聚天冬氨酸与钨酸钠复配对黄铜缓蚀作用的光电化学研究

应用光电化学的方法研究了两种环境友好型缓蚀剂聚天冬氨酸(PASP)和钨酸钠(Na2WO4)的单一配方及其复配对黄铜在含硼砂硼酸缓冲溶液的模拟水中的缓蚀作用. 结果表明, 在光电流循环伏安测试中, 单一的PASP与Na2WO4均能够使黄铜表面Cu2O膜引起的p-型光电流响应增大, 这说明缓蚀剂增大了Cu2O膜的厚度, 使黄铜的腐蚀速率减小. 单一的PASP与Na2WO4的最佳添加浓度分别为20与25 mg•L－1. 若以总浓度为20 mg•L－1时对两者进行复配, 当PASP与Na2WO4的质量比为1∶1时, 两者复配比单一使用时的p-型电流光响应都更大, 黄铜的腐蚀更小, 即缓蚀剂的效果更好.     

Metallurgical behaviour of iron in brass studied using Mössbauer spectroscopy

The behaviour of small amounts of Fe in brass is investigated using Mössbauer spectroscopy. Different samples, made from the same ingot material, but run through different annealing temperatures and duration times and then quenched to room temperature, have different amount of γ-Fe. The present work shows that a suitable heat treatment can increase the amount of these precipitations and, that a heat treatment at 650°C is the optimal one for having the highest amount of this phase.     

H70黄铜-OCr18Ni9不锈钢滑动磨损表面材料的相互转移之研究

作者对H70黄铜(销)—OCr18Ni9不锈钢(盘)在真空(6.65×10~(-3)Pa)和大气中滑动磨损表面材料的相互转移进行了研究,并且提出了摩擦表面的原子扩散模型。文章指出,由于摩擦的热效应致使表面原子的扩散加剧,不论是软材料还是硬材料,它们的表面微凸体在滑动摩擦过程中都可能发生局部熔化,因而磨损表面出现了材料的相互转移,即使是硬材料中的Fe原子也转移到了软材料黄铜销的磨损表面上。销材料中的Zn原子在摩擦温度较高时的扩散系数是Cu原子的2～3倍,故在摩擦副的两个磨损表面都有Zn原子富集,且以真空下的更加明显。     

半金属摩擦材料与灰铸铁滑动摩擦表面层特性的分析研究

半金属摩擦材料具有摩擦系数稳定，耐磨性好，对环境污染小和对偶件表面损伤小等优点，但其在摩擦热和界面应力等因素作用下，表层会发生弹性变形，塑性变形，元素扩散，组分转移和摩擦化学反应等现象，因此，利用扫描电子显微镜Ｘ射线能量色散谱和差热－热重分析，对铜纤维增强的半金属摩擦材料与灰铸铁滑动摩擦表面层的特性作了分析研究，考察了表面层特性对摩擦损行为的影响。结果表明，在给定的试验条件下，半金属摩擦材料摩擦表     

FCC Rolling Textures Reviewed in the Light of Quantitative Comparisons between Simulated and Experimental Textures

The crystallographic texture of metallic materials has a very strong effect on the properties of the materials. In the present article, we look at the rolling textures of fcc metals and alloys, where the classical problem is the existence of two different types of texture, the “copper-type texture” and the “brass-type texture.” The type of texture developed is determined by the stacking fault energy of the material, the rolling temperature and the strain rate of the rolling process. Recent texture simulations by the present authors provide the basis for a renewed discussion of the whole field of fcc rolling texture. We simulate the texture development with a model which allows us to vary the strength of the interaction between the grains and to vary the scheme for the calculation of the lattice rotation in the individual grains (type CL/MA or PR/PSA). For the deformation pattern we focus on {111}<110> slip without or with deformation twinning, but we also consider slip on other slip planes and slip by partial dislocations. We consistently make quantitative comparison of the simulation results and the experimental textures by means of a scalar correlation factor. We find that the development of the copper-type texture is best simulated with {111}<110> slip combined with type CL/PR lattice rotation and relatively strong interaction between the grains — but not with the full-constraint Taylor model and neither with the classical relaxed-constraint models. The development of the brass-type texture is best simulated with {111}<110> slip combined with PR/PSA lattice rotation and weak interaction between the grains. The possible volume effect of deformation twins on the formation of the brass-type texture is a controversial question which we discuss on the basis of our simulations as seen together with other investigations.     

Interferometric Sensor for Electrochemical Studies of Metallic Alloys in Aqueuos Solution

In a previous study a mathematical model relating surface and bulk behaviors of metals in aqueous solution was developed. The model was established based on principles of holographic interferometry for measuring microsurface dissolution, i.e., mass loss, and on those of electrochemistry for measuring the bulk electronic current, i.e., corrosion current. In the present work, an interferometric sensor was built based on the above model, and the corrosion current density of coated copper and brass in seawater were obtained using this sensor. The interferometric sensor was also utilized for the first time to measure the initial stage of the anodization process (oxidation) of aluminium samples in aqueous solution. This was carried out chemically in different acid concentrations (3.125–25% H₂SO₄) at room temperature. The sensor was further used for observation of catalytic activities, i.e., pitting corrosion, which occurred subsequent to the anodization of the aluminium samples in aqueous solutions, after an oxide film had been formed.     

含铅黄铜儿童仿真饰品标准物质的研制

4介绍含铅黄铜儿童仿真饰品标准物质的研制方法。以铜锭、锌锭、铅粒为原料,利用坩埚熔炼及模具加工制备黄铜儿童仿真饰品标准物质,采用电感耦合等离子体发射光谱法进行均匀性检验、稳定性检验和定值。从样品中随机抽取15份进行均匀性检验,经F检验表明在95%的置信区间内样品均匀性良好。在常温条件下,经过12个月长期稳定性试验考察,结果表明样品稳定性良好。铅含量定值结果为136.1 mg/kg,合成扩展不确定度为0.72 mg/kg(k=2)。该标准物质满足ISO Guide 35:2006技术要求,可用于黄铜儿童仿真饰品检测的方法校正和质量控制。     

Comparison Between Different Methods of Analysis of Corrosion Products of Aluminum Brass in Sea Water: Chemical analysis,X-Ray Diffractometry,Auger Spectroscopy

Abstract

The oxidation layer formed on the surface of aluminum brass corroded in sea water at 40° C for 15 days was analysed by using different techniques (chemical analysis after selective dissolution, X-ray diffreactometry and Auger spectroscopy) and was found to be formed by Cu oxychlorides, basic Zn sulfates, Al and Mg Car bonates, Al oxides.

Chemical and diffractometric analyses yield an average value of the composition of the corrosion layer, whose thickness should be greater than 60-80° Å for chemical and than 100 Å for diffraacto metric analysis.

Auger speactroscopy permits the analysis of thin films and of small surface areas, and gives results that agree with those of the other two techniques when the corrosion layer is homogeneous.     

The void nucleation mechanism within lead phase during spallation of leaded brass

The incipient spall behaviours of Cu-34%Zn-3%Pb leaded brass samples with annealed and cryogenic-treated conditions were loaded using one-stage light gas gun experiments. The effect of Pb-phase on dynamic damage nucleation in leaded brass specimens was investigated by means of optical microscopy, scanning electron microscopy and x-ray computer tomography. It was found that the voids of incipient spall were mainly nucleated in the interior of the lead (no tensile stress would be produced within lead according to the impact theory) instead of nucleated at the phase interface as expected by quasi-static damage fracture theory. A nucleation model is proposed in the present work that is the asymmetry high compression zones in the centre of the lead-phase were formed by the rarefaction wave convergence effects of matrix/quasi-spherical lead interface, which caused adiabatic temperature rise that exceeded melting point of lead due to severe plastic deformation, finally led to local melting and void nucleation. In addition, the spall strength and damage rate increased with the increase in the Pb-phase number.     

Fatigue crack initiation life of fine grain brass H62

Fine grain alloys possess excellent properties entailing high strength and toughness. Fine brass H62 is made by re-crystallization with grain size ranging from 5 to 10 μm. Fatigue initiation life is investigated from specimens tested on Instron 1341 machine a frequency of 30 Hz. Furthermore fatigue crack initiation life of this fine brass H62 is predicted by the energetic approach. It is found that: (1) the finer the grain size, the longer the fatigue life, which is due to its higher toughness; (2) intergranular cracking is the main mechanism of fatigue failure. Concave pits were found in the zone of fatigue crack propagation; and (3) the energetic approach gave acceptable fatigue crack initiation life estimation.