非晶态Ni-S-Co合金的制备和电化学性能

用电沉积方法制备非晶态Ni-S-Co合金镀层,研究了镀层的电化学性能.结果表明,与非晶态Ni-S合金相比,Co的引入可提高镀层中S的含量.在析氢反应中非晶态Ni-S-Co合金电极具有很高的电化学活性,电流密度为150 mA·cm-2时其析氢过电位仅为70 mV,比非晶态Ni-S合金低20 mV.在长时间电解过程中S发生溶出反应有助于提高电极的表面粗糙程度,是提高电极析氢活性的重要原因之一.在析氢过程中,非晶态Ni-S-Co合金电极吸附大量的H原子,使反应的活化能降低,这是其析氢活性高的主要原因.非晶态Ni-S-Co合金镀层的析氢机理为电化学脱附机理,即-快速的Volmer反应(电化学步骤)和一较慢的Heyrovsky反应(电化学脱附步骤).     

Electrochemical behaviour of Cu24Zn5Al alloy in alkaline medium in the presence of chloride ions and benzotriazole

This paper deals with electrochemical behaviour of Cu24Zn5Al alloy in a sodium tetraborate solution (borax), in the presence of chloride ions and benzotriazole. It was found that during anodic polarization of the investigated alloy, in a sodium tetraborate solution, at lower potentials, copper (I)-oxide formed on the alloy surface. The voltammograms show peak potential shifts corresponding to the formation of Cu₂O towards more positive values with longer immersion time. It was found that chloride ions had an activating effect in a sodium tetraborate solution containing various concentrations of chloride ions (0.001, 0.005, 0.010, 0.050 and 0.100 mol dm⁻³ Cl⁻). It was observed that Cu24Zn5Al alloy corroded more intensely in more concentrated solutions and with longer exposure to Cl⁻. Investigations of the effect of inhibitor concentrations (8.4 × 10⁻⁶, 8.4 × 10⁻⁵, 8.4 × 10⁻⁴ and 8.4 × 10⁻³ mol dm⁻³ BTA in 0.1 mol dm⁻³ borax solution) showed that BTA had a good protective effect. The inhibiting effect of BTA was also confirmed with various times of immersion of this alloy in a 1.7 × 10⁻² mol dm⁻³ solution of this inhibitor.     

Ni-S-Co涂层电极的制备及其电化学性能的研究

采用电沉积的方法以泡沫镍为基体制备出非晶Ni-S-Co合金电极.用电化学测试方法分析涂层的电化学行为.结果表明,较好的制备涂层电极条件为: CoSO4·7H2O掺杂浓度为10g/L,电流密度为50mA/cm2,温度为50℃,电沉积时间为40min,pH值为4.当电解电流密度为1200A/m2时,非晶Ni-S-Co合金电极的极化电位较非晶Ni-S合金电极低95mV,较Ni金属电极低405mV;根据Tafel曲线计算出Ni、非晶Ni-S以及非晶Ni-S-Co电极的表面活化能分别为49.5、40.3和38.6kJ/mol.Ni-S-Co电极具有更高的交换电流密度和更低的析氢活化能,因此具有更高的析氢催化活性.     

Al-Zn-Bi系合金在NaCl溶液中的电化学性能研究

采用CHI660C电化学工作站测试了Al-5Zn-0.5Bi和Al-5Zn-0.5Bi-0.06Sn合金在3%NaCl溶液中的极化曲线和电化学阻抗谱(EIS),考察了合金的电化学性能.结果表明,Al-5Zn-0.5Bi中添加0.06%的Sn元素后,自腐蚀电位Ecorr升高0.017V,耐腐蚀性能有所增强.等效电路RS(RPC)(QRD(RaL))较好地拟合了Al-5Zn-0.5Bi系合金在3%NaCl溶液中的EIS谱,基本反映了该铝合金的电化学腐蚀过程.随着合金在3%NaCl溶液中浸泡时间的延长,腐蚀产物膜增厚并部分脱落,主要形成点蚀.另外,腐蚀产物更容易在含Sn合金氧化膜缺陷处形成,阻碍了腐蚀介质中Cl-向其内部扩散,从而减缓了点蚀和自腐蚀速度,有助于提高该合金材料作为牺牲阳极的电流效率.     

非晶合金变压器铁芯制备及性能研究

采用宽度低的国产非晶合金带材制成铁芯后沿着带材宽度方向叠加成为高度合适的铁芯,并对其进行线切割,研究了铁芯切缝处的结构、形貌及切割前后工频下的磁性能。结果表明,线切割后切缝处结构由非晶态向晶态发生转变;切割后不改变铁芯的饱和磁感应强度,但磁化困难,损耗增加,铁芯切割后在B=1.3T,f=50Hz下的励磁容量由切割前0.32VA/kg增加到7.70VA/kg,损耗值由0.16W/kg增加到0.30W/kg;铁芯叠加不影响其磁性能,此法适用于制备非晶合金变压器。     

非晶态Ni-Cu-P合金镀层的结构及性能研究

研究了化学镀Ni-Cu-P非晶态合金镀层的成分，结构、硬度及形貌等性能．研究结果表明：镀层中铜含量随着镀液中硫酸铜浓度的增加而提高，镍、磷含量随着镀液中硫酸铜浓度的增加而降低。由于铜具有优先析出的特征，导致合金镀层中Cu／Ni质量比远高于镀液中Cu^2＋／Ni^2＋质量比．在镀态下，Ni-Cu-P合金镀层为含铜、磷原子的镍基饱合固溶体．X-ray衍射表明：在镀态下及300℃以下热处理时，Ni-7．929％Cu-8．227％P（质量分数）合金镀层为非晶态结构，经400℃热处理后，开始有热力学平衡相Ni3P和Cu3P析出，合金镀层已转为晶态结构．Ni-7．929％Cu-8．227％P合金镀层的硬度随热处理温度的升高而增加，在400℃时，硬度达到最大值（845HV），热处理温度继续升高，合金镀层的硬度反而下降．     

Magnetoelastic properties of an amorphous ferromagnetic alloy annealed by electric current

The magnetoelastic wave propagation velocity and the magnetic-field-induced change in the elastic modulus (ΔE effect) have been studied as functions of the magnetic field strength in thin stripes of an amorphous ferromagnetic alloy (Fe₆₄Co₂₁B₁₅) annealed by direct electric current of variable density. It is shown that such treatment is an effective method for obtaining amorphous ferromagnetic alloy ribbons with uniaxial anisotropy and high magnetoelastic characteristics.     

Electrochemical analysis of p-nitrophenol in acidic or alkaline medium using silver nanoparticle decorated multi-walled carbon nanotubes

Silver nanoparticle decorated multi-walled carbon nanotubes (Ag/MWCNT) were prepared by a simple chemical plating method. The Ag/MWCNT nanocomposite modified glassy carbon electrode (Ag/MWCNT/GC) was fabricated. Electrochemical behavior of p-nitrophenol at the Ag/MWCNT/GC was studied by cyclic voltammetry. The Ag/MWCNT/GC electrode shows good electrocatalytic activity for the reduction of p-nitrophenol. Voltammetric determination of p-nitrophenol was carried out. Under optimal experimental conditions, the reduction peak current of p-nitrophenol is linearly proportional to its concentration in a range from 3.0 × 10^?6 to 1.2 × 10^?4 mol L^?1 in acidic medium and 3.5 × 10^?5 to 1.4 × 10^?4 mol L^?1 in alkaline medium, respectively.     

Mechanical properties of amorphous alloy compacts prepared by different consolidation techniques

Amorphous alloy compacts of Fe₇₈B₁₃Si₉ prepared by three different techniques (explosive consolidation, high hydrostatic pressure consolidation and warm extrusion) were deformed in compression between 573 and 723 K at a strain rate ranging from 8.3×10^–5–4.2×10^–4s^–1. Explosively consolidated compacts had high strength ranging from 1.9–2.5 GPa below 623 K and could be plastically deformed to a strain of more than 50% at 673 K while preserving the amorphous state. Amorphous alloy compacts prepared by high hydrostatic pressure consolidation showed lower compressive strength. Those produced by warm extrusion were anisotropic in strength, the highest strength being as high as 2.74 GPa. It was also found that the geometry of the starting powders had a profound effect on the strength of the product compacts. Compacts prepared from flaky powders were stronger than those prepared from spherical ones. It is concluded that the mechanical properties of the amorphous alloy compacts depend on the consolidation technique, powder geometry and surface conditions of the powders, especially existence of oxide films.     

Structures and mechanical properties of amorphous alloy compacts prepared in an inert atmosphere

A new technique has been developed to prepare amorphous alloy compacts where all the processes, from powdering to consolidation, are carried out in an argon atmosphere. Amorphous alloy ribbons were crushed into powders at low temperature using a planetary ball mill. These powders were consolidated using a cubic-type anvil apparatus under a high hydrostatic pressure. Amorphous alloy powders and compacts thus prepared were oxidized to a much lesser extent than those prepared in air using a conventional method. The compressive strength of the compacts prepared in an argon atmosphere was higher by 30%–100% than that of those prepared conventionally in air. The strengthening mechanism is discussed based on the results of characterization of the powders and compacts.     

冷热循环处理对钛基非晶合金摩擦学性能的影响EI北大核心CSCD

钛合金的耐磨性较差,在钛合金活动部件表面制备钛基非晶合金涂层是一种保持钛合金优势又提升其耐磨性的选择。采用X射线衍射仪、差示扫描量热仪、SEM、摩擦磨损试验机,对冷热循环处理前后钛基块体非晶合金的组织结构与摩擦行为进行比较研究。结果表明:经过冷热循环处理后的钛基块体非晶合金仍然保持着完全非晶态,弛豫焓提升11%。冷热循环处理后钛基非晶合金的平均纳米硬度从6.84 GPa降低到6.59 GPa,平均弹性模量从118.70 GPa降低到103.43 GPa,但硬度与弹性模量的比值增大。冷热循环处理后,钛基块体非晶合金在5 N和10 N的载荷下磨损率减小了约10%。与TC4合金相比,其在5 N和10 N载荷下的磨损率分别减小了20%和50%。TC4合金由于硬度较低,呈现较为严重的黏着磨损。冷热循环处理后,钛基非晶合金的磨损机制从铸态的磨粒磨损为主向磨粒磨损、黏着磨损和氧化磨损共同作用转变,且随着载荷的增大,黏着磨损减轻,磨粒磨损占据主导。因此,冷热循环处理是提升钛基块体非晶合金摩擦学性能的一种有效方法。     

电脉冲快速退火对铁基非晶合金性能的影响

采用大电流交流脉冲对非晶Ｆｅ７８Ｂ１３Ｓｉ９合金进行了去应力退火。初步探讨了电脉冲加热对加热速率和该合金内应力释放、退火脆化以及最终软磁性影响的基本规律。结果表明：电脉冲加热可以得到远高于常规退火的加热速率，选择合适工艺参数可使非晶合金内应力释放９０％，软磁性（Ｈ＿ｃ和Ｂ＿ｓ）达常规退火后的９５％以上，与此同时使合金的延性（断裂应变ε＿ｆ）维持在０．９以上，从而有望实现非晶合金磁性与延性的合理配合。     

直径对玻璃包覆非晶合金微丝磁性的影响

采用Taylor-Ulitovsky方法制备了直径分别在6.3～28.0μm、20.2～28.0μm和14.0～35.2μm之间的玻璃包覆非晶态FeCuNbVSiB、FeBSiCMn和CoNiFeSiB微丝。通过X射线衍射、扫描电镜、振动样品磁强计分别测试了玻璃包覆微丝的组织结构、微观形貌和磁性,研究了不同成分玻璃包覆磁性合金微丝的玻璃包覆层厚度、合金芯直径对微丝磁性能的影响。结果表明了,玻璃包覆磁性合金微丝的磁性能的影响因素由大到小依次为：饱和磁致伸缩系数、微丝成分和微丝尺寸。轴向磁化时随着微丝直径及玻璃包覆层厚度的增大,3 种微丝的径向饱和场强度降低,FeCuNbVSiB和FeBSiCMn微丝的轴向矫顽力先分别由508 A/m和390 A/m降低到486 A/m和278 A/m后再升高到2570 A/m和342 A/m,CoNiFeSiB微丝的轴向矫顽力由171 A/m降低到63 A/m。     

Structure and mechanical properties of a Fe90Zr10 amorphous alloy

The structure of a Fe₉₀Zr₁₀ amorphous alloy was investigated by means of small angle X-ray scattering as well as large-angle diffraction measurements. For as-quenched specimens, SAXS was found to be relatively weak, but spread over a wide scattering angle. After quantitative analysis, it was concluded that a compositional fluctuation occurs on a fine scale of about 0.6 nm. When the specimen was heat treated below the crystallization temperature, the amorphous structure changed to a more stable dual structure consisting of pure iron and a structure similar to Fe₃Zr. By prolonged heat treatment, the iron-rich regions crystallized initially from the amorphous state. An apparent correspondence was found to exist between the changes in the amorphous structure and in the mechanical properties. The microscopic phase separation within the amorphous state resulted in an increase of ultimate tensile strength and fracture toughness. The deterioration of mechanical properties was suggested to be attributed to the gradual crystallization of iron-rich regions.     

Magnetic properties and surface crystallization induced by selective oxidation in Fe-B-Si amorphous alloy

The relationship between the annealing atmosphere and the magnetic properties of Fe_78.5B₁₃Si_8.5 amorphous alloy has been studied, showing that annealing in nitrogen, argon, hydrogen and air significantly improved the iron loss of the amorphous ribbon, giving much better results than annealing in an H₂ + H₂O atmosphere. A boron-depletion zone with the alloy composition O to 3 mol % B and 9 to 11 mol% Si was detected by Auger electron spectroscopy under the oxide film formed during annealing in H₂ + H₂O. The iron crystalline phase is formed only on the ribbon surface after annealing in H₂ + H₂O. A mechanism is proposed explaining the deleterious effect of annealing in the H₂ + H₂O, whereby the H₂O in this atmosphere selectively oxides boron in the amorphous alloy to form a B₂O₃ film and the boron-depletion zone, and the alloy in this zone is then crystallized into -Fe. This surface crystalline layer induces out-of-plane magnetic anisotropy in the amorphous alloy ribbon (which was observed by transmission Mössbauer spectroscopy) and thus deterioration of the iron loss.     

Manufacture of amorphous alloy ribbons

Amorphous alloys are prepared in continuous ribbon form by rapid quenching directly from the melt. In particular, the process of chill block melt-spinning involves the continuous impingement of molten alloy against a rapidly moving substrate surface. Principles of chill block melt-spinning are presented with regard to the formation of continuous, rapidly-quenched amorphous alloy ribbon. The effects of numerous process variables on sample geometry and physical properties are examined through experimental results obtained by the author and by other researchers. Principles of narrow ribbon manufacture are extended to describe means of fabricating wide ribbon. Manufacturing problems unique to extended runs and potential solutions are cited. Effects of process parameters on magnetic and physical properties of as-cast samples are discussed.     

Ni-B非晶态催化材料研究进展

Ni-B非晶态合金作为一种新型的催化材料,具有较高的催化活性和选择性,且易于制备,受到了众多化学工作者的重视.本文简要地介绍了制备Ni-B非晶态催化剂的化学还原方法和机理,并且讨论了载体、退火晶化行为、稀土改性等对催化剂的活性、热稳定性和抗硫中毒性的影响.最后展望了Ni-B非晶态催化剂在工业上的应用前景.     

Effects of crystalline particles on mechanical properties of strip-cast Zr-base bulk amorphous alloy

Effects of crystalline phase particles formed in a strip-cast Zr-base bulk amorphous alloy on strength, ductility, and fracture toughness were investigated by directly observing microfracture processes using an in situ loading stage installed inside a scanning electron microscope chamber. The compressive and fracture toughness test results indicated that strength, ductility, and fracture toughness of the strip-cast amorphous alloy were higher than those of the as-cast monolithic amorphous alloy, although the strip-cast alloy contained a considerable amount (4.5 vol.%) of hard, brittle crystalline particles. According to the in situ microfracture observation, crystalline particles were easily cracked under low stress levels, acted as blocking sites of shear band or crack propagation, and provided initiation sites of multiple shear bands. Thus, the improvement of mechanical properties in the strip-cast alloy could be explained by mechanisms of (1) blocking of crack propagation, (2) formation of multiple shear bands, and (3) crack deflection by crystalline particles.