Corrosion performance of a hot-dip galvanized steel treated by different kinds of conversion coatings

The anticorrosive performance of various kinds of conversion coatings including Cr(VI) and Cr(III) were studied on hot galvanized steel (HDG). The effect of Co(II) and Ni(II) ions was also examined on the Cr(III) coating performance. DC and electrochemical impedance spectroscopy (EIS) were conducted when the specimens were immersed in 3.5 wt.% sodium chloride solution. The coating morphology was observed using SEM. Micro-cracks were observed on both Cr(III) and Cr(VI) treated samples. The results indicated a decrease in the corrosion rate of HDG when the Cr(III) or Cr(VI) conversion coatings were found on the surface. The greater anticorrosion resistance of a Cr(VI) treated sample (compared with a Cr(III) one) was obtained at low immersion times. However, a significant decrease in self healing behavior and therefore corrosion resistance of the Cr(VI) treated sample was observed at longer immersion times. The anticorrosion resistance of Cr(III) treated samples was significantly improved using Co(II) or Ni(II) conversion coatings on Cr(III) treated samples. On the other hand, a lower decrease in corrosion performance of samples treated by Cr(III) and Co(II) or Ni(II) was obtained after a long immersion time in corrosive environment. It was found that, the passive and barrier layer which the Co(II) or Ni(II) conversion coating can produce on the Cr(III) coating can superiorly improve its anticorrosion resistance.     

A new partitioning process for high-level liquid waste by extraction chromatography using silica-substrate chelating agent impregnated adsorbents

To separate the long-lived minor actinides (MA(III) = Am(III), Cm(III)) and some specific fission products (FP) such as Pd(II), Mo(VI), Cs(I) and Sr(II) from high-level liquid waste (HLLW), we have been studying a new partitioning process by extraction chromatography using several novel silica-based extraction resins. In this work, we examined the separation behavior of the elements contained in a simulated MA-effluent by the CMPO/SiO₂P packed column. In addition, as an attempt to further isolate Am(III) and Cm(III) from the heavy RE(III) such as Eu(III), Gd(III) and Dy(III) contained in the MA-effluent, we investigated the possibility of separation by using a silica-based cationic exchange resin. Furthermore, to isolate Sr(II) from the HLLW, adsorption and separation performances of Sr(II) and some other FP elements were studied by using a novel silica-based crown ether extraction resin, DtBuCH18C6/SiO₂P. The experimental results demonstrated that the elements in the simulated MA-effluent can be successfully separated to (1) Pd, (2) MA-hRE and (3) Zr–Mo, by CMPO/SiO₂P packed column using water and a dilute DTPA solution as eluents. Am(III) and Cm(III) are expected to be effectively separated from light RE(III) and Y(III) by the SiSCR cationic resin. However, more effective separation between Am(II), Cm(III) and heavy RE(III) such as Eu(III), Gd(III) and Dy(III) needs further approach. DtBuCH18C6/SiO₂P showed a highly selective adsorption for Sr(III) so that the Sr(II) could be completely separated from other FPs except a portion of Ba(II).     

MICROSTRUCTURAL CHARACTERIZATION OF Nd_(34)Fe_(60)O_(6) ALLOY

The microstructure of Nd_(34)Fe_(60)O_6 alloy was characterized by means of scanning electronmicroscope,Auger electron multiprobe,X-ray diffraction,differential thermal analysesand thermomagnetic analyses.It is found that the equilibrium microstructure of the alloy iscomposed of a Nd_2Fe_(17) matrix,an oxygen-containing Nd-rich phase anda Nd-Fe-O ternary ferromagnetic phase (referred to T_1).This phase forms via aperitectic reaction between Nd_2Fe_(17) and Nd-rich phase at 840 ℃.Its composition isaround Nd_(36)Fe_(54)O_(10),and Curie temperature 180℃.The X-ray diffraction peaks can beindexed on a tetragonal cell with lattice parameter of a=0.771nm and c=2.228nm.Thisstable phase is believed to be transformed from the metastable phase (A_1) in Nd-Febinary system as a result of oxygen introduced.     

Comparative analysis of the phosphorescence characteristics of copper(II), platinum(II), and osmium(II) porphyrinates in polystyrene matrix at temperatures of 77 and 298 K

Comparative analysis of phosphorescence spectra of 15-crown-5-substituted copper(II) (Cu(II)TCP), platinum(II) (Pt(II)TCP), and osmium (II) (Os(II)TCP) posphyrinates in a polystyrene film, as well as of phosphorescence quenching curves, at the temperatures of 298 and 77 K is carried out. It is found that the halfwidth of emission bands decreases under cooling due to a decrease in the population of the vibration satellites of electron transitions and a shift of the emission band maximums into the blue spectral range is observed. The curves of phosphorescence quenching of metal porphyrinates at 298 and 77 K are analyzed. It is shown that copper(II) porphyrinate Cu(II)TCP can be of interest as a low-temperature sensor due to the considerable change in the phosphorescence lifetime at a decrease in temperature.     

Interface structure and formation mechanism of diffusion-bonded joints of TiAl-based alloy to titanium alloy

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New imidazole-based dimers as potential inhibitors for mild steel corrosion in acidic media: Electrochemical and DFT evaluation

We report the synthesis and corrosion inhibition performance of two imidazole-based materials, 1,1′-(4-methyl-1,3-phenylene)bis(3-(3-(1H-imidazol-1-yl)propyl)urea) (PIP) and 1,1′-(hexane-1,6-diyl)bis(3-(3-(1 H-imidazol-1-yl)propyl)urea) (HIP) dimers, in 1.0 M HCl. Electrochemical assessments indicated that the synthesized dimers facilitated the formation of a protective layer at the metal-electrolyte interface and, as a result, blocked the active corrosion sites. At a concentration of 100 ppm, PIP behaved as a potential mixed-type anticorrosive material with an overall efficiency of 99%. Density functional theory calculations showed that the aromaticity existing in the PIP backbone plays a major role in facilitating the corrosion-inhibition role.     

含钇聚碳硅烷制备碳化硅纤维(英文)

将钇元素作为烧结助剂引入到聚碳硅烷(PCS)中制备含钇PCS。由含钇PCS制成SiC(OY)和SiC(Y)2种碳化硅纤维。对SiC(OY)纤维转变成SiC(Y)纤维的结构与相关特性的变化进行研究。SiC(OY)纤维的化学组成为SiC1.23O0.05Y0.005,纤维是无定型结构;SiC(Y)纤维含有大量的直径为50nm的β-SiC晶粒和少量的α-SiC晶粒,钇元素存在于SiC晶粒之间。SiC(OY)的拉伸强度为2.25GPa,断裂韧性为2.37MPa.m1/2;SiC(Y)的拉伸强度为1.61GPa,断裂韧性为1.91MPa.m1/2;SiC(Y)纤维比SiC(OY)纤维具有更好的热稳定性。     

Space-charge limited conduction with a field and temperature dependent mobility in Alq light-emitting devices

Electrical transport in organic light-emitting devices (OLEDs) based on tris(8-hydroxyquinolato)aluminium (Alq) is investigated as a function of temperature and organic layer thickness. It is shown that the thickness dependence of the current provides a unique criterion to discriminate between (1) injection limited behavior, (2) trap-charge limited conduction with an exponential trap distribution and a field independent mobility, and (3) trap-free space charge limited conduction with a field and temperature dependent mobility. The observed thickness and temperature dependent current–voltage characteristics are found to be in excellent agreement with trap-free SCLC with a hopping type charge carrier mobility.     

熔融盐法合成高密度锂离子电池正极材料LiNi0.8Co0.2-xAlxO2

利用低共熔组成的0.38LiOH-0.62LiNO3混合锂盐体系,与高密度前驱体Ni0.8Co0.2-xAlx(OH)2(0≤x≤0.15)在低温下自混合,无需前期研磨和后续洗涤,直接制备出高密度Co-Al共掺杂的锂离子电池正极材料LiNi0.8Co0.2-xAlxO2(0≤x≤0.15)。X射线衍射分析结果表明,合成的LiNi0.8Co0.2-xAlxO2具有规整的层状α-NaFeO2结构。扫描电镜显示产物颗粒均匀,LiNi0.8Co0.15Al0.05O2的振实密度达2.97g·cm-3。电性能测试表明,在0.2C放电倍率和3.0～4.3V的电压范围内,LiNi0.8Co0.15Al0.05O2首次放电比容量达167.5mAh·g-1,且具有良好的循环性能。     

Electrochemical oligomerization of arenemethylidenes. Attempts to synthesize low bandgap systems

The electrochemical oligomerization of the arenemethylidenes, 1,3-dihydro-bis-1,3-(2-thienylmethylidene)-isothianaphthene (1b), 1,3-dihydro-bis-1,3-[2-(N-methylpyrryl)methylidene]isothianaphthene (4b), 1,3-dihydro-bis-1,3-(2-thienylmethylidene)thieno[3,4-c]thiophene (5b), 2,5-dihydro-bis-2,5-(2-thienylmethylidene)thiophene (6b), 1,3-dihydro-bis-1,3-(2-thienylmethylidene)isothianaphthene-2-oxide (1a), 1,3-dihydro-bis-1,3-[2-(N-methylpyrryl)methylidene]isothianaphthene-2-oxide (4a), 1,3-dihydro-bis-1,3-(2-thienylmethylidene)thieno[3,4-c]thiophene-1-oxide (5a) and 2,5-dihydro-bis-2,5-(2-thienylmethylidene)thiophene-1-oxide (6a), is investigated by cyclovoltammetry, coulometry, spectroelectrochemistry (UV-Vis-NIR, EPR) and a.c. impedance spectroscopy. Detailed spectroelectrochemical investigation of the oxidation process of compounds 1a, 1b, 4a, 4b, 5a, 5b, 6a and 6b reveals red-shifted absorptions after oxidation indicating the formation of larger π-electron systems. The oxidatively formed layers are electroactive as shown by independent cyclovoltammetry and spectroelectrochemistry measurements; the layers show a reversible switching behaviour between the oxidized and reduced forms. The reactive side of the arenemethylidene precursors in electrochemical oligomerization is determined by blocking possible linking positions with methyl groups. The 4,4′-disubstituted 1,3-dihydro-bis-1,3-(4-methyl-2-thienylmethylidene)isothianaphthene (2b) is oxidatively oligomerizable. The 5,5′-disubstituted 1,3-dihydro-bis-1,3-(5-methyl-2-thienylmethylidene)isothianaphthene (3b) does not form oligomer layers on the electrode due to the methyl-blocked 5,5′-(,′) positions and 3b exhibits hyperfine structure in the EPR spectrum. From this it is concluded that the monomer units within an oligomer chain of polyarenemethylidenes are - linked. The bandgap values of the polyarenemethylidenes are determined from UV-Vis-NIR spectra to be in the range 1.8–2.1 eV. The conductivity of the oxidized oligomer layers is higher than the reduced layers as shown by a.c. impedance spectroscopy. 2,5-Bis-(di-2-thienylmethylidene)-2,5-dihydrothiophene (7) is not oxidatively oligomerizable due to the formation of stable triheteroaryl methyl cationic structures.     

Enhanced performance of polythiophene derivative based light emitting diodes by addition of europium and ruthenium complexes

Fabrication of polymer light emitting diodes (PLEDs) from a urethane containing processable polythiophene derivative, poly[2-(3-thienyl) ethanol n-butoxy carbonylmethyl urethane], (PURET) and its composites with luminescent Ruthenium (II) and Europium (III) complexes is discussed. Enhanced electroluminescence (EL) performance was observed, when 1% by weight of europium (III) or ruthenium (II) complexes were added to the PURET polymer. Multi-layered devices with polyaniline as a hole injecting layer and tris-8-hydroxyquinoline-aluminum as an electron injecting layer have also been fabricated. PLEDs from PURET polymer have a threshold voltage of 3.6 V and emit an orange-red light with a brightness of about 500 cd/m² under forward bias of 9 V, upon the addition of 1% of europium (III) thenoyl trifluoroacetonate complex to the polymer.     

Extraction Separation of Sc(III) and Fe(III) from a Strongly Acidic and Highly Concentrated Ferric Solution by D2EHPA/TBP

The solvent extraction and separation process of Sc(III) and Fe(III) from a strongly acidic and highly concentrated ferric solution using mixtures of di(2-ethylhexyl) phosphate (D2EHPA) and tri-n-butyl phosphate (TBP) in sulfonated kerosene was studied. The effects of various parameters, including D2EHPA concentration, dosage of TBP, and phase ratio, were investigated for the extraction process. The results indicated that the extraction rate of Sc(III) was 99.72% with 1.09% Fe(III) co-extracted after two stages of counter-current extraction under optimal conditions. Moreover, saturation capacity and slope analysis were used to determine the reaction mechanism. Sc(III) is extracted in the form of HSc(SO₄)₂·4HL. Further separation of Sc(III) and Fe(III) was realized in a scrubbing and stripping process. First, 98.67% of the co-extracted iron in the loaded organic phase was scrubbed with a dilute HCl solution by a three-stage counter-current scrubbing. Then, 85.00% of Sc(III) can be stripped efficiently with a 2-mol/L NaOH solution saturated in 1-mol/L NaCl by three-stage cross-current stripping.     

抗氧化纳米铜粉的制备及表征

超细铜粉在以铜代银并在电子浆料、陶瓷材料和化工催化剂等材料的制备中具有较好的应用前景。本研究用Vc作还原剂，PVP，PVA和PAA作为保护剂并在反应前预先配成还原剂／保护剂体系，用于铜氨溶液的还原，可以得到粒度分布均匀的纳米铜粉。所得铜粉用油酸钝化可以有效地防止铜粉的表面氧化。反应温度和n(保护剂)：n(Cu)值对铜粉颗粒的粒径和形状影响很大，当n(PVP)：n(Cu)处于0．03～0．1时，铜颗粒基本上为长方体形。PVA和PAA作为保护剂时所得铜粉颗粒的形状为非球形的n(保护剂)：n(Cu)的范围分别为0．02～0．09和0．02～0．08。其原因可归于高分子分散剂对铜粒子的部分保护作用。     

Improved efficiency in red phosphorescent organic light-emitting devices using double doping structure

Light emission efficiency of red phosphorescent organic light-emitting diodes was improved by using a double doping structure in light emitting layer. Red devices with tris(2-phenylpyridine) iridium (Ir(ppy)₃) as a co-dopant for tris(1-phenylisoquinoline) iridium (Ir(piq)₃) showed higher efficiency than Ir(piq)₃ device. Ir(ppy)₃ acted as a sensitizer for energy transfer from (4,4′-N,N′-dicarbazole)biphenyl to Ir(piq)₃ and enhanced luminance efficiency of Ir(piq)₃ by 30%.     

Coordination polymers with [Au(CN)4]- building blocks: a 1-d chain of molecular NiII2AuIII2 squares

A new coordination polymer utilizing the neglected cyanoaurate anion [Au(CN)₄]- building block is reported. Reaction of a Ni(II) salt, diethylenediamine (dien) and K[Au(CN)₄] yields Ni(dien)[Au(CN)4]₂, which consists of a unique bimetallic Ni(II)₂/Au(III)₂ supramolecular square through cis N(cyano) bridging of the [Au(CN)₄]- building block to [Ni(dien)]²⁺ cations. These squares further aggregate into a 1-D chain via Au-N(cyano) interactions; no Au(III)-Au(III) interactions are observed. Within the square, the magnetic coupling between the Ni(II) centres is very weak, indicating that the [Au(CN)₄]- unit is a poor mediator of magnetic exchange in this system.     

Photo-, and electroluminescence studies of 2,5-bis[2′-(4″-(6-hexoxy benzyl))-1′-ethenyl]-3, 4-dibutyl thiophenes

We have synthesized a thiophene-based compound 2,5-bis[2′-(4″-(6-hexoxy benzyl))-1′-ethenyl]-3, 4-dibutyl thiophene (HBDT) and a copolymer poly(2,5-bis(2′-(4″-(6-hexoxy benzyl))-1′-ethenyl)-3,4-dibutyl thiophene-1,6-diisocyanatohexane) (HBDT-PU) consisting of alternating HBDT and urethane spacer units. Absorption and photoluminescence (PL) spectra of the compounds coincide indicating that emission in HBDT-PU occurs from the thiophene containing unit. PL is emitted in the blue–green region with a maximum at 460 nm. Concentration quenching occurs in pure materials: PL efficiency is strongly enhanced when the compounds are dispersed in a polymer matrix like poly(N-vinyl carbozole) (PVK) or poly(methyl metacrylate) (PMMA). Light emitting devices were fabricated using a PVK:2-(4-biphenylyl)-5-(4-tert-butylphenyl)-1,3,4-oxadiazole (PBD) blend doped with HBDT as the emitter material. Efficient energy transfer from PVK:PBD to HBDT molecules takes place in blended films. The electroluminescence (EL) spectra coincided with the PL spectra of HBDT indicating that EL emission comes solely from HBDT molecules. The influence of the doping concentration on the EL efficiency was found to coincide with the concentration dependence of the PL quantum yield.     

镁合金表面磁控溅射DLC/SiC薄膜的纳米压痕与摩擦磨损性能

采用室温磁控溅射技术在镁合金(AZ91D)表面制备出DLC/SiC(类金刚石/碳化硅)双层薄膜(SiC为中间层),研究了薄膜的纳米压痕行为、膜基黏附力和膜基系统的摩擦磨损性能.结果表明:DLC薄膜具有低的纳米硬度(3.05 GPa)、低的弹性模量(24.67 GPa)和高的硬弹比(0.122);膜基系统具有高的界面黏附力和好的摩擦磨损性能;在以氮化硅球为对摩件的室温干摩擦条件下其磨损速率在10~(-6)mm~3·m~(-1)·N~(-1)级,摩擦系数约为0.175.分析表明:膜基系统具有的良好抗磨性能与其薄膜具有高的塑性和硬弹比、膜基系统具有好的弹性模量匹配是相一致的;DLC薄膜具有的不寻常力学行为(很低的硬度和弹性模量等)与其基材是镁有关.     

低钴储氢合金Ml0．9Mg0．1Ni3．4Co0．3Al0．3电化学性能研究

为了降低AB5犁储氢合金的成本，对低钴的Ml0．9Mg0．1Ni3．4Co0．3Al0．3合金的组织结构和性能进行了研究，并与工业储氢合金MmNi3.55Co0.75Mn0.4Al0.3进行了对比。实验结果表明：此低钴合金是由LaNi5主相和LaNi3第二相构成。它们的储氢晕（ω,％）分别为1．36％和1．37％，最大放电容量分别为320mAh／g和324mAh／g，循环稳定性为：300次充放电循环后，2种合金剩余容晕都是88％。但Ml0．9Mg0．1Ni3．4Co0．3Al0．3的高倍率放电性能明显优于MmNi3．55Co0．75Mn0．4Al0.3合金。主要原因是由于LaNi3第二相的乍成不仪提高了合金颗粒表面的电化学催化活性，而且提高了结构韧性从而抵消了低钴合金颗粒粉化的不利影响。     

Deformations of engineering surfaces under static loads

A computer-aided-system has been developed to provide (i) 3-D assessments of engineering surfaces; (ii) quantifications of surface degradations due to wear and deformation processes; and (iii) predictions of the true area of contact formed between two initially-isothermal, circular cross-sectional surfaces of a soft rough material (duralumin) and a relatively-harder smooth material (titanium) pressed together by a mechanical load. This system is based on a stylus profile-tracing instrument and incorporates an automatically-controlled parallel-profile digitising stage.     

Research and Development Techniques 1: Potentiodynamic Studies of Copper Metal Deposition

The electrochemistry of copper (II)/(I) ions in aqueous chloride solution, at pH2, is used to demonstrate the application of voltammetry techniques in characterising electrode processes. The electrolyte used is 1.5 M sodium chloride containing 20 to 50 × 10^?3 M cupric chloride at 20°C, in which both Cu(II) and Cu(I) ions are stable. A platinum rotating disc electrode (RDE, radius 0.365 cm) is used to provide controlled mass transport under laminar flow conditions. Cyclic voltammetry, at a stationary disc electrode, is used to characterise the general electrochemistry. Four current peaks due to reduction of Cu(II) ions to Cu(I) ions, deposition of Cu from Cu(I) ions, anodic stripping of Cu to form Cu(I) ions and oxidation of Cu(I) ions to Cu(II) ions are seen. Analysis of the Cu(II)/Cu(I) couple indicates a reversible process. A potential sweep rate experiment allows the diffusion coefficient of Cu(II) ions to be calculated. The anodic stripping peak in the cyclic voltammogram is used to estimate the amount of copper deposited. Reduction of Cu(II) to Cu(I) then to Cu is examined at a range of rotation speeds (150–1870 rpm) using linear sweep voltammetry at the RDE. Mass transport data are obtained in the form of limiting current density as a function of the RDE speed, allowing the diffusion coefficients of Cu(II) and Cu(I) ions to be calculated.