Corrosion behavior of aluminum alloys in Na2SO4 solution using the scanning electrochemical microscopy technique

The corrosion behavior of aluminum alloys 1060 and 2A12 in a 10 mM Na2SO4+5 mM KI solution was investigated by scanning electrochemical microscopy (SECM) and scanning electron microscopy (SEM).The potential topography and corrosion morphology results show that the potential of the sample surface over the same area changes with the increase of immersion time.The corrosion area becomes large,and the potential becomes more negative.The corrosion potential of the 2A12 alloy surface is lower than that of 1060 aluminum,and 2A12 alloy becomes easily corrosive.This is the reason that preferential dissolution in the boundary region of some intermetaUic particles (IMPs) occurs and different dissolution behaviors are associated with different types of IMPs because of different potentials.     

Preparation of β-SiC by combustion synthesis in a large-scale reactor

The feasibility of 5 kg β-SiC synthesized in one batch was demonstrated through igniting the mixture of Si, C-black and polytetrafluoroethylene (PTFE) under different nitrogen pressures. The effect of experimental parameters, including the contents of PTFE, nitrogen pressure, preheating, and raw materials distribution forms were investigated. The results show that the products are β-SiC with equiaxed grains. The average grain size is less than 200 nm. The powders loaded loosely promote reaction heat dispers...     

Numerical simulation of the temperature fields of stainless steel with different roller parameters during twin-roll strip casting

The temperature field of stainless steel during twin-roll strip casting was simulated by experiment and a finite element (FE) model. By comparing the measured result with the simulated values, it is found that they fit close to each other, which indicates this FE model is effective. Based on this model, the effects of roll gap (0 and roll radius (R) on solidification were simulated. The simu-lated results give the relationship between t or R and the position of the freezing point. The larger the t is and the smaller the R is, the closer the position of the freezing point is to the exit.     

Effect of sintering time on the electrochemical properties of spinel LiMn_2O_4 synthesized by solid-state reaction

LiMn_2O_4 powder as a cathode materials for rechargeable lithium-ion batteries was prepared by solid-state reaction from Li_2CO_3 and electrolytic MnO_2 at different sintering periods(2,6,18,and 32 h).X-ray diffraction(XRD)patterns of the prepared samples are identified as the spinel structure with a space group of Fd(?)m.The lattice parameters almost remain the same as the sin- tering periods increase.The sample with a sintering period of 32 h shows good cycling performance at both low and high current densities,and also elevated temperature.It is believed that the excellent electrochemical behavior of this sample results from its good crystallinity and large grain size compared with other samples.Different electrochemical measurements were conducted to investi- gate the electrochemical properties of spinel LiMn_2O_4.     

间接模板剂法合成介孔SAPO-11分子筛及其加氢异构化性能

采用水热合成法,将未焙烧的介孔材料SBA-15作为硅源合成介孔SAPO-11分子筛。利用X射线衍射、N2吸附-脱附等温曲线,BET物理吸附,NH3-TPD以及扫描电子显微镜等对分子筛的形貌和孔结构性质进行表征。将正十二烷作为原料,考察负载量为0.5%的Pt/SAPO-11分子筛催化剂的加氢异构化反应催化性能。结果表明:以未焙烧的SBA-15作为硅源制备介孔SAPO-11分子筛,介孔比表面积为77.2 m2/g以及介孔孔容为0.261 m~3/g,有效降低孔道传质阻力,酸量显著增加,活性位增多,使长链烷烃加氢异构化的选择性达到65.21%。     

几种萘酞菁硅配合物的光动力效应的研究

研究了7种轴向配位的萘酞菁硅配合物的激发态性质、产生单重态氧的能力及对几种氨基酸的光敏氧化能力.研究表明,对于相同浓度的不同配合物来说,随着轴向配位基团推电子能力的逐渐增强,激发三重态寿命降低,产生单重态氧的能力逐渐下降,而产生单重态氧的能力是光敏氧化氨基酸反应速率的决定因素,因此,其光敏氧化氨基酸的一级反应速率常数逐渐减小.     

鱼尼丁受体杀虫剂Flubendiamine

本文介绍了鱼尼丁受体杀虫剂Flubendiamine的创制经纬、作用机制、生物活性、毒性及合成。     

塑料型材挤出模CAE技术的研发状况

从技术及应用的角度介绍了塑料型材挤出模CAE技术的概况、内涵及发展趋势。系统地将挤出模CAE技术的发展从五个方面给予了总结。     

Preliminary Study on MgO.Al2O3 Spinel Fiber

1IntroductionMgO·Al2 O3spinelisanimportantceramicmaterialextensivelyusedinrefractoriesindustry ,especiallyforapplicationsathightemperaturecriticalareaswherether malshockresistanceandslagpenetrationresistanceareprimaryrequisites[1] .ButlittleinformationaboutMgO·Al2 O3spinelfibershasbeenreportedinliterature .Inthiswork ,itisfoundthatwhenpressedspecimenscomposedofpulverizedMg Al Omaterialwithappropriateoxide metalratioarefiredat 15 0 0℃for 6hoursundercon trolledatmosphere ,MgO·Al2 O3spi…     

Perpendicular exchange bias of (Pt/Co)_n/FeMn multilayers

(Pt/Co)n/FeMn multilayers with perpendicular anisotropy (PA) were prepared by magnetron sputtering with Pt as the buffer layer and the capping layer. The dependence of perpendicular exchange bias (PEB), Hex, on the thickness of the FeMn antiferromagnet (AFM) layer is similar to that of in-plane exchange bias. The value of Hex for the (Pt/Co)3/FeMn multilayer reaches 22.3 kA/m. A thin Pt spacer was inserted between the Co/FeMn interface to enhance PEB. The PEB reaches the largest at 39.8 kA/m when the thickness of the Pt spacer is 0.4 nm.