关注产品：贵金属首饰饰品

产品简介 贵金属饰品是指贵金属材料制成的首饰和摆件。主要有4类：金及其合金饰品,如118K、22K、足金、千足金饰品等;铂及其合金饰品,如850铂、900铂、950铂、足铂、千足铂饰品等;钯及其合金饰品,如950钯、足钯、千足钯饰品等;银及银合金饰品,如925银、足银、千足银饰品等。     

首饰用抗变色银合金研究进展

简要分析了银合金变色的原因.评述了表面处理以及贵金属合金化、贱金属合金化、稀土合金化等方法以提高银合金抗变色性能的特点.并着重介绍了当前研究最多的贱金属合金化法制备的典型银合金成分及其抗变色机理.     

金属饰品钎焊工艺的研究

金属饰品包括贵金属饰品和普通金属饰品,金属饰品的焊接以钎焊工艺为主。文章介绍了钎焊的金属学微观原理,以合金相图为理论依据的钎料选择,金属饰品常用的钎料、钎剂,焊接操作和注意事项。既有理论,又有实践。     

载银锌4A沸石抗菌剂抗变色性能的研究

通过调整抗菌剂中银、锌离子的含量,研究了载银锌4A沸石抗菌剂的抗变色性能.利用ICPS测定了样品的银、锌含量,通过XRD、IR、TEM表征了抗菌剂的结构和形貌,并对其抗变色性能和抗菌性能进行了测试和分析.结果表明,减少ZLSZ抗菌剂中银离子(Ag )的含量,增加锌离子(Zn2 )的含量,抗菌剂样品的抗菌性能变化不大,而抗变色性能却大幅度提高.从抗菌剂的成本、抗菌性能和抗变色性能等方面综合考虑,载银锌4A沸石抗菌剂中,银含量为0.41wt%,锌含量为3.83wt%为宜.     

含钇银铟合金硫化腐蚀及力学、光学性能研究

采用真空熔炼炉制备了Ag-In稀土Y合金。利用XRD、扫描电镜、光纤光谱仪等设备对样品进行测试,实验结果表明,未添加稀土样品晶粒粗大,添加稀土钇能明显细化晶粒,枝晶发育细小,与925银相比抗硫化腐蚀能力增强。随着In含量的增加,析出Ag3In脆性相,对合金起到了强化作用,含钇银铟合金对可见光具有较高反射率,色调与纯银相比略显暖色。     

抗变色仿金合金的研究

本文研究了合金化元素对仿金合金色译,抗变色性及加工工艺性能的作用。在Cu-Zn-Al系中(α+β＇)和β＇相合金具有金黄色译;适量的硅不仅使合金更加呈现金黄色译,而且使仿金合金抗变色性能提高;过高的含铝量并不能改善合金的抗变色性,3％Al是较佳含量,锌对于提高抗变色性有明显作用,高锌铜合金尤其具有较高的抗变色性。通过相同条件下对比试验,从96种仿金合金中优选出IG—01仿金合金,它在色译,抗变色性和加工工艺性上达到最优水平。     

GH4090合金圆柱螺旋弹簧应力松弛性能研究

以航空发动机用GH4090合金圆柱螺旋弹簧为研究对象,研究了不同温度下弹簧的静态和动态抗松弛性能。结果表明,静态抗松弛实验下,时效态GH4090合金弹簧在室温和300℃下无松弛、无蠕变;350和400℃下应力松弛率分别为1.08%和1.09%。动态抗松弛实验下,时效态GH4090合金弹簧在室温下无松弛,350℃下应力松弛率为3.23%;变形态GH4090合金弹簧在室温和350℃下应力松弛率分别为3.30%和16.85%。变形态和时效态GH4090合金弹簧的松弛率均随温度的升高而增大,且变形态松弛率变化尤为明显。     

稀土在银基接触材料中的作用与应用

介绍了稀土在银及银合金电接触材料中的作用、特点及影响效果,阐述了国内外稀土银合金电接触材料的应用情况,展望了稀土银合金的发展前景。     

金、铂饰品中有害元素含量分析时元素波长的选择

常见的贵金属饰品有金、银、铂、钯四大类,为了达到饰品的美观性,部分不法商家会在饰品的辅料和焊料中添加一些有害金属。研究金、铂饰品中有害元素测定时元素的干扰以及波长的选择,能更加客观准确地分析其中有害元素的含量。     

新型电接点材料—铌铈合金

为开发稀土元素的应用,创制新型电接点材料,研制了一种含少量稀土元素铈的银铈合金。合金的制备采用银-金属间化合物的途径。铸锭经金相分析和X-射线分析确定,是以银为基和银铈金属间化合物(Ag_5Ce)的两相组织。研究了铈对合金基本物理性能的影响。发现加入少量铈后,合金仍然基本上保留了纯银作为接点材料的那些优异特性,基本物理性能和银相近,并且具有良好的加工性能和工艺稳定性。用日本Rigaku的TG(热重分析)装置研究了合金的氧化特性,结果表明,银铈合金具有与纯银显著不同的氧化性能。介绍了该合金在CHZ-1型直流接触器(32V、100A、动作40000次)和DZ-810中间继电器(直流60W;交流250VA,动作1×10~7次)上的使用情况,并与纯银和AgCdO_(12)材料作了对比实验。实验结果表明,银铈合金具有优良的导热性和导电性,接触电阻低而稳定,有一定的灭弧能力和有用的氧化特性。特别是由于铈的加入,使该合金具有特别优异的抗熔焊性能。因此,大大提高了电器的使用寿命和接触可靠性。最后在发射光谱仪上,模拟继电器的工作状态,用分光分析的方法对银铈合金在电弧作用下的物理化学过程进行了初步探讨,提出了铈在电弧中“外氧化机理”的观点。(图3,表4,参考文献3。)     

FATIGUE-MICROSTRUCTURE RELATIONSHIPS IN SOME AGED ALUMINIUM ALLOYS

Abstract Aluminium–copper–magnesium alloys show a high response to age hardening but have relatively poor fatigue properties, whereas the reverse is true for aluminium magnesium alloys. Small additions of silver (∼0.1 atomic %) change both the type and dispersion of precipitates in Al–Cu–Mg alloys and promote age hardening in Al–Mg alloys in which it is normally absent. The paper is concerned with the effects of silver on the behaviour of representative Al–Cu–Mg and Al–Mg alloys tested under fatigue conditions.
Despite the fact that silver increases the response to age hardening in Al–Cu–Mg alloys, the fatigue endurance limit is reduced. This effect is even more marked with the alloy Al–5% Mg in which the 0.2% proof stress was increased from 85 to 200 MPa by adding silver, whereas the fatigue endurance limit fell from ±87 to ±48 MPa. In both systems, silver promotes formation of finely dispersed precipitates, and the poor fatigue properties are associated with the concentration of dislocations in intense slip bands. On the other hand, when large precipitate particles are present, dislocations are more uniformly dispersed and the fatigue properties are improved.     

Characterizations of silver alloys used in modern Mexican coins

This paper presents a complete methodology for the characterization of silver alloys used in modern coin production. Mexican coins with a nominal silver concentration from 10% to 99.99% were used in this study. Calibrated Glow Discharge Optical Emission Spectrometers were used to determine the chemical composition of the alloys as a function of the depth, while inductively coupled plasma was used to determine the total element composition in bulk. Scanning Electron Microscope was used to study the phase distributions in the different silver coins. According to Glow Discharge Optical Emission Spectrometers and inductively coupled plasma, the silver content found in the studied samples was consistently greater than that of the nominal silver content reported by the Mexican mint. This may lead to a review of the new methods of analysis used nowadays in contemporary coin minting. This result is very important because silver is increasing in value as metal and, considering the volume of production of silver coins, this may increase further as a consequence of a growing popular confidence in silver currency.In the case of silver studies, an advantage of the absence of silver detector in the Glow Discharge Optical Emission Spectrometers system is that it allows for the recalibration to have a better range of detection of other metals present in the alloys. A calibration curve using the copper content obtained by inductively coupled plasma (bulk) and Glow Discharge Optical Emission Spectrometers (depth profile) was performed. The relevance of control in modern silver coin minting was clarified, especially in minimizing the discrepancy between the nominal and the core fineness. The physical and chemical properties of the alloys studied are defined, revealing important variations in silver and copper contents. A new methodology and metrology for the control of coinage are suggested.     

Thermodynamic properties of silver–palladium alloys determined by a solid state electrochemical method

Silver–palladium alloys have various industrial applications, such as in hydrogen permeation and hydrogen storage materials. The objective of the present study is to determine experimentally the thermodynamic properties of solid state silver–palladium alloys in low temperatures. Thermodynamic measurements of silver–palladium alloys have been performed over a temperature range of 450–750 K by the electromotive force method with superionic conductor AgI as the solid electrolyte. The activity and partial molar Gibbs energy of silver were obtained for Ag–Pd alloys over the whole composition range, and the thermodynamic properties of palladium were calculated using the Gibbs–Duhem equation. The results show that activities of silver exhibit fairly large negative deviations over most of the composition range, and the activities of palladium are characterized by both negative and positive deviations from the ideal Raoultian behavior. The results also show the minimum integral enthalpy of mixing of Ag–Pd alloys to locate at around 60 at.% Ag.     

Degradable silver-based alloys

Noble metals solved in iron implants are effective cathodes, which can suit to accelerate the corrosion rate of the base material. In terms of its antibacterial behavior as well as lower costs in comparison with gold or platinum, silver seems to be an attractive candidate to adapt the corrosion rate of implants to the medical requirements. However, the degradation of silver in human bodies is a time-consuming process, and is controversially discussed due to the unknown long-term effect of silver on the human organism. Alloying silver with chemical elements less resistant to corrosion in aqueous mediums, particularly, in simulated body fluid, can improve the degradability of silver. Therefore, the current study addresses the design of adapted silver alloys exhibiting improved degradability in comparison with pure silver. Pure silver and binary silver alloys containing silicon, magnesium and calcium are studied in terms of their microstructure, open-circuit potential and degradation rate.     

Oxidation of NiAl-Ag Alloys at 1000℃ in 0.1 MPa O2

Small amounts of silver have been added to the intermetallic compound NiAl with the purpose of improving its mechanical properties. Four ternary NiAl-Ag alloys containing 0.5, 1, 5 and 10 at. pct Ag, denoted as NiAl-0.5Ag, NiAl-1Ag, NiAl-5Ag and NiAl-10Ag, and the Ag-free NiAl have been oxidized at 1000℃ for 24 h in 0.1 MPa O2 to study the effect of the presence of silver on the oxidation behavior of NiAl. All the NiAl-Ag alloys are composed of a matrix of β-NiAl containing a dispersion of isolated particles of a second silver-rich phase. A continuous external layer of Al2O3 formed on all the alloys. In addition, the scales formed on NiAl-5Ag contained a thin and discontinuous layer of pure silver located at the alloy/Al2O3 interface, while those formed on NiAl-10Ag contained isolated particles as well as discontinuous layers of silver at various locations in the scale extending up to the gas/scale interface. The kinetic curves of all the alloys were generally composed of two main parabolic stages with smaller parabolic rate constants for the final stage. The addition of silver does not significantly affect the oxidation behavior of the NiAl intermetallic compound in all cases, as expected because silver is essentially present only as a second phase due to its very small solubility in β-NiAl.     

Correlation Between Chemical Composition of Silver Alloys and Photothermal Radiometry Signals

The development of nondestructive and noncontact techniques for evaluation of metallic materials is invaluable to metal characterization. The photothermal radiometry (PTR) amplitude and phase images of silver alloys were used to study the silver distribution in alloys rich in silver and copper for Ag concentrations between 37?mass% and 92?mass%. The silver concentration was determined using inductively coupled plasma. It was found that for Ag concentrations lower than 50?mass%, the PRT signals are governed by the thermal and optical properties of copper and vice versa. It was possible to establish a good correlation between the PTR amplitude and phase signal with the Ag concentration. This means that after calibration it is possible to determine the Ag concentration using nondestructive evaluation.     

An estimation of the reflectivity of gold- and platinum-group metals alloyed with copper

The reflectivity of some noble metals alloyed with copper of the formula Cu _x M_1?x , where M is gold, platinum, palladium and silver, has been modelled using only the available optical constants of the pure parent metals, copper, gold, platinum, palladium and silver. The results are compared with experimentally determined reflectivity for some of these alloys and shown to give reasonable approximations, suggesting that the method has utility for the estimation of the reflectivity of alloys when no experimental data are available. The method of estimation of reflectivity has been extended to include two-phase alloys as well as homogenous alloys.     

The effect of silver addition on 7055 Al alloy

The effect of silver addition on the microstructure and mechanical properties of the 7055 Al alloy was investigated. Mechanical properties of various alloys used in this study are correlated with the formation of constituent particles and microstructural changes of fine precipitates. According to the experiment, tensile strength of the 7055 Al alloy decreased by the addition of silver, although silver additions were observed to refine η′. The low tensile strength is attributed to the relatively low number density of η′ in silver-bearing alloys in which a large amount of hardening elements, such as Zn and Mg, are consumed to form silver-bearing constituent particles.     

Modification in tin-antimony alloys

Sn-10.4% Sb alloys containing 0 or 1% of only one of silver, copper or zinc were cooled from the liquid state rapidly and slowly. Then the alloys were examined by metallographic and electron (transmission and scanning) microscopy. Microhardness measurements were also carried out. The results obtained show that rapid cooling, compared with the slow cooling, greatly affects the structure and properties of Sn-Sb alloys. It leads to a much finer-grained structure and, therefore, gives rather better mechanical strength. It also leads to the formation of new phases, not found under equilibrium conditions, including a quasi-amorphous phase in the case of addition of silver.