Small Additions Of Silver Research Articles

Forged coins from early medieval settlement centre in Pawłówek on southern border of East Pomerania (northern Poland)

Abstract In the course of explorations of an early medieval fortified centre in Pawłówek on the periphery of East Pomerania and Kuyavia, as many as 49 coins and one planchet were found deposited within cultural layers dated back from the turn of the 1070s to the beginning of the 1100s. Nearly half of them showed characteristics typical of coin counterfeiting. Physical-chemical studies proved that they were manufactured using mainly copper with a small addition of silver, tin, zinc, or lead. It is the most numerous series of this kind of coins ever unearthed in the area of Poland, second only to the hoard of Włynkowo in East Pomerania. The variety of these finds in terms of manufacturing technique and technology suggests that they come from different sources. Due to the nature of the examined centre that served for treasurial and fiscal purposes (customs chamber), it was concluded that a considerable number of the counterfeit coins in this place can be linked to an intentional selection of such coins from the ore mass that constituted customs duties and/or local manufacturing of forged coins.

Micro-Addition of Silver to Copper: One Small Step in Composition, a Change for a Giant Leap in Biocidal Activity.

The use of copper as an antimicrobial agent has a long history and has gained renewed interest in the context of the COVID-19 pandemic. In this study, the authors investigated the antimicrobial properties of an alloy composed of copper with a small percentage of silver (Cu-0.03% wt.Ag). The alloy was tested against various pathogens, including Escherichia coli, Staphylococcus aureus, Candida albicans, Pseudomonas aeruginosa, and the H1N1 virus, using contact exposure tests. Results showed that the alloy was capable of inactivating these pathogens in two hours or less, indicating its strong antimicrobial activity. Electrochemical measurements were also performed, revealing that the small addition of silver to copper promoted a higher resistance to corrosion and shifted the formation of copper ions to higher potentials. This shift led to a slow but continuous release of Cu2+ ions, which have high biocidal activity. These findings show that the addition of small amounts of silver to copper can enhance its biocidal properties and improve its effectiveness as an antimicrobial material.

Effect of Ag-Addition on the Catalytic and Physicochemical Properties of Ni/ZrO2 Catalyst in Oxy-Steam Reforming of CH4 and LNG Processes

This work presents, for the first time, the catalytic studies of bimetallic Ag-Ni catalysts in the oxy-steam reforming (OSR) of liquefied natural gas (LNG) to hydrogen generation. The physicochemical properties of monometallic Ni and bimetallic catalysts were investigated using various techniques, such as: BET, TPR-H2, TPD-NH3, XRD, TG and SEM-EDS. The catalytic studies showed that the promotion of 20% Ni/ZrO2 catalyst by silver (by 1 or 2 wt.%) improves the efficiency of the produced hydrogen in the oxy-steam reforming of LNG at high temperature. The promotional effect of silver on the reducibility of a Ni/ZrO2 catalyst has been proven. The interactions between Ag and Ni have been proven, and explain the catalytic activity of the catalysts in the investigated processes. TG-DTA-MS results obtained for the spent catalysts proved that the small addition of silver to monometallic nickel catalyst reduces the amount of the carbon deposit formed on the catalyst surface during the oxy-steam reforming of LNG process. Obtained results in this work confirmed that liquid natural gas processing may become an alternative to fossil fuels and confirmed the validity of the hydrogen production via oxy-steam reforming of LNG.

Interphase boundary segregation of silver and enhanced precipitation of Mg17Al12 Phase in a Mg-Al-Sn-Ag alloy

Aging-hardening response of Mg-7Al-2Sn (wt%) alloy can be remarkably accelerated by a small addition of silver (Ag). Using high-angle annular dark-field scanning transmission electron microscopy (HAADF-STEM) coupled with high resolution energy dispersive X-ray spectroscopy (EDS) mapping, for the first time, segregation of solute atoms (Ag in this case) was observed at the interphase boundary between continuous Mg17Al12 precipitate and magnesium matrix in Mg-7Al-2Sn alloy with 0.7 wt% Ag addition. Substantial size refinement and increased number density of Mg17Al12 precipitates may be responsible for the enhanced aging-hardening response in Mg-7Al-2Sn alloy with Ag addition.

Cr2N - Ag Thin Films - a Short Review

The current paper summarizes briefly the results obtained by comprehensive investigations of magnetron sputtered Cr2N thin films with small additions of silver, whereas the pure Cr2N is used as a reference material. The main aspects reported here are: growth rate of the films, their growth manner, phase constitution, mechanical properties being represented by Young modulus and nanohardness, adhesion on the substrate made from Cr-V ledeburitic steel having a hardness of 60 HRC, tribological performance and effect on the mechanical properties of the substrate.

Mechanical, tribological, and biocompatibility properties of ZrN‐Ag nanocomposite films

Nanocomposite films of ZrN-Ag were produced by reactive unbalanced magnetron sputtering, and their structural, chemical, mechanical, tribological, haemocompatibility, and antibacterial properties were studied as a function of film composition. The films formed a dense and homogeneous microstructure whereby nanocrystals of Ag are distributed evenly throughout the ZrN matrix. For small additions of silver, the hardness was found to increase, whereas the elastic modulus was found to decrease drastically. In the process of optimizing the deposition conditions, three kinds of coatings were prepared on 316 L surgical steel and tested by accelerated electrochemical polarization tests in order to detect the influence of Ag and the value of the bias potential on the corrosion performance of the system. Films produced under the optimum deposition conditions were, subsequently, deposited on medical grade Ti-Al-V and worn against ball-bearing steel using a ball-on-disk tribotester in bovine serum and were found to have superior tribological properties compared with single-phase ZrN coatings. The haemocompatibility of the films was assessed by investigating the adsorption of human serum albumin and fibrinogen on samples with different phase compositions. Quantification of the protein adsorption was carried out using spectroscopic ellipsometry, which confirmed the haemocompatibility of the films. Antibiotic activity of the films was quantified by incubating the films in bacterial cultures, namely, Staphylococcus epidermis, Staphylococcus aureus, and Escherichia coli. Films with a silver content > 10% exhibited superior antibacterial activity compared with the uncoated samples.

Thermodynamics and phase diagrams of lead-free solder materials

Many of the existing and most promising lead-free solders for electronics contain tin or tin and indium as a low melting base alloy with small additions of silver and/or copper. Layers of nickel or palladium are frequently used contact materials. This makes the two quaternary systems Ag-Cu-Ni-Sn and Ag-In-Pd-Sn of considerable importance for the understanding of the processes that occur during soldering and during operation of the soldered devices. The present review gives a brief survey on experimental thermodynamic and phase diagram research in our laboratory. Thermodynamic data were obtained by calorimetric measurements, whereas phase equilibria were determined by X-ray diffraction, thermal analyses and metallographic methods (optical and electron microscopy). Enthalpies of mixing for liquid alloys are reported for the binary systems Ag-Sn, Cu-Sn, Ni-Sn, In-Sn, Pd-Sn, and Ag-Ni, the ternary systems Ag-Cu-Sn, Cu-Ni-Sn, Ag-Ni-Sn, Ag-Pd-Sn, In-Pd-Sn, and Ag-In-Sn, and the two quaternary systems themselves, i.e. Ag-Cu-Ni-Sn, and Ag-In-Pd-Sn. Enthalpies of formation are given for solid intermetallic compounds in the three systems Ag-Sn, Cu-Sn, and Ni-Sn. Phase equilibria are presented for binary Ni-Sn and ternary Ag-Ni-Sn, Ag-In-Pd and In-Pd-Sn. In addition, enthalpies of mixing of liquid alloys are also reported for the two ternary systems Bi-Cu-Sn and Bi-Sn-Zn which are of interest for Bi-Sn and Sn-Zn solders.

Mécanismes de durcissement structural des alliages plombcadmium (étain, argent) pour grilles de batterie III — alliages plomb-cadmium-argent

The reequilibration of supersatured Pb-Cd-Ag alloys was studied by several experimental methods: hardness measurements, optical and electron microscopy, electron microprobe. Two structural states were considered: as-cast alloy, rehomogenised alloy. Lead-cadmium-silver alloys with 2 or 3.2 weight% Cd and 0.07, 0.15 or 0.3 weight% Ag were studied. The explored temperatures were 20, 80 and 100 °C. Globally, a small addition of silver results in an increase in hardness. For the Pb 3.2%Cd 0.15%Ag alloy, the microstructure is charcterized by the formation of coarse Ag 5Cd 8 cristals during soldification. With an increase in the Ag level in the Pb 2%Cd X%Ag (X = 0.07, 0.15, 0.3) the quantity of eutectic increases.

Effects of small silver addition to AuCu on the AuCu I ordering process and age-hardening behaviours

The effects of small silver additions to an equiatomic AuCu on the AuCu I ordering process and age-hardening behaviours at 300 °C were investigated by hardness testing, X-ray powder diffraction, optical microscopy, and transmission electron microscopy. The twinned structure developed at 300 °C in all of the experimental alloys containing silver of up to 6.0 at.%. However, the widening rate of the inter-twin spacing and the growth rate of the antiphase domain size markedly slowed down with the addition of silver to AuCu. The softening rate in the overageing stage also markedly slowed down with increasing the silver content. The strong tendency of retaining a high hardness value in the silver-containing alloys was attributed to the high densities of both twin boundary and antiphase boundary in these alloys. The small silver addition to an equiatomic AuCu tends to stabilize the mechanical properties of the aged alloy. This effect is beneficial in designing and producing a high-duty dental casting gold alloy.

Pre-precipitate clustering in an AlCuMgAg alloy

Small additions of silver can modify age hardening in aluminum alloys that contain magnesium. Thus, although silver has no significant effect on artificial aging on Al-Cu alloys, it causes a complete change to precipitation processes that normally occur in aged Al-Cu-Mg alloys. In this regard, special interest has been shown in those alloys with high Cu:Mg ratios in which silver promotes formation of a new precipitate, designated [Omega]. [Omega] forms as a uniform dispersion of thin, hexagonal-shaped plates that precipitate on the (111)[sub [alpha]] planes of these Al-Cu-Mg-Ag alloys when they are aged in the medium temperature range. The thinness of the [Omega] plates is attributed to the fact that they are coherent with the matrix along the (111)[sub [alpha]] planes whereas there is a misfit of approximately 9% around the edges. The aim of the present work was to gain an understanding of the actual mechanism by which nucleation of [Omega] occurs through a study of the decomposition of supersaturated Al-Cu-Mg-Ag alloys immediately after quenching. Special use has been made of atom probe field ion microscopy (APFlM) supplemented by transmission electron microscopy (TEM) to study alloys in the as-quenched condition and after aging for very short times at 180more » C.« less

Effect of small addition of silver on the formation of a soft surface layer in age-hardened Al12 mass% Zn alloy: Kanadani, T., Hosokawa, N., Kaneeda, T. and Sakakibara, A. Phys. Status Solidi A Jan. 1992 129 (1) K1–K4

Effect of small addition of silver on the formation of a soft surface layer in age-hardened Al12 mass% Zn alloy: Kanadani, T., Hosokawa, N., Kaneeda, T. and Sakakibara, A. Phys. Status Solidi A Jan. 1992 129 (1) K1–K4

Effect of Small Addition of Silver on the Formation of a Soft Surface Layer in Age-Hardened A1-12mass%Zn Alloy

Effect of Small Addition of Silver on the Formation of a Soft Surface Layer in Age-Hardened A1-12mass%Zn Alloy

Study of silver addition to Y1Ba2Cu3O7−y screen printed thick films

A study of the effect on the superconducting and microstructural properties of YBa2Cu3O7−x screen printed thick films as a function of silver content (in the form of Ag and Ag2O) from 0 to 40 wt. % by employing different experimental techniques has been carried out. It has been found that silver improves the sinterability and intergrain connectivity and reduces the normal state resistivity. The superconducting transition temperature of the above films was found to be in the range of 82 to 91 K. Our results show that a small addition of silver (Ag or Ag2O) helps in enhancing the superconducting properties. However, large amounts lead to formation of 211 phase as the decomposed product and thereby deteriorate the quality of the superconductor. Silver has been found to remain as metal in the samples for the entire range. Further, in light of our results, it seems that an addition of Ag metal is more beneficial than the addition of Ag2O.

Effect of small additions of silver on the eutectic temperature in the lead-tin system

Recent work on the thermodynamic properties and phase diagram of the lead-tin system has provided an excellent opportunity to evaluate the lowering of the eutectic temperature by the addition of a small amount of silver. For these low silver content, ternary solders, the Pb-Sn eutectic temperature is decreased by 3.3 °C owing to the addition of 1 wt pct silver.

Effect of small additions of silver on the eutectic temperature in the lead-tin system

Effect of small additions of silver on the eutectic temperature in the lead-tin system

Influence of silver on structure and properties of low-carbon steel

Silver has only slight solubility in low–carbon steel at elevated temperatures (~ 0·08 wt-% at the solidus) and precipitates on cooling as fine particles (< 10 nm) in the interphase mode. When present in as-cast steel at an estimated volume fraction of ~ 0·0006, silver can cause precipitation strengthening of up to 50 MN m−2. In as–rolled and in normalized steels, silver (0·02 wt-%) improves both strength and toughness mainly through grain refinement, with only a small influence from precipitation hardening. An important observation is the improvement to the heat affected zone toughness of high heat input welds which can result from small silver additions (0·02 wt-%) to C–Mn–AI–V steels. However, because of its relatively high cost, it remains to be demonstrated whether silver will impart sufficient benefit to steel properties to be commercially acceptable as an alloying addition.MST/44

Influence of silver on structure and properties of low-carbon steel

Silver has only slight solubility in low–carbon steel at elevated temperatures (~ 0·08 wt-% at the solidus) and precipitates on cooling as fine particles (< 10 nm) in the interphase mode. When present in as-cast steel at an estimated volume fraction of ~ 0·0006, silver can cause precipitation strengthening of up to 50 MN m−2. In as–rolled and in normalized steels, silver (0·02 wt-%) improves both strength and toughness mainly through grain refinement, with only a small influence from precipitation hardening. An important observation is the improvement to the heat affected zone toughness of high heat input welds which can result from small silver additions (0·02 wt-%) to C–Mn–AI–V steels. However, because of its relatively high cost, it remains to be demonstrated whether silver will impart sufficient benefit to steel properties to be commercially acceptable as an alloying addition.MST/44

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.

Thermodynamic properties of zinc in dilute solution with silver in molten tin in the range 723 to 923 K

The influence of small additions of silver on the thermodynamic properties of a dilute solution of zinc in molten tin has been studied using an electrochemical method. The Wagner interaction parameter ε Zn Ag has been determined in the temperature range 723 to 923 K: ε Zn Ag = 2.94 − 4353( K T ) .

The Influence of Small Additions of Silver on the Structure and Properties of Aged Aluminum Alloys

1. Small additions of silver can exert marked effects on the structure and properties of several aluminum alloys. It is believed that so-called trace elements effects such as this will assume increasing importance in the future because, in many alloy systems, the combinations of major alloying elements have been investigated. 2. The most significant effects of silver additions are observed in alloys based on the Al-Zn-Mg system. On the basis of endurance lives in a range of environments, the stress-corrosion resistance of Al-Zn-Mg-Cu alloys is increased while still maintaining a high level of strength. The addition of silver has been shown to increase the threshold stress for stress-corrosion cracking in an industrial atmosphere but this has not been confirmed for alternate immersion tests in a NaCl solution. Overall, the effects of silver are most marked if the addition of silver is made in conjunction with minor modifications to certain other alloying elements, and a higher ageing temperature is used (e.g. 165°C). 3. There is evidence that the stress-corrosion resistance of welded Al-Zn-Mg alloys is increased if silver is added to the parent metal or solely to the filler rod. 4. Silver additions may modify the structure and properties of aged Al-Mg and Al-Cu-Mg alloys (providing the Mg: Cu ratio is sufficiently high). One possible practical implication of these results is that silver may increase the elevated temperature stability of certain Al-Cu-Mg alloys and preliminary results have been obtained for one experimental composition. 5. From the fundamental viewpoint, it is considered that the effects of silver on the precipitation processes in certain aluminum alloys arise because of an interaction between silver atoms, magnesium atoms, and vacant lattice sites. The interaction is believed to modify the nucleation processes of the particular precipitates although the mechanisms differ depending on the alloy concerned. In alloys based on the Al-Zn-Mg system, silver stimulates nucleation of the existing precipitate whereas silver promotes the formation of a different precipitate in a wide range of Al-Cu-Mg alloys.