贵金属催化动力学光度法

本文评述了贵金属催化动力学光度法新近发展状况。     

催化动力学分光光度法测定电镀液中的钯

利用痕量Ｐｄ＾２＋在ＨＣｌ介质中的催化作用建立了Ｐｄ的催化动力学分光光度测定法，测定线性范围：４０￣２００ｎｇＰｄ／ｍｌ。应用于电镀中Ｐｄ含量的测定，相对标准偏差在２．５％以内，回收率为９７．０￣１０１．１％。电镀液中的７种添加剂对Ｐｄ的测定无干扰。     

铁催化动力学光度法在矿冶分析中的实际应用

本文评述了铁催化动力学光度法在矿冶分析中实际应用的新近发展状况。     

孔雀绿在贵金属催化动力学分析中的新应用

基于Ｒｕ（Ⅲ）、Ｒｈ（Ⅲ）、Ｉｒ（Ⅳ）对ＫＩＯ４氧化孔雀绿反应的强烈催化作用及Ｐｄ（Ⅱ）、Ａｕ（Ⅲ）对ＰＯ２＾３－还原孔雀绿的催化作用，采用单扫描示波极谱作孔雀绿的检测技术，分别建立了测定０．０００８￣０．０４ｎｇ／ｍｌＲｕ、０．０３￣２ｎｇ／ｍｌＲｈ、０．２４￣１．６ｎｇ／ｍｌＩｒ、０．５￣１１ｎｇ／ｍｌ Ｐｄ及２０￣５００ｎｇ／ｍｌ Ａｕ的催化动力学分析新方法，并用于试样分析。     

铜的分光光度法在贵金属分析中的应用

1.前言:由于原子吸收光谱法在有色金属分析中具有干扰少、无须分离、便于大宗试样分析等优点,而越来越被人们所重视.然而,在贵金属冶金分析中,有色金属元素的分光光度测定法仍不失为一个操作简便、重现性好、适用范围宽的好方法.这是因为在其物料中,存在各种不同含量的铂族元素,可以通过铜的不同分光光度法所具有的特效性、选择性以及灵敏度来完成复杂物料中铜的测定.下面讨论铜的各种分光光度法在贵金属冶金分析中的应用.     

催化动力学分光光度法测定痕量铕

利用过氧化氢氧化丽春红褪色,以Eu3+为催化剂,建立一种新的测定铕的动力学分光光度法。在6.0×10-2mol/L的盐酸介质中,Eu3+-H2O2-丽春红体系的最大吸收峰位于450nm,Eu3+量在0～22μg/25mL范围内与吸光度差值△A呈良好的线性关系,其回归方程为△A=0.0221C+0.0241(C=μg/25mL),相关系数r=0.9968,方法检出限为2.42μg/L。本方法用于水样中铕的测定,13次测定相对标准偏差为0.49%～1.76%,加标回收率为95.20%～101.3%。     

钴催化动力学光度法在环境分析中的应用

评述了钴催化动力学光度法在环境分析中的实际应用新近发展状况，指示反应体系及其条件，以及相应光度分析方法的检出限，干扰情况和测定范围等。     

铜催化动力学光度法

本文评述了铜催化动力学光度法新近发展状况。     

钒催化动力学光度法

本文介绍了钒催化动力学光度法新近发展状况，论述了指标应体系统及其条件，以及相应光度分析方法的检测限、干扰情况和测定范围等「。     

钒催化动力学光度法在环境分析中的实际应用

本文介绍了钒催化动力学光度法在环境分析中的实际应用新近发展状况，论述了指示反应体系及其条件，以及相应光度分析方法的检测限，测定范围和干扰情况等。     

ICP—AES在有色金属材料中的应用

近年ICP-AES的分析技术和装置不断发展和完善,该法已在许多领域中得到应用,本文叙述了ICP-AES在轻金属、重金属、难熔金属、贵金属、超导材料、精细陶瓷材料、稀土金属分析中的应用。     

微量元素对Al-Ag合金时效早期微结构演变影响的Kinetic Monte Carlo模拟研究

采用基于Multi-States Ising Model的Kinetic Monte Carlo算法,模拟研究了添加微量元素对Al-Ag合金时效初期微观结构的演变过程的影响。结果表明：在Al-Ag合金中,In,Sn,Be元素显著地抑制了合金时效初期的Ag原子偏聚,这是这些元素的原子与空位强烈地相互作用的结果。Mg元素对Ag原子的偏聚的抑制次之,添加Mg元素的合金,时效过程中出现了Mg-Ag原子团簇和Ag-Mg-Va团簇,Mg-Ag之间以及Mg-Va之间的共同作用影响了Ag原子的偏聚。Li,Cd原子与Ag原子和空位均无明显作用,因此Li和Cd元素对时效早期Ag原子的团聚影响较小。微量元素是通过与构成析出相的主要溶质元素以及空位的相互作用来实现对原子偏聚过程的影响,进而来影响Al-Ag合金的时效过程的,其中微量元素与空位的相互作用起到关键的作用。锁定单空位和空位团聚进而降低空位可动性是影响Al-Ag合金时效过程的两种重要机制。     

电工用铝合金熔体净化技术研究现状及展望

研究铝合金熔体净化方法对提高电工用铝合金杆的质量具有重要意义。净化方法有吸附净化、非吸附净化和复合净化3类,综述了电工用铝合金熔体净化方法研究应用现状及进展。其中吹气法、熔剂法、过滤法、超声波净化法、电磁净化法等方法的研究应用成果较多,以追求高效便捷为目标的复合净化方法正成为该领域关注的热点。     

Formation of grain refined and non-dendritic microstructure of an aluminum alloy under angular oscillation

A new technique to achieve sound semi-solid slurry by introducing angular oscillation during the earlier stage of solidification is reported. The effects of melt superheat and oscillation intensity on the grain refinement and morphology of primary Al particles in aluminum alloy A356 were investigated. Results confirmed that a fully grain refined and non-dendritic microstructure could be obtained using proper processing conditions, and the superheat of melt could be increased to a higher level. The primary Al particle had average diameter of 58 μm and average shape factor of 0.84, and featured zero entrapped eutectic.     

Inhibition of the Corrosion of Grey Cast Iron in Ethanediol/Water Solutions by Benzoate/Benzotriazole Mixture: A Synergistic Effect

Abstract

The synergistic effects of sodium benzoate and benzotriazole in inhibiting the corrosion of grey cast iron in 50% ethanediol/water solutions are described. Good inhibition can be obtained in the presence of both inhibitors at concentrations of eachwhich are ineffective when either inhibitor is present alone. The results also showthat the inhibitors are effective on both ‘as-cast’ and machined surfaces. Limited information is presented to demonstrate a similar synergistic effect for the inhibition of corrosion of an aluminium alloy. Some possible adsorption mechanisms to explain these effects are considered briefly.     

Influence of plastic deformation on the velocity and ultrasonic attenuation of copper single crystals

High-purity copper single crystal samples were plastically deformed between 0.02% and 1% in the direction. The absolute ultrasonic velocity and attenuation related to the dislocations in copper single crystal were measured as a function of the plastic deformation. The amplitude-independent Swing Model for dislocation resonance was considered to obtain information about the evolution of the dislocation density (Λ) with the degree of plastic deformation (%). The experimental data were interpreted as resulting from the contribution of two kinds of dislocations that lie in a cell structure. The results show a linear increase with the deformation of the density of dislocations (Λ_I) that lies in the cell walls [Λ_I (cm⁻²)≈1.5×10⁹ %]. The dislocation density inside the cell (Λ_II) is about two orders of magnitude lower than Λ_I.     

Comparison between the ultrasonic and the low frequency Bordoni peaks in copper

A comparison between properties of the Bordoni peaks at low and high frequency is realised from experimental data of attenuation and velocity obtained at Hz and MHz frequencies. The measurements were obtained in crystalline samples, all of them cut from the same crystal lot. Significant differences on secondary properties are obtained for the low and the high frequency peaks. The high frequency relaxation is interpreted as produced by a single relaxation process due to kink pair formation with kink diffusion in dislocation lines, but the low frequency relaxation must be considered as a more complicated process.     

High temperature diffusion induced liquid phase joining of a heat resistant alloy

Transient liquid phase bonding (TLP) of a nickel base superalloy, Waspaloy, was performed to study the influence of holding time and temperature on the joint microstructure. Insufficient holding time for complete isothermal solidification of liquated insert caused formation of eutectic-type microconstituent along the joint centerline region in the alloy. In agreement with prediction by conventional TLP diffusion models, an increase in bonding temperature for a constant gap size, resulted in decrease in the time, t_f, required to form a eutectic-free joint by complete isothermal solidification. However, a significant deviation from these models was observed in specimens bonded at and above 1175 °C. A reduction in isothermal solidification rate with increased temperature was observed in these specimens, such that a eutectic-free joint could not be achieved by holding for a time period that produced complete isothermal solidification at lower temperatures. Boron-rich particles were observed within the eutectic that formed in the joints prepared at the higher temperatures. An overriding effect of decrease in boron solubility relative to increase in its diffusivity with increase in temperature, is a plausible important factor responsible for the reduction in isothermal solidification rate at the higher bonding temperatures.     

Influence of Fermi energy equalization on crystal nucleation in glass melts

The energy saving produced by the equalization of Fermi energies of a crystal and a melt has been associated to the crystal formation in undercooled melts to determine the new homogeneous-nucleation critical-temperature T₂ and the new nucleation critical barrier as a function of the temperature T. Small unmelted clusters act as nuclei by reducing the critical energy barrier and the nucleation times; the glass transition temperature T_g occurs near T = T₂. The temperature dependence of the specific heat difference of the undercooled melt with the glass, the viscosity weakening below T_g and the nose of the temperature–time–transformation diagrams are successfully predicted.