长的反射率小于1%;总反射率为0.45%,总透射率为98.85%,雾度为0%。采用旋涂法涂DTES进行表面疏水修饰，预水解时间为18 h时，可获得超疏水性能，水接触角为150.86°,滚动角为5.9°。表面疏水修饰对减反射性能影响很小。     

提拉法制备二氧化硅陶瓷膜的形貌及性能

采用浸渍提拉工艺在复合镀镍的A3钢表面制备氧化硅陶瓷膜。借助扫描电镜观察陶瓷膜的微观形貌,应用电化学阻抗谱测试陶瓷膜的耐蚀性能并揭示耐蚀机理。用平面磨耗试验机测试了陶瓷膜的耐磨性能。结果表明:在500℃下烧结的氧化硅陶瓷膜为类似微裂纹镀铬的表面形貌;在400℃下烧结的氧化硅陶瓷膜与微孔镀铬的表面形貌相似;400℃及500℃烧结后形成无定形的SiO2陶瓷膜。阻抗较高的氧化硅陶瓷膜在3.5%(质量分数)NaCl溶液中的腐蚀过程为扩散控制,能明显抑制镀镍A3钢的腐蚀。氧化硅陶瓷膜降低了复合镀镍层的孔隙率。浸渍提拉成膜后膜层耐磨性能显著优于只复合镀镍的A3钢,浸渍提拉法能提高铁基体复合镀镍的耐磨性能。     

基体预处理对稀土转化膜耐蚀性能的影响

为了优化转化膜的预处理工艺和耐蚀性能,选用不同的预处理工艺制备了系列转化膜。通过盐雾实验评价了预处理工艺对转化膜耐蚀性能的影响,获得两种较优工艺(4#和8#)。采用动态极化曲线和电化学阻抗谱方法研究了经4#和8#预处理后转化膜在3.5%(质量分数)NaCl溶液中耐腐蚀性能的变化;借助扫描电子显微镜(SEM)、能谱(EDS)和润湿角测试仪,系统研究了4#和8#预处理工艺对成膜前后表面的形貌、成分和润湿性的影响;利用涡流测厚仪、显微硬度计和摩擦磨损试验机研究了4#和8#预处理工艺对转化膜生长速度、表面硬度和耐磨性的影响。结果表明,较佳的预处理工艺使铝合金表面阴极点适当暴露分布均匀、润湿性好、成膜速度适中,生成的转化膜致密完整、膜层更厚,耐蚀性更好;研究显示8#是较佳预处理工艺。     

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.     

The Influence of Nitrogen and Boron Implant into Silicon Substrate on the Phase and Internal Stress of c-BN Films

Cubic boron nitride(c-BN) film was deposited on a Si (100) substrate by the RF-magnetron sputtering.The mainly problems for fabrication of c-BN films are the low purity and high intrinsic compressive stress. In order to solve the two problems, the c-BN film with the buffer interlayer was deposited on the substrate which had been implanted with nitrogen and/or boron ions. The results show: the implantation of nitrogen ions can obviously increase c-BN content and reduce the internal stress slightly; while the implantation of boron shows no obvious improvement to the content of c-BN, which can reduce the internal stress in the film obviously. In addition, it is suggested that the implantation of nitrogen and boron shows the best result, which not only can increase the content of c-BN, but also reduce the internal stress in the c-BN film obviously.