钆提高YT14硬质合金耐磨性的机制

研究了不同Ｙ添加量对ＹＴ１４硬质合金显微组织，结构和耐磨性的影响。结果表明，在ＹＴ１４硬质合金名添加微量Ｙ，可显著提高合金铁耐磨性。Ｙ的主要作用是均匀细化碳化物相和Ｃｏ相，提高Ｃｏ粘结相中Ｗ，Ｔｉ元素的固溶量α－Ｃｏ相所占的体积分数，从而提高Ｃｏ粘结相的强韧性。     

钇提高YT14硬质合金耐磨性的机制

研究了不同Ｙ添加量对ＹＴ１４硬质合金显微组织、结构和耐磨性的影响。结果表明，在ＹＴ１４硬质合金中添加微量Ｙ，可显著提高合金的耐磨性。Ｙ的主要作用是均匀细化碳化物相和Ｃｏ相；提高Ｃｏ粘结相中Ｗ、Ｔｉ元素的固溶量及αＣｏ相所占的体积分数，从而提高Ｃｏ粘结相的强韧性；Ｙ在合金中形成Ｙ２ＷＯ６，表明Ｙ还可还原和清除碳化钨表面氧化膜，增强Ｃｏ粘结相与硬质相之间的结合强度     

La, Ce在钛镍合金中的作用

以近等原子比钛镍形状记忆合金为研究对象，通过向其分别添加微量第三元素稀土La，Ce，利用示差扫描热分析法、X射线衍射法分析研究了稀土元素La和Ce对Ti-Ni形状记忆合金相变类型、相变温度、物相组成的影响，利用透射电子显微镜观察和分析了马氏体相的形貌1和结构。加入微量稀土元素能提高Ti-Ni合金相变程度，但是合金的物相组成无明显变化，仍为B2母相和畸变单斜马氏体相B19。结果表明，可以通过添加第三元素La，Ce得到一定工作条件下性能优良的Ti-Ni形状记忆合金，提高Ti-Ni合金在实际中的应用价值。     

镧、铈对铝铜合金凝固过程及凝固组织的影响

本文用热分析对比法和金相法研究了微量镧、铈对Al-5wt％Cu合金的凝固过程和凝固组织的影响规律。发现微量镧、铈能改变该合金的凝固参数,增大其过冷度和明显细化组织,微量镧、铈改变了Al-5wt％Cu合金的凝固过程,使其在α相析出之后共晶析出之前有一中间相析出。加微量铈可形成Al_8Cu_4Ce。理论分析认为,Le_2O_3、Ce_2O_3、La(OH)_3和Ce(OH),可做为α相的异质核心。     

石墨炉原子吸收法测定钢铁及合金中微量钒

探讨了石墨炉子吸收法测定钢铁及合金中微量钒的各种实验条件及影响因素。实验表明，采用热解涂层管与光控升温相结合并在温度稳定的情况下原子化，可改善信号峰形，提高灵敏度，消除记忆效应。方法用于钢铁及合金中钒的分析，结果令人满意。     

表面活性剂加醇析相光度法测定微量磷

研究了表面活性剂ＴｒｉｔｏｎＸ－１００ｌｋ ｕｙｇｈｓｇｙｂｓｒｈ ｓｈ ｃｆ ｄｏｑｈｑｕｘ ｑｈｇ ａｊｔｌｖｓ杂酸的萃取行为。结果表明，析相萃取效率高，络合物的稳定性好，所建立的析相萃取光度法已成功地用于岩矿中微量磷测定。     

Al-5Mg-Er合金中Al3Er相的析出及其热力学计算分析

通过应用Miedema热力学模型方法对添加了微量Er的Al-5Mg合金中的Er的存在形式进行了初步的分析，并结合XRD，TEM试验进行了验证。微量Er在Al-5Mg合金中主要是以Al3Er的形式存在，并且不会出现元素Mg与Er之间的金属间化合物；同时通过XRD和TEM分析证实，含微量Er（0．1％～0．7％）的Al-5Mg合金中Er是以Al3Er相存在并且弥散分布，讨论了Al3Er相与Al基体之间的取向关系，分析了Al3Er相的存在能够改善Al-5Mg合金材料的机械性能。     

固相萃取ICP-AES法测定多种微量元素的研究

建立了以微晶萘作为吸附载体的固相萃取ＩＣＰ－ＡＥＳ法测定微量Ｆｅ、Ｃｏ、Ｎｉ、Ｃｕ、Ｚｎ、Ｃｄ、Ａｌ、Ｍｎ的新方法。研究了溶液酸度、试剂浓度、萘用量以及共存离子对待测物回收率的影响。方法可用于生物标样品的测定,分析结果满意。     

固相萃取ICP-AES法测定多种微量元素的研究

建立了以微晶萘作为吸附载体的固相萃取 Ｉ Ｃ Ｐ Ａ Ｅ Ｓ 法测定微量 Ｆｅ 、 Ｃｏ 、 Ｎｉ、 Ｃｕ 、 Ｚｎ 、 Ｃｄ 、 Ａｌ、 Ｍｎ 的新方法。研究了溶液酸度、试剂浓度、萘用量以及共存离子对待测物回收率的影响。方法可用于生物标准样品的测定,分析结果满意。     

离子色谱电导与紫产合测定镀镍液中硝酸根及其它阴离子

探讨了用ＤＸ－３００型离子色谱仪测定在其它高浓度阴离子存在下微量ＮＯ＾－３的方法，采用电导检测器与紫外检测器联用技术，既可克服基体高背影对微量ＮＯ＾－３测定的干扰，又可同时测定共存在的其它阴离子，如Ｃｌ＾－，ＳＯ＾２－４等。方法用于测定镀镍及其原料硫酸镍中ＮＯ＾－３的分析，得到了满意结果。     

盐水振荡研究的新发现

在对化学振荡的研究中,无论是溶液均相氧化还原形成的振荡反应,还是界面扩散受阻形成的界面振荡,都普遍采取各种电极法来监测。前文[1,2]研究了各种不同电极监测液膜振荡的变化,本文将讨论不同的电极方法在监测盐水振荡现象过程中的新发现。1970年,地球物理学家Martin[3]发现把     

溶胶-凝胶法设计与制备金属及合金纳米材料的研究进展

溶胶-凝胶法是常见的制备金属氧化物的方法之一。在溶胶-凝胶法中,各种反应物能达到分子级的均匀混合,因此能制备成份复杂的氧化物材料。目前,溶胶-凝胶法也应用于设计与制备金属纳米材料,特别是合金纳米颗粒。例如,溶胶-凝胶法能应用于制备CoPt、FePt等磁性纳米合金材料以及CoCrCuNiAl高熵合金纳米材料,以及物相结构为有序相的Cu3Pt合金纳米材料。本文综述溶胶-凝胶法设计制备金属纳米材料的研究进展,包括溶胶-凝胶法实施的基本步骤、该方法在制备金属纳米材料方面的具体应用,并着重论述采用热力学计算设计金属及化合物的基本原理。该基本原理包括计算金属氧化物与还原性气体如氢气的还原反应的吉布斯自由能的变化量、金属氧化物的标准电极电位(不同于金属离子的标准电极电位)。最后探讨溶胶-凝胶法设计制备金属纳米材料存在的问题以及后续可能的发展方向。     

Spectroelectrochemical studies of bilayers of phospholipids in gel and liquid state on Au(111) electrode surface

Differential capacity, chronocoulometry and Polarization Modulation Fourier Transform Infrared Reflection Absorption Spectroscopy (PM FTIRRAS) were employed to investigate spreading of small unilamellar vesicles (SUVs) of DOPC and DMPC onto a Au(111) electrode surface. The electrochemical experiments demonstrated that vesicles fuse onto the electrode surface and at E>-0.5V (SSCE) or at charge densities -10-0.5 V (SSCE), the tilt angle increases to approximately 42 degrees. The increase of the tilt angle is discussed in terms of a change in the packing of the polar head of the phospholipids molecules in the bilayer adsorbed at the electrode surface.     

A simple and versatile PSA system for heavy metal determinations

An easy to build potentiometric stripping analysis system for heavy metal determinations (Zn, Cd, Pb, Cu) is described which reaches good sensitivity and precision. Main components are an IBM compatible computer, an ADDA-conversion card and two selfmade electrodes, so it can be realized for one tenth of the price of complete commercial systems. A graphite pencil lead covered with a Hg-film is used as working electrode and a Ag/AgCl electrode as a combined reference/counter electrode. Reproducibility and calibration measurements are reported, heavy metal determinations on soil samples are compared with AAS results.     

A simple and versatile PSA system for heavy metal determinations

An easy to build potentiometric stripping analysis system for heavy metal determinations (Zn, Cd, Pb, Cu) is described which reaches good sensitivity and precision. Main components are an IBM compatible computer, an ADDA-conversion card and two selfmade electrodes, so it can be realized for one tenth of the price of complete commercial systems. A graphite pencil lead covered with a Hg-film is used as working electrode and a Ag/AgCl electrode as a combined reference/counter electrode. Reproducibility and calibration measurements are reported, heavy metal determinations on soil samples are compared with AAS results.     

Hydroxyapatite Wrapped Multiwalled Carbon Nanotubes/Ionic Liquid Composite Electrode: A High Performance Sensor for Trace Determination of Lead Ions

A nanocomposite consisting of multiwalled carbon nanotubes wrapped with hydroxyapatite (HA/MWCNTs) was used in the construction of a new composite paste electrode using an ionic liquid as the binder. The stable surface in aqueous solutions as well as the high sorptive behaviors towards heavy metal ions and the favorable charge transfer make the electrode highly efficient especially for stripping or adsorptive analysis. The analysis of Pb²⁺ as a model of heavy metal ions has been performed. Good sensitivity, detection limit, selectivity and reproducibility were obtained for the suggested sensor. The linear range of the electrode response covered four orders of magnitude (1 nM–10 µM), in two linear ranges. The obtained detection limit for Pb²⁺ was 2×10^?11 M.     

The Electrochemical Behavior in Aqueous Media of Conducting Polymers: I: The Methanol Soluble Fraction Obtained on the Cu(II) Catalyzed Polymerization of 2,5-Dibromo-3-Methylthiphene

Abstract

The methanol soluble amorphous fraction obtained on the CuCl₂ induced polymerization of 2,5-dibromo-3-methylthiophene exhibits redox waves on cyclic voltammetric potential polarization for a copper redox couple (for the metal ion incorporated in the polymer matrix) and a redox couple associated with the polymer matrix itself. Furthermore, when used as an electrode for the ferri/ferrocyanide couple in the electrolyte phase it acts as a well behaved electrode surface. Electrodes made from this material show a remarkable stability in aqueous media.     

Stripping Voltammetry at Microdisk Electrode Arrays: Theory

Anodic stripping voltammetry (ASV) is an extremely powerful tool for detection of metal ions in solution through a two step process of preconcentration of the metal at the electrode surface, followed by electrodissolution. The second phase produces an electroanalytical response proportional to the amount of material deposited in the first phase. This paper utilizes theory to explore the electrochemical signals produced when considering ASV at a microelectrode or ultramicroelectrode arrays. The theory outlined is applicable mostly to thin mercury film absorption and metal adsorption.     

Dynamics of metal deposition onto a porous electrode of poor initial conductivity, with the electrode operating in a direct-flow regime at high solution flow rates

The process of metal electrodeposition onto a porous matrix with poor initial conductivity is studied with the aid of a dynamic model for a porous electrode (PE), which was designed earlier and which was complemented with a block for calculating local conductivity of the solid phase. It is established that, despite a very low initial metal deposition rate, the final weight of the deposit inside the PE in the electrolysis conditions under consideration is greater than that inside a PE with a high conductivity of the solid phase. It is demonstrated that the additional metal amount is localized largely in the rear part of the PE and undergoes deposition chiefly in the initial electrolysis stage, specifically, until the instant of full metallization of the porous matrix and the PE conversion into an equipotential electrode. Specific features characterizing variations in the metal’s deposition rate in the course of its deposition onto a low-conductivity porous matrix and possible reasons for such variations are considered.     

A stannum-bismuth composite film electrode for simultaneous determination of zinc(II) and cadmium(II) using differential pulse anodic stripping voltammetry

The development and use of 'green' electrode materials is extremely attractive for the routine use of disposable metal sensors. Bismuth is an environmentally-friendly element and a bismuth film electrode was proposed as an alternative to mercury film electrodes. Compared with bismuth, stannum is a more 'environmentally friendly' material. The stannum-bismuth composite film electrode prepared by the in situ electrodeposition of stannum and bismuth on the glassy carbon substrate is reported for the first time. Compared with bismuth film and stannum film electrodes, the stannum-bismuth composite film electrode revealed better electroanalytical performance, and can be used as a possible alternative electrode for electrochemical stripping analysis of trace heavy metals.