Journal articles: 'BBC metals'

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Lazarescu, Lucian, Ioan Ciobanu, Ioan Pavel Nicodim, Dan Sorin Comsa, and Dorel Banabic. "Effect of the Mechanical Parameters Used as Input Data in the Yield Criteria on the Accuracy of the Finite Element Simulation of Sheet Metal Forming Processes." Key Engineering Materials 554-557 (June 2013): 204–9. http://dx.doi.org/10.4028/www.scientific.net/kem.554-557.204.

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The accuracy of the finite element simulation of sheet metal forming processes is mainly influenced by the shape of the yield surface used in the mechanical model and, in particular, by the number of input values used in the identification of the yield surface. This paper investigates the effect of the input values used for identifying the BBC 2005 yield criterion on the accuracy of the finite element predictions. The accuracy assessment of the simulation is based on the comparison of the numerical predictions obtained using the commercially available FE programme AUTOFORM and experimental measurements obtained from the hydraulic bulging of sheet metals. Thickness and strain distributions, as well as the geometry of the bulged specimen were taken as comparison parameters. The accuracy of the finite element predictions obtained using the Hill-48 and Barlat-89 yield criteria is also studied and discussed in comparison with the results provided by the BBC 2005 yield and the experimental data.

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SUMALAN, Radu L., Cornelia MUNTEAN, Ana KOSTOV, et al. "The cup plant (Silphium perfoliatum L.) – a viable solution for bioremediating soils polluted with heavy metals." Notulae Botanicae Horti Agrobotanici Cluj-Napoca 48, no. 4 (2020): 2095–113. http://dx.doi.org/10.15835/nbha48412160.

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Heavy metal pollution, manifested by the accumulation, toxicity and persistence in soil, water, air, and living organisms, is a major environmental problem that requires energetic resolution. Mining tailing areas contain metal minerals such as Cu, Zn, Pb, Cr and Cd in high concentrations that pollute the environment and pose threats to human health. Phytoremediation represents a sustainable, long-term, and relatively inexpensive strategy, thus proving to be convenient for stabilizing and improving the environment in former heavy metal-polluted mining sites. This study presents the bioremediation potential of Silphium perfoliatum L. plants, in the vegetative stages of leaf rosette formation, grown on soil polluted with heavy metals from mining dumps in Moldova-Noua, in the Western part of Romania. The bioaccumulation factor (BAF), translocation factor (TF), metal uptake (MU) and removal efficiency (RE) of Cu, Zn, Cr and Pb by S. perfoliatum plants were determined in a potted experiment in controlled environmental conditions. The reference quantities of heavy metals have been determined in the studied soil sample. The experiment followed the dynamics of the translocation and accumulation of heavy metals in the soil, in the various organs of the silphium plants, during the formation of the leaf rosette (13-18 BBCH). The determination of the amount of heavy metals in soil and plants was achieved by the method of digestion with hydrochloric and nitric acid 3/1 (v/v) quantified by atomic absorption spectroscopy (AAS). The obtained experimental results demonstrate that the substrate has a high heavy metal content being at the alert threshold for Zn (260.01 mg kg-1 in substrate compared with alert threshold 300 mg kg-1) and at intervention thresholds for other metals (Cu -234.66 mg kg-1/200 mg kg-1; 299.08 mg kg-1/300 mg kg-1 and Pb-175.18 mg kg-1/100 mg kg-1). The average concentration of the metals determined in dynamics in the dry biomass of plants varied between roots, petioles, and laminas. The root is the main accumulator for Cu and Cr (Cu – 37.32 mg kg-1 -13 BBCH to 43.89 mg kg-1-15 BBCH and 80.71 mg kg-1 – 18 BBCH; Cr – 57.43 mg kg-1 – 13 BBCH to 93.36 mg kg-1 -18 BBCH), and for Zn and Pb the lamina seems to carry the same function. Preliminary results show that Silphium perfoliatum may be a viable alternative in the bioremediation and treatment of heavy metal-contaminated area.

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Sakthivelu, S., P. P. Sethusundaram, M. Meignanamoorthy, and M. Ravichandran. "Synthesis of Metal Matrix Composites through Stir Casting Process – a Review." Mechanics and Mechanical Engineering 22, no. 1 (2020): 357–70. http://dx.doi.org/10.2478/mme-2018-0029.

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AbstractMetal is the one of the important material in engineering materials because of their high strength to weight ratio. However the pure metals cannot be used as engineering materials due to their ductile property. So, to improve their mechanical properties, some of the high strength materials (not metals) were added as reinforcement to improve the mechanical properties of pure metals and the newly developed material is called as metal matrix composites. At present, Aluminium, Copper, Magnesium, Titanium and Iron have been used as matrix materials and materials like TiC, SiC, B4C, WC, Cr3 C, TiO2, ZrO2, Gr, MoS2 and Si3N4 have been used as reinforcements. There are many processing techniques to fabricate metal matrix composites namely stir casting, ultra-sonic assisted casting, compo-casting, rheo casting, powder metallurgy technique, etc,. Among these, stir casting process is the most suitable and economical method to fabricate the metal matrix composites. In this article, an effort has been made to review the work of various researchers to fabricate metal matrix composites through stir casting process.

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Goldsmith, L. B., A. J. Sinclair, and P. B. Read. "Exploration implications of production and location data for Ag-rich vein deposits, Trout Lake mining camp, southeastern B.C." Canadian Journal of Earth Sciences 23, no. 10 (1986): 1627–40. http://dx.doi.org/10.1139/e86-152.

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Ore tonnage production data from 43 former producers in the Trout Lake mining camp are examined using plots of spatial density of deposits and statistical methods. Outlines of mineral belts are established from spatial density with the 0.5 deposit per 4 km2 contour. Probability plots of ore tonnages distinguish two lognormal populations of deposits. Probablity plots of metal grades show four lognormal populations of silver and two of gold. A metal content versus ore tonnage graph draws attention to the similarity in proportions of metals produced from high-tonnage and from medium- + low-tonnage deposits. Triangular graphs of metal contents emphasize the direct relationship between silver and lead; metal ratios suggest some relationships that may be dependent upon host rocks. Linear correlation coefficients of tonnage and metal content show an inverse relationship between tonnage and precious metals and a direct relationship between silver and lead. Multiple regression models established between production tonnages and average grades can estimate deposit size within one order of magnitude.Systematic evaluation of quantitative production and location data can augment exploration decisions.

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Pirjol, Bogdan Stefan Negreanu, Ticuta Negreanu Pirjol, and Dan Razvan Popoviciu. "Copper, Manganese and Zinc Bioaccumulation in Some Common Poaceae Species Along Romanian Black Sea Coast." Revista de Chimie 68, no. 11 (2017): 2488–91. http://dx.doi.org/10.37358/rc.17.11.5912.

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Copper, manganese and zinc bioaccumulation potential was screened for three common Poaceae species, Hordeum murinum ssp. murinum L., Leymus racemosus ssp. sabulosus (M. Bieb.) Tzvelev and Lollium perenne L., abundantly growing along the Romanian Black Sea Coastal area, Constanta County. The concentration of the selected heavy metals was analyzed though atomic absorption spectrometry in samples of aboveground plant organs and soils. To assess the potential for phytoaccumulation, the Biological Accumulation Coefficients (BAC) were calculated. Considering the minimal thresholds widely accepted in literature for Cu, Mn and Zn hyperaccumulators, none of the selected species can fit in this category. The highest average copper concentration was found in Hordeum murinum ssp. murinum L. (5.45 mg/kg). For manganese, the highest value was found in Lollium perenne L. (104.08 mg/kg), while for zinc, the maximum was reached in Leymus racemosus ssp. sabulosus (M. Bieb.) Tzvelev, tissue (62.95 mg/kg). BAC values showed that all species are manganese excluders, with a remarkable maximum value of 0.55 in Lollium perenne. L. All species had average BAC above 1 for Cu and Zn, with a maximum in Leymus racemosus ssp. sabulosus (M. Bieb.) Tzvelev (4.85 and 2.98, respectively). However, there was a significant variation among individuals, usually, a high metal content in plant tissue being associated with low metal concentration in soil. The exception was Lollium perenne L., with BAC constantly above 1 (average BAC of 2.27 for Cu and 1.69 for Zn). These results emphasize a significant potential for phytostabilization of copper- and zinc-rich soils and open the way for heavy metals phytoextraction capacity studies of the Poaceae species along Romanian littoral.

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Mai, Nguyen Thi Phuong, Bui Thi Hieu, and Nguyen Duc Luong. "Pilot study on assessment of trace metals in PM10 at road sites in Bac Giang province, Vietnam." Journal of Science and Technology in Civil Engineering (STCE) - NUCE 15, no. 1 (2021): 121–31. http://dx.doi.org/10.31814/stce.nuce2021-15(1)-11.

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In this study, characterization of PM10 mass and its trace metals concentration at road sites in Bac Giang province located in the North of Vietnam during two different seasons has been performed. PM10 samples at 11 road sites using the high volume SIBATA HV-500R (Japan) at the flow rate of 400 L/min were collected during 10 hours (from 7:00 to 17:00) at flat low-lying plain, midland, mountain and highland areas. Data on PM10 mass and metals were used to estimate the pollution level of PM10 and trace elements bounded with PM10. The results showed that 10-hour mean PM10 concentrations at road sites in Bac Giang ranged from 103.4 µg/m3 to 577.9 µg/m3 with the average value of 292.6 µg/m3. Generally, the level of trace metals appeared to be higher in autumn than that in summer period. Additionally, concentrations of trace metals were higher at the sites with high traffic density than those with low traffic density. While the concentrations of Cd, Mn and Cr exceeded the guideline values of WHO, arsenic concentration was larger than the concentration limit of EU Directives. The degree of contamination values suggested that level of metal was high contamination at flat low-lying plain, while those values were from low to considerable contamination at the mountain and highland areas. The pollution load index values at most of sampling sites were larger than 1, which indicated the existence of dust pollution at road sides in Bac Giang province. Keywords: PM10; trace metals; degree of contamination; pollution load index, roadsides.

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Krasnovskaya, Olga, Daniil Spector, Alexander Zlobin, et al. "Metals in Imaging of Alzheimer’s Disease." International Journal of Molecular Sciences 21, no. 23 (2020): 9190. http://dx.doi.org/10.3390/ijms21239190.

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One of the hallmarks of Alzheimer’s disease (AD) is the deposition of amyloid plaques in the brain parenchyma, which occurs 7–15 years before the onset of cognitive symptoms of the pathology. Timely diagnostics of amyloid formations allows identifying AD at an early stage and initiating inhibitor therapy, delaying the progression of the disease. However, clinically used radiopharmaceuticals based on 11C and 18F are synchrotron-dependent and short-lived. The design of new metal-containing radiopharmaceuticals for AD visualization is of interest. The development of coordination compounds capable of effectively crossing the blood-brain barrier (BBB) requires careful selection of a ligand moiety, a metal chelating scaffold, and a metal cation, defining the method of supposed Aβ visualization. In this review, we have summarized metal-containing drugs for positron emission tomography (PET), magnetic resonance imaging (MRI), and single-photon emission computed tomography (SPECT) imaging of Alzheimer’s disease. The obtained data allow assessing the structure-ability to cross the BBB ratio.

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HASEBE, Tadashi. "Anomaly in Bauschinger Effect for BCC Metals." Proceedings of The Computational Mechanics Conference 2003.16 (2003): 415–16. http://dx.doi.org/10.1299/jsmecmd.2003.16.415.

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Maksimović, Tanja, Srđan Rončević, and Biljana Kukavica. "Utricularia vulgaris L. and Salvinia natans (L.) All. heavy metal (Fe, Mn, Cu, Zn and Pb) bioaccumulation specificity in the area of Bardača fishpond." Ekológia (Bratislava) 38, no. 3 (2019): 201–13. http://dx.doi.org/10.2478/eko-2019-0016.

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AbstractPaper deals with seasonal changes in heavy metal bioaccumulation (Fe, Mn, Cu, Zn and Pb) in Utricularia vulgaris L. and Salvinia natans (L.) All. of two localities (Necik and Sinjak – active fishpond basins) in the area of Bardača fishpond. According to our results, the better accumulator of Fe (3035 mg/kg) and Zn was S. natans (163.55 mg/kg), whereas Utricularia vulgaris better accumulates Mn (620 mg/kg) and Cu (10.18 mg/kg). Amounts of Pb in both investigated macrophyte were below the detection level (<0.51 mg/kg). The values of the bioaccumulation factor (BAC) of the tested metals were >1 or ~1 for both species, and the BAC values decreased in the following order in both investigated species: Fe > Mn > Cu > Zn. The results obtained indicated that tested macrophyte show very good characteristics as bioaccumulators and, thanks to this fact, they could be used in phytoremediation technique successfully in water-polluted ecosystem.

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Krutskii, Yuriy L., Tatiana M. Krutskaya, Tatiana S. Gudyma, Konstantin B. Gerasimov, Roman R. Khabirov, and Anna V. Mass. "Carbothermal and boron carbide reduction of oxides of some transition metals." MATEC Web of Conferences 340 (2021): 01040. http://dx.doi.org/10.1051/matecconf/202134001040.

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The study presents a possible mechanism to produce carbides and diborides of transition metals, such as titanium, vanadium, chromium and zirconium. The carbothermal synthesis of transition metal carbides has defined the direct dependence between the thermodynamic stability of oxides and the temperature range of the reduction onset (the stronger the oxide, the higher the value of the temperature is). It reaches 2000-2100, 1500-1600, 1300-1400 and 2100-2200°C for such carbides as TiC, VC0,88, Cr3C2 and ZrC respectively. The same dependence has not been found for the diborides of these metals. Optimum synthesis temperatures for all these compounds lie in the range of 1600-1700 °C. This viable method to produce transition metal carbides consists in the transfer of vaporous higher and lower oxides. Diborides preparation involves the transfer of oxides and boron vapors onto the surface of the carbon material with the subsequent chemical interaction. In the case of carbide-boron reduction of zirconium oxide in excess of boron carbide, the reaction product will be a composite material (B4C – ZrB2). The ceramics based on this composite possesses high performance properties.

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Baghel, Anuj Singh, Ankur Tiwari, R. S. Rana, and Vilas Warudkar. "A Short Review on Effect of Heat Treatment on Microstructure and Mechanical Properties of ADC12/SiC Metal Matrix Composite." Applied Mechanics and Materials 813-814 (November 2015): 3–8. http://dx.doi.org/10.4028/www.scientific.net/amm.813-814.3.

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Aluminium, being the second most abundant metal in earth’s crust, has emerged as an important metal in human civilization’s development. It has served as an excellent substitute for many conventional materials like wood, copper, iron and steel. Now a days, more Aluminium is consumed (on a volumetric basis) than all other non-ferrous metals/alloys including copper.Aluminium and aluminium alloy are gaining huge industrial significance because of their good combination of mechanical, physical properties over the base alloy. In some few recent years the use of metal matrix composite material increases very rapidly due to their high weight to strength ratio, low density, low thermal expansion coefficient, low maintenance and high temperature resistance. Metal matrix composites are widely used in aerospace and automotive engine components. The aluminum alloys are reinforced with Al2O3, B4C and TiC and fabricated by stir casting, centrifugal casting, and powder metallurgy process. In the fabricated metal matrix composites some different tests were conducted to show mechanical properties, micro-structural characterizations of materials were also done. When composite subjected to heat treatments then it significantly affects the micro-structural developments of composite causing to relieving of stress.

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Tsampiri, Mailinta. "Obsidian in the prehistoric Aegean: Trade and uses." Bulletin of the Geological Society of Greece 53, no. 1 (2018): 28. http://dx.doi.org/10.12681/bgsg.18588.

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This paper studies the prehistoric use of obsidian quarries in the Aegean. Obsidian sources in the eastern Mediterranean have been traced on certain islands of the Aegean: Melos, Antiparos and Giali. Due to its hardness, this material was already being used by the end of the Upper Palaeolithic to produce blades with sharp edges to serve as knives, scrapers and razors, arrowheads and spears, axes, saws and mattocks. This naturally occurring glass was also used for ornamental purposes. During the Late and the Final Neolithic Period (ca. 5300-3200 B.C.), when the systematic habitation of the Cyclades developed, the transportation of obsidian was incorporated in the gradually developing trade networks of the Aegean. The material was much in demand in the early Bronze Age. During the later Bronze Age its use declined and by the classical period it seems to have been replaced by metal. Around 1100 B.C. the use of obsidian was discontinued because of the increasing popularity of metals. During the Roman period obsidian, was used in the manufacture of mosaics and decorative objects, such as mirrors

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Olaru, Ioana-Iulia. "1. Necklaces and Pendants of the Metal Age on the Territory of Romania." Review of Artistic Education 14, no. 1 (2017): 130–38. http://dx.doi.org/10.1515/rae-2017-0017.

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Abstract The present paper will refer to an aspect of processing metals on the territory of Romania, in Bronze Age and Iron Age (the second age habing been studied up to the moment when Prehistory ended: 1st century B.C., being continued by Antiquity). Unfortunately, few pieces were found in settlements and in necropoleis, so it is difficult to attribute the artifacts of the Metal Age to one or other of the existing cultures, though the region where they were produced can be mentioned. Consequently, their study can lead to another classification than the chronological one, and that is of the field of ornamental arts in metal. We will focus only on two types of objects that embellish the neck and the chest: necklaces and pendants, which help us create a vivid image of this important artistic field of the Iron Age on the territory of our country, these two joining the other important types of jewels: bracelets, rings, fibulae, phaleras.

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Yasrebi, Mehrdad, Gyeung H. Kim, David L. Milius, Mehmet Sarikaya, and Ilhan A. Aksay. "Processing and characterization of B4C-Al laminated cermets." Proceedings, annual meeting, Electron Microscopy Society of America 48, no. 4 (1990): 1022–23. http://dx.doi.org/10.1017/s0424820100178240.

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B4C-Al composites show enhanced fracture strength and fracture toughness values over monolithic B4C.1-2 A controlled change in structural morphologies such as lamination further enhances mechanical properties of the composite over the B4C-Al composites processed to form a monolithic morphology. This paper summarizes microstructure-property correlations studied in B4C-Al laminated composites.The laminated composite is formed either by metal infiltration of B4C tapes sandwiched with Al sheets, type (a), (Fig. 1a) or by lamination of B4C tapes of different porosity and then subjected to metal infiltration of the laminated body, type (b), (Fig. 1b). In the first method, after thin tapes of B4C were formed, each tape was individually sintered between polished graphite discs, then layered with Al sheets, and the entire stack was heated to induce infiltration. In the second method, tapes of B4C with different green densities were stacked and laminated under pressure and temperature. The laminated body was then sintered and subsequently infiltrated with Al.

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Ogorodnikova, O. V., M. Majerle, J. Čížek, et al. "RADIATION DEFECT FORMATION IN BCC METALS IRRADIATED WITH HIGH ENERGY PROTONS, SELF-IONS AND NEUTRONS WITH DIFFERENT SPECTRA." Problems of Atomic Science and Technology, Ser. Thermonuclear Fusion 44, no. 2 (2021): 167–68. http://dx.doi.org/10.21517/0202-3822-2021-44-2-167-168.

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Rebba, Bhargavi, and N. Ramanaiah. "Investigations on Mechanical Behaviour of B4C and MoS2 Reinforced AA2024 Hybrid Composites." Journal for Manufacturing Science and Production 15, no. 4 (2015): 339–43. http://dx.doi.org/10.1515/jmsp-2015-0001.

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AbstractThe results of an experimental investigation of the mechanical properties of boron carbide (B4C) and molybdenum disulphide (MoS2) reinforced aluminium alloy (AA2024) hybrid composite samples, processed by stir casting process are reported in this paper. Based on the previous studies, it was concluded that for 4% of weight of the B4C powders reinforced in AA2024 metal matrix have better mechanical properties like tensile strength and hardness than the base alloy. Also the 4% of MoS2 reinforced in AA2024 metal matrix exhibited good mechanical properties than the matrix metal. Hence an attempt has been made to further improve the properties of the composite using both B4C and MoS2 as reinforcement particles in the AA2024 matrix. in the present study hybrid composite specimen were developed varying the weight% of B4C and MoS2, viz., 1%+3%, 2%+2%, 3%+1% B4C and MoS2 respectively in the AA2024 matrix. The prepared samples were subjected to a series of mechanical tests like tensile and hardness tests. Further, SEM & XRD analyses were performed on the prepared samples to study the microstructure and to ensure the proper dispersion of the reinforced particles in the metal matrix.

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KURAIEVA, I. V., T. O. KOSHLIAKOVA, K. V. VOVK, and K. S. ZLOBINA. "Features of Heavy Metals Distribution in Environmental Components of Urban Park Landscapes of Kyiv City." Mineralogical journal 43, no. 2 (2021): 58–73. http://dx.doi.org/10.15407/mineraljournal.43.02.058.

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We investigated the impact of the urban environment on the park ecosystems in Kyiv. As representatives of vegetation the species Taraxacum officinale Wigg. and Tilia cordata Mill., were chosen. The content of heavy metals (Cu, Pb, Zn, Ni, Mn, Cr, and Cd) in soil and leaf samples within the ecosystems of the parks Feofaniya, Kyiv Polytechnic Institute, Mariyinsky, Pushkin, and Nyvky was measured. The highest level of soil contamination with heavy metals was found in the areas of parks located near highways and public transport stops. The most polluted park was the Kyiv Polytechnic Park, and the least polluted Feofaniya Park. High levels of metals found in soil samples did not always coincide with their highest levels in the biomass of the studied plants leaves. We found that, according to the phytotoxicological classification of metals by the biological absorption coefficient (BAC) by plants within the studied park ecosystems, Cu, Pb, Zn, Ni, Mn, and Cr belong mainly to the elements of low absorption (hazard class IV) except for Mariyinsky Park, where Zn according to the BAC value belongs to the elements of moderate absorption (hazard class III). The order of amount of metal bioaccumulation in plants obtained by us show a fairly wide range for different park ecosystems, which confirms the principle of ecological congruence (compliance), according to which the living components of an ecosystem have developed appropriate adaptations coordinated by the abiotic environment. In order to identify additional ways of migration of heavy metals to the ecosystem of Feofaniya Park, hydrochemical data from the surface of the first aquifer, circulated within the study area, were involved. It has been suggested that the increased concentrations of Cu, Pb, Zn, Ni, and Mn in the soils of Feofaniya Park are connected with the Pirogivsky landfill, and the groundwater discharged into the park ponds serves as the main way of migration of pollutants to the natural environment, in particular to the soil-plant system. Our results confirm the need to involve biogeochemical data for ecological assessment of the urban environment and early diagnosis of negative influence, when the plants have not yet manifested morphological and anatomical abnormalities.

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Radev, Dimitar D. "Pressureless Sintering of Boron Carbide-Based Superhard Materials." Solid State Phenomena 159 (January 2010): 145–48. http://dx.doi.org/10.4028/www.scientific.net/ssp.159.145.

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Boron carbide-based materials B4C-MexBy were densified by pressureless sintering in a vacuum furnace. Some transition metal carbides (TiC, ZrC, HfC, Cr3C2 and WC) from groups IV-VI were used as sintering aids. The optimal sintering temperature in the range 2220-2250oC was used for any composition. Here we show the possibilities to activate the mass transport of the B4C by the mechanism of liquid phase sintering. The method of reactive sintering of B4C in the presence of additives of some transition metal carbides allows in situ synthesis of dense B4C-MexBy materials. Structural properties and fracture toughness of the B4C-based composite materials were discussed. The properties of some of these materials and the possibilities for their application are also discussed.

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Krutskii, Yu L., N. Yu Cherkasova, T. S. Gudyma, O. V. Netskina, and T. M. Krutskaya. "Diborides of transition metals: Properties, application and production. Review. Part 1. Titanium and vanadium diborides." Izvestiya. Ferrous Metallurgy 64, no. 2 (2021): 149–64. http://dx.doi.org/10.17073/0368-0797-2021-2-149-164.

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The properties, applications and methods for producing titanium and vanadium diborides are considered. These diborides are oxygen-free refractory metal-like compounds. As a result, they are characterized by high values of thermal and electrical conductivity. Their hardness is relatively high. Titanium and vanadium diborides exhibit significant chemical resistance in aggressive environments. For these reasons, they have found application in modern technics. So, they are used as surfacing materials when applying wear-resistant coatings on steel products. It is also possible to use vanadium diboride as a catalyst in organic synthesis and the anode in renewable electrochemical current sources. Perspective are ceramics B4C – TiB2 and B4C – VB2 , which make it possible to obtain products based on boron carbide with high-quality performance characteristics, in particular, with increased crack resistance. Such composite ceramics are obtained by means of hot pressing, spark plasma sintering and pressureless sintering. The properties of refractory compounds depend on the content of impurities and dispersion. Therefore, to solve a specific problem associated with the use of refractory compounds, it is important to choose the method of their preparation correctly, to determine the admissible content of impurities in the starting components. This leads to the presence of different methods for the synthesis of borides. The main methods for their preparation are: synthesis from simple substances (metals and boron); borothermal reduction of oxides; carbothermal reduction (reduction of mixtures of metal oxides and boron with carbon; metallothermal reduction of mixtures of metal oxides and boron; carbide-boron reduction. Plasma-chemical synthesis (deposition from the vapor-gas phase) is also used to obtain diboride nanopowders. Each of these methods is characterized in the article.

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Venkatraman, B. R., S. Parthasarathy, A. Kasthuri, P. Pandian, and S. Arivoli. "Adsorption of Chromium Ions by Acid Activated Low Cost Carbon-Kinetic,Thermodynamic and Equilibrium Studies." E-Journal of Chemistry 6, s1 (2009): S1—S11. http://dx.doi.org/10.1155/2009/134010.

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A carbonaceous adsorbent prepared from an indigenous waste, by acid treatment was tested for its efficiency in removing metal ions. The process parameters studied include agitation time, initial metal ions concentration, carbon dose, pH and temperature. The adsorption followed first order reaction equation and the rate is mainly controlled by intra-particle diffusion. Freundlich and Langmuir isotherm models were applied to the equilibrium data. The adsorption capacity (Qm) obtained from the Langmuir isotherm plot were found to around 30 mg/g at an initial pH of 7.0. The temperature variation study showed that the metal ions adsorption is endothermic and spontaneous with increased randomness at the solid solution interface. Significant effect on adsorption was observed on varying the pH of the metal ion solutions. The Langmuir and Freundlich adsorption isotherms obtained, positive ΔH0value, pH dependent results and desorption of metal ions in mineral acid suggest that the adsorption of metal ions on BBC involves chemisorption as well as physisorption mechanism.

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Stech, Tamara, and Vincent C. Pigott. "The Metals Trade in Southwest Asia in the Third Millennium B.C." Iraq 48 (1986): 39. http://dx.doi.org/10.2307/4200250.

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YALÇIN, Emre Deniz, and Aykut ÇANAKÇI. "CORROSION AND WEAR PERFORMANCE OF ZA27/GRAPHENE/B4C HYBRID NANOCOMPOSITES PRODUCED BY POWDER METALLURGY." Acta Metallurgica Slovaca 26, no. 3 (2020): 126–31. http://dx.doi.org/10.36547/ams.26.3.538.

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In this research paper, dry sliding (unlubricated), corrosion and abrasive wear behavior of ZA27/ Graphene/ B4C hybrid nanocomposites were studied. The hybrid nanocomposite samples were fabricated by powder metallurgy technique. Tribological tests were performed by employing a ball-on-disc type in the unlubricated situation and different loads (1, 2, 5 and 10 N). The examination of the worn and corroded surfaces, the powder characterization was performed using scanning electron microscopy (SEM). The findings indicated that the increase in B4C nano-particle content can positively effect on the corrosion and wear behavior of the hybrid nanocomposites. The electrochemical polarization measurements showed that increasing of the nano B4C content causes high corrosion resistance in the hybrid nanocomposites. The corrosion tests showed that the corrosion rate value of the ZA27/Graphene/B4C hybrid nanocomposites decreased from 59.02 mpy to 16.77 mpy with increasing the nano B4C content from 0.25% to 2%.

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MUTHUSAMY, SARAVANAN, and GANESAN PANDI. "INVESTIGATION OF MECHANICAL AND CORROSION PROPERTIES OF AA2024–B4C–TiC HYBRID METAL MATRIX COMPOSITES." Surface Review and Letters 25, no. 05 (2018): 1850109. http://dx.doi.org/10.1142/s0218625x18501093.

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Metal matrix composites are widely applied in the automotive and aircraft structural components. This work investigates the influence of mechanical and corrosion properties hybrid aluminium 2024 metal matrix composites having 5%, 10%, 15% and 20% of TiC and B4C (equal amount) reinforcement compositions. The increase in volume fraction of B4C and TiC particle in matrix alloy increases the hardness, yield strength, ultimate strength and decreases the ductility of the composite. SEM images show microstructure of the composites with particles having a different volume percentage of reinforcement. The uniform distribution of B4C and TiC particles is most predominant in composite fabrication and the reinforcement particle additions have proved improved corrosion resistance in AA2024–B4C–TiC MMCs.

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Kim, D. K., J. M. Kim, W. W. Park, Y. T. Im, and Y. S. Lee. "Prediction of Deformation Texture in BCC Metals based on Rate-dependent Crystal Plasticity Finite Element Analysis." Transactions of Materials Processing 23, no. 4 (2014): 231–37. http://dx.doi.org/10.5228/kstp.2014.23.4.231.

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Satishkumar, D., and M. Kanthababu. "Optimization of Wedm Parameters for Surface Roughness on Hybrid Mmcs." Advanced Composites Letters 23, no. 3 (2014): 096369351402300. http://dx.doi.org/10.1177/096369351402300303.

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Metals or alloys when reinforced with more than one reinforcement materials are generally considered as hybrid metal matrix composites (MMCs). The superior properties of the hybrid MMCs deter its wide applications due to the difficulty in machining. Wire electrical discharge machining (WEDM) is an effective unconventional machining process which can be used to machine difficult to machine materials. This work is aimed towards optimizing the WEDM parameters to achieve better surface roughness ( Ra) during machining of stir cast unreinforced A17075 alloy and A17075/B4C/Al2O3 based hybrid MMCS. The experiments were carried out as per central composite design of response surface methodology (RSM). It is observed that all the process parameters such as pulse-on time ( TON), pulse-off time ( TOFF), wire feed (F), gap voltage (V) considered in this work were significant.

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Wu, Hui-Fen, Shun-Min Huan, and Chun-Fu Wu. "Conformational Analysis and Binding Affinity Determination for Host—Guest Complexation of Alkali Metal Ions with Bis-Crown Ethers by Electrospray Mass Spectrometry and Molecular Modeling." European Journal of Mass Spectrometry 8, no. 5 (2002): 375–80. http://dx.doi.org/10.1255/ejms.516.

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This study presents the application of electrospray ionization mass spectrometry (ESI/MS) to investigate the host–guest complexation phenomenon for an array of alkali metal ions with bis[(benzo-15–crown-5)-15–ylmethyl] pimelate (BBCP). The results have shown that potassium ions possess the best binding affinity with the BBCP, owing to formation of the very stable sandwich-type (1:1) complexes and the strong K+ cation-π electron interactions between the K+ ion and the benzene rings of BBCP. The results of the competition experiments indicate the selectivity for BBCP toward the alkali metal ions is K+ > Rb+ > Cs+ > Na+ > Li+. In addition, combining the results of ESI/MS and molecular mechanics conformational searches reveal that the formation of sandwich-type (1:1) complexes can be observed for larger metal ions including K+, Rb+ and Cs+. As for Na+ ions, both 1:1 and 1:2 complexes can be observed.

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Dwivedi, Shashi Prakash, and Garima Dwivedi. "Utilization of RHA in development of green composite material using RSM." Journal of the Mechanical Behavior of Materials 28, no. 1 (2019): 20–28. http://dx.doi.org/10.1515/jmbm-2019-0004.

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AbstractIn the present investigation, rice husk waste from rice mill was utilized in the development of aluminum based green metal matrix composite. Response surface methodology (RSM) was employed to develop green metal matrix composite by considering tensile strength as a response. Rice husk ash (RHA) was used as primary reinforcement material and B4C was used as a secondary reinforcement material in the development of composite. Microstructure results showed a uniform distribution of RHA and B4C in aluminum based matrix material. The optimum combination of reinforcement parameters was found to be RHA weight percentage of 7.8%, RHA preheats temperature of 231.12∘C, B4C preheats temperature of 435.24∘C and B4C wt.% of 6.67% respectively to achieve a tensile strength of 249.867 MPa.

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Tamizifar, H., A. M. Hadian, and M. Tamizifar. "The Comparison between Boron Carbide (B4C) with other Common Inhibitors on Physical and Mechanical Properties of WC/Co." International Journal of Modern Physics: Conference Series 05 (January 2012): 102–10. http://dx.doi.org/10.1142/s2010194512001900.

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The hardness, toughness and sum of cracks measurement of fine-grained WC - Co hard metals were studied. Thirty commercial and experimental hard metal grades with different additives such as boron carbide ( B 4 C ), vanadium carbide ( VC ), chromium carbide ( Cr 3 C 2) and silicon carbide ( SiC ) were prepared in a commercial sinter HIP furnace. Physical, mechanical and microstructure properties were investigated to build up a representative hardness/sum of cracks measurement band. This band was then used to estimate the most effective sintering temperature and the amount of each additives. Afterwards, influence of grain growth inhibitors in optimum condition were compared. The results showed that the grades, doped with B 4 C and VC as growth inhibitor exhibits more hardness than other comparable doped alloys. However, Cr 3 C 2 is favorable in toughness improvement.

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Ohmura, Takahito, and Nobuaki Sekido. "107 Dislocation motion and local deformation behavior of BCC metals." Proceedings of The Computational Mechanics Conference 2015.28 (2015): _107–1_—_107–2_. http://dx.doi.org/10.1299/jsmecmd.2015.28._107-1_.

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Shu, Dayu, Xiuqing Li, and Qingxia Yang. "Effect on Microstructure and Performance of B4C Content in B4C/Cu Composite." Metals 11, no. 8 (2021): 1250. http://dx.doi.org/10.3390/met11081250.

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In this paper, boron carbide (B4C) ceramics were added to a copper (Cu) base, to improve the mechanical properties and wear resistance of pure copper. The B4C/Cu composites with different B4C contents, were obtained by mechanical mixing and discharge plasma sintering methods. Scanning electron microscopy (SEM), energy spectrum analysis (EDS), and electron probe microanalysis (EPMA) were used, to observe and analyze the microstructures of the B4C/Cu composites. The influences of the B4C content on the hardness, density, conductivity, and wear resistance were also studied. The experimental results show that B4C has an important effect on Cu. With increasing B4C content, both the density and conductivity of the B4C/Cu composites gradually decrease. The hardness of the Cu-15 wt.% B4C composite has the highest value, 86 HBW (Brinell hardness tungsten carbide ball indenter), which is 79.2% higher than that of pure copper. However, when the B4C amount increases to 20 wt.%, the hardness decreases due to the metallic connection being weakened in the material. The Cu-15 wt.% B4C composite has the lowest volume loss, indicating that it has the best wear resistance. Analyses of worn B4C/Cu composite surfaces suggest that deep and narrow grooves, as well as sharp ridges, appear on the worn pure Cu surface, but on the worn Cu-15 wt.% B4C composite surface, the furrows become shallow and few. In particular, ridge formation cannot be found on the worn Cu-15 wt.% B4C composite surface, which represents the enhancement in wear resistance.

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Lee, Donghyun, Junghwan Kim, Sang-Kwan Lee, Yangdo Kim, Sang-Bok Lee, and Seungchan Cho. "Effect of Boron Carbide Addition on Wear Resistance of Aluminum Matrix Composites Fabricated by Stir Casting and Hot Rolling Processes." Metals 11, no. 6 (2021): 989. http://dx.doi.org/10.3390/met11060989.

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In this study, to evaluate the effect of boron carbide (B4C) addition on the wear performance of aluminum (Al), Al6061 and 5, 10, and 20 vol.% B4C/Al6061 composites were manufactured using the stir casting and hot rolling processes. B4C particles were randomly dispersed during the stir casting process; then, B4C particles were arranged in the rolling direction using a hot rolling process to further improve the B4C dispersion and wear resistance of the composites. Furthermore, a continuous interfacial layer between B4C and the Al6061 matrix was generated by diffusion of titanium (Ti) and chromium (Cr) atoms contained in the Al6061 alloy. Wear depth and width of the composites decreased with increasing B4C content. Furthermore, with B4C addition, coefficient of friction (COF) improved as compared with that of Al6061. The results indicate that interface-controlled, well-aligned B4C particles in the friction direction can effectively increase the wear properties of Al alloys and improve their hardness.

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Xiaozhou, Cao, Wang Chao, Xue Xiangxin, and Cheng Gongjin. "Effect of Ti Addition on the Residual Aluminium Content and Mechanical Properties of the B4C-Al Composites Produced by Vacuum Infiltration / Wpływ Dodatku Tytanu Na Resztkową Zawartość Aluminium I Właściwości Mechaniczne Kompozytów B4C-Al Wytworzonych Przez Infiltrację Próżniową." Archives of Metallurgy and Materials 60, no. 4 (2015): 2493–98. http://dx.doi.org/10.1515/amm-2015-0404.

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The effect of Ti addition on the residual Al content and mechanical properties of B4C-Al composites fabricated by vacuum infiltration was investigated in the present study. The B4C-Al composite materials were fabricated using [Ti+B4C] preforms preheated at 1700ºC for 1 h and Al alloys infiltrated in vacuum atmosphere at 1100ºC for 2 h. The phase composition indicated that TiB2 has high wettability to Al as a result of the preheating. SEM and EDX results revealed a number of Al dimples are on the fracture surface due to the existence of TiB2. When the content of added Ti increases to 30%, the [Ti+B4C] preform is characterized by a minimal porosity (33.11%) and a maximal density, a corresponding amount of residual Al of 33.11% and a minimal fracture toughness (5.03 MPa·m1/2) with a hardness of up to 63 HRC. The residual Al and the mechanical properties of the composite material preform were determined by the Ti content of the preform.

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Ravichandran, Manickam, Arumugam Manikandan, and Meenakshi Sundaram Omkumar. "Investigations on Properties of Al-B₄C Composites Synthesized through Powder Metallurgy Route." Applied Mechanics and Materials 852 (September 2016): 93–97. http://dx.doi.org/10.4028/www.scientific.net/amm.852.93.

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Powder metallurgy is a popular technique to synthesize metal matrix composites with uniform distribution of the reinforcements. The present work aims to synthesize Al-B4C composites through powder metallurgy route and study their properties. The compositions of the composites are Al-5%B4C, Al-10%B4C & Al-15%B4C. Blending of powders, compaction and sintering process were carried out as per standard powder metallurgy procedure. The distributions of the reinforcements were analyzed for the sintered specimens by the help of scanning electron microscope. The effect addition of B4C in the Aluminium matrix on the properties such as density, porosity, hardness and compressive strength were discussed. Results show that addition of B4C improves the properties of Al-B4C composites.

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Mogilevsky, P., and E. Y. Gutmanas. "Experimental study of reactive diffusion of metals on SiC and B4C surface." Materials Letters 28, no. 4-6 (1996): 457–61. http://dx.doi.org/10.1016/0167-577x(96)00098-5.

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Suresh, R. "Comparative study on dry sliding wear behavior of mono (Al2219/B4C) and hybrid (Al2219/B4C/Gr) metal matrix composites using statistical technique." Journal of the Mechanical Behavior of Materials 29, no. 1 (2020): 57–68. http://dx.doi.org/10.1515/jmbm-2020-0006.

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AbstractIn the present study, aluminium metal matrix composites (AMMC’s) reinforced with boron carbide (B4C) and graphite (Gr) particles were prepared by stir casting method. Dry sliding wear behavior of developed composites was conducted on pin on disc apparatus with variation in sliding distance, applied load and sliding speed. Taguchi method was employed to optimize the data in a controlled way. Analysis of variance was employed to examine the wear behavior of base alloy (Al2219), mono (Al/B4C) and hybrid (Al/B4C/Gr) metal matrix composites. The correlations were established by linear regression models and validated using confirmation tests. The obtained results indicated that B4C content, sliding distance is highly affected by the dry sliding wear followed by sliding speed and applied load. The incorporation of B4C and Gr particles in aluminium improves the tribological characteristics. The SEM images of mono composite shows the deep grooves on worn surface. It demonstrates the signs of abrasive wear of mono composite. The hybrid composite exhibits excellent wear resistance when compared to mono composite and base alloy. The main reason of that is the Gr particles act as a solid lubricating material in the hybrid composite (Al/B4C/Gr).

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Hajizamani, M., A. Alizadeh, N. Ehsani, and M. Mirjani. "A study on the effect of reducing agent content on the thickness of electroless Ni3P deposits on B4C nanoparticles." Revue de Métallurgie 110, no. 2 (2013): 147–52. http://dx.doi.org/10.1051/metal/2012047.

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Abioye, TE, H. Zuhailawati, AS Anasyida, SP Ayodeji, and PK Oke. "Effects of particulate reinforcements on the hardness, impact and tensile strengths of AA 6061-T6 friction stir weldments." Proceedings of the Institution of Mechanical Engineers, Part L: Journal of Materials: Design and Applications 235, no. 6 (2021): 1500–1506. http://dx.doi.org/10.1177/1464420721995544.

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Due to loss of structural strengthening at temperatures beyond 250°C, heat-treated aluminium alloys (e.g. AA 6061-T6) weldments are usually characterized with poor mechanical properties including hardness, tensile and impact strengths. In this work, friction stir weldments of AA 6061-T6 reinforced with the additions of SiC, B4C and Al2O3 particles at the joints were produced and investigated for improved hardness, tensile strength and impact strength over the unreinforced weldment. The results showed that the entire reinforced welded joint exhibited improved hardness because of the enhanced metal matrix grain refinement and inherent high hardness of the reinforcement particles. B4C particle addition produced hardest joint of about 81% of the base metal hardness (∼114 HV0.3). The impact energies of the SiC (16.9 J), B4C (16.5) and Al2O3 (12.2 J) reinforced weldments are closer to that of the base metal (18.6 J) compared with the unreinforced weldment (9.6 J). The reinforced weldments showed no significant improvement over the tensile strength of the unreinforced weldment. B4C and SiC reinforcements produced the highest improvements in the hardness (at the joint) and impact strength of the AA 6061-T6 friction stir weldments, respectively.

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Zhang, Shuang, Ying Shui Yu, Jing Han Tu, and Ting Ju Li. "Al/B₄C Laminated Composite Fabricated by Powder Metallurgy Process and its Mechanical Property." Advanced Materials Research 602-604 (December 2012): 80–84. http://dx.doi.org/10.4028/www.scientific.net/amr.602-604.80.

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A new type of laminated composite with B4C particle reinforced Al matrix composites as its inner layer and metal Al as outer layer was fabricated by powder metallurgy process. The effects of sintering time on the density and the mechanical properties of Al/B4C laminated composites were investigated. In the inner layer, Vicker’s hardness was enhanced with the addition of B4C. With the extension of sintering time from 2h to 4h at 300°C, aggregation of B4C particles reduced, while the density and Vicker’s hardness improved.

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M.C., Kalai selvan, Hendry Thomas X, Siddharthan B, and Divya Kumar P. "Mach inability Studies on Metal Matrix Composite’s Using Abrasive Water Jet Machining." Bulletin of Scientific Research 1, no. 1 (2019): 24–33. http://dx.doi.org/10.34256/bsr1914.

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The non-traditional machining of particulate reinforced metal matrix composites is relatively new. This paper covers studies on match inability of aluminium - Boron carbide metal matrix composites (Al-B4C MMCs) with abrasive water jets (AWJs). Two different compositions of Al-B4C MMCs were processed with various mesh size, abrasive flow rate, transverse rate and water pressure with a view to identify the performance of the abrasive water jet machine for effective processing of MMCs with AWJs. The maximum penetration ability of AWJs in different MMCs was examined by conducting the experiments on trapezoidal shaped Al-B4C MMC specimens, prepared with stir casting method. Optical micrographs of MMC samples and scanning electron microscopic (SEM) examination of AWJ cut surfaces enabled to explain the trends of material removal by the abrasives. Analysis of results clearly indicated the choice of 80 mesh size abrasives, higher water pressure and flow rate and lower transverse rate for effective processing of Al-B4C MMCs with AWJs.

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Pramono, Agus. "Accumulative Roll Bonding for Improvement mechanical properties of Aluminum based Composite." INSIST 3, no. 2 (2018): 184. http://dx.doi.org/10.23960/ins.v3i2.184.

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The Aluminum has special properties such as light weight, ductile and a lower melting point. It has very suitable for applied as composite material, with ceramic as reinforcement. Accumulative roll bonding (ARB) is part of technology of Severe Plastic Deformation (SPD) that has been developed of manufacturing process for metals, alloys and composites as well. It has a potential becoming an industrial process to produce composite and ultrafine-grained (UFG) metal sheets. In this research, the development of aluminum-based composites is made by SPD technology using the ARB method on aluminum plate sheets with boron carbide (B4C) as reinforcement, is expected to improve its mechanical properties along with the rules of microstructure analysis. To get of the UFG metallic materials where the mean grain size must be smaller than 1μm are expected can be exhibit excellent mechanical properties. The ARB process consists of multiple cycles of rolling, cutting, stacking and solid-state deformation bonding. Two plates were prepare for the ARB sample process, cleaning uses acetone liquid to prevent attachment of dust and dirt on the surface to be made in contact with other samples. Acetone and grinding to produce a rough surface to facilitate the surface binding process between samples, B4C powder is sprinkled between the centers of aluminum plate surface and stacked going together.

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Hammond, Matthew. "Tectonics Glasgow, 1–3 May 2015." Tempo 69, no. 274 (2015): 62–64. http://dx.doi.org/10.1017/s0040298215000376.

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Ilan Volkov's Tectonics series continues to break new ground in contemporary music programming and curating. Tectonics has now seen its third edition in Glasgow, where Volkov conducts the BBC Scottish Symphony Orchestra, and has also sprung up in other locations to which he has connections – beginning in his home city of Tel Aviv, the series has spread also to Reykjavik, Adelaide and New York. The common theme is a blend of new commissions (usually orchestral works), important recent works, and performances from figures from other areas of avant-garde music making – free improvisation, electronic music and the outer fringes of noise and metal.

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Mahesh, V. P., Praseeda S. Nair, T. P. D. Rajan, B. C. Pai, and R. C. Hubli. "Processing of surface-treated boron carbide-reinforced aluminum matrix composites by liquid–metal stir-casting technique." Journal of Composite Materials 45, no. 23 (2011): 2371–78. http://dx.doi.org/10.1177/0021998311401086.

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Boron carbide is one of the potential neutron-shielding materials and its use can be maximized for structural shielding application by dispersing it into metal matrixes such as aluminum. Dispersion of B4C and its interfacial stability is a major issue during its processing. This investigation is on the synthesis of B4C-reinforced 6061 aluminum matrix composite by liquid–metal stir-casting technique under optimized conditions after solving the issues related to the processing, and evaluation of the structural, mechanical, and interfacial characteristics. During processing of composites, pretreatment of B4C particles is necessary to improve its dispersion. However, higher preheating temperatures above 300°C lead to particle agglomeration in the matrix due to the formation of B2O3 phase during preheating. B2O3 is formed due to the surface oxidation of B4C particles above 300°C and this glassy phase leads to particle sintering and lump formation. Incorporation of particles preheated at 250°C has shown uniform distribution of particles in the composite. Interfacial characterization of the composite and the extracted B4C particles from the matrix has shown the presence of interfacial reaction products such as AlB2, Al3BC, AlB12, and AlB10.

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Zhong, Ping, Xueqian Cao, and Lunlin Shang. "Effect of Negative Bias Voltage on Tribological Properties under High Relative Humidity Environment and Corrosion Resistance of Boron Carbide Coatings." Metals 11, no. 10 (2021): 1518. http://dx.doi.org/10.3390/met11101518.

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Humid air is a very important service environment, in which metal friction parts should be enhanced to offer excellent corrosion resistance and wear resistance. The B4C coating is an excellent candidate material to enhance the corrosion resistance and tribological behaviors. The purpose is to investigate the effect of negative bias voltages on the tribological properties of B4C coatings under a high relative humidity environment. Amorphous B4C coatings were successfully prepared by closed field unbalanced magnetron sputtering technology and its microstructure, hardness, elastic modulus, adhesive force and tribological properties were systematically studied. Results demonstrate that the B4C coatings deposited at each negative bias voltage have a columnar structure and the surface roughness remained unchanged (about 1.0 nm), while the thickness, hardness, elastic modulus and adhesion force increase first and then decrease with the negative bias voltage increasing. Among them, the B4C (−50 V) coating showed the best mechanical properties. It should be noted that the B4C (−50 V) coating with an excellent corrosion resistance also exhibits the lowest friction coefficient (~0.15) and wear resistance (7.2 × 10−7 mm3·N−1·m−1) under humid air (85% RH). This is mainly due to the tribochemical reaction of B4C during a sliding process to produce boric acid at the sliding interface. B4C coatings can provide an excellent corrosion resistance and high wear resistance due to their high chemical stability and high hardness.

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Wain, Alison. "INVESTIGATING THE CONDITION OF HISTORIC ORGANIC COATINGS ON METALS USING ELECTROCHEMICAL TECHNIQUES." AICCM Bulletin 20, no. 2 (1995): 27–37. http://dx.doi.org/10.1179/bac.1995.20.2.003.

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Pott, Ute, and David H. Turpin. "Changes in atmospheric trace element deposition in the Fraser Valley, B.C., Canada from 1960 to 1993 measured by moss monitoring with Isothecium stoloniferum." Canadian Journal of Botany 74, no. 8 (1996): 1345–53. http://dx.doi.org/10.1139/b96-163.

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Moss monitoring, a common bioindication method, was used to investigate temporal changes of atmospheric trace element deposition since the 1960s in the Fraser Valley, British Columbia. Vancouver, Canada's third largest metropolitan area, is located in the west of the Fraser Valley and has a significant effect on the air quality of the region. Changes in atmospheric deposition of lead, cadmium, chromium, nickel, zinc, and manganese were estimated by analyzing local samples of the common woodland moss Isothecium stoloniferum Brid. collected during three different time periods: 1960–1966, 1975–1980, and 1993. A significant decrease was found for lead, cadmium, chromium, nickel, and zinc, when samples from 1960–1966 were compared with those collected in 1993. The declining metal levels are associated with a change in industrial activity, a reduction in fuel oil combustion for space heating, and abandonment of leaded gasoline. Manganese concentration in the moss samples increased significantly over the past 30 years. This increase might be related to the replacement of the antiknock additive, tetraethyl lead, with methylcyclopentadienyl manganese tricarbonyl. The present study shows how changes in human activity can affect and counterbalance increasing pressure from a fast-growing population in respect to trace element pollution. Keywords: moss monitoring, bioindication, heavy metals, trace elements, Isothecium stoloniferum, air pollution, metal deposition.

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Lee, Donghyun, Junghwan Kim, Byeongjin Park, et al. "Mechanical and Thermal Neutron Absorbing Properties of B4C/Aluminum Alloy Composites Fabricated by Stir Casting and Hot Rolling Process." Metals 11, no. 3 (2021): 413. http://dx.doi.org/10.3390/met11030413.

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In this study, to fabricate neutron shielding material, boron carbide (B4C)-reinforced aluminum (Al) alloy composites were successfully fabricated by stir casting followed by a hot rolling process. Microstructural analysis of B4C/Al6061 composites with different volume fractions (5, 10, 20, 25, and 30%) revealed that the composites had volume ratios similar to the target volume ratios of B4C. Furthermore, B4C reinforcements were uniformly dispersed in the Al matrix, forming multi-interfacial layers of Al4C3/(Ti,Cr)B2. The interfacial layer generated during stir casting maintained its own structure after the hot rolling process, indicating strong interfacial bonding strength. The tensile strengths of the B4C/Al6061 composites increased to 20 vol.% and stayed above the value for Al6061, even reaching 30 vol.%. The measured thermal neutron shielding rate increased with increasing B4C content, and the highest thermal neutron shielding rate was observed at 30 vol.% composite, which corresponds to 95.6% neutron shielding at 0.158-cm thickness.

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Fu, Xuelong, Zhengbo Ji, Wei Lin, Yunfeng Yu, and Tao Wu. "The Advancement of Neutron Shielding Materials for the Storage of Spent Nuclear Fuel." Science and Technology of Nuclear Installations 2021 (May 7, 2021): 1–13. http://dx.doi.org/10.1155/2021/5541047.

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With the development of nuclear industry, spent nuclear fuel (SNF) generated from nuclear power plants arouses people’s attention as a result of its high radioactivity, and how to guarantee the reliable operation of nuclear facilities and the staff’s safety occupies a crucial position. To avoid the lethal irradiation, a lot of functional neutron shielding composites have been developed to transform fast neutrons into thermal neutrons which can be absorbed with high macroscopic cross-sectional elements. Irradiation characteristics of nuclear industry have promoted the advancement of neutron shielding materials. Here, we review the latest neutron shielding materials for the storage of spent nuclear fuel containing additives such as boron carbide (B4C), boron nitride (BN), boric acid (H3BO3), and colemanite. Different types of neutron shielding materials, including metal matrix alloys, polymer composites, high density concrete, heavy metals, paraffin, and other neutron shielding composites with high macroscopic cross-sectional elements, arediscussed. The elemental composition, density, and thermal and mechanical properties of neutron shielding materials are also summarized and compared.

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Hasnaoui, Said El, Mouna Fahr, Catherine Keller, et al. "Screening of Native Plants Growing on a Pb/Zn Mining Area in Eastern Morocco: Perspectives for Phytoremediation." Plants 9, no. 11 (2020): 1458. http://dx.doi.org/10.3390/plants9111458.

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Screening of native plant species from mining sites can lead to identify suitable plants for phytoremediation approaches. In this study, we assayed heavy metals tolerance and accumulation in native and dominant plants growing on abandoned Pb/Zn mining site in eastern Morocco. Soil samples and native plants were collected and analyzed for As, Cd, Cu, Ni, Sb, Pb, and Zn concentrations. Bioconcentration factor (BCF), translocation factor (TF), and biological accumulation coefficient (BAC) were determined for each element. Our results showed that soils present low organic matter content combined with high levels of heavy metals especially Pb and Zn due to past extraction activities. Native and dominant plants sampled in these areas were classified into 14 species and eight families. Principal components analysis separated Artemisia herba-alba with high concentrations of As, Cd, Cu, Ni, and Pb in shoots from other species. Four plant species, namely, Reseda alba, Cistus libanotis, Stipa tenacissima, and Artemisia herba-alba showed strong capacity to tolerate and hyperaccumulate heavy metals, especially Pb, in their tissues. According to BCF, TF, and BAC, these plant species could be used as effective plants for Pb phytoextraction. Stipa tenacissima and Artemisia herba-alba are better suited for phytostabilization of Cd/Cu and Cu/Zn, respectively. Our study shows that several spontaneous and native plants growing on Pb/Zn contaminated sites have a good potential for developing heavy metals phytoremediation strategies.

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Moreira, Aida B., Laura M. M. Ribeiro, and Manuel F. Vieira. "Production of TiC-MMCs Reinforcements in Cast Ferrous Alloys Using In Situ Methods." Materials 14, no. 17 (2021): 5072. http://dx.doi.org/10.3390/ma14175072.

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This literature review aims to summarize the research conducted on the production of locally reinforced ferrous castings based on metal matrix composites reinforced with TiC (TiC-MMCs). One way to improve the wear resistance of cast components is to reinforce critical regions locally with metal matrix composites (MMCs) without changing the toughness of the component core. The in situ method of self-propagating high-temperature synthesis is one of the main approaches for the production of this enhanced material. Using this approach, the reinforcement is formed from a powder compact inserted in the mold cavity. The temperature of the liquid metal then produces the combustion reactions of the powders, which promote the formation of the ceramic phase. This paper focuses on eight powder systems used to synthesize TiC: Ti-C, Ni-Ti-C, Ni-Ti-B4C, Fe-Ti-C/Fe-Cr-Ti-C, Cu-Ti-B4C, Al-Ti-C, and Al-Ti-B4C, and provides an overview of the methodologies used as well as the effect of processing variables on the microstructural and mechanical characteristics of the reinforcement zones.

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Han, Yu Mei, and X. Grant Chen. "Corrosion Characteristics of Al-B₄C Metal Matrix Composites in Boric Acid Solution." Materials Science Forum 877 (November 2016): 530–36. http://dx.doi.org/10.4028/www.scientific.net/msf.877.530.

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The corrosion behavior of Al-B4C metal matrix composites in H3BO3 solutions with different Cl- contents was investigated using potentiodynamic polarization and zero resistance ammetry techniques. Results show that the corrosion of Al-B4C composites in H3BO3 solution increases with increasing B4C volume fraction in the composites. The main corrosion characteristic of Al-B4C composites in H3BO3 solution is the galvanic corrosion between Al matrix and B4C particles. In the galvanic couple, B4C particle acts as cathode and Al matrix acts as anode. The cathodic reaction is hydrogen revolution reaction, which controls the corrosion mechanism of Al-B4C composites. Pitting is not observed on the composite surface in the H3BO3 solution with zero Cl-. However, with addition of Cl- in H3BO3 solution, pitting occurs and the corrosion resistance remarkably decreases with increasing Cl- content. The corrosion resistance of Al-B4C composites in H3BO3 solutions is compared with that in the standard 3.5% NaCl solution.

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Journal articles on the topic 'BBC metals'

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