Academic literature on the topic 'Gold Silver Lead'
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Journal articles on the topic "Gold Silver Lead"
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Sahu, Sushama, Srishti Sharma, and Kallol K. Ghosh. "Novel formation of Au/Ag bimetallic nanoparticles from a mixture of monometallic nanoparticles and their application for the rapid detection of lead in onion samples." New Journal of Chemistry 44, no. 35 (2020): 15010–17. http://dx.doi.org/10.1039/d0nj02994g.
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Petrovic, N., D. Budjelan, S. Cokic, and B. Nesic. "The determination of the content of gold and silver in geological samples." Journal of the Serbian Chemical Society 66, no. 1 (2001): 45–52. http://dx.doi.org/10.2298/jsc0101045p.
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Amethod has been elaborated for the determination of the content of gold and silver in geological samples by atomic absorption spectrophotometry (AAS) in combination with the fire assay method. The weight of sample used for analysis was 10 g. Sulphur present as sulphide, which is an undesirable element in smelting, was removed by the addition of iron to the charge. The sample was smelted with fluxes and lead oxide to replace the silver and gold by lead and to transfer non-precious elements to slag. Lead was separated from precious metals by cupellation. The separated silver and gold alloy was dissolved with aqua regia with addition of hydrochloric acid in excess. Silver and gold were determined from the same solution. For determination of the silver content, the AAS method with an air-acetylene flamewas used. Goldwas determined in a graphite furnace with the addition of a matrix modifier in an argon current, at an atomization temperature of t = 2200 ?C. The lower determination limit for silver was 0.05 g/t and for gold 0.005 g/t. The results of the analysis for silver and gold obtained with the proposed method showed good agreement with the results of the analysis of the same samples with the fire assay method.
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Scaiano, Juan C., Paul Billone, Carlos M. Gonzalez, Luca Marett, M. Luisa Marin, Katherine L. McGilvray, and Nathan Yuan. "Photochemical routes to silver and gold nanoparticles." Pure and Applied Chemistry 81, no. 4 (January 1, 2009): 635–47. http://dx.doi.org/10.1351/pac-con-08-09-11.
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The photochemistry of aromatic ketones through the Norrish type I cleavage of benzoins and via photoreduction generates ketyl radicals that readily reduce many metal ions, including silver and gold. Reduction to Au(0) and Ag(0) leads to the spontaneous formation of nanoparticles (NPs) in aqueous or micellar solutions. Careful consideration of kinetic factors to minimize triplet quenching by metal ions can lead to rapid NP generation. These materials are quite stable and have interesting reactivities due to the essentially unprotected characteristics of the surface.
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Bokshits, Yu V., N. P. Osipovich, E. A. Strel’tsov, and G. P. Shevchenko. "Underpotential deposition of lead on silver and gold colloids." Colloids and Surfaces A: Physicochemical and Engineering Aspects 242, no. 1-3 (August 2004): 79–83. http://dx.doi.org/10.1016/j.colsurfa.2004.03.024.
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MOISEENKO, NATALIA VALENTINOVNA, and SVETLANA MIKHAILOVNA AVRAMENKO. "SILVER IN THE GOLD DEPOSITS OF THE AMUR REGION." Messenger AmSU, no. 93 (2021): 130–36. http://dx.doi.org/10.22250/jasu.93.27.
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The main minerals of native silver hubs on gold deposits of the Amur region (Albyn, Malomyr, Pioner, Pokrovskoe) were studied. It has been established that silver has a positive correlation with gold, zinc, arsenic, antimony, lead and cadmium. There is a negative correlation of silver with zirconium, yttrium, hafnia, tantalum and rare earth elements.
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Pushkar, Svetlana, and Oleg Verbitsky. "SILVER AND GOLD LEED COMMERCIAL INTERIORS: CERTIFIED PROJECTS." Journal of Green Building 14, no. 3 (June 2019): 95–113. http://dx.doi.org/10.3992/1943-4618.14.3.95.
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Leadership in Energy and Environmental Design Commercial Interiors (LEED-CI) is more relevant to interior design, which, according to the sharing layer concept, differs from exterior design (which is usually evaluated with the LEED New Construction sub-scheme). LEED-CI requires separate empirical analyses of LEED-CI certified buildings to further improve this sub-scheme. Therefore, in this study, Silver and Gold projects certified under LEED-CI-2009 in 14 US states were considered. Three project performance analyses, (i) certification, (ii) category, and (iii) cross-certification, were studied. The following results were revealed: (i) the range of the medians for Silver- and Gold-certified projects were 51–57 pts and 62–71 pts, respectively; (ii) in both Silver- and Gold-certified projects, Sustainable Sites (SS), Water Efficiency (WE), and Innovation in Design (ID) were the best-performing; Energy and Atmosphere (EA) and Indoor Environmental Quality (EQ) were intermediate-performing; and Material and Resources (MR) was the worst-performing categories; and (iii) in Silver-Gold cross-certification, category-focused (in 10 of 14 states) and category-unfocused (in four of 14 states) strategies were determined; in the category-focused strategy, the highest popular category was EA; the intermediate popular categories were WE, MR, and ID; and the lowest popular category was SS. Pooling all projects and all states into one frame can lead to the obscurement of the actual LEED-CI-2009 strategy(ies) in the transition from Silver to Gold certification in the US.
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Zhou, Xin Mu, Huan Peng, and Zhi Jun Cen. "Recycling of Lead and Zinc from Gold and Silver Tailings." Advanced Materials Research 455-456 (January 2012): 840–44. http://dx.doi.org/10.4028/www.scientific.net/amr.455-456.840.
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The recycling conditions of lead and zinc from gold and silver tailings by wet processing are as follows: leaching in confined condition and liquid to solid ratio of 5, at 90 ∽ 950C, for 4h, using NaCl (300g / L), CaCl2 (105% of theoretical amount), the acidity is 130% theoretical amount and the granularity is 300 mesh size; sponge lead can be obtained by using reduced iron (110% of theoretical amount) at 75∽850C for 3h; iron and zinc can be separated from hydrochloric acid system by TBP and then used for the preparation of the corresponding products; all the mother liquor can be recycled and the consumption amount of raw materials is low because there is no need for additional sodium chloride in the cycling. This processing method has better economic and environmental benefits.
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Zhou, Xin Mu, Huan Peng, and Zhi Jun Cen. "Recycling of Lead and Zinc from Gold and Silver Tailings." Advanced Materials Research 455-456 (January 2012): 840–44. http://dx.doi.org/10.4028/scientific5/amr.455-456.840.
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Rodliyah, Isyatun, and Siti Rochani. "Extracting silver from anode slime after lead and gold separations." Indonesian Mining Journal 20, no. 1 (April 28, 2017): 31–38. http://dx.doi.org/10.30556/imj.vol20.no1.2017.180.
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Iorio, Morena, Valerio Graziani, Sergio Lins, Stefano Ridolfi, Paolo Branchini, Andrea Fabbri, Gabriel Ingo, Gabriella Di Carlo, and Luca Tortora. "Exploring Manufacturing Process and Degradation Products of Gilt and Painted Leather." Applied Sciences 9, no. 15 (July 26, 2019): 3016. http://dx.doi.org/10.3390/app9153016.
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In this work, we studied the manufacturing processes and the conservation state of gilt and painted leather fragments from Palazzo Chigi in Ariccia (Italy) by using different analytical techniques. Leather fragments present a silver leaf superimposed onto leather support. A gold varnish and different painted layers decorate it all. A top-down analytical approach was used to investigate this complex multilayer structure, which adopted techniques with different sampling depths. Organic and inorganic constitutive materials together with related degradation products were studied by time of flight secondary ion mass spectrometry (ToF-SIMS), attenuated total reflectance-Fourier transform infrared spectroscopy (ATR-FTIR), and macro X-ray fluorescence (MA-XRF). The findings have revealed the presence of different elements and species as calcium and iron in the leather support, which was attributed to the un-hairing process in the leather tanning. Regarding what concerns the silver leaf, where the varnish cracked, silver chlorides, oxides, and sulfides were detected as degradation products of the silver leaf. Proteinaceous compounds were also identified where the silver leaf is unprotected by the varnish. These ion signals reveal a potential use of animal glue on both sides of the silver leaf to promote durable adhesion. In the gold varnish, the surface analysis revealed organic compounds such as resins and oils. In particular, the copresence of linoleic, arachidonic, and lignoceric acid ion signals in the yellow area suggests the use of aloe as a colorant. Lead ions in the same area were detected and attributed to the use of lead as siccative. Blue areas were obtained by using indigo and lead white in addition to an oil binder. This is confirmed by the detection of indigotin, fatty acid, and lead soap ion signals. A copper-based pigment was used to depict the green areas and copper oxalates were identified as its degradation products. Lastly, no significant information about the red colorant was obtained. Colophony is present as a component of the final varnish.
Dissertations / Theses on the topic "Gold Silver Lead"
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Benia, Hadj Mohamed. "Spatially resolved optical measurements on supported metal particles and oxide surfaces with the STM." Doctoral thesis, Humboldt-Universität zu Berlin, Mathematisch-Naturwissenschaftliche Fakultät I, 2008. http://dx.doi.org/10.18452/15862.
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In der vorliegenden Arbeit wurde mit Hilfe eines Photon-STM die Korrelation zwischen optischen Eigenschaften und der lokalen Morphologie an zwei unterschiedlichen Systemen untersucht. Hierfür wurden zum einem oxidgetragene Ensemble von Silber-Partikeln präpariert, wobei sowohl die Partikelform (Kuppel- und Scheibenform) als auch die deponierte Partikeldichte variiert werden konnte. Neben der Präparation solcher Partikel auf Al10O13/NiAl, konnten sphärische Silber-Kolloide geordnet, als auch ungeordnet auf HOPG aufgebracht und untersucht werden. Dabei zeigte sich, dass das Verhältnis von Höhen zu Breiten nicht nur einen signifikanten Einfluss auf die Mie-Resonanz des einzelnen Partikels hat, sondern auch die elektromagnetische Kopplung der Partikel in einem Ensemble stark kontrolliert. Die energetische Lage der Mie-Resonanz zeigt im Fall der kuppelförmigen Ag-Partikel eine starke Abhängigkeit vom Intepartikel-Abstand, was sich in einer Verschiebung zu höheren Energien für eine steigende Partikeldichte äußert. Eine solche Abhängigkeit konnte bei den Ensembles der scheibenförmigen Partikel nicht beobachtet werden. Des weiteren zeigte sich, dass, verglichen mit den ungeordneten Ensembles, die selbstorganisierte langreichweitige Ordnung der Silber-Kolloide auf HOPG nur einen schwachen Einfluss auf die energetische Position der Mie Resonanz hat.Das zweite hier untersuchte System sind dünne MgO Filme unterschiedlicher Dicken auf einem Mo(001) Substrat. Diese zeigen ein reichhaltiges Wachstumsverhalten, welches durch eine Differenz in den Gitterkonstanten von 5.3% begründet ist und erst ab etwa 25 ML zu einem flachen und defektarmen Film führt. Die so induzierte Spannung relaxiert bis zu einer Dicke von etwa 7 ML in einer periodischen Überstruktur die aus abwechselnd flachen und verkippten Ebenen an der MgO-Mo Grenzschicht hervorgeht. Für MgO Filme mit einer Dicke von etwa 12 ML werden dann Schraubenversetzungen, ausgedehnte verkippte Ebenen und Stufenkanten mit einer Orientierung entlang der Richtung beobachtet. Die optische Charakterisierung durch Feldemission von Elektronen aus der STM-Spitze in den MgO-Film wird dominiert von zwei Emissionsmaxima bei Energien von 3.1 eV und 4.4 eV. Die kontrollierte Nukleation von Gold Partikeln und die Erzeugung von Farbzentren im MgO Film erlaubten eine Zuordnung dieser Emissionen zu strahlenden Zerfällen von Exitonen an Ecken, Kinken bzw. Stufen des Magnesiumoxids. Solche Emissionsprozesse konnten allerdings nur unter Einstellungen beobachtet werden, bei denen ein gleichzeitiges Rastern der Oberfläche unmöglich ist. Bei moderaten Einstellungen war auch eine ortsaufgelösten Spektroskopie möglich, wobei dann neue Emissionsmechanismen beobachtet wurden. Dabei sind zwei Prozesse wesentlich; zum einen die Ausbildung von sog. Spitzen-induzierten Plasmonen im Bereich zwischen Spitze und dem Mo-Substrat, zum anderen strahlende Elektronenübergänge zwischen sog. Feldemissionsresonanzen, die sich im Spitze/MgO-Film System ausbilden.In this thesis, the correlation between the optical properties and the local morphology of supported silver nanoparticle ensembles and MgO thin films deposited on Mo(001) systems is explored by means of Photon-STM. In the first section, dome and disk shaped Ag nanoparticle ensembles with increasing density on an alumina film on NiAl(110) were analyzed as well as ordered and disordered ensembles of Ag nanocolloids on HOPG. The aspect ratio of the Ag nanoparticles was found to have a significant influence not only on the Mie plasmon resonance of a single particle, but also on the electromagnetic coupling within the nanoparticle ensembles. The Mie resonance in the ensemble of dome shaped Ag nanoparticles shows a strong dependence on the interparticle distance, where it shifts to higher energies with increasing particle density, due to destructive interference effects. In the disk-like Ag ensembles, however, the plasmon energy is independent of particle-particle separation. The long-range lateral ordering of size-selected Ag nanocolloids is found to induce a high dipole-dipole coupling within the ensemble. This is mainly reflected by the enhancement of the spectral intensity of the in-plane Mie mode, due to constructive coupling. However, ensembles with either well-ordered or disordered arrangements reveal no important difference in their optical properties, reflecting the weak influence of the long-range order in the particle ensemble. Thin MgO films with different thicknesses were grown on a Mo(001) surface. The stress resulting from the 5.3% lattice mismatch between the MgO(001) and the Mo(001) lattice parameters is found to control the surface morphology of the MgO film until thicknesses of around 25ML at which flat and defect-poor films are obtained. The relaxation of the stress induces a periodic network in the first 7ML of the MgO film, consisting of alternated flat and tilted mosaics. The presence of screw dislocations, steps oriented along the MgO directions, and tilted planes is observed when the MgO films are approximately 12ML thick. In addition, an increase of the MgO work function around these new surface features is revealed from STM spectroscopy. The photon emission induced by field-emitted electron injection from the STM tip into the MgO films is dominated by two emission bands located at 3.1eV and 4.4eV. To check the origin of these bands, further experiments, namely, nucleation of Au particles and creation of F-centers on the MgO surface, have been performed. The nucleation of Au particles at the low coordinated sites is found to quench the MgO optical signal, while the creation or annihilation of F-centers does not alter the MgO emission bands. The 3.1eV and the 4.4eV bands are therefore assigned to the radiative decay of MgO excitons at corner and kink sites, and step sites, respectively. Besides, spatially resolved optical measurements in the tunneling mode of the STM revealed different light emission mechanisms. These radiative processes are mainly related to tip-induced plasmons that form between the tip and the Mo support and to electron transitions between field-emission-resonance states in the STM tip-MgO film junction. The signal from exciton decays at corners and kinks of the MgO surface is however only observed at excitation conditions where the spatial resolution is already strongly reduced.
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Patel, Naazlene. "Biosynthesis and antibacterial activity of silver and gold nanoparticles from the leaf and callus extracts of Amaranthus dubius, Gunnera perpensa, Ceratotheca triloba and Catharanthus roseus." Thesis, 2013. http://hdl.handle.net/10321/914.
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Submitted in complete fulfillment for the Degree of Master of Technology: Biotechnology, Durban University of Technology, 2013.The biosynthesis of NPs has many advantages over the tedious, expensive and toxic physical and chemical methods of synthesis. Plants are stocked with valuable metabolites that are capable of reducing metal salts to form NPs. In this study, aqueous leaf extracts of A. dubius, G. perpensa, C. roseus and C. triloba were reacted with AgNO3 and HAuCl4 to determine the plants reducing abilities and hence synthesis of Ag and Au NPs capabilities. The synthesis reactions were carried out at different temperatures and extract concentrations for optimization. The goal was to form NPs within the specific wavelength range. Polar solvents: methanol and ethyl acetate extractions were carried out at the optimized conditions to evaluate the best solvent for the extraction of phytochemicals from the plants. The plant leaf extracts that were successful (A. dubius, G. perpensa and C. triloba) in synthesizing NPs were then micropropagated to form callus cultures. The reducing abilities of these callus cultures extracts were determined by varying temperature and concentration parameters. Characterization of the NPs formed by the different extracts was performed using UV-vis, TEM and FTIR. UV-vis spectrophotometry was used as a confirmatory as well as characterizing tool. TEM analysis was able to provide a description on the size and shape of the NPs whereas FTIR provided information on the biomolecules responsible for synthesis and capping of NPs. The stability of the NPs was determined by UV-vis scans over a period of 30 days which allowed observation of the alteration in peak shape and absorbance and hence condition of particles. Phytochemical tests were performed on the leaf extracts of the four plants to elucidate possible phytochemicals responsible for the reduction of metal salts. Antibacterial activity of the NPs was evaluated by using the disk diffusion assay and MICs were determined by the broth dilution method against pathogenic bacteria. A. dubius, G. perpensa and C. triloba were capable of synthesizing Ag NPs and Au NPs which were indicated by yellowish orange and reddish purple colour changes respectively. G. perpensa was able to spontaneously form Ag and Au NPs without any addition of heat whereas A. dubius and C. triloba required heat to form Au NPs. As the temperature of the reactions increased, the absorbance and possibly the number of NPs produced, increased. When the concentration of the extract was doubled, the absorbance was seen to decrease. C. roseus did not produce any Ag or Au NPs with any of the leaf extracts. Only A. dubius and C. triloba callus extracts were investigated for NP synthesis and it was found that A. dubius callus extracts were unsuccessful in synthesizing NPs and C. triloba callus extracts were able to form unstable Ag and Au NPs. The spherical Ag NPs that were formed from aqueous extracts of A. dubius were slightly larger than the methanolic Ag NPs. The Ag NPs produced by G. perpensa were in the same size range for aqueous and methanolic extracts. C. triloba Ag NPs formed from the methanolic extract were closer in size to A. dubius aqueous Ag NPs but the C. triloba aqueous extract produced much larger Ag NPs than the other extracts. The Ag NPs produced from A. dubius aqueous and methanolic extracts as well as C. triloba methanolic extracts exhibited the longest stability of 30 days. Ag NPs from G. perpensa aqueous extracts had the least stability. G. perpensa did not form any hexagonal Au NPs and the spherical and triangular Au NPs were smaller unlike in A. dubius and C. triloba Au NPs. The Au NPs formed by the aqueous extracts of A. dubius and C. triloba were larger in comparison to their methanolic counterparts. The Au NPs produced from G. perpensa aqueous and methanolic extracts as well as A. dubius and C. triloba methanolic extracts exhibited the longest stability of 30 days. Au NPs were stable for longer in comparison to Ag NPs. FTIR provided evidence that Ag and Au NPs have a chemical bond with the amide group in amino acids. However the intensities of biomolecules for Au NPs are more pronounced compared to the Ag NPs. It was also found that the Ag NPs synthesized by methanolic leaf extracts have slightly higher intensities than Ag NPs synthesized from aqueous leaf extracts. Phytochemical screening showed the absence of tannins in the C. roseus leaf, A. dubius and C. triloba callus extracts and presence in the other three plants. C. triloba methanolic extract Ag NPs showed the highest activity against Gram-positive S. aureus. Aqueous and methanolic Ag NPs from G. perpensa and C. triloba as well as A. dubius methanolic Ag NPs had activity against all fourteen bacteria. A. dubius aqueous Ag NPs had no activity against Enterobacter spp. and a strain of Klebsiella pneumoniae. G. perpensa Ag NPs had better antibacterial activity and lower MICs against Gram-positive and Gram-negative pathogenic bacteria compared to A. dubius and C. triloba. There was no antibacterial activity seen with Au NPs. The size and shape of NPs are the keys to their biomedical properties. Green synthesis of NPs is a feasible way for the future. This study showed that NPs can be synthesized very easily and economically. A key finding of this study is that different plants produce varying sizes and aggregation of NPs.
Books on the topic "Gold Silver Lead"
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Energy, Mines and Resources Canada. Mine reserves and currently promising deposits: Gold, silver, lead, zinc, copper, nickel, molybdenum. Ottawa: Energy, MInes and Resources Canada, 1985.
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Minerals, Canada. Mine Reserves and Currently Promising Deposits: Gold, Silver, Lead, Zinc, Copper, Nickel, Molybdenum. S.l: s.n, 1985.
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Sandberg, R. G. Recovery of silver, gold, and lead from a complex sulfide ore using ferric chloride, thiourea, and brine leach solutions. Pittsburgh, Pa: U.S. Dept. of the Interior, Bureau of Mines, 1986.
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McCammon, Richard B. Undiscovered deposits of gold, silver, copper, lead, and zinc in the conterminous United States. [Reston, Va.?]: U.S. Dept. of the Interior, U.S. Geological Survey, 1997.
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United States. Bureau of Mines. Recovery of Silver, Gold, and Lead From A Complex Sulfide Ore Using Ferric Chloride, Thiourea, and Brine Leach Solutions. S.l: s.n, 1986.
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Cartwright, Cosmo T. The production of copper, gold, lead, nickel, silver, zinc, and other metals in Canada during the calendar year, 1913. Ottawa: Govt. Print. Bureau, 1997.
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McCammon, Richard B. National mineral-resource assessment: The 1996 estimate of undiscovered gold, silver, copper, lead, and zinc remaining in the United States. [Reston, VA: U.S. Dept. of the Interior, U.S. Geological Survey, 1997.
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McCammon, Richard B. National mineral-resource assessment: The 1996 estimate of undiscovered gold, silver, copper, lead, and zinc remaining in the United States. [Reston, VA: U.S. Dept. of the Interior, U.S. Geological Survey, 1997.
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McCammon, Richard B. National mineral-resource assessment: The 1996 estimate of undiscovered gold, silver, copper, lead, and zinc remaining in the United States. [Reston, VA?]: U.S. Geological Survey, 1997.
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McCammon, Richard B. National mineral-resource assessment: The 1996 estimate of undiscovered gold, silver, copper, lead, and zinc remaining in the United States. [Reston, VA: U.S. Dept. of the Interior, U.S. Geological Survey, 1997.
Find full textBook chapters on the topic "Gold Silver Lead"
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Bilston, D. W., W. J. Bruckard, D. A. McCallum, G. J. Sparrow, and J. T. Woodcock. "Comparison of methods of gold and silver extraction from Hellyer pyrite and lead-zinc flotation middlings." In Sulphide deposits—their origin and processing, 207–21. Dordrecht: Springer Netherlands, 1990. http://dx.doi.org/10.1007/978-94-009-0809-3_14.
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Kim, Beom Soo, and Jae Yong Song. "Biological Synthesis of Gold and Silver Nanoparticles Using Plant Leaf Extracts and Antimicrobial Application." In Biocatalysis and Biomolecular Engineering, 447–57. Hoboken, NJ, USA: John Wiley & Sons, Inc., 2010. http://dx.doi.org/10.1002/9780470608524.ch29.
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Sarah, Guillaume. "From Local Supply to Long-Distance Trade Networks." In Silver, Butter, Cloth, 189–205. Oxford University Press, 2018. http://dx.doi.org/10.1093/oso/9780198827986.003.0011.
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This chapter introduces the third theme of the volume: the sources of Viking wealth. It presents a theoretical and methodological framework for ‘fingerprinting’ early medieval silver by archaeometric methods. A combined approach, integrating elemental (especially gold and bismuth) and lead isotope analysis, is advanced. The methods involved, including state-of-the-art laser ablation ICP-MS, are introduced, and the limitations of the approach clearly laid out. These methods are then used to evaluate the diffusion of silver produced at the mine of Melle (Aquitaine, France): a major source of silver coinage in the Frankish kingdoms, which the Vikings acquired through their raids in Aquitaine during the ninth century.
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Farjana, Shahjadi Hisan, M. A. Parvez Mahmud, and Nazmul Huda. "Life Cycle Assessment of Copper–Gold– Lead–Silver–Zinc Beneficiation Process." In Life Cycle Assessment for Sustainable Mining, 115–40. Elsevier, 2021. http://dx.doi.org/10.1016/b978-0-323-85451-1.00005-6.
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Wothers, Peter. "Goblins and Demons." In Antimony, Gold, and Jupiter's Wolf. Oxford University Press, 2019. http://dx.doi.org/10.1093/oso/9780199652723.003.0008.
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The belief that there were no more than seven metals persisted for hundreds of years, and it was not until the seventeenth century that the inconvenient, inescapable realization came that there were probably many more. I’ve already mentioned Barba’s report from 1640 about the new metal bismuth; it was one of a number of metals or metal-like species that began to be noticed in the sixteenth and seventeenth centuries. In his History of Metals from 1671, Webster begins Chapter 27: ‘Having now ended our Collections and Discourse of the seven Metals, vulgarly accounted so; we now come to some others, that many do also repute for Metals; and if they be not so, at least they are semi-Metals, and some of them accounted new Metals or Minerals, of that sort that were not known to the Ancients.’ In the chapter Webster speaks of antimony, arsenic, bismuth, cobalt, and zinc. While we now understand these as distinct elements, earlier on there was great confusion, with the names being used for compounds rather than the elements themselves—and, furthermore, the different compounds and elements often being mistaken for each other. This makes unravelling their history all the more complicated. We’ll start with Barba’s ‘Mettal between Tin and Lead, and yet distinct from them both’: bismuth. The first mention of bismuth predates Barba’s reference by more than one hundred years. The name appears in its variant spelling, ‘wissmad’, in what is probably the very first book on mining geology. This was published around the turn of the sixteenth century and attributed to one Ulrich Rülein von Calw, the son of a miller who entered the University of Leipzig in 1485. Ulrich mentions in passing that bismuth ore can be an aid to finding silver, since the latter is often found beneath it. Consequently, miners called bismuth ‘the roof of silver’. As Webster later put it in his History of Metals, ‘The ore from whence it is drawn . . . is also more black, and of a leaden colour, which sometimes containeth Silver in it, from whence in the places where it is digged up, they gather that Silver is underneath, and the Miners call it the Cooping, or Covering of Silver.’
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Hinton, David A. "Adapting to Life Without the Legions." In Gold and Gilt, Pots and Pins. Oxford University Press, 2005. http://dx.doi.org/10.1093/oso/9780199264537.003.0006.
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If gold and silver are a measure of wealth, late Roman Britain was very rich. Hoards of coins, jewellery, and plate buried in the late fourth and early fifth centuries show that their owners’ lifestyle was coming to an end as central imperial authority broke down, troops were withdrawn from the island, villas fell into disuse, and towns lost their markets and trade. Raiders threatened by land and sea: Irish from the west, Pictish from the north, Frisian, Saxon, and others from the east; and as civic order broke down, the likelihood of robbery by people living south of Hadrian’s Wall grew worse. The hoards’ owners were right to worry, and their subsequent failure to retrieve their valuables must testify to many personal catastrophes. Hoards containing dishes, bowls, and spoons as well as coins and jewellery have been found on the east side of Roman Britain from Canterbury, Kent, in the south to Whorlton, Yorkshire, in the north. Further west, coin-hoards are quite plentiful, although none has any plate. Some contain jewellery, like one found in 1843 at Amesbury, Wiltshire, that included three silver finger-rings; in the same area, another hoard with eight gold coins and one of silver was found in 1990, apparently concealed in a pot around the year 405, to judge from the date of the latest coin. But as with plate so with jewellery, the contrast with the east is still considerable; Thetford, Norfolk, has gold finger-rings as well as ornamental chains, bracelets, and a buckle; Hoxne, Suffolk, has gold bracelets, and again chains, these with elaborate mounts. Some of the craftsmanship shown in these pieces is of a high order, that only well-off patrons could have afforded. The plate suggests displays of tableware by a society that set great store on being able to offer lavish feasts and entertainment. These late Roman treasures may be giving a slightly false impression of Britain’s prosperity. Silver was probably extracted from the same native deposits that yielded lead, so would have been more available than in most parts of the Empire. Some may also have entered Britain from Ireland, where evidence of Roman intervention is accumulating.
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Emsley, John. "The empire of lead." In The Elements of Murder. Oxford University Press, 2005. http://dx.doi.org/10.1093/oso/9780192805997.003.0019.
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Lead is useful, surprising, unpredictable, dangerous – and deadly. Lead is useful. Previous generations found it to be an essential part of civilized living: pipes, pewter, pottery, paints, and even potions were made with it. Toy soldiers were cast from it, port wine protected by it; grey hair was disguised with it, church roofs covered with it; cosmetics contained it, and cans of food were sealed with it. Lead is surprising. In 1859, Professor Lyon Playfair was taking the 18-year-old Prince of Wales, and future King Edward VII, round the chemistry laboratories of Edinburgh University when they came across a pot of molten lead. Playfair then carried out a remarkable demonstration: he poured the molten metal over the fingers of his assistant and to the Prince’s amazement the young man’s hand was unharmed. The Prince too wanted to try the same test, and after rinsing his hand in dilute ammonia solution, lead was poured over his fingers as well – again without scalding them. This demonstration was still being performed before stunned audiences in the 1950s, and the trick is to have the hand wet, so that as the metal hits the film of water on the skin it forms an instant layer of vapour that both protects the skin and causes the lead to bounce off in tiny droplets. Lead is unpredictable. In Shakespeare’s Merchant of Venice those who would seek to marry the fair Portia are offered three caskets from which to choose: gold, silver, or lead. The man who chooses the casket containing her portrait will win her hand in marriage. Of course the winning choice is lead, the casket with the curiously foreboding inscription: ‘Who chooseth me must give and hazard all he hath’ and her would-be suitor Bassanio reasons that this must be the right one saying: …‘. . . but thou, thou meagre lead, Which rather threat’nest than does promise aught, Thy plainness moves me more than eloquence, And here choose I; joy be the consequence!’ [The Merchant of Venice, III, ii]…
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Gordon, Robert B., and Patrick M. Malone. "Scarce Metals and Petroleum." In The Texture of Industry. Oxford University Press, 1994. http://dx.doi.org/10.1093/oso/9780195058857.003.0011.
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Lured by the potential for substantial wealth, Americans have focused a disproportionate share of their industrial effort on extracting and processing resources that are both scarce and in high demand. Gold and silver were always valuable and eagerly sought, but in the nineteenth century, the demand tor other nonferrous metals and (or petroleum rose to unprecedented levels. Obtaining these scarce, nonrenewable resources brought new patterns of industrial land use and new environmental consequences. The continuing effects on our land, water, and air are serious concerns in American society today. The hope of finding gold and silver, the metals of wealth and display, drew numerous adventurers to North America in the seventeenth century. In the East, those hoping to repeat the Spanish experience in South America and Mexico were disappointed. Although colonial prospectors did discover small deposits of nonferrous-metal ores on the east coast and in the Appalachians, most of the metals were not in the precious category. There was a demand for utilitarian metals as well: English colonists depended on lead for pipes, window carries, and shot; they cooked with copper kettles, drank the products of copper stills, and set their tables with pewter (a tin alloy) tableware. Nevertheless, Americans generally found it cheaper and easier to use imported nonferrous metals until the mineral resources of the center of the continent were exploited in the nineteenth century. Iron was the only metal extensively mined in the English colonies. One of the few relicts of pre-Revolutionary nonferrous metallurgy is the Simsbury Copper Mine in East Granby, Connecticut. This mining enterprise obtained its charter in 1706. The state now preserves the site, not as an industrial monument but because the mine served for a time as the state prison. Visitors can enter the underground workings. Physical evidence of the first gold discovery in the United States, in 1799, exists at the Reed Gold Mine, a state historic site near Georgiaville, North Carolina. Most of the milling survivals are from later development at the mining site in 1854 and 1896. North Carolina led the nation in gold production until the California gold rush of 1849.
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Herz, Norman, and Ervan G. Garrison. "Metallic Minerals and Archaeological Geology." In Geological Methods for Archaeology. Oxford University Press, 1998. http://dx.doi.org/10.1093/oso/9780195090246.003.0018.
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Economic geology had its inception in the ancient utilization of rocks and minerals. The first economic materials were nonmetallic and include flint, quartz, diabase, rhyolite, obsidian, jade, and other stones, which were sought for weapons, implements, adornment, and even art. Beginning with the Upper Paleolithic Aurignacian period, clay began to be widely used for simple figurines, then brick and finally pottery. S. H. Ball identifies 13 varieties of minerals—chalcedony, quartz, rock crystal, serpentine, obsidian, pyrite, jasper, steatite, amber, jadite, calcite, amethyst, and fluorspar—as economic within the Paleolithic. Add to this list the use of ochres and mineral paints together with nephrite, sillimanite, and turquoise. In the standard reference on the nonmetallic deposits, "Industrial Minerals and Rocks", 6th edition published in 1994, deposits are classified by use and the minerals and rocks described as commodities. The fourteen use groups include such items as abrasives, constructions materials, and gem materials; the 48 commodities include clay, diamonds, feldspar, etc. Metalliferous minerals as ore deposits are unevenly distributed throughout the world. The formation of a mineral deposit is an episode or series of episodes in the geological history of a region and reflects three broad categories: (1) igneous activity, (2) sedimentary processes, and (3) metamorphism. Table 12.1 summarizes general features of the three categories of mineral deposits. Admixtures of metals are by far the most common form of mineral deposits. Gold, silver, and copper occur either as native metals or admixed with other metals and compounds. Most ore deposits are actually mixtures of metals: silver commonly with lead, zinc with cadmium, iron with copper. Many metallic ore deposits are products of igneous activity. Conditions change in the magma chamber as the principal rock-forming minerals crystallize, temperature falls as the magma cools, pressure is lowered as the magma rises in the crust, and volatiles increase in the magma chamber.
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Emsley, John. "Testing your metal: An exhibition of the metals which our body must have." In Molecules at an Exhibition. Oxford University Press, 1998. http://dx.doi.org/10.1093/oso/9780198502661.003.0006.
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Ask people which metals are essential for healthy living and I suspect most would say zinc and iron. Some might mention sodium and potassium, although sodium is often regarded as something deleterious to healthy living; and a few people will know that calcium is a metal also, and important. In fact the human body needs fourteen metal elements to function properly. But for every metal that we do need, there is another that our body contains that we could well do without. These metals serve no known purpose, but they come with the food we eat, the water we drink, and the air we breathe and our body absorbs them, mistaking them for more useful elements. As a result we find that the average adult contains measurable amounts of aluminium, barium, cadmium, caesium, lead, silver and strontium. There are also trace amounts of many others, including gold and uranium. Because strontium so closely resembles calcium we absorb a lot of this element, and the average person has about 320 mg in their body, far more than of many of the essential elements. On the other hand the weight of gold in the average person is only 7 mg, worth but a few pence, and the weight of uranium is only 0.07 mg, although turned into pure energy this could drive your car for five kilometres. Our body tends to retain these unwanted intruders either in our skeleton, as in the case of uranium which has a special propensity to bind to phosphate, or in our liver which has proteins that can trap metals like gold. The table below lists the amounts of the essential 14 metals in the average adult—someone who weighs 70 kg (155 pounds). As we would expect, calcium heads the list because, along with phosphate, it is what makes up the bones of our skeleton, which weighs 9 kg on average. Of this, i kg is calcium and 2.5 kg is phosphate. In fact 99% of the body's calcium and 85% of its phosphate is in the skeleton. Bone also contains water and the protein collagen, plus the elements sodium, potassium, iron, copper and chlorine.
Conference papers on the topic "Gold Silver Lead"
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Srinivasan, G., R. Murcko, and K. Srihari. "Evaluation of Secondary Wire Bond Integrity on Ag Plated and Ni/Pd Based Lead Frame Plating Finishes." In ASME 2009 InterPACK Conference collocated with the ASME 2009 Summer Heat Transfer Conference and the ASME 2009 3rd International Conference on Energy Sustainability. ASMEDC, 2009. http://dx.doi.org/10.1115/interpack2009-89241.
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As the legislatures demand the use of lead (Pb) free plating finishes in lead frame manufacturing, different plating finishes are being offered by the lead frame makers. Lead frames are most often designed with two different Pb free plating finishes, primarily tin and nickel/palladium (Ni/Pd) based. The tin post mold plated lead frames use silver selective plating on the lead fingers for secondary wire bonding whereas the pre-plated Ni/Pd based lead frames use the same Ni/Pd based finish throughout. Enhanced versions of Ni/Pd based plating finishes such as nickel/palladium/gold (Ni/Pd/Au), nickel/palladium/gold-palladium (Ni/Pd/Au-Pd) and nickel/palladium/gold-silver (Ni/Pd/Au – Ag) are now available to further improve the wirebondability, solderability and reliability of the package. The development of a new lead frame finish involves a wide variety of concerns which must be addressed and thus mandates further evaluation of these new structures. Using the common Pb free lead frame plating finish of selectively plated silver (Ag) as the basis, a comparative approach was used to evaluate the secondary wire bond integrity of a 25 micron (1 mil) thick gold wire on Ni/Pd based lead frame plating finishes. The integrity of the secondary wire bonds for different plating finishes was investigated at various assembly thermal exposure stages using the wire pull strength test as the arbiter. Reliability tests, such as High Temperature Storage (HTS) and Unbiased Highly Accelerated Stress Test (UBHAST), were also conducted. Finally, failure analysis was conducted with the help of metallographic cross sectioning, SEM/EDX (Scanning Electron Microscope/Energy Dispersive X-ray) analysis and statistical analysis of the wire pull strength test results. Before wire bonding the lead frames, the plating surface was investigated for its surface integrity with the help of plating quality tests, such as: (i) adhesive tape test, (ii) bend test, (iii) heating test and the (iv) scribing test. Also, since wire pull is a destructive test, a statistical method called a nested gauge R&R study was used to estimate the repeatability and reproducibility of the measurement system. Failure analysis showed that there were silver and copper migrations over the Ag plated lead frame when exposed to a high temperature storage test at 175°C for 1000 hrs, but this did not affect the bond integrity. However, the Ni/Pd based lead frames did not show any metal migration since nickel acts as a barrier against the base metal diffusion.
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Bai, John G., Zach Z. Zhang, Jesus N. Calata, and Guo-Quan Lu. "Low-Temperature Sintering of Nanoscale Silver Pastes for High-Performance and Highly-Reliable Device Interconnection." In ASME 2005 International Mechanical Engineering Congress and Exposition. ASMEDC, 2005. http://dx.doi.org/10.1115/imece2005-79187.
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In this paper, we report our development on making of nanoscale silver pastes and their low-temperature sintering for semiconductor device interconnections. The nanoscale silver pastes were prepared by dispersing 30-nm silver powder under ultrasonic vibration and mechanical agitation in an organic vehicle. Sintering of the silver paste prints at 280°C for 10 minutes resulted in a density of ~80% in the air ambient. Some important properties of the low-temperature sintered silver include ~2.4 W/K-cm for thermal conductivity, ~3.8 × 10−6 Ω-cm for electrical resistivity, and ~9 GPa for the effective elastic modulus. SiC Schottky rectifiers attached to either silver- or gold-coated direct bond copper (DBC) substrates show low forward voltage drops. The silver joints do not contain large voids but rather uniformly distributed microscale pores. Die-shear tests showed that bonding strengths of the silver joints were around 21 MPa on the gold-coated DBC substrates and 38 MPa on the silver-coated DBC substrates, respectively. The latter is comparable to that of reflowed eutectic lead-tin solder joints. Based on the findings in this work, the low-temperature sintering of nanoscale silver pastes is promising to be a high performance and highly-reliable semiconductor device bonding solution for high power packages.
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Lakhkar, Nikhil, Mohammad M. Hossain, Puligandla Viswanadham, and Dereje Agonafer. "Mechanical Characterization of Sn-Ag-Cu Solder With Gold Addition Under Tensile Loading." In ASME 2007 InterPACK Conference collocated with the ASME/JSME 2007 Thermal Engineering Heat Transfer Summer Conference. ASMEDC, 2007. http://dx.doi.org/10.1115/ipack2007-33543.
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Lead (Pb)-free implementation for electronic assembly has created a stir in electronic packaging industry during the last five years since Europe and eastern Asian countries decided to restrict the use of lead in electronic packages. Lead (Pb) content in solders is mandated to be less than 0.2 wt % (USA) and 0.1 wt % (EU). Sn-Ag-Cu (Tin, Silver, and Copper) solder is selected as one of the options to replace tin-lead solders. This solder is a preferred option as it comes closest to tin-lead solder in terms of parameters such as melting temperature (∼217°C), wettability, cost, availability, and reliability. Various agencies like NEMI, JEIDA and IDEALS recommend Tin-rich Lead (Pb) free solders as the possible alternatives to Pb-Sn solder [1]. Addition of elements like Au, Co, Fe, Ni, etc in small quantities can affect the properties of Sn-Ag-Cu solder. It has been reported that the addition of Au in small quantities improves the properties of lead-free solder. Au has very high reactivity with Sn and also improves the wettability of solder. Au forms a β-phase with Sn at the interface. This phase is considered beneficial in terms of improving fatigue life and fracture toughness as this β phase acts as a crack arrester thereby improving its strength Addition of Au also reduces the liquidus temperature to 204 °C. In this paper we tested and compared the strength of pure Sn-Ag-Cu solder and Sn-Ag-Cu solder with Au addition and it was concluded that the strength of material increases from 50 MPa to 70 MPa under tensile loading.
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Mizernaya, M., B. Dyachkov, A. Miroshnikova, and A. Mizerny. "INDUSTRIAL TYPES OF GOLD DEPOSITS OF THE EAST KAZAKHSTAN." In GEOLINKS International Conference. SAIMA Consult Ltd, 2020. http://dx.doi.org/10.32008/geolinks2020/b1/v2/14.
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The East Kazakhstan territory is the unique geologic province where a number of large-scale non-ferrous and gold deposits are concentrated [1]. Gold base metals (gold-containing) type is represented by gold containing sulphide complex deposits. It is characterized by many large-scale commercial deposits of copper, lead and zinc where gold as well as silver, cadmium, platinum, selenium and other elements are the associate component of copper-sulphide and sulphide complex deposits [2]. There are following ore types are distinguished: gold-listvenite type occurs in the Irtysh zone (Maraliha deposit); the gold-sulphide vein-disseminated type associated with island-arc, volcanogenic-carbonate-terrigenous formation С1v2-3 (Suzdalskoye, Baibura, Mirazh, Zhaima); gold-quartzite type is characterized by gold-quartzite-vein deposits in West Kalba zone (Kuludzhun, Sentash, Kazan-Chunkur and others); gold-arsenic-carbon-bearing type is presented by large, middle and small deposits of Bakyrchik’s group (Bakyrchik, Bolshevik, Gluboky Log and others). Last one is formed on middle-Hercynian collision ore-bearing level (С2-С3) [3]. Multiple-stage concentration of gold contributed to formation of very large deposits. Gold content ranges from is 0.2 to 60 g/t, average is 8-9 g/t. Considerable part of gold is found in micro- and nanoparticles, nanotubes containing Au, Ag, Pt, Pd, W, Mo, Sn, Y, Yb, Ta and other elements [
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Kam, Pascal, Aaron Coppage, Calvin Kam, Sharin Shafian, Bong Steven Chun, and Jinny Rhee. "Lead-Free, Fluxless Solder Joints to Synthetic Diamond." In ASME 2008 International Mechanical Engineering Congress and Exposition. ASMEDC, 2008. http://dx.doi.org/10.1115/imece2008-67068.
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With the recent trends towards smaller heat sources and higher heat fluxes, conduction spreading resistance can become a bottleneck to efficient heat dissipation from temperature-sensitive components such as advanced microelectronics and high power light-emitting diodes (LEDs). However, the use of a high thermal conductivity heat spreader such as a synthetic chemically vapor deposited (CVD) diamond results in an additional interface between two materials. The near elimination of thermal interface resistance at material boundaries is critical for this application to be viable from a thermal standpoint. A lead-free, fluxless soldering process for joining metal substrates to a CVD diamond heat spreader was sought in this study to achieve the low thermal interface resistance and Restruction of Hazardous Substances Directive (RoHS) compliancy desired for this application. A typical titanium-platinum-gold metallization was applied to the surfaces of the diamond to enable it to bond with metal solders. Both indium solder and a popular tin-silver-copper solder (SAC305) were examined in this work. The indium was cold-welded to the substrates under pressure. The SAC305 solder was reflowed in a nitrogen furnace with variable pressure at the joint. The resulting solder thicknesses and joint quality were assessed using a scanning electron microscope (SEM). Lastly, a prototype of high-heat flux source with a CVD diamond spreader and forced convection with air was built to illustrate the thermal advantages of properly incorporating a diamond spreader with a fluxless solder bond.
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Subbarayan, Guhan, Buck Warnock, Purushothaman Damodaran, Krishnaswami Srihari, and Jorge Arellano. "An Experimental Study of Lead-Free Wave Soldering Using SAC 305 and No-Clean Flux." In ASME 2006 International Mechanical Engineering Congress and Exposition. ASMEDC, 2006. http://dx.doi.org/10.1115/imece2006-13927.
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The transition to lead-free assembly will have a significant effect on wave soldering operations. Since the wetting ability of lead-free solder is usually less than that of tin-lead solder, it can result in unacceptable hole fills and inconsistent top side wetting - especially in the case of thick Printed Circuit Boards (PCBs). Presently, there is very little data available on lead-free wave soldering with tin-silver-copper (SnAgCu or SAC) alloy and no-clean flux chemistry. Although some researchers and consortia recommend tin-copper (SnCu) for lead-free wave soldering, demonstrating the feasibility of using the SAC alloy for wave soldering operation can aid manufacturers to use the same alloy for both reflow and wave soldering operations. In this study, SAC 305 alloy and no-clean flux were evaluated in terms of percentage of hole fill and solderability on a 93 mil thick test vehicle with Immersion Silver (ImmAg) surface finish. The evaluation was performed on a nitrogen equipped wave soldering equipment. It has 4 preheating zones (3 convection bottom heaters and 1 infrared top heater) that provides good control to develop the required preheat profile. A partial factorial experiment was conducted to study the main effects of solder pot temperature, topside preheat temperature and conveyor speed on wave soldering performance. Wave soldering was performed after two reflow cycles. A 100% visual inspection was done for all the through hole components using a 10X microscope to determine top side wetting, percentage of hole fill, bridging, flux residue and solder balling. Thickness of the hole fill was also measured using digital X-Ray equipment. The data generated from this experiment was used to determine the 'optimum' lead-free process parameters for wave soldering using a SAC 305 alloy with a no-clean flux chemistry. The 'optimized' process parameters were then used to evaluate boards with Organic Solderability Protective (OSP) and Electroless Nickel Immersion Gold (ENIG) surface finishes. The designed experiments approach adopted to determine the optimum process settings and the research findings are explained in detail.
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Kardak, Ajay A., Elizabeth J. Podlaha-Murphy, Michael C. Murphy, and Ram V. Devireddy. "Electrodeposited Micro Copper Bumps for Packaging Module of a Micro-Thermoelectric Cooler." In ASME 2008 Summer Bioengineering Conference. American Society of Mechanical Engineers, 2008. http://dx.doi.org/10.1115/sbc2008-192588.
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Flipchip assembly is the direct electrical connection of the device die on the substrates or circuit boards using conductive stud bumps. Stud bumps help in the reduction of the number of bond wires and weight, and improve performance. Ueno et al. [1] fabricated copper column bumps with a diameter of 75 μm, a height of 50 μm and a pitch of 200 μm. Ni/Au bumps were also fabricated using electroless plating method with a pitch of 50 μm [2]. Tomita et al. [3] successfully fabricated tip capped copper column bumps with a height of 5 μm that were spaced 100 μm apart. Lead free solder bumps have been fabricated using pure-tin (Sn), tin-bismuth (80wt%Sn:20wt%Bi), tin-copper (99.3wt%Sn:0.7wt%Cu), tin-silver (96.5wt%Sn:3.5wt%Ag), and tin-silver-copper (93.8wt%Sn:3.5wt%Ag:0.7wt%Cu) alloys with a diameter of 200 μm and a pitch of 400 μm [4]. Low cost gold bumps have also been fabricated on polymer substrates with dimensions of 40 μm in diameter, 41 μm in height and a pitch of 100μm [5]. More recently Chu et al. [6] have demonstrated the use of cylindrical indium solder bumps with 80 μm diameter for optical interconnect and microwave applications.
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Armendariz, Norman J., and Prawin Paulraj. "Materials Characterization of Lead Free Compositions for Minimum Temperature SMT Processes at the SLI-Second Level Interconnect Solder Joint." In ISTFA 2004. ASM International, 2004. http://dx.doi.org/10.31399/asm.cp.istfa2004p0261.
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Abstract The European Union is banning the use of Pb in electronic products starting July 1st, 2006. Printed circuit board assemblies or “motherboards” require that planned CPU sockets and BGA chipsets use lead-free solder ball compositions at the second level interconnections (SLI) to attach to a printed circuit board (PCB) and survive various assembly and reliability test conditions for end-use deployment. Intel is pro-actively preparing for this anticipated Pb ban, by evaluating a new lead free (LF) solder alloy in the ternary Tin- Silver-Copper (Sn4.0Ag0.5Cu) system and developing higher temperature board assembly processes. This will be pursued with a focus on achieving the lowest process temperature required to avoid deleterious higher temperature effects and still achieve a metallurgically compatible solder joint. One primary factor is the elevated peak reflow temperature required for surface mount technology (SMT) LF assembly, which is approximately 250 °C compared to present eutectic tin/lead (Sn37Pb) reflow temperatures of around 220 °C. In addition, extended SMT time-above-liquidus (TAL) and subsequent cooling rates are also a concern not only for the critical BGA chipsets and CPU BGA sockets but to other components similarly attached to the same PCB substrate. PCBs used were conventional FR-4 substrates with organic solder preservative on the copper pads and mechanical daisychanged FCBGA components with direct immersion gold surface finish on their copper pads. However, a materials analysis method and approach is also required to characterize and evaluate the effect of low peak temperature LF SMT processing on the PBA SLI to identify the absolute limits or “cliffs” and determine if the minimum processing temperature and TAL could be further lowered. The SLI system is characterized using various microanalytical techniques, such as, conventional optical microscopy, scanning electron microscopy, energy dispersive spectroscopy and microhardness testing. In addition, the SLI is further characterized using macroanalytical techniques such as dye penetrant testing (DPT) with controlled tensile testing for mechanical strength in addition to disbond and crack area mapping to complete the analysis.
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Subbarayan, Guhan, Robert Kinyanjui, Pei Fang Tsai, and Krishnaswami Srihari. "Mechanical Reliability Evaluation of Stripped and Replated Component Termination Finishes." In ASME 2007 InterPACK Conference collocated with the ASME/JSME 2007 Thermal Engineering Heat Transfer Summer Conference. ASMEDC, 2007. http://dx.doi.org/10.1115/ipack2007-33666.
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The termination finish of Small Output Integrated Circuit (SOIC) and Small Output Transistor (SOT) chip components were converted from Pb-free to Sn-Pb (backward conversion) and vice versa (forward conversion). The motivation for these conversions is due to a combination of factors such as the supply chain constraints on component availability, European Union’s (EU) legislation on “Restriction of Hazardous Substances” (or RoHS), and the growth of tin whiskers on matte tin finish components. The conversions were performed using a “Robotic Stripping and Solder Dipping Process”, and the mechanical reliability of the converted components was evaluated through lead pull testing. In this experiment, a 100% (all finishes are given in weight percentage unless otherwise specified) matte tin finish was first stripped and re-plated with an eutectic Sn-Pb finish. Then, components with 100% matte tin and eutectic Sn-Pb termination finish were replaced with a Pb-free Sn-3.5%Ag-0.5%Cu (SAC305) finish. Three Printed Circuit Board (PCB) surface finishes namely Immersion Silver (ImAg), Organic Solderable Preservative (OSP), and Electroless Nickel/Immersion Gold (ENIG), were evaluated with Sn-Pb and Pb-free processes. All the assembled boards were subjected to an initial analysis, which includes visual inspection with an optical microscope and X-Ray analysis. Subsequently, a time zero analysis was performed which includes cross sectioning, Scanning Electron Microscope (SEM) analysis and lead pull testing. The pull testing was performed on a Chatillon TCM 201-SS equipment. All the leads were pulled orthogonal to the surface of the PCB. After isothermal aging at 150°C for a time period of 10 days (240 hours), cross sectioning and pull testing were performed to study its effect on Intermetallic Compound (or IMC) growth and reliability.
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Espinasse, Philippe. "Deepsea Pilot SMS Mining System for Harsh Environments." In ASME 2010 29th International Conference on Ocean, Offshore and Arctic Engineering. ASMEDC, 2010. http://dx.doi.org/10.1115/omae2010-20477.
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Following the trend of oil and gas production in deep waters, ore mining is about to start in the deep waters of the Pacific Ocean. If the first system will most probably be installed in the quiet though deep waters of Papua New Guinea, other prospects lie in the more turbulent areas of New Zealand and the Tongas. The ore accumulations to be mined are high grade hydrothermal mineral deposits rich in copper, gold, zinc, lead and silver located directly on the seabed. However, the excavation techniques need to be quite different from what had been envisaged for manganese nodules due to the morphology of the deposits. Based on its deep water construction experience, Genesis France, a company of the Technip Group has been contracted to perform a screening study of the various technologies to be applied to cut, crush, lift to the surface and pre-process the massive seabed sulphide deposits in a safe, efficient and profitable manner while minimizing the environmental impact of such work. This paper presents the conceptual screening study, the systems that have been evaluated, the selection criteria and the resulting operating system.
Reports on the topic "Gold Silver Lead"
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Cathro, M. S. Gold and Silver, Lead Deposits of the Ketza River District, Yukon: Preliminary Results of Field Work [Modified From Cathro, 1988]. Natural Resources Canada/ESS/Scientific and Technical Publishing Services, 1991. http://dx.doi.org/10.4095/132335.
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Epigenetic lead, zinc, silver, antimony, tin, and gold veins in Boulder Basin, Blaine and Custer counties, Idaho; potential for economic tin mineralization. US Geological Survey, 2002. http://dx.doi.org/10.3133/b2064jj.
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Map showing mineral resource assessment for vein and replacement deposits of gold, silver, copper, lead, zinc, manganese, and tungsten in the Butte 1 degree by 2 degrees Quadrangle, Montana. US Geological Survey, 1992. http://dx.doi.org/10.3133/i2050d.
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Geochemistry, geochronology, mineralogy, and geology suggest sources of and controls on mineral systems in the southern Toquima Range, Nye County, Nevada; with geochemistry maps of gold, silver, mercury, arsenic, antimony, zinc, copper, lead, molybdenum, bismuth, iron, titanium, vanadium, cobalt, beryllium, boron, fluorine, and sulfur; and with a section on lead associations, mineralogy and paragenesis, and isotopes. US Geological Survey, 2003. http://dx.doi.org/10.3133/mf2327c.
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