Nickel Silver Research Articles

A Novel Approach of In-Situ Electrobiosynthesis of Metal Oxide Nanoparticles Using Crude Plant Extract as Main Medium for Supporting Electrolyte

Abstract The release of dyes into the environment during textile fibre dyeing and finishing processes is a main source of water pollution. There is a need to look for effective treatment processes to overcome this problem. Photocatalytic method becomes the most effective to remove the dyes. In this study, in-situ electrobiosynthesis of various metal oxide such as silver oxide (AgO), copper oxide (CuO), zinc oxide (ZnO), and nickel oxide (NiO) using plant extract as new green electrolyte was performed with enhancement behaviour and structural of the catalyst for excellent photodegradation of malachite green (MG) dye from aqueous solution. The MG was successfully degraded at optimum condition of 10 mg/L of initial concentration with 0.5 g/L of catalyst dosage of AgO, CuO, ZnO, and NiO; at pH of 2 under visible light irradiation within 1 hour of contact time at room temperature which were 91.7 %, 94.0%, 98.5 %, and 97.3 %, respectively. Therefore, the effectiveness of eelctrobiosynthesis of AgO, CuO, ZnO, and NiO metal catalyst via electrochemical method using 100 % crude plant extract as new supporting electrolyte was established and confirmed through this study. The synthesized metal oxide catalyst has a great potential as a photocatalyst in photocatalytic reaction for degradation of organic pollutants in wastewater.

The optimization of methods of synthesis of nickel–silver core–shell nanoparticles for conductive materials

Nickel–silver core–shell (Ni@Ag) nanoparticles (NPs) were formed in a two-step process: (1) the formation of a dispersion of Ni NPs; and (2) the transmetalation (galvanic displacement) reaction, where the surface of the Ni NPs acted as the reducing agent of Ag ions. Ni NPs were synthesized by the ‘wet’ chemical method, i.e., by the reduction of metal ions by using NaBH4 as the reducing agent. The influence of the concentration of polymeric stabilizer, reducing agent and Ag precursor on the properties of synthesized NPs was evaluated. In the optimal condition of synthesis, Ni@Ag NPs with about 50 and 210 nm-diameter Ni core coated with a thin (∼10–20 nm) Ag shell, were obtained. Finally, the stability of the synthesized spherical-shaped Ni@Ag NPs was tested and the results indicate long-term stability against aggregation and Ni oxidation. Thus, the resulting NPs are promising candidates for application in electronic devices, e.g., as components of conductive inks or pastes.

Green synthesis of antibacterial bimetallic Ag–Cu nanoparticles for catalytic reduction of persistent organic pollutants

In this report, we used facile, active, cheap, re-usable and high surface area catalyst for the synthesis of green substrate turmeric (Curcuma longa) powder support mixed silver copper (Ag–Cu/TP), copper nickel (Cu–Ni/TP) and nickel silver (Ni–Ag/TP) nanoparticles. For nanoparticles synthesis the turmeric powder were kept in 0.5 M aqueous metal salt solution and then treated with aqueous solution of NaBH4 for in situ conversion of metal ions into their nanoparticles. Fourier transform infrared spectroscopy (FT-IR), X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), Field emission scanning electron microscopy (FESEM) and Energy dispersive X-ray spectroscopy (EDX) confirm the formation of nanomaterials. Silver mix nanoparticles show excellent activities against Escherichia coli (E. coli). The prepared nanoparticles were employed for the reduction of fluoroquinolone antibiotics ciprofloxacin (CIP) and levofloxacin (LVO) as well as for Methyl orange (MO), Congo red (CR), Methylene blue (MB) and Rhodamine B (RhB) dyes. Ag–Cu/TP catalyst showed excellent catalytic activity for the reductive transformation of antibiotics as well as for the remediation of MO, CR, MB and RhB dyes. The rate constants of pseudo first order reaction for CIP and LVO were 1.27 × 10−3 s−1 and 1.52 × 10−3 s−1 respectively. Ag–Cu/TP also showed excellent recyclability till the 5th cycle for MO reduction. The abundant nature, low cost, excellent reusability and effective catalytic degradation make Ag–Cu/TP suitable candidates for the reduction of organic molecules.

Preparation of silver coated nickel particles by thermal plasma with pre-treatment using ball milling

Recently, reducing noble metals in electric devices has been identified as a key factor to lower product cost. Among these, noble metal coated particles are considered an alternative with the potential to dramatically reduce the usage of noble metals. A dense coating of noble metals over all surfaces is desirable for maintaining the properties of noble metal. However, our previous research showed that coated surfaces onto which the nanoparticles were attached were non-uniform because of evaporation of the raw materials. Therefore, in this study, we improved the coverage ratio of silver coated nickel particles using thermal plasma processing followed by ball mill pre-treatment. Silver and nickel particles were mixed using a ball mill, then injected into the thermal plasma jet. The silver particles were subsequently attached onto the surface of the nickel particles through ball mill processing, after which the silver attached nickel particles were melted through thermal plasma processing to produce silver coated nickel spherical particles. The cross section of the as-prepared particles showed a dense silver shell and nickel core, while the sintered body of the as-prepared particles showed the net-like silver covering over the nickel cores. These findings suggest that attachment of silver on nickel could lead to complete silver coatings by limiting the formation of nanoparticles.

The ‘reverse transmetalation’ reaction of the pyrrole-based PNP pincer Ni(II) complexes: X-ray structures of binuclear silver(I) and thiocyanate nickel(II) complexes

Treatment of [{C4H2N-2,5-(CH2PPh2)2-κ3PNP}NiX] (X = Cl (1a), Br (1b), and I (1c)) with the silver salt AgBF4 containing the weakly coordinating anion BF4− yielded two types of complexes: monohalide ion bridged cationic binuclear silver(I) complexes, [Ag2(μ-X){μ-C4H2NH-2,5-(CH2PPh2)2-κ2PP}2][BF4] [X = Cl (2a) and Br (2b)] and the dihalide ions bridged neutral binuclear silver(I) complex, [Ag(μ-I){μ-C4H2NH-2,5-(CH2PPh2)2-κ2PP}]2 (3c). The analogous reaction with AgOTF afforded complex [Ag2(μ-Cl){μ-C4H2NH-2,5-(CH2PPh2)2-κ2PP}2]OTf (2a′). Interestingly, the 31P NMR spectrum of the reaction mixture showed the formation of the cationic complex, [Ni(NCCH3){C4H2N-2,5-(CH2PPh2)2-κ3PNP}][BF4], at the beginning of the reaction, which slowly changes to give the binuclear silver(I) complexes containing the neutral PNP pincer ligand upon crystallization in open atmosphere. Interestingly, the nickel complex 1a reacts with AgSCN containing the coordinating anion SCN− to give both the chlorine-substituted N-bonded thiocyanate neutral complex [Ni(NCS){C4H2N-2,5-(CH2PPh2)2-κ3PNP}] (4) and the dichloride bridged complex [Ag(μ-Cl){μ-C4H2NH-2,5-(CH2PPh2)2-κ2PP}]2 (3a). The structures of all these complexes were determined by single crystal X-ray diffraction studies. The Ni-NNCS bond distance of 1.849(3) Å in 4 is considerably shorter than those reported in the literature.

Evaluation of Tribological Properties of Thermally Sprayed Copper and Copper Alloy Coatings

Thermally sprayed copper and copper alloy coatings are among the most widely used coating materials for several industrial and medical applications to serve various functions such as corrosion resistance, wear resistance and antibacterial coating applications. In the present study, wear behavior of twin arc spray Cu, Cu 4%Sn (tin bronze), Cu 17%Ni 10%Zn (German silver) and Cu 17%Al 1%Fe (aluminum bronze) coatings is investigated experimentally. Wear tests were conducted using ball-on-disk configuration against a 440C stainless steel ball as a counterface. The effect of normal load on the coefficient of friction and wear behavior was investigated. SEM and 3D optical profilometry were used to characterize the coatings in terms of morphology and surface roughness. It is observed that copper coatings with aluminum and tin bronzes have high wear resistance and low coefficient of friction among the tested coatings, mainly due to their high hardness and coherent splats. It was also found that wear rate increases with the normal load.

Ions release Evaluation and Changes in Mini-implant Orthodontic Surface

To evaluate, in vitro, the mini-implant surface changes and the release of ions after immersion in artificial saliva during follow-up of 60 and 120 days. As for the surface features, examined in a scanning electron microscope (SEM), before and after immersion in artificial saliva, there was a rough and uneven surface, suggestive of corrosion areas for the two trademarks evaluated after 120 days of immersion. The extracts generated in artificial saliva analysis were submitted to energy dispersive spectroscopy to identify the solid corrosion products produced on the surfaces of miniscrews. Both SIN miniscrews and Neodent brands were observed to release minimal quantities of silver ions, chromium, iron, nickel, titanium, and vanadium. Regarding titanium, this index varied from 88.84% in the control group of Neodent brand, and 91.29% in the control group of SIN brand. For the aluminum content, the quantities ranged from 4.91% in group immersed for 60 days in Neodent brand to 8.71% for the SIN control group. Considering vanadium, the index ranged from 2.65% in the group immersed for 120 days to 4.53% in the control group, both for Neodent brand. Statistically significant differences in iron ion were observed between the control group and the miniscrews brand SIN after 60 and 120 days and for Neodent after 60 days of immersion. The titanium ions suffered statistically significant decrease for both brands after 120 days of storage when compared with the control group. The studied miniscrews showed results consistent with the biosafety of alloys for use, in vivo. The knowledge of the physical/chemical state of corrosion products released in the oral cavity is very important for the toxicological assessment of metal alloys used in dental miniscrews.

A new high temperature design to determine electrical and thermal conductivities and thermoelectric power. Applications to the sintered composite AgNi (90/10) “pseudo-alloy”

The aim of this paper is the description of a new high temperature design, tested up to 1100 °C, to measure electronic transport and to determine, for the first time to our knowledge at high temperatures, the electronic transport properties of a “pseudo alloys”, i.e. the silver nickel (90/10) one, which is used in contact materials for electrical engineering. Nickel and silver are mutually insoluble in liquid state. Thus, the alloy cannot be obtained by solidification. The solid is realized by sintering silver and nickel micrometric grains. This “pseudo alloy” is used in electrotechnics. To do these measurements, we had to develop a new experimental design that we describe, in order to measure very small resistance/resistivity up to 700 °C.We measure the electrical resistivity and the Absolute Thermoelectric Power (A.T.P. also called absolute thermopower or absolute Seebeck coefficient) of the Ag-Ni pseudo-alloy between room temperature and 700–800 °C. We determine the electronic thermal conductivity, using the Wiedemann–Franz law in the same temperature range. The electronic transport measurements do not only characterize the resistivity, the thermopower and the thermal conductivity for themselves, they also characterize change of phases happening in the solid. Indeed electronic transport is a probe of the state of matter and of its changes. For pseudo alloys, electronic transport properties allow also to determine ageing effects as function of temperature and of time through a drift of these properties.The variation of resistivity and thermopower are represented and discussed. Our results show that the thermal conductivity of the Ag-Ni “pseudo-alloy” is only 10% below that of the best thermal conductor (pure silver). We also observe, after two temperature cycles up to 700 °C that the thermal conductivity increases of about 1%. We compare the SEM micrographs of the samples before and after heating. Finally we showed that the behavior of a pseudo-alloy is different from that of an alloy and we interprete this behavior semi quantitatively.

Cu-Ni-Zn 15-20 Alloy - Particular Qualities of Alloying and Crystallization Parameters

The article is devoted to the study of Cu-Ni-Zn ternary alloy properties. German silver is applied in the instrument making industry, shipbuilding industry, and medical tool production. Furthermore, German silver is extensively used for domestic goods and costume jewelry. It is known that the aluminum and tin additions improve the Cu-Ni-Zn alloy flowing and casting mold fillability. It is a matter for the figurine and thin section casting production. That is why, using the experiment planning method we have studied the effect of Al and Sn alloyage and crystallization temperature on structure, casting characteristics and the casting characteristics of German silver. The study was realized by casting samples which were produced with lost wax method. Aluminum microadditives (0.4 %) have a positive impact on the casting mold fillability and improve markedly surface quality of casting samples. Tin leading into melt (about 4 %) ensure the marked growth of yield strength (by 65...70 %), while the elongation is maintained. The role of the mold temperature has a lesser impact on the yield strength. The mold temperature reduction from 550 °C to 450 °C leads to the grain size decrease and the little yield strength increase. Moreover, the surface condition measurement shows that aluminum and tin additions greatly reduce the castings surface roughness.

Effect of Composition and Thickness on the Hardness and Scratch Resistance of Copper and Copper Alloy Coatings

Coatings are extensively used as corrosion resistance, wear resistance, and antibacterial surfaces. Copper and copper alloys are among the most widely applied coating materials for industrial and medical applications. In this work, mechanical assessment of Cu, Cu 4%Sn, Cu 17%Ni 10%Zn (German Silver), and Cu 17%Al 1%Fe coatings deposited on stainless steel 316L substrates using twin wire arc thermal spraying is studied experimentally. Microstructure, hardness, and scratch resistance were studied for all coated samples. The effects of having different coating compositions on the mechanical properties are analyzed. The effect of the coatings thickness is also investigated for Cu 17%Ni 10%Zn and Cu 17%Al 1%Fe coatings with different thicknesses between 200 and $$400\,\upmu \hbox {m}$$ . The study focused on how the scratch resistance increases with increasing the coating thickness on the expense of the adhesion. A comparison of the coating hardness profile between different copper and copper alloy compositions was presented. An interesting observation was that even though scratch hardness increases with the coating thickness, hardness decreases as a function of the distance from the interface.

On the provenance of a historic sledge shoe fragment, said to have been collected by Edward Wilson at the South Pole in 1912

ABSTRACTThis paper discusses the authentication of a metal sledge shoe fragment, believed by the owner to have been collected by Edward Wilson close to the South Pole on 18 January 1912. Microscopic and elemental analysis show that the object is made from ‘German silver’, a copper alloy used only on Norwegian Nansen-style sledges in the late nineteenth and early twentieth century, and that it was used to clad a tapering sledge runner end about 10 mm thick. By comparing related objects, including sledges used by Amundsen and Scott in their South Pole journeys and a sledge from the Discovery Expedition, we show that the object cannot have come from an English sledge, but would have fitted one of Amundsen's modified sledges. Written sources have been extensively searched, but no direct written provenance for the object exists. However, contemporary Norwegian and British accounts explain specific features of the object and exclude other possible provenances. We conclude that it is most likely that the proposed provenance and history attached to this artefact are correct.

Observation of promoted C-O bond weakening on the heterometallic nickel-silver: Photoelectron velocity-map imaging spectroscopy of AgNi(CO)n.

We report a joint experimental and theoretical study on heterodinuclear silver-nickel carbonyl clusters: AgNi(CO)n- and AgNi(CO)n (n = 2, 3). The photoelectron spectra and photoelectron angular distribution provide information on the electronic structures and geometries of these complexes. Electron affinities of AgNi(CO)2 and AgNi(CO)3 are measured from the photoelectron velocity-map imaging spectra to be 2.29 ± 0.03 and 2.32 ± 0.03 eV, respectively. The complementary theoretical calculations at the B3LYP level and Franck-Condon simulations are performed to establish their geometrical structures. The C-O stretching modes are activated upon photodetachment and determined to be 2024 and 2028 cm-1 for AgNi(CO)2 and AgNi(CO)3, respectively, which are notably red-shifted with respect to those of corresponding unsaturated binary nickel carbonyls. These findings will shed light on the promoted C-O bond weakening by the introduction of a foreign atom to binary unsaturated TM carbonyl complexes.

Microstructure, mechanical and tribological properties of plasma-sprayed NiCrAlY-Mo-Ag coatings from conventional and nanostructured powders

The conventional and nanostructured NiCrAlY-Mo-Ag composite coatings were prepared by atmospheric plasma spraying so as to make the hot parts achieve and maintain excellent tribological properties at elevated temperature of up to 900°C. The microstructure, mechanical and tribological properties of these two composite coatings were investigated and compared. The X-ray diffraction (XRD), micro-Raman, scanning election microscopy (SEM) and transmission electron microscopy (TEM) were used to analyze the composition and microstructure of the composite coatings. Results show that the nanostructured composite coating presented higher microhardness and adhesive strength than conventional composite coating. Meanwhile, the nanostructured composite coating had less defects, lower porosity, more compact microstructure and smaller grains as compared to the corresponding conventional coating which was useful to improve the performance of the composite coating. The nanostructured composite coating possessed better tribological properties as compared with the conventional composite coating. The sliding process could promote the tribo-chemical reaction between silver, nickel and molybdenum to form silver molybdates and nickel molybdates lubricating films on the worn surface at high temperature. The silver molybdates and nickel molybdates could also enhance tribological properties of composite coatings at high temperature.

DRY ELECTRODE MATERIAL TESTING AND GAIN ANALYSIS FOR SINGLE ARM ECG SYSTEM

Electrocardiography (ECG) is a medical diagnostic procedure used to record the electrical activity of the heart and display it as a waveform. For picking the ECG waveform, wet and dry electrodes can be utilized. Lots of dry electrode related studies have been carried out in different parts of the world. This paper focuses on the acquisition of ECG from the left arm and right arm separately and comparing the waveforms and gain required for the system. In addition to that, different dry electrode materials and dimensions are used to check the acquisition of ECG waveform from the single arm. Dry electrodes employed in this study include copper, brass, phosphor bronze and nickel silver. The various dimensions used in this study are 3[Formula: see text]cm[Formula: see text][Formula: see text][Formula: see text]3[Formula: see text]cm[Formula: see text][Formula: see text][Formula: see text]0.5[Formula: see text]mm, 2.5[Formula: see text]cm[Formula: see text][Formula: see text][Formula: see text]2.7[Formula: see text]cm[Formula: see text][Formula: see text][Formula: see text]0.5[Formula: see text]mm, 2.5[Formula: see text]cm[Formula: see text][Formula: see text][Formula: see text]2.5[Formula: see text]cm[Formula: see text][Formula: see text][Formula: see text]0.5[Formula: see text]mm, 2[Formula: see text]cm[Formula: see text][Formula: see text][Formula: see text]3[Formula: see text]cm[Formula: see text][Formula: see text][Formula: see text]0.5[Formula: see text]mm, 2[Formula: see text]cm[Formula: see text][Formula: see text][Formula: see text]2[Formula: see text]cm[Formula: see text][Formula: see text][Formula: see text]0.5[Formula: see text]mm and 1[Formula: see text]cm[Formula: see text][Formula: see text][Formula: see text]3[Formula: see text]cm[Formula: see text][Formula: see text][Formula: see text]0.5[Formula: see text]mm. A total of five healthy subjects are used in this study for the acquisition of ECG. The results are very much promising in that the gain required for the left arm ECG system is less than that needed for the right arm ECG system and moreover a clear ECG is obtained from the left arm compared to the right arm ECG waveform. All the dry electrodes used in the study can pick the ECG except for the dimension 1[Formula: see text]cm[Formula: see text][Formula: see text][Formula: see text]3[Formula: see text]cm[Formula: see text][Formula: see text][Formula: see text]0.5[Formula: see text]mm. Copper and brass provide stable output compared to nickel silver and phosphor bronze.

Tribological properties of NiAl matrix composite coatings synthesized by plasma spraying method

Abstract

Influence of Silver Contents on the Tribological Properties of Ni-Based Self-Lubricating Coatings by Atmospheric Plasma Spraying

The NiCrAlY–Mo–Ag composite coatings were prepared by atmospheric plasma spraying. The tribological properties of the composite coatings were investigated from 25 to 900 °C in details. The tribo-layer formed on the worn surface of the composite coatings and influenced the tribological properties at different temperatures. The addition of silver could effectively decrease the friction coefficient and wear rate of the coatings at the wide range of temperature. The rubbing process could form the nickel molybdate and promote the formation of silver molybdate within the worn surfaces at high temperature. The synergistic lubricating effects of nickel molybdate and silver molybdate are attributed to the improvement of the tribological properties of coatings at high temperature.

Nickel–Silver Monotectic in Alumina Crucible for Use with Contact Thermometry

Previously, the authors have published work describing a pure Ni fixed point within alumina crucibles. The success of this study stimulated working with the Ni–Ag monotectic point in alumina crucibles. Similar to eutectic points, the Ni–Ag monotectic temperature is an invariant point but it differs from a eutectic reaction in such a way that the monotectic phase change takes place from Ni–Ag liquid solution to Ni–Ag solid solution and Ag rich Ni–Ag liquid solution. In the phase diagram references, the Ni–Ag monotectic phase transition temperature is assigned to be about 20 $$^{\circ }$$ C below the pure Ni melting/freezing point. As is the case for pure Ni, mechanical stability is one of the concerns. Therefore, proper cell design is necessary to avoid breakage of the alumina crucible. The techniques used for the fabrication and measurement of the pure Ni cell were applied to the Ni–Ag cell as well. The cells have been successfully fabricated and the temperature measurement at the fixed point was carried out for more than 20 thermal cycles in total. A Pt/Pd thermocouple was used to measure the temperature and was calibrated from the tin point to the gold point to measure the ITS-90. Freezing plateaus are realized with the technique of “recurrent offset freezing method with reserved solid”. The duration of each freezing plateau is a minimum of 30 min. The monotectic transformation temperature for the best performed cell is determined as 1428.27 $$^{\circ }$$ C with a combined uncertainty of ±0.06 $$^{\circ }$$ C ( $${k}=1$$ ).

Isolation of Arsenic Resistant Escherichia coli from Sewage Water and Its Potential in Arsenic Biotransformation

Arsenic contamination in drinking water from ground water poses a threat to the health of a large population in developing countries in Asia. This has sparked great interests in the potential of different microbes in arsenic resistance and removal from water. This study involves isolation of arsenic resistant Escherichia coli from sewage water from Kathmandu University and investigation of its attributes. Arsenic resistant E. coli was successfully isolated which could survive in high concentration of arsenic. The maximum tolerance of arsenite was 909.79 mg/L (sodium arsenite) and 3120.1 mg/L arsenate (sodium arsenate) which is well above most natural concentration of arsenic in ground water. This particular E. coli tolerated multiple heavy metal like silver nitrate, cobalt sulphate, cadmium chloride, nickel chloride, mercury chloride, copper sulphate, and zinc chloride at concentration 20 µM, 1 mM, 0.5mM, 1mM, 0.01 mM, 1 mM, and 1 mM respectively which are concentrations known to be toxic to E. coli. Biotransformation of arsenite to arsenate was also checked for by a qualitative silver nitrate technique. This E. coli was able to transform arsenate to arsenite. It showed some sensitivity to Ciprofloxacin, Gentamicin and Nalidixic Acid. As E. coli and its genome are very widely studied, these particular properties have a lot of potential in microbial remediation or microbial recovery of metals and possible recombination approaches.

Microstructural and tribological characterization of NiAl matrix self-lubricating composite coatings by atmospheric plasma spraying

The NiAl-Mo-Ag and NiAl-Cr2O3-Mo-Ag composite coatings were fabricated by atmospheric plasma spraying with the substrate material of Inconel 718. The effect of heat treatment on the microstructure, adhesive strength, microhardness and tribological properties of NiAl-Cr2O3-Mo-Ag composite coating was investigated. The heat treatment temperatures were chosen as 400, 500 and 600°C. The composition and microstructure of composite coatings were analyzed by X-ray diffraction (XRD), scanning election microscopy (SEM) and transmission electron microscopy (TEM). The results show that the addition of Cr2O3 could effectively reduce the wear rate of NiAl-Mo-Ag composite coating. The adhesive strength, microhardness and tribological properties of NiAl-Cr2O3-Mo-Ag composite coating were improved by heat treatment. After 500°C heat treatment, the microstructure of composite coating became more homogeneous and the coating had the highest adhesive strength, microhardness and the best tribological properties. The sliding process could promote the silver, nickel and molybdenum occur tribo-chemical reaction to form silver molybdates and nickel molybdates lubricating films which were responsible for the good tribological properties of composite coatings at elevated temperatures.

Evaluation of Microstructure and Magnetic Properties of Aluminium Doped Copper Nickel Zinc Spinel Ferrites

Evaluation of Microstructure and Magnetic Properties of Aluminium Doped Copper Nickel Zinc Spinel Ferrites