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1
Cramer, Larry A. "The extractive metallurgy of south africa’s platinum ores." JOM 53, no. 10 (October 2001): 14–18. http://dx.doi.org/10.1007/s11837-001-0048-1.
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Scott, David A. "The La Tolita—Tumaco Culture: Master Metalsmiths in Gold and Platinum." Latin American Antiquity 22, no. 1 (March 2011): 65–95. http://dx.doi.org/10.7183/1045-6635.22.1.65.
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AbstractThe archaeological setting of the La Tolita—Tumaco culture is briefly discussed as a framework for the examination of the metallurgy of the area, in particular the gold—platinum alloys used to make platinum-coated gold objects, platinum—gold sintered alloys, and platinum—gold foil—plated objects. The sophisticated approach to the manipulation of metallic materials resulted in several notable advances being made by the La Tolita—Tumaco culture: the production of extremely fine rectangular wire, bimetallic tumbaga alloys, small lead spheres inlaid with platinum, soldering, granulation, and a degree of sophistication to metalworking that is very impressive and, in some cases, unique in the world. Some selected examples are discussed, and the microstructure of a representative selection of the La Tolita material, bimetallic tumbaga construction, the initial sintered gold—platinum product, platinum-plated gold, and heavily worked gold—platinum composite artifacts are presented.
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Liu, Si Qing, Bao Xu Song, Quan Jun Liu, and Wan Ping Wang. "Process Mineralogy of a Low Grade Cu-Ni-PGM Sulphide Ore and its Implications for Mineral Processing." Advanced Materials Research 524-527 (May 2012): 1023–28. http://dx.doi.org/10.4028/www.scientific.net/amr.524-527.1023.
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Based on process mineralogical study of a low-grade Cu-Ni-platinum group metal(PGM) sulfide ore in SW China, the occurrence of Cu and Ni, the distribution of platinum group minerals (PGMs) and their relationships with other minerals are determined in detail, which provides scientific reference for forthcoming mineral processing and extractive metallurgy. The mineralogical results show that 18 individual PGMs containing all the 6 platinum group elements (PGEs) are investigated, and it can be concluded that the PGMs in the ores mainly occur as individual minerals. SEM images show that the PGMs are mainly disseminated in sulphides, most occur as inclusions or semi-inclusions, and part are inlayed along the other minerals to form coarse compound grains. Due to the the complex mineral composition and texture, processing the Cu-Ni-PGM ores by traditional flotation may be difficult to get a good processing performance.
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Kwapisiński, Piotr. "Metallurgy at KGHM Polish Copper SA." Key Engineering Materials 682 (February 2016): 299–307. http://dx.doi.org/10.4028/www.scientific.net/kem.682.299.
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Metallurgy of KGHM Polska Miedź S.A. is one of the world leaders in the production of copper. It is the result of high volume and quality production of copper and silver, as well as the use of modern technology direct to copper process in flash smelting furnace in HMG II. Soon this will be also the case for HMG I. The intention is to modernise, and upgrade technological processes within all the smelters to increase effectiveness, also to decrease production costs, and improve contamination of environment. In the year 2014 production of electrolytic copper increased about 2% in respect to 2013, and reached the record value 577 thousands ton. Production of silver increased 8% attaining value of 1256 ton. These perfect results were obtained through optimisation of smelting processes from one side, and rising the content of own concentrates, and foreign batches with higher content of precious metals. Production of metallic gold in 2014 was equal to 2,5t. Moreover KGHM is the third world producer of rhenium. They produce also lead technical and refined, as well as selenium, nickel sulphate, and platinum-palladium concentrate. The KGHM is also substantial producer of sulphuric acid, what is the direct effect of very efficient technology of desulphurisation of exhausts in the used metallurgical processes. The challenge for future is to increase retrieving of elements associated with copper production on every phase of the production. Due to the use of new technologies one expects also to achieve improved retrieving of other metals. Since 20% of KGHM revenue comes from silver, this is an important position in the overall balance of corporation focused mainly on copper exploitation. This is also why KGHM develops co-operations with scientific centres on the level bigger than laboratory (i.e. demo and/or pilot scales). The corporation is directly involved in research and development (subsidised national and international projects), while the value of these projects exceeds 200 mln PLN. There were created several collaborations with academic institutions targeting improvement of retrieval of energy from exploration processes, increase automation, remote control mining, and others. All of them are state of the art, and very modern technologies. KGHM must stay innovative, to preserve its market advantage. Metallurgy itself using own implemented technologies, resumes extended efforts to explore fully the richness of elements associated with the main metals.
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Catrin, R., A. F. Lasagni, C. Gachot, U. Schmid, and F. Mücklich. "Microstructural Design of Advanced Architectures in Titanium/Platinum Thin Films by Laser Interference Metallurgy." Advanced Engineering Materials 10, no. 5 (May 2008): 466–70. http://dx.doi.org/10.1002/adem.200700328.
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Chikosha, Silethelwe, and Hilda Kundai Chikwanda. "TiPt HTSMA Produced by Spark Plasma Sintering of Elemental Powders." Materials Science Forum 738-739 (January 2013): 579–83. http://dx.doi.org/10.4028/www.scientific.net/msf.738-739.579.
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Titanium-platinum (Ti50Pt50) alloy has been identified as a potential candidate for high temperature shape memory alloy (HTSMA) applications such as actuators in jet engines. This work evaluates powder metallurgy as an alternative processing route with the added benefit that near net shaped components can be formed. Spark plasma sintering (SPS) of blended elemental titanium and platinum powders was carried out. The sintering conditions used were: temperatures ranging from 1200 to 1400 °C and sintering times ranging from 10 to 30 minutes. SEM with EDS, XRD and DSC were carried out to study the results. Results showed that SPS only achieved high density, but not homogenisation of the alloys. All sintering conditions resulted in formation of the martensitic TiPt phase of interest, together with some or all of the following phases: Ti, Ti3Pt, Ti4Pt3, Ti3Pt5 and Pt. Post sintering annealing treatments were carried out to homoginise the alloys at 1300 °C for times ranging from 5 to 15 hours. With sufficient annealing times a two phase microstructure was produced with TiPt as the majority matrix phase and Ti3Pt5 as the precipitate phase.
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Igarashi, Tadashi. "The 200th Anniversary of Beginning of Modern Powder Metallurgy-Malleable Platinum by William H. Wollaston and Its Historical Backdrop-." Journal of the Japan Society of Powder and Powder Metallurgy 50, no. 10 (2003): 731–36. http://dx.doi.org/10.2497/jjspm.50.731.
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Shahbazi, Samson, and Mark Challingsworth. "How Silver Powder Metallurgy Affects the Physical Properties of Low Temperature Firing Silver Conductor." International Symposium on Microelectronics 2011, no. 1 (January 1, 2011): 000099–106. http://dx.doi.org/10.4071/isom-2011-ta3-paper4.
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With the implementation of RoHS (the Restriction of Hazardous Substance) Directive banning the use of Lead, Cadmium, Mercury and Hexavalent Chromium, hybrid microelectronic manufacturers are globally embracing the lead free movement. These manufacturers must not only understand the implications of their material choice but must be aware of the interaction between lead free solder alloys and their RoHS compliant thick film materials. It is commonly known that lead free solder alloys process at much higher reflow temperatures than lead containing solder which can directly impact the fired film leach resistance and the loss of adhesion. There are also other concerns; lead free solders alloys generally require a different organic flux system to promote wetting and reflow, but this change may cause a fired film conductor to leach more easily than the flux used in the lead containing solders. The use of lead free solders such as SAC305, SAC405 or 95/5 on a low firing (550–570 °C) pure silver conductor has the tendency of leaching the fired film more readily than conductors containing small amounts of palladium or platinum. Many of these situations provide new challenges for the hybrid circuit manufacturer. There is little information available regarding the effects of the lead free solders on low firing silver thick film conductors. This paper discusses the results of a newly developed Pb and Cd free silver thick film conductor paste with a modified silver powder metallurgy to improve the leach resistance, solder acceptance and adhesion using lead free solder. In addition, the pure silver conductor was fired on top of a low temperature dielectric paste. This conductor was evaluated by comparing lead free solder alloys to traditional tin-lead-silver solder alloys. This study included evaluations based on SEM photos, solderability, leach resistance, and initial and long term adhesions. Results are published describing the difference in behavior between the different solder alloys in conjunction with the different silver powder metallurgy.
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Marković, Ivana, Marijana Mladenović, Svetlana Ivanov, Dragoslav Gusković, Uroš Stamenković, Vesna Grekulović, and Dragan Manasijević. "Study of low-temperature isothermal annealing in the PM Cu-Pt alloys after plastic deformation." Tehnika 75, no. 4 (2020): 313–17. http://dx.doi.org/10.5937/tehnika2003313m.
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The investigation was performed on pure sintered (PM) copper and dilute PM copper-based alloys with 3 and 5.9 wt.% of platinum. Investigated PM samples were obtained using the standard powder metallurgy technique by mixing the elemental powders in proper ratio followed by pressing in hydraulic press and sintering in a hydrogen atmosphere. The PM samples were further cold deformed by rolling at ambient temperature to a total rolling reduction of 60 %. On pre-deformed samples, the low-temperature isothermal annealing up to the 100 hours was accomplished. During all stages of isothermal annealing, the values of Vickers hardness, micro-hardness, and electrical conductivity were measured. Also, the microstructure was analyzed using the scanning electron microscopy (SEM). This investigation has shown a slight increase in all measured properties for both dilute Cu-Pt alloys. An increase in mechanical properties was some more pronounced for more alloyed Cu-5.9wt%Pt alloy. During the low-temperature isothermal annealing, there were no significant changes in properties for pure pre-deformed copper.
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Catrin, R., A. F. Lasagni, C. Gachot, U. Schmid, and F. Mücklich. "Cover Picture: Microstructural Design of Advanced Architectures in Titanium/Platinum Thin Films by Laser Interference Metallurgy (Adv. Eng. Mater. 5/2008)." Advanced Engineering Materials 10, no. 5 (May 2008): NA. http://dx.doi.org/10.1002/adem.200890011.
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Jacob, K. T., and A. K. Shukla. "Kinetic decomposition of Ni2SiO4 in oxygen potential gradients." Journal of Materials Research 2, no. 3 (June 1987): 338–44. http://dx.doi.org/10.1557/jmr.1987.0338.
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Nickel orthosilicate (Ni2SiO4) has been found to decompose into its component binary oxides in oxygen potential gradients at 1373 K. Nickel oxide was formed at the high oxygen potential boundary, while silica was detected at the low oxygen potential side. Significant porosity and fissures were observed near the Ni2SiO4/SiO2 interface and the SiO2 layer. The critical oxygen partial pressure ratio required for decomposition varied from 1.63 to 2.15 as the oxygen pressures were altered from 1.01 ⊠ 105 to 2.7X 10−4 Pa, well above the dissociation pressure of Ni2SiO4. Platinum markers placed at the boundaries of the Ni2SiO4 sample indicated growth of NiO at the higher oxygen potential boundary, without any apparent transport of material to the low oxygen potential side. However, significant movement of the bulk Ni2SiO4 crystal with respect to the marker was not observed. The decomposition of the silicate occurs due to the unequal rates of transport of Ni and Si. The critical oxygen partial pressure ratio required for decomposition is related both to the thermodynamic stability of Ni2SiO4 with respect to component oxides and the ratio of diffusivities of nickel and silicon. Kinetic decomposition of multicomponent oxides, first discovered by Schmalzried, Laqua, and co-workers [H. Schmalzried, W. Laqua, and P. L. Lin, Z. Natur Forsch. Teil A 34, 192 (1979); H. Schmalzried and W. Laqua, Oxid. Met. 15, 339 (1981); W. Laqua and H. Schmalzried, Chemical Metallurgy—A Tribute to Carl Wagner (Metallurgical Society of the AIME, New York, 1981), p. 29] has important consequences for their use at high temperatures and in geochemistry.
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Hauptmann, Andreas, Sabine Klein, Paola Paoletti, Richard L. Zettler, and Moritz Jansen. "Types of Gold, Types of Silver: The Composition of Precious Metal Artifacts Found in the Royal Tombs of Ur, Mesopotamia." Zeitschrift für Assyriologie und vorderasiatische Archäologie 108, no. 1 (July 16, 2018): 100–131. http://dx.doi.org/10.1515/za-2018-0007.
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Abstract The many gold and silver artifacts from the Early Dynastic Royal Tombs of Ur in Mesopotamia are among the greatest metal finds of Ancient Mesopotamia in the third millennium BC. Within the framework of a research project, 32 of these artifacts were analyzed for their composition using a portable X-ray fluorescence spectrometer and a scanning electron microscope. Predominantly gold-silver alloys rather than pure gold were identified, containing up to 50 wt.% of silver and often with additional copper content well above 10 wt.%. This spectrum of composition ranges from alloys that could be of natural origin to alloys that were intentionally produced. Some gold artifacts were deliberately blended to gold-silver-copper alloys for color gradation. In addition, Sumerian written sources from the end of the third millennium BC can be compared to the results of the analyses of this study and offer more information on the processing of these metals at that time. In the present study, it is shown that gold originating from placer deposits was brought to Ur. Direct association of gold artifacts with lapis lazuli in many precious objects from the Royal Tombs and the particular composition of inclusions of platinum group minerals in the worked gold both point to a possible provenance in northern Afghanistan. One significant result was the confirmation of the use of depletion gilding for the removal of copper from surfaces; the technique of refining silver-bearing gold, known as parting, is not thought to have been known at this time.A previous version of this paper has been presented as a talk at the 62e Rencontre Assyriologique Internationale of Philadelphia 11th–15th July 2016 by A. Hauptmann, S. Klein and R. Zettler under the title: “A. Hauptmann, S. Klein, and R. Zettler, Sorts of Gold, Sorts of Silver from the Royal Tombs of Ur, Mesopotamia”. “For the late Hans-Gert Bachmann, the pioneer of ancient gold metallurgy. (Andreas Hauptmann)”
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Barnes, John E., William Peter, and Craig A. Blue. "Evaluation of Low Cost Titanium Alloy Products." Materials Science Forum 618-619 (April 2009): 165–68. http://dx.doi.org/10.4028/www.scientific.net/msf.618-619.165.
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Titanium has extremely attractive properties for air vehicles ranging from excellent corrosion resistance to good compatibility with graphite reinforced composites and very good damage tolerance characteristics. At current Buy to Fly ratios, the F-35 Program will consume as much as seven million pounds of titanium a year at rate production. This figure is nearly double that of the F-22 Program, which has a much higher titanium content. Lockheed Martin has initiated “Project Black Ti” to reduce the cost of titanium parts by reducing the titanium consumption but not the quantity of titanium parts. Ultimately, we want to reduce the inherent waste in the current processing of titanium alloy products. The Kroll process, by which most titanium product is made today, is nearly 60 years old. Kroll himself predicted the process would be replaced within 15 years due to inherent inefficiencies – in 1950. Titanium is also mis-characterized as a precious metal, which it is not. It is the ninth most abundant element on the earth’s surface. Aluminum by comparison is the third most abundant but has a much more efficient method to convert it to a usable form. Until the turn of the 20th century, aluminum was considered to be as precious as platinum until the Bayer Process brought prices down from $1200/kg to $0.60/kg. Regarding titanium, one way to improve efficiency and buy less material to make the same parts is via Powder Metallurgy (PM). Until recently, titanium alloy powder was very expensive. However, new methods of producing titanium alloy have been developed which generate powder as an output versus massive ingots, which require multiple melts to achieve homogeneity. With powder, in theory, we should be able to get much closer to net shape and reduce the initial buy and reduce significant machining costs. These low cost titanium powders are becoming commercially available, which has the potential to initiate a paradigm shift in the applications of titanium. PM technologies and the consolidation of these new powders are now economically viable with the potential cost of the new powders running approximately an order of magnitude less than conventional PM grade powders. This paper will present the current status of “Project Black Ti” and its potential impact to the F-35 program.
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Grebenyuk, Pavel S. "Russian Gold Mining Output in 1901-1917: A Source Studies Aspect." Herald of an archivist, no. 3 (2018): 679–91. http://dx.doi.org/10.28995/2073-0101-2018-3-679-691.
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This paper explores the problem of gold mining output in the Russian empire in 1901-1917 drawing on published and archival data. The aim of the study is to clarify indicators of gold mining production, since in the leading studies the data vary due to the peculiarities of metal accounting. It draws on published materials and archival documents of the State Institute for Design of Enterprises of Gold and Platinum Industry of the Glavzoloto of the People's Commissariat of Nonferrous Metallurgy (Giprozoloto), prepared in 1944 as a ‘Collection of Materials on the Gold Industry: 1493 - 1943’ and stored in the State Archive of the Magadan Region. Materials of the Giprozoloto Institute contain calculations of gold production in Russia and the USSR from 1745 to 1943, as well as technical and economic information on national gold mining industry in the early 20th century. The analysis shows that gold mining indices in scientific literature and sources are given according to data from gold log-books or gold-smelting laboratories. Gold log-books did not reflect the volume of actual mining, they only showed the gold registered in mines; moreover, some gold was withheld, and then came in to laboratories for alloy. Accounting for metal in the gold-smelting laboratories showed higher and more accurate production figures, since it included artisanal mining gold. However, as the source study demonstrates, figures of gold production in 1901-1917 according to the Giprozoloto Institute (805.4 tons) and according to L.B. Kafengauz (814.6 tons) based on data of gold-smelting laboratories and incorporated volumes of uncleaned bullion gold entered in there. The results of the study change the views on the volume of gold mining in Russia in this period that prevail in the historiography. It should be noted, that according to calculations, confirmed indicators of industrial production of chemically pure gold in Russia in 1901-1917 amounted to 682.5 tons. Final figures of gold industry of the period in amount of chemically pure gold obtained in gold-smelting laboratories corresponded to indices of value of gold production used in the analysis industry dynamics, and is considered correct, when compared with the USSR gold-mining indices.
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Tang, Hui Yi, Bao An Wu, Qin Bin Liu, Bu Ying Zhai, De Mao Chen, Jian Sheng Wang, Feng Lan Luo, and Xing Han Chen. "The Preparation and Properties Study of the Zirconia Dispersion-Strengthened Platinum Materials." Advanced Materials Research 873 (December 2013): 19–23. http://dx.doi.org/10.4028/www.scientific.net/amr.873.19.
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s: The zirconia dispersion-strengthened platinum thermocouple materials were successfully fabricated by powder metallurgic method. It was studied the zirconia grains influences on platinum materials. The results of the study show that its density is 21.4g/cm3 and its relative density is 99.8%. Its tensile strength obvious overtop pure platinum, the maximum tensile strength is 930MPa. The cures of tensile strength with the processing rate improved of the materials obey a analogy-linear law. The resistance ratio (R100/R0)1.3922, and thermal electromotive force of Pt matched PtRh10 meet I measuring accuracy grade relative to GB/T1598-2010 stander.
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GEZERMAN, AHMET OZAN. "INVESTIGATION OF SOME PROPERTIES OF ZINC-NICKEL ALLOY PLATING WITH TRIETHANOLAMINE, p-AMINOBENZENESULFONIC ACID, AND GELATINE." Surface Review and Letters 27, no. 12 (August 7, 2020): 2050018. http://dx.doi.org/10.1142/s0218625x20500183.
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Anticorrosion requirements for the metallurgy, automotive, and aeronautical industries have increased in recent years, for which alternative plating chemicals must be developed. This study focuses on obtaining a Zn-Ni alloy plating with higher corrosion resistance and brightness. For this purpose, tetraethylenepentaamine as complexing agent, triethanolamine as the surfactant, and gelatin and [Formula: see text]-aminobenzenesulfonic acid as brightening agents for the plating were selected and their optimal concentrations were determined for applications. The optimal Zn-Ni ratio and plating thickness were analyzed using an X-ray Dal device. Improved plating performance of the Zn-Ni alloys was achieved with a Zn-Ni alloy containing 12–14% Ni.
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Ju, Zhi Lan, Guo Ran Hua, and Hua Zhang. "Effect of Different Modified Mechanism on Mechanical and Cutting Properties of WC-Co(Ni)." Advanced Materials Research 295-297 (July 2011): 1709–13. http://dx.doi.org/10.4028/www.scientific.net/amr.295-297.1709.
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Cemented carbide tools are widely used in machining industry due to their superior properties. WC-Co composite cemented carbide tool materials reinforced with Ni and SiC nano particles were fabricated by using powder metallurgy followed by hot extrusion. Different modified mechanism (nano-SiCp modified，binder(Co, Ni) modified and Co electoless plating coated WC ) of WC-based cemented carbide tool materials were fabricated by using powder metallurgy followed by hot extrusion. Microstructure，mechanical and cutting properties were studied. The results show that the heat-resistance, as well as high-temperature behaviors (hardness, wear-resistance and obdurability ) ，can be improved by adding nano-SiCp on WC-based cemented carbide. Ni-Ti replaced Ni as binder can improve hardness and red-hardness of tool. Mechanical properties are enhanced due to Co as binder having more wettability on WC surface than Ni .
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Azmi, K., M. A. A. Mohd Salleh, and M. N. Derman. "Synthesis and Characterization of Electroless Copper Coated SiC Particles." Advanced Materials Research 795 (September 2013): 233–36. http://dx.doi.org/10.4028/www.scientific.net/amr.795.233.
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Silicon carbide reinforced copper matrix (Cu-SiCp) composites fabricated via the conventional powder metallurgy methods have inferior thermophysical properties due to the weak bonding between the copper matrix and the SiCp reinforcement. In order to improve the bonding between the two constituents, the SiCp were copper coated via electroless coating process. Based on the experimental results and findings, a continuous copper deposition on the SiCp was obtained via the electroless plating process. The copper film was found to be high in purity and homogeneously deposited on the SiCp surfaces. The thickness of the coated copper layer was roughly estimated to be around 1μm.
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Lee, Seo-Hyang, and Jae-Ho Lee. "Pulse Electroplating of Ni–W Alloy for the Diffusion Barrier in Under Bump Metallurgy." Journal of Nanoscience and Nanotechnology 21, no. 5 (May 1, 2021): 3016–19. http://dx.doi.org/10.1166/jnn.2021.19137.
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Ni–W alloy was electroplated from citrate bath. The crack-free coatings were obtained using the pulse electroplating method. The surface hardness was increased up to 700 Hv and it is twice as high than that of the electroplated Ni. The surface hardness was increased as the content of W in the coating increased. However, the higher W contents made surface cracks and the surface hardness was decreased. Ni–W alloy made less intermetallic components (IMC) and the shear force of solder ball was increased as much as 20% compared with conventional Ni plating.
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Zou, Haohao, Xu Ran, Weiwei Zhu, Yong Wang, Siqi Zhan, and Zhikang Hao. "Tribological Behavior of Copper–Graphite Composites Reinforced with Cu-Coated or Uncoated SiO2 Particles." Materials 11, no. 12 (November 29, 2018): 2414. http://dx.doi.org/10.3390/ma11122414.
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Copper–graphite composites reinforced with SiO2 particles were fabricated by powder metallurgy technique. Electroless copper plating was introduced to improve the interfacial bonding between SiO2 particles and copper matrix. The microstructure, density, and hardness of the composites were characterized. The tribological properties, such as friction coefficient and wear rate of the composites, were studied using a pin-on-ring tribometer. The results show that the hard SiO2 can restrict the severe plastic deformation and adhesion contact in the process of wear. At the same time, parts of SiO2 particles can be broken into fine particles during wear process, which is helpful for decreasing adhesion wear and abrasive wear. Therefore, the addition of SiO2 leads to increasing friction stability and friction coefficient, and decreasing wear rate. In addition, the electroless copper plating improves the interfacial bonding between SiO2 and copper matrix, which prevents separation of SiO2 from copper matrix and further increase tribological properties of the composites.
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Zhang, Guo Shang, Yi Min Gao, Jian Dong Xing, Shi Zhong Wei, Ji Wen Li, and Liu Jie Xu. "The Effects of Nickel-Plating on Al2O3 Particles Reinforced Steel Matrix Composites." Applied Mechanics and Materials 117-119 (October 2011): 777–81. http://dx.doi.org/10.4028/www.scientific.net/amm.117-119.777.
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The wettability between ceramic particles and metal play an important role in fabrication of ceramic particles reinforced metal matrix composites(PRMMCs). In present paper, Al2O3 particles were coated with nickel by chemical plating to modify the preparation and properties of Al2O3 particles reinforced steel matrix composites. Using the Al2O3 particles treated by chemical nickel-plating, Al2O3 particles reinforced steel matrix composites were fabricated by powder metallurgy process(PM). And the wear resistance of the composites was investigated. The results show that: the nickel coating can fully and tightly cover on the surface of Al2O3 particles, and the nickel coating thickness is uniform about 2~3 micron; The nickel coating can effectively improve the uniform distribution of Al2O3 particles in the composites. And the treated Al2O3 particles can be tightly bonded with steel matrix,which improve the wear resistance of composites. The wear resistance of composites reinforced treated and untreated Al2O3 particles each is 2.5 and 1.6 times of Hadfield steel.
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Lu, Ze Long, Lai Ma Luo, Jun Zhang, Yong Qing Qin, Xin Min Huang, Guang Nan Luo, Xiao Yong Zhu, Xiang Zan, Ji Gui Cheng, and Yu Cheng Wu. "Fabrication of W-Cu/Lu2O3 Composites with High Strength and Electrical Conductivity Prepared by Electroless Plating and Powder Metallurgy." Materials Science Forum 849 (March 2016): 825–30. http://dx.doi.org/10.4028/www.scientific.net/msf.849.825.
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W–Cu (0, 0.25, 0.75, 1.5, and 3 wt.%)/Lu2O3 composite materials were prepared through electroless plating with simplified pretreatment method and powder metallurgy. The phases and morphologies of the W–Cu/Lu2O3 composites were characterized by X-ray diffraction, field emission scanning electron microscopy and energy dispersive spectroscopy. The relative density, microhardness, electrical conductivity, and bending strength of the sintered samples were examined. The experimental results show that W–Cu composites with uniform structures can be obtained with pretreated W using the simplified method, followed by electroless Cu plating. The microstructure and properties of the composites were significantly affected by the addition of Lu2O3 nanoparticles, resulting in high electrical conductivity and strength. The electrical conductivity of W–Cu/1.5 wt.% Lu2O3 composites reached 63.3%, which is higher than the national standard value of 50.71%. The bending strength of W–Cu/1.5 wt. % Lu2O3 reached 1306.7 MPa, which is 65.41% higher than the national standard. These results may be attributed to the uniform distribution of refined particles with Lu2O3 content increased to 1.5 wt. %.
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Guo, Zhong Quan, Hao Ran Geng, and Sha Sha Feng. "Study on Mechanical Properties and Physical Properties of Copper Based Electrical Contact Materials Reinforced by CNT." Advanced Materials Research 139-141 (October 2010): 67–71. http://dx.doi.org/10.4028/www.scientific.net/amr.139-141.67.
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A new method of carbon nanotube with electroless plating of nickel is proposed. It is shown that in a certain condition, the compacted and well-distributed coating of nickel is obtained without the process of sensitization and activation. Upon the surface treatment of the carbon nanotube, the CNT-consolidated composites for copper-based electrical contact have been made in the way of powder metallurgy. Some important mechanical properties and physical properties, including sliding wear property, electrical conductivity and fusion resistance, were investigated. The experiment results showed that Carbon nanotube inside the composite was uniformly distributed and a proper addition of CNT effectively improves the comprehensive property of the composites. When the carbon nanotube takes up 4vol. % in the material, it is highly effective in improving its sliding wear property and fusion resistance; though its electrical conductivity drops. Its overall properties meet the requirements of electrical contact materials
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Zhang, Dan Dan, Zai Ji Zhan, Chang Hong Guo, and Gong Min Tang. "Preparation and Properties of Cu Matrix Reinforced with Ti2AlN Ceramic Particles." Key Engineering Materials 602-603 (March 2014): 523–26. http://dx.doi.org/10.4028/www.scientific.net/kem.602-603.523.
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Cu matrix composites with various contents of Ti2AlN were fabricated by powder metallurgy using spark plasma sintering (SPS) method. Ti2AlN ceramic particles were pre-treated by electroless copper plating, the result showed that Ti2AlN reinforcement and Cu matrix were strongly bonded. The effects of Ti2AlN content on microstructure, electrical resistivity and mechanical properties were systematically investigated. With the addition of low fraction of Ti2AlN, the hardness and tensile strength of matrix were improved without losing the fracture toughness too much. Tensile strength of Ti2AlN/Cu composites were about 380 MPa with the content of 7 wt. % reinforcing phase, and the conductivity of the composites remained about 61.5 % IACS. Moreover, the wear tests illustrated that the loads were effectively born by the Ti2AlN reinforcement, the main tribological mechanism changed from adhesive wear to abrasive wear compared with Cu, thus the friction and wear resistance was also obviously improved.
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Cao, Chuan Liang, Xiang Lin Zhang, Chun Fa Dong, and Xiang Zha. "Effect of Annealing on Properties of the TiN & TiAlN Coatings Deposited on Powder Metallurgy High Speed Steel ( S790 )." Applied Mechanics and Materials 477-478 (December 2013): 1397–402. http://dx.doi.org/10.4028/www.scientific.net/amm.477-478.1397.
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To improve the mechanical properties of the physical vapor deposition (PVD) coatings deposited on fine-blanking tools and increase the tool life, TiN and TiAlN coatings were deposited on the powder metallurgy high speed steel S790 substrates by Multi-arc ion plating, and then annealed at the temperature of 500°C for one hour in vacuum enviroment. The phase variation, residual stress, morphology, surface microhardness and adhesion strength of coatings were respectively analyzed by X-ray diffraction (XRD), scanning electron microscopy (SEM), Vickers hardness tester and automatic scratch tester. The preferred orientations in the coatings are not changed after annealing, indicating no disparities in the crystal structure of the coatings. The residual stress of coatings released a little after annealing, however the adhesion strength between the coatings and substrates increased obviously, which indicated that the properties of the TiN and TiAlN coatings deposited on S790 steel were improved.
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Cao, Chuan Liang, Xiang Lin Zhang, and Hai Yang Wang. "Analysis on Residual Stress in TiN Coating with Different Thicknesses." Applied Mechanics and Materials 217-219 (November 2012): 1306–11. http://dx.doi.org/10.4028/www.scientific.net/amm.217-219.1306.
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TiN coating is often coated on fine blanking tools made of with the powder metallurgy high speed steel S790 by Multi-arc ion plating. The phase variation, residual stress and microhardness of TiN coatings were respectively analyzed by X-Ray Diffraction(XRD) and Vickers hardness tester in this research. The result shows that: there is obvious preferred orientation in the crystal surface (1 1 1) and (2 2 2) of TiN coating, the residual stress of TiN coating ranges from -2 347 MPa to -1 920 MPa, and that of the substrate from -154.9 MPa to -69.21 MPa, both of which decrease with the increasing of coating thickness. The TiN coating on the S790 substrate was annealed at temperature 500°C for one hour. It was revealed that the stress state of TiN coating was better and thus the properties of the TiN coating were improved.
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Dong, Shuhan, Huiyong Yuan, Xiaochao Cheng, Xue Zhao, Mingxu Yang, Yongzhe Fan, and Xiaoming Cao. "Improved Friction and Wear Properties of Al6061-Matrix Composites Reinforced by Cu-Ni Double-Layer-Coated Carbon Fibers." Metals 10, no. 11 (November 19, 2020): 1542. http://dx.doi.org/10.3390/met10111542.
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The friction and wear properties of an Al6061 alloy reinforced with carbon fibers (CF) modified with Cu-Ni bimetallic layers were researched. Cu-Ni double layers were applied to the CF by electroless plating and Al6061-matrix composites were prepared by powder metallurgy technology. The metal-CF/Al interfaces and post-dry-wear-testing wear loss weights, friction coefficients, worn surfaces, and wear debris were characterized. After T6 heat treatment, the interfacial bonding mechanism of Cu-Ni-CF changed from mechanical bonding to diffusion bonding and showed improved interfacial bonding strength because the Cu transition layer reduced the fiber damage caused by Ni diffusion. The metal–CF interfacial bonding strongly influenced the composite’s tribological properties. Compared to the Ni-CF/Al and Cu-CF/Al composites, the Cu-Ni-CF/Al composite showed the highest hardness, the lowest friction coefficient and wear rate, and the best load-carrying capacity. The wear mechanisms of Cu-Ni-CF/Al composite are mainly slight abrasive wear and adhesive wear.
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Jia, Dongming, Junbing Ma, Xueping Gan, Jingmei Tao, Ming Xie, Jianhong Yi, and Yichun Liu. "A Comparison Study of Ag Composites Prepared by Spark Plasma Sintering and Hot Pressing with Silver-Coated CNTs as the Reinforcements." Materials 12, no. 12 (June 17, 2019): 1949. http://dx.doi.org/10.3390/ma12121949.
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In this study, carbon nanotube-reinforced silver composites (CNT/Ag) were prepared by the powder metallurgy process via spark plasma sintering (SPS) and hot pressing sintering (HP) with composite powders through an improved electroless plating method assisted by ultrasonic spray atomization. The dispersion of CNTs was effectively improved by ultrasonic spray atomization, and uniform silver layers were deposited on the surface of CNTs by electroless deposition. The property testing results showed significant improvements of the electrical conductivity, hardness, and tensile strength in the samples prepared by SPS, as compared to their HP sintered counterparts. When the volume fraction of CNTs reached 2.5%, the tensile strength reached a maximum value of 221 MPa, which was more than twice that of the pure silver samples. The structural analysis indicated different degrees of CNT agglomeration and matrix mean grain sizes in the composites prepared by SPS and HP, which are responsible for the differences in properties.
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Leng, Jin Feng, Xin Ying Teng, Fu Lei Jiang, De Jiang Hu, and Hao Ran Geng. "Preparation of Graphene and Graphene/Al Composites." Materials Science Forum 816 (April 2015): 177–81. http://dx.doi.org/10.4028/www.scientific.net/msf.816.177.
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Metal matrix composites reinforced by graphene particles exhibit physical and mechanical property and are developed and qualified for use in aerospace structure, bioengineering, energy storage material and photoelectric device. In the present paper, graphene was fabricated by modify Hummers method, and then was surface modified by chemical plating copper. The graphene/Al composites were fabricated by powder metallurgic method. Morphology characterization of graphene and composites were detected by XRD and SEM,the fabrication parameters of composites were optimized by testing harness and density. The volume fraction of graphene particles was 3%, the density of composites was maximum of 96.5%. The hardness had a maximum of HB 42.6, and the hardness of graphene/Al composites increased by 33.5%.
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León, Carlos Alberto, Gabriel Rodríguez-Ortiz, E. A. Aguilar-Reyes, Makoto Nanko, and M. Takeda. "Microstructural and Thermal Characterization of Copper Based Composites for Thermal Management in Electronic Packaging." Advanced Materials Research 976 (June 2014): 148–53. http://dx.doi.org/10.4028/www.scientific.net/amr.976.148.
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Copper based composites with 30, 40, 50 and 60 vol.% Al2O3 were fabricated by powder metallurgy and consolidated by pulsed electric current sintering (PECS). For the purpose of determining the advantage of using coated fillers, composite alumina particles with 18 vol.% copper were prepared by electroless copper plating. Coatings were continuous and homogeneous through alumina surface. Thus, composites consolidated by the modified process increased contact between the matrix and filler, which resulted in superior thermo-physical properties. Thermal conductivities of 210-99 and 227-114 W/mK were obtained for Cu/Al2O3 made by the admixture and the coated filler method, respectively. Such superiority is mainly attributed to the continuity in the matrix phase; the thermal conductivity values observed are similar to those shown by the traditional materials used in electronic packaging. The coefficient of thermal expansion was slight lower in composites fabricated by the coated filler method; values in the ranges of 14-11 and 13-10.5 μm/m°C were obtained for the admixture and the coated filler method, respectively.
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Anhaeusser, C. R. "The Geology, Geochemistry, Mineralogy and Mineral Beneficiation of Platinum-Group Elements.: Edited by Louis J. Cabri. CIM Special Volume 54, Canadian Institute of Mining, Metallurgy and Petroleum, Suite 1210, 3400 de Maisonneuve Boulevard West, Montreal, Quebec H3Z 3B8, Canada. 852 pages, US$150/CDN$220 for non-members, US$100/CDN$140 for members, US$ 70/CDN$100 for students (hard cover). ISBN 1 894475 27 5." Canadian Mineralogist 41, no. 2 (April 1, 2003): 544–46. http://dx.doi.org/10.2113/gscanmin.41.2.544.
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Xiang, Dong, Li Qun Jia, and Ke Gao Liu. "Structure and Performance of Chemical Duplex Plating Ti Metal Layer on Diamond Surface by Hydrothermal Method." Advanced Materials Research 936 (June 2014): 1676–80. http://dx.doi.org/10.4028/www.scientific.net/amr.936.1676.
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As a surface of diamond has a higher interfacial energy and worse binding force, the diamond shed from matrix easily. For solving this, the microstructures and properties of the metallic coating on diamond surface were studied. The different temperatures, such as 110, 120, and 130 °C for 6 h, were used for coating diamond in the high-pressure reactor respectively. The structure and performance of the metallic coating on diamond surface were tested by Scanning Electron Microscopy (SEM), X-ray Diffraction (XRD) and diamond compressive strength instrument. The results showed that a continuous and compact coating of Ni, W and Ti on the diamond surface is obtained by the hydrothermal coating technology (chemical duplex plating) at 120 °C. After heat treatment at 850 °C for 1 h, the better layer coatings form for protecting diamonds and reducing the trend of oxidize. Because the carbides of W and Ti present at the boundries between the coating and diamond surface, the combination of chemistry and metallurgy is gotten. The compress strength of diamonds after hydrothermal and heat treatment is higher than that of uncoated particles (those are 54.40% and 85.48%, respectively).
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Yener, K. Aslıhan. "The Anatolian Middle Bronze Age kingdoms and Alalakh: Mukish, Kanesh and trade." Anatolian Studies 57 (December 2007): 151–60. http://dx.doi.org/10.1017/s0066154600008577.
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AbstractThe comparisons at the heart of this article concern the varying roles of cuneiform texts, instrumental analysis and artefacts at the Bronze Age capital of Alalakh, located in the northeastern Mediterranean region of southern Turkey. The production of fine artefacts, such as sophisticated metallurgy, glass, faience, ivory carving and, especially, bronze, was under palace patronage, while trade and the networks of inter-regional relations facilitated the transport of materials across great distances in the ancient Near East. Several lines of evidence suggest that exchange relationships between Alalakh and the Middle Bronze Age central Anatolian kingdoms, such as Kanesh, were established prior to the arrival of Hattusili I. One category of artefact, ivory and bone with metallic embellishments, is emphasised here since the crafting of ivory and bone entails the use of local resources, while the plating with precious metals reflects artistic expression and exploitation that is international in scope. Several analytical techniques are presented, such as lead isotope ratios, scanning electron microscopy and polarizing light microscopy, which have aided in defining the artistic expression of Alalakh and the production of artefacts of power and prestige.
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Zhan, Si Qi, Xu Ran, and Hao Hao Zou. "Effect of Nickel Plating on MoS2 on Friction and Wear Properties of Cu-MoS2 Composites." Materials Science Forum 993 (May 2020): 1124–33. http://dx.doi.org/10.4028/www.scientific.net/msf.993.1124.
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The copper-molybdenum disulfide composites were prepared by powder metallurgy under argon sintering atmosphere. The effects of nickel plating on the surface of the molybdenum disulfide on the friction and wear properties of the composites were studied. Friction and wear experiments with different frictional speeds and loads were carried out on the surface micromechanical testing system of UNMT-1 material. The microstructure and friction/wear morphology of the materials under different conditions were observed by laser scanning confocal microscopy(LSCM), scanning electron microscopy (SEM) and optical microscopy(OM). The results show that the sintering temperature increased from 720 °C to 920 °C, and the microhardness and wear properties were obviously improved. The reaction products of nickel-plated molybdenum disulfide and nickel-free samples were the same at different sintering temperatures, whereas the product content was the same. There was a significant difference between the micro-morphology and the surface of the molybdenum disulfide. The friction coefficient of the nickel-plated molybdenum on the surface of the molybdenum disulfide was relatively high, the wear was relatively serious, the wear surface was relatively rough, and the unnickel-plated sample exhibited good friction and wear properties.
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Wei, D. B., M. F. Li, X. Zhou, F. K. Li, S. Q. Li, and P. Z. Zhang. "Preparation of NiCr/YSZ two-layered burn-resistant coating on γ-TiAl alloys based on plasma surface metallurgy and ion plating methods." Journal of Mining and Metallurgy, Section B: Metallurgy 57, no. 1 (2021): 83–96. http://dx.doi.org/10.2298/jmmb200902005w.
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The NiCr/YSZ coating was fabricated on ?-TiAl alloy by double glow plasma surface metallurgy technology and multi-arc ion plating technology. The microstructure, microhardness, bonding strength, and burn resistance of NiCr/YSZ coating were studied in detail. The results showed that the NiCr/YSZ coating was dense and homogeneous, including a duplex structure of top YSZ ceramic coating and underlying Ni-Cr bond coating. The average microhardness of NiCr/YSZ coating was raised by a factor of about 2 compared to the ?-TiAl substrate. The thermal shock test indicated that the composite structure had superior bonding strength and the defects such as metal droplets on the ceramic coating were the source of cracks. The high-energy laser beam destroyed the surface of ?-TiAl alloy, forming protruding combustion products in ablation zone and splashing residues around ablation zone. When coated by NiCr/YSZ coating, the combustion process was delayed through isolating and dissipating heat. The ablation range was controlled and the ablation damage was reduced at the same irradiation power. The NiCr/YSZ coating preliminarily realized to improve the burn resistance of ?- TiAl alloy.
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Dong, Cuige, Richu Wang, and Suqing Guo. "Microstructures and Mechanical Properties of Cu-Coated SiC Particles Reinforced AZ61 Alloy Composites." Coatings 9, no. 12 (December 3, 2019): 820. http://dx.doi.org/10.3390/coatings9120820.
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The pure Cu coating was plated on the surface of silicon carbide particles (SiCP) by two different methods, hydrazine hydrate direct reduction method and hydrazine with glucose pre-reduction method. The hydrazine with glucose pre-reduction method is more suitable for Cu plating on the surface of SiCP in terms of morphology and microstructure. AZ61 composites reinforced with different volume fractions (3~15%) uncoated and Cu-coated SiCP were prepared by powder metallurgy followed by hot extrusion. The effect of Cu coating on the morphology of SiCP/AZ61 composite was analyzed by optical microscope (OM), scanning electron microscopy (SEM), energy dispersive spectrometer (EDS), electronic probe micro-analyzer (EPMA) and X-ray diffractometer (XRD). The properties of the composite were characterized by Brinell hardness tester and mechanical testing machine. The effects of Cu coating on the micro-hardness, tensile strength and elongation of SiCP/AZ61 composite were analyzed. The tensile strength of AZ61 composite reinforced with Cu-coated SiCP increased by 3.5~6.3% and the elongation increased by 7.4~35.0% compared with AZ61 composite reinforced with uncoated SiCP. Therefore, the Cu coating can ameliorate the microstructure and properties of the SiCP/AZ61 composite effectively, reduce the defect rate in the composite, and improve the hardness, relative density, tensile strength, elongation of the composite.
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Le, Thuy Thi Xuan, Thuy Thi Xuan Le, Quyen Hong Ho, and Mai Thi Sao Nguyen. "Removal of copper and zinc from plating wastewater by megnatic separation method." Science and Technology Development Journal - Natural Sciences 1, T3 (September 30, 2017): 47–54. http://dx.doi.org/10.32508/stdjns.v1it3.465.
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Copper (Cu) and Zinc (Zn) are two popular heavy metals using in the mining operation, metallurgic industry, metal plating facilities, etc., and their effecs on the environment and human health are quite seriously. Application of a new adsorbent γ-PGM (-poly glutamic acid coated magnetite) is one of the new methods to separate toxic heavy metals Cu and Zn from water and wastewater. This study showed that 0.2 g/L γ-PGM at pH 6 with the shaking speed 200 rpm in 10 minutes were the best conditions for removal of Cu and Zn. The efficient removal of Cu and Zn was 99.91 % and 99.75 %, respectively. Besides, regeneration the ability of γ-PGM particles reached to 12 times while using hydrochloric acid HCl 0.1 N for 1 hour for desorption of the materials which is the best optimal conditions for separating Cu2 + and Zn2 + ions from the surface of γ-PGM particles. The results indicated that γ-PGM was the potential material for the application to the heavy metals removal in water and wastewater with various outstanding characteristics.
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Rodrigues, Lais Morandini, Elis Andrade Lima Zutin, Elisa Mattias Sartori, Daniela Baccelli Silveira Mendonça, Gustavo Mendonça, Yasmin Rodarte Carvalho, and Luana Marotta Reis de Vasconcellos. "Influence of Titanium Alloy Scaffolds on Enzymatic Defense against Oxidative Stress and Bone Marrow Cell Differentiation." International Journal of Biomaterials 2020 (July 29, 2020): 1–8. http://dx.doi.org/10.1155/2020/1708214.
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Studies have been directed towards the production of new titanium alloys, aiming for the replacement of Ti-6 Aluminium-4 Vanadium (TiAlV) alloy in the future. Many mechanisms related to biocompatibility and chemical characteristics have been studied in the field of implantology, but enzymatic defenses against oxidative stress remain underexplored. Bone marrow stromal cells have been explored as source of cells, which have the potential to differentiate into osteoblasts and therefore could be used as cells-based therapy. The objective of this study was to evaluate the activity of the antioxidant enzymes superoxide dismutase (SOD) and catalase (CAT) in porous scaffolds of Ti-6 Aluminium-4 Vanadium (TiAlV), Ti-35 Niobium (TiNb), and Ti-35 Niobium-7 Zirconium-5 Tantalum (TiNbZrTa) on mouse bone marrow stromal cells. Porous titanium alloy scaffolds were prepared by powder metallurgy. After 24 hours, cells plated on the scaffolds were analyzed by scanning electron microscopy (SEM). The antioxidant enzyme activity was measured 72 hours after cell plating. Quantitative real time PCR (qRT-PCR) was performed after 3, 7, and 14 days, and Runx2 (Runt-related transcription factor2) expression was evaluated. The SEM images showed the presence of interconnected pores and growth, adhesion, and cell spreading in the 3 scaffolds. Although differences were noted for SOD and CAT activity for all scaffolds analyzed, no statistical differences were observed (p>0.05). The osteogenic gene Runx2 presented high expression levels for TiNbZrTa at day 7, compared to the control group (TiAlV day 3). At day 14, all scaffolds had more than 2-fold induction for Runx2 mRNA levels, with statistically significant differences compared to the control group. Even though we were not able to confirm statistically significant differences to justify the replacement of TiAlV regarding antioxidant enzymes, TiNbZrTa was able to induce faster bone formation at early time points, making it a good choice for biomedical and tissue bioengineering applications.
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Beaman, Brian, and Jean Audet. "High Current Testing and Simulation for Land Grid Array Sockets." International Symposium on Microelectronics 2017, no. 1 (October 1, 2017): 000659–62. http://dx.doi.org/10.4071/isom-2017-poster3_002.
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Abstract Land grid array (LGA) sockets are commonly used for industry standard and custom microprocessors to meet the increased performance challenges for a variety of server applications. Along with the need for increased high speed signaling capabilities comes the challenge to support lower voltages and higher currents. Typical testing that is conducted by the LGA socket suppliers does not provide an accurate assessment of the maximum current capabilities in a real product application due to the test card design and construction limitations. Typical test card designs use daisy chain connections to wire multiple LGA socket contacts in series. The daisy chain wiring in the test card adds to the resistive heating and results in an inaccurate maximum current rating. Also, the test cards typically do not have a cross section construction that is representative of a real product application with multiple ground planes that provide improved thermal dissipation of the heat generated by the LGA socket interface. Hardware testing was conducted to better understand the performance limitations for a new product application. The test card was designed to use multiple voltage and ground planes in the circuit card cross section to provide a low impedance path for current flow and a low voltage drop through the LGA socket interface. In addition to the test card construction, the test hardware included a special test module with a shorted chip to provide a more accurate power distribution path through the socket and processor package. The test variables included different plating metallurgy options for the LGA socket and the processor module along with different configurations for the voltage supply and ground return contacts. Electrical and thermal modeling techniques were used to simulate the test hardware configuration with good correlation between the hardware and modeling results. Based on the positive correlation results, additional modeling was conducted to simulate the worst case power mapping conditions for the processor chip along with a more accurate power distribution. The additional modeling results provided further insights into the maximum current capabilities for the LGA socket based on the temperature increase from the resistive heating in the socket contacts.
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Panteleeva, Viktoria V., Ilya S. Votinov, Igor S. Polkovnikov, and Anatoliy В. Shein. "КИНЕТИКА КАТОДНОГО ВЫДЕЛЕНИЯ ВОДОРОДА НА МОНОСИЛИЦИДЕ МАРГАНЦА В СЕРНОКИСЛОМ ЭЛЕКТРОЛИТЕ." Kondensirovannye sredy i mezhfaznye granitsy = Condensed Matter and Interphases 21, no. 3 (September 26, 2019): 432–40. http://dx.doi.org/10.17308/kcmf.2019.21/1153.
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Методами поляризационных и импедансных измерений изучена кинетика реакции выделения водорода на MnSi-электроде в сернокислых растворах с различной концентрацией ионов водорода. Сделано предположение о механизме выделения водорода на силициде. Отмечено влияние тонкой оксидной пленки на кинетику выделения водорода на MnSi при невысоких катодных поляризациях.
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Handwerker, Carol A., Heather N. Lechtman, Ryna B. Marinenko, David S. Bright, and Dale E. Newbury. "Fabrication of Platinum-Gold Alloys in Pre-Hispanic South America: Issues of Temperature and Microstructure Control." MRS Proceedings 185 (1990). http://dx.doi.org/10.1557/proc-185-649.
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AbstractPlatinum and platinum-gold metallurgy was fully developed by smiths in the Esmeraldas-Tumaco Pacific coast area of present day Ecuador and Colombia long before the arrival of Europeans in South America and centuries before platinum metallurgy became practicable in the Western world. Using gold to sinter together nuggets of native placer platinum, then alternately working and annealing the resultant solid, these South American smiths produced hard, fairly homogeneous platinum-gold alloys of a range of colors for fabrication into items of adornment, and small tools, such as needles, tweezers, awls, and fishhooks.The microstructures and compositions of sintered Pt-Au objects from La Tolita, Ecuador, and of experimentally simulated Pt-Au alloy samples were analyzed using new electron microprobe microanalysis (EPMA) techniques and data from the Pt-Au phase diagram in an effort to determine the fabrication temperatures used by Pre-Hispanic South American smiths. A comparison of EPMA results from the simulated materials with the corresponding results from the La Tolita Pt-Au objects suggests that the Pt-Au objects were never heated as high as 1100°C and probably never contained a liquid phase. As illustrated by this comparison, the qualitative and quantitative information provided by these new digital acquisition and display techniques far exceeds what conventional line scan and x-ray dot maps could provide.
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Kalashnikova, M. I., P. M. Saltykov, and E. G. Saltykova. "Analyzing the applicability of hydrometallurgical techniques to the Voronezh region ores." Tsvetnye Metally, December 28, 2020, 77–82. http://dx.doi.org/10.17580/tsm.2020.12.11.
Full textAbstract:
Copper-nickel sulphide ores serve as the main source of nickel, cobalt and platinum group metals in Russia. The conventional metallurgy of proces sing copper-nickel sulphide concentrates involves producing converter matte and its further refining. Ores found in the Voronezh Region are characterized with high concentrations of arsenic and magnesium, which hinders the application of pyrometallurgical techniques. At the same time, there is a trend in today’s science and industry to develop and adopt hydrometallurgical techniques, and this also applies to copper-nickel sulphide ores. Such techniques enable comprehensive utilization of ore and are environmentally friendly, highly efficient and easily automatable. The paper examines a number of well-known hydrometallurgical techniques for processing copper-nickel sulphide concentrates. Some of them have been implemented in industry and some have been studied by several authors on a laboratory or pilot scale. The most advanced techniques were identified for the ore concentrates obtained from the Voronezh Region ores. Studies were conducted in hydrometallurgical processing of copper-nickel ore concentrates of varying composition, including the copper-nickel concentrates obtained from the Voronezh ores. It is shown that these techniques can potentially be applied to copper-nickel concentrates, including those which have high concentrations of impurities, which would not be acceptable for conventional processing technology. Having analyzed the available solutions, as well as the results of the conducted studies, the authors have come to a conclusion that pressure oxidation leaching would offer the most innovative technology to be applied to the Voronezh Region ores.
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Zhao, Jing, Yitian Peng, Qianguang Zhou, and Kun Zou. "The Current-Carrying Tribological Properties of Cu/Graphene Composites." Journal of Tribology 143, no. 10 (February 12, 2021). http://dx.doi.org/10.1115/1.4049696.
Full textAbstract:
Abstract Excellent current-carrying tribological properties including the low-friction, high anti-wear, high current-carrying efficiency, and stability are important for the current-carrying application in transmitting electrical signals and power. Here, the Cu/graphene composites with graphene uniformly distributed in Cu matrix were successfully prepared by combining the electroless plating process and powder metallurgy process. The current-carrying tribological properties including friction, wear, and electrical stability of the Cu/graphene composites with brass pairs were investigated by varying normal applied load and sliding speed under multiple applied voltages. The friction reduction and anti-wear properties of Cu/graphene composites were enhanced by the introduction of graphene. The friction coefficient of the Cu/graphene composites keeps stable under current-carrying and non-current-carrying conditions due to the benefit of the graphene enhancement to Cu. The graphene on wear surface reduces friction force and wear. The current-carrying efficiency and stability increased with the increase of applied load but decreased with increasing sliding speed. The contact stability increased with applied load, while high sliding speed caused the drastic vibration of sliding contact. The studies can provide a beneficial guideline for the current-carrying applications of Cu/graphene composites to reduce the friction and wear.