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1
Zhu, Feng, Jiujun Xu, Xiaoguang Han, Yan Shen e Mei Jin. "Deposit formation on chromium-plated cylinder liner in a fully formulated oil". Proceedings of the Institution of Mechanical Engineers, Part J: Journal of Engineering Tribology 230, n. 12 (12 novembre 2016): 1415–22. http://dx.doi.org/10.1177/1350650116636508.
Abstract (sommario):
Chromium plated cylinder has been wildly used in large bore diesel engines due to its light weight, good durability, and low induced liner wear. Deposits accumulated in the grooves and micro-crack on chromium plated cylinder could smooth the running surface, reduce the oil retention capability, and increase the engine’s oil consumption. In the present research, deposit formation on chromium-plated cylinder in fully formulated oil under different loads and temperatures was investigated by using a reciprocating sliding tester. Surface analytical techniques such as SEM, EDX, and XPS have been used to gain the knowledge about deposits’ origin, distribution, and factors affecting the deposit formation. The deposits are mainly derived from C, O, and S in the lubricating oil and anti-wear additive ZDDP (Zn and P). Deposits only accumulated in the depression (honing grooves and micro-cracks) on chromium plated cylinder surface, and there were no deposits found on the plateaus. The deposit formation increased with the increasing of load and temperature, and increased sharply over 60 MPa and 150℃. The deposit formation on liner surface was significantly different between chromium-plated coating and cast iron in component and distribution.
2
Leonova, L. V., A. A. Galeev e A. A. Galeev. "Microfossils in bottom-hydrothermal sediments of the Saf'yanovskoe Cu-Zn deposit (Middle Urals)". LITHOSPHERE (Russia) 22, n. 3 (2 luglio 2022): 376–90. http://dx.doi.org/10.24930/1681-9004-2022-22-3-376-390.
Abstract (sommario):
Research subject. Framboidal pyrites and sulfide micro-concretions in carbonaceous-siliceous and ore rocks of the Safyanovskoye deposit (Middle Urals). Aim. To identify the signs of vital activity of microbial communities in bottomhydrothermal deposits using the example of the Safyanovskoye sulfide deposit. The methods. Scanning electron microscopy (SEM) and energy dispersive X-ray analysis (EDX). Results. TThe analyzed ore and carbonaceous-siliceous rock samples showed the presence of mineralized silicon dioxide films covering framboidal pyrites. Micro-concretions were found to consist of microfossils of filamentous organisms and framboids. Pyrite samples included the remains of tubular casts of sulfidized vestimentifera and polychaetes, associated with framboids. The possibility of using fossilized remains of microbial communities for distinguishing bottom-hydrothermal facies among pyrite deposits was confirmed. Conclusions. Hydrothermal-sedimentary deposits are characterized by the traces of specific microbial communities, since prokaryotic organisms were pioneers in hydrothermal oases. Their long active existence created a basis for the second trophic link, i.e. filter feeding macrofauna and endosymbiotrophs. These organisms, in turn, formed another level in the food chain of the trophic pyramid. It is believed that micro-concretions and framboidal pyrites are indicators of the vital activity of microbial communities.
3
Jhavar, S., C. P. Paul e N. K. Jain. "Experimental investigation on geometrical aspects of micro-plasma deposited tool steel for repair applications". International Journal of Modern Physics: Conference Series 32 (gennaio 2014): 1460347. http://dx.doi.org/10.1142/s2010194514603470.
Abstract (sommario):
Recent advancement in direct material deposition processes found wide applications in rapid prototyping, manufacturing and tooling industry. Micro-plasma deposition is one of the recent developments in this domain. This paper reports the deployment of newly integrated micro-plasma deposition system for the deposition of AISI P-20 tool steel on the AISI P20 tool steel substrate. A number of test tracks for single track deposition were deposited at the various combination of processing parameters. The sets of parameters yielding good deposits were selected to deposit overlap tracks. The geometry of single and overlapped tracks was evaluated to understand the parametric dependence. The study indicates that the aspect ratio of track geometry (ratio of width to height of track) is dependent on the processing parameters and the discharge current is identified as the most dominating parameters (contribution = 44%), followed by scan speed (contribution = 26.68%) and wire feed rate (contribution = 26.98%) with almost same effect. The microscopic study of the deposits indicates that the material deposited at the optimum processing parameters is free from surface and bulk defects. The estimated material properties are found to be at par with conventional processed material. This feasibility study proved that the micro-plasma deposition can be used for the generation of surfaces and multi-featured material deposition. It paved a way for the application of the process in die/mold repairs.
4
Renna, Gilda, Paola Leo e Caterina Casavola. "Effect of ElectroSpark Process Parameters on the WE43 Magnesium Alloy Deposition Quality". Applied Sciences 9, n. 20 (17 ottobre 2019): 4383. http://dx.doi.org/10.3390/app9204383.
Abstract (sommario):
This research aims to investigate the effects of process parameters on the quality of WE43 coatings deposited on homologue substrate by ElectroSpark Deposition (ESD) technology. ESD is new technology used to apply coatings or for the restoration and refurbishment of worn or damaged high valued parts. The depositions were processed using five different levels of Energy input (Es, Spark Energy). The microstructure of both the base material and deposits cross-section were characterized by optical and scanning electron microscopies. Also, X-ray diffraction technique was used. In addition, stereological studies of the through-thickness heterogeneities of the deposits (e.g., voids) were performed. The mechanical properties were evaluated by Vickers micro-hardness. The results show that the deposits exhibited a fine grained microstructure due to the rapid solidification. The average micro-hardness values of the deposits are lower than that of the substrate and distributed in a small range (49–60 HV). The lower hardness of the deposits respect to the base material is due to the presence of defectiveness such as spherical, laminar and random shaped voids. The defects area percentage inside the deposits remains well below than 11%. All the deposits were mainly affected by laminar morphology defects. The results indicate that the deposits defectiveness decreases as the energy input increases.
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Bhat, Ramesh Sooryanarayana, Manjunatha Krishna Balakrishna, Poornesh Parthasarathy e Ampar Chitharanjan Hegde. "Structural Properties of Zn-Fe Alloy Coatings and Their Corrosion Resistance". Coatings 13, n. 4 (15 aprile 2023): 772. http://dx.doi.org/10.3390/coatings13040772.
Abstract (sommario):
Single-layer and multilayer alloy deposits were coated onto a mild steel substrate by a single-bath electroplating process. The developed coating consists of Zn and Fe alloys having different compositions with different layers. The anticorrosion behavior of single-layer and multilayer deposits was evaluated by the potentiodynamic polarization method. The surface morphology of the deposits was studied with a scanning electron microscope. The crystal structure of the deposits was analyzed with the X-ray diffraction technique. The Fe content in the deposit was analyzed by a colorimeter and verified with energy-dispersive X-ray spectroscopy. The micro-hardness tester with a Vickers indenter was used to evaluate the microhardness of the developed single-layer and multilayer coatings. It was found that the microhardness increased with applied current densities. The Zn-Fe multilayer coatings with 300 layers deposited with square and triangular pulses at the applied current density of 2.0/3.0 A dm−2 were five and four times more corrosion-resistant, respectively, than the single-layer coating of the same thickness. The development of Zn-Fe coatings that are resistant to corrosion is particularly important for the automotive industry and steel-based vehicle parts.
6
Macuda, Jan, Paweł Baran e Marian Wagner. "Evaluation of the Presence of Methane in Złoczew Lignite: Comparison with Other Lignite Deposits in Poland". Natural Resources Research 29, n. 6 (16 maggio 2020): 3841–56. http://dx.doi.org/10.1007/s11053-020-09691-7.
Abstract (sommario):
Abstract Catastrophic cases of methane explosion during exploratory drilling within the Bełchatów ortholignite deposit have led to testing for methane in other Polish ortholignite mining areas, as well as in the Złoczew deposit, where it is planned to begin mining operations. Initial tests have shown Złoczew lignite to have the highest methane content among the Polish deposits so far studied, comparable with lignite from the Bełchatów deposit, with a methane capacity in excess of 2.5 dcm3/kg at a pressure of 10 bar. Based on the computed values of the Langmuir constant, a determination was made of the quantity of methane that can be desorbed from a pressure of 10 bar to 1 bar, as well as the residual methane content. For all of the tested samples, the residual methane content is between 30 and 50% of the sorption capacity at a pressure of 10 bar. The thermal sorption equations were used to compute values of the limiting isosteric heat of adsorption. Higher values of the heat of adsorption at zero surface capacity may indicate the presence of a small quantity of micro-pores. In the case of the samples with the highest sorption capacity, the limiting isosteric heats of adsorption are low, indicating a low proportion of micro-pores in the lignite. This was confirmed by tests of nitrogen adsorption at 77 K. The proportion of micro-pores in the studied lignites is 2–3%, while the dominant pore fraction is the meso-pores, which in lignite from the Złoczew and Bełchatów deposits account for 50–66% of total pores. It is concluded that the significant adsorption of methane in the ortholignite occurs chiefly in meso-pores because of compression of the gas under increased orogenic pressure. A link is made between the higher methane-bearing capacity of the ortholignite deposits and the degree of gelification of the huminite components, based on simple statistical correlations between the methane sorption capacity and the content of humic gelified maceral. The results concerning methane sorption in lignite from the Złoczew deposit have enabled a preliminary classification of the methane-bearing capacity of Polish ortholignite deposits, which may also be of significance for similar deposits in other countries.
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Zhang, Chun Hua, Chao Wang, Song Zhang, Ming Sheng Wang, Yu Jiang Xie e Jun Zhe Tan. "Growth Mechanism of Micro-Arc Spark Deposited Stellite Alloy Coatings". Applied Mechanics and Materials 455 (novembre 2013): 83–87. http://dx.doi.org/10.4028/www.scientific.net/amm.455.83.
Abstract (sommario):
Micro-arc spark deposition with Stellite6 alloy as the coating material on SCH13 steel substrates was carried out using high-energy micro-arc process with different processing parameters. The microstructure, chemical compositions and phase identification of the deposition layers were examined by using scanning electron microscopy (SEM), energy dispersive Xray spectroscopy (EDS) and X-ray diffraction (XRD), respectively. Meanwhile the form and growth mechanism of a single pulse deposit were focused on. The results show that the morphology of the single pulse deposit is splashshape. A large number of single pulse deposits deposited and superimposed continuously and then deposition layers with a certain thickness were formed. The epitaxial growth coating with columnar grains was then achieved by the micro-arc spark deposition. The prepared Stellite6 alloy coating has a good metallurgical combination with the SCH13 steel substrate and the elements at the interface are smooth transition. Because of the effects of the temperature gradient and the solidification rate, the microstructure of the deposition layer is slightly coarser with the increasing of the processing voltage. The coatings are consisted of γ-Co solid solution and chromium carbides.
8
Aldunate, Felipe. "Deposit Insurance, Bank Risk-Taking, and Failures: Evidence from Early Twentieth-Century State Deposit Insurance Systems". Review of Corporate Finance Studies 8, n. 2 (15 aprile 2019): 260–301. http://dx.doi.org/10.1093/rcfs/cfz001.
Abstract (sommario):
Abstract I use the introduction of deposit insurance in eight U.S. states in the early twentieth-century to study the effects of deposit insurance on the banking system. Using a triple difference approach exploiting regulatory differences between national and state banks and between states, I find that insured banks experienced higher deposit growth and decreased funding costs. I also observe a replacement of demand deposits by riskier time deposits. However, I find no aggregate effects on failure rates or risk-taking. Using hand-collected micro-level data, I show that small and large banks reacted differently and that banks facing funding problems especially benefited. Received July 20, 2017; editorial decision November 12, 2018 by Editor Efraim Benmelech.
9
Wang, Xi Ran, Hui Lu, Ying Wei Zhang, Xin Gang Hu e Jing Wu. "The Influence of Plating Temperature on the Properties of Electroless Ni-Cu-P Alloys on Aluminum". Advanced Materials Research 189-193 (febbraio 2011): 1096–99. http://dx.doi.org/10.4028/www.scientific.net/amr.189-193.1096.
Abstract (sommario):
In this work, the effect of plating temperature on the electroless plating rate and the properties of the electroless Ni-Cu-P deposits was studied. The corrosion resistance, hardness, surface morphology and components of the coating were studied by using electrochemical workstation, digital micro-hardness SEM and EDS. The results show that the optimum plating temperature is 75°C. The deposition rate, hardness and corrosion resistance are all good when the optimal temperature is 75°C. The adhesion between the deposits and the matrix is better. The deposits is smooth and uniformity, smooth by SEM. The deposit contains Ni 77.80%, Cu 7.68%, P 14.52% by the analyses of energy disperse X-ray.
10
Jiang, Yiming, Chun-Yi Chen, Tso-Fu Mark Chang, Xun Luo, Daisuke Yamane e Masato Sone. "Electrodeposition of Ni-Co Alloys and Their Mechanical Properties by Micro-Vickers Hardness Test". Electrochem 2, n. 1 (24 dicembre 2020): 1–9. http://dx.doi.org/10.3390/electrochem2010001.
Abstract (sommario):
Nanocrystalline Ni-Co alloy deposits with grain sizes less than 30 nm were produced by electrodeposition with a direct current in a sulfamate bath. Surfaces of the Ni-Co alloy deposits showed granular morphology. The size of the granular particles and the Co content decreased when a lower current density was applied. Addition of NiBr2 and a surface brightener (NSF-E) into the bath resulted in the grain refinement effect and an increase of Co content in the deposit. The grain size reached roughly 14 nm and 60 at.% of Co content in Ni-Co alloys electrodeposited with the bath containing the two additives. Ni-Co alloys obtained in this study showed higher microhardnesses than those of pure Ni and Co deposits prepared under the same condition, which revealed the solid solution strengthening effect. With a decrease in the grain size, the microhardness further increased, and this trend followed the Hall–Petch relationship well. The maximum microhardness value of 862.2 Hv was obtained owing to both the grain boundary and solid solution strengthening effects.
11
Carmassi, Jacopo, Sonja Dobkowitz, Johanne Evrard, Laura Parisi, André F. Silva e Michael Wedow. "Completing the Banking Union with a European deposit insurance scheme: who is afraid of cross-subsidization?" Economic Policy 35, n. 101 (1 gennaio 2020): 41–95. http://dx.doi.org/10.1093/epolic/eiaa007.
Abstract (sommario):
SUMMARY This paper investigates the impact and appropriateness of establishing a fully mutualized European deposit insurance scheme (EDIS) using a unique supervisory micro-level data set on euro area banks’ covered deposits and their other liabilities. We find that an ex-ante funded deposit insurance fund (DIF) with a target size of 0.8% of euro area covered deposits would be sufficient to cover losses even in a severe banking crisis. We then derive risk-based contributions to the DIF based on the different bank- and country-specific factors, showing that they can take into account the relative riskiness of banks and banking systems to tackle moral hazard. We also find that smaller and larger banks would not excessively contribute to EDIS relative to the amount of covered deposits in their balance sheet. Finally, we show that there would be no unwarranted systematic cross-subsidization within EDIS in the sense of some banking systems systematically contributing less than they would benefit from the DIF.
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Ponomarenko, E. S. "Lower Ludfordian (Upper Silurian) slope deposits in the Lyagadin section (Ilych River, the Northern Urals)". LITHOSPHERE (Russia) 22, n. 1 (2 marzo 2022): 75–100. http://dx.doi.org/10.24930/1681-9004-2022-22-1-75-100.
Abstract (sommario):
Research subject. Upper Silurian (Lower Ludfordian) slope deposits of the Lyagadin section (Ilych River, Northern Urals).Materials and methods. The composition and structure of 40 rock samples collected across the section during fieldworks in 2019 were studied. Thin sections were examined under a polarising microscope. Eight samples were investigated by silicate analysis, and clay minerals from 2 samples were determined by X-ray diffraction analysis of oriented samples.Results. The Lyagadin section with a visible thickness of 70 m is represented by an uneven alteration of clayey-siliceouscalcareous schists, micro-grained limestones with burrows, micro-fine-grained layered limestones, fine lime sandstones, coarse- and medium-grained lime sandstones, lime conglogravelites and lime conglobreccias. Clayey-siliceous-calcareous schists and micro-grained limestones with burrows characterise the background periplatform clayey-carbonate deposits. The part of micro-fine-grained layered limestones (their horizontally layered varieties) are bottom current sediments. Gravity flow deposits are represented by clastic rock assemblage. The most characteristic of them is the assemblage composed of lime conglogravelites with an erosional bottom, which pass into gradational-layered lime sandstones, first coarse- and medium-grained, and further the into their fine-grained varieties. They are covered, in turn, with micro- fine-grained limestones with cross or convolute stratifications. That association is interpreted as calciturbidites. Calcidebrites are characterised by lime conglobreccias. The deposits of grainy flows (?) are represented by the layers of lime sandstones not revealing the characteristic features of the Bouma sequence.Conclusion. The reconstructed background sedimentation on the continental slope during Early Ludfordian was characterised by the accumulation of hemi-pelagic clay deposits together with a certain amount of microscopic quartz, orthoclase and organic matter. Periodically appearing thin layers of micro-grained limestones with burrows correspond to the periods of increased supply of carbonate material, which could be attributed to “marine snow”. The irregular nature of the distribution of gravity flow deposits in the Lyagadin section suggests that the studied slope deposits are, most likely, the formation of the outer apron of slope bottom, rather than calciclastic fans.
13
Andreasch, Michael, e Peter Lindner. "Micro- and Macrodata: a Comparison of the Household Finance and Consumption Survey with Financial Accounts in Austria". Journal of Official Statistics 32, n. 1 (1 marzo 2016): 1–28. http://dx.doi.org/10.1515/jos-2016-0001.
Abstract (sommario):
Abstract This article compares the results of Austria’s Household Finance and Consumption Survey (HFCS) on savings deposits and estimates on total financial assets with administrative records from the national accounts for the household sector. The microdata that are newly generated through the HFCS and the detailed (internally available) breakdown of savings deposits in the existing macrodata (financial accounts) lend themselves to a more in-depth analysis of the similarities and differences in these two sources. Comparing the data shows that the HFCSbased aggregate estimates are lower than the financial accounts data, which is in line with evidence from the literature. The article also shows, however, that the survey adequately captures the underlying patterns at the microlevel in terms of the overall financial portfolio allocation and the distribution of savings deposits over detailed breakdowns. Moreover, a simulation based on the HFCS data demonstrates the effect that the inclusion of savings deposits in the most affluent tail of the distribution has on common statistics. Undercoverage above all of the upper deposit ranges suggests an underestimation or bias in the statistics. This underestimation, however, can be shown to be relatively minor, particularly in the case of robust statistical measures, such as the median or percentile ratios.
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Damian, Buzatu, Apopei, Szakács, Denuț, Iepure e Bârgăoanu. "Valentinite and Colloform Sphalerite in Epithermal Deposits from Baia Mare Area, Eastern Carpathians". Minerals 10, n. 2 (30 gennaio 2020): 121. http://dx.doi.org/10.3390/min10020121.
Abstract (sommario):
Valentinite forms through the alteration of stibnite in sulphide deposits. Colloform sphalerite is a widespread mineral in low-temperature deposits, particularly those of the Mississippi-Valley type. We identified valentinite and colloform sphalerite in hydrothermal deposits occurring in the Baia Mare area. The Baia Mare metallogenic district of Neogene age occurs in the northwestern part of the Neogene volcanic chain within the Eastern Carpathians. The Neogene volcanism from Baia Mare area is related to the subduction processes of the East European plate under two microplates, Alcapa and Tisza-Dacia/Tisia, in the post-collisional compressive phase. We have identified valentinite in the Dealul Crucii and Baia Sprie deposits, associated with other epithermal minerals, in the absence of the stibnite. Valentinite is deposited in the final phase of the epithermal process after calcite and manganese-bearing calcite. Micro-Raman and microprobe determinations indicate the presence of valentinite. The formula of valentinite is close to stoichiometric Me2O3 and contains small amounts of tin as an antimony substituent. Colloform sphalerite was identified in the Baia Sprie ore deposit associated with minerals formed in the final epithermal phase. It was deposited on idiomorphic crystals of stibnite, which it corrodes. Its structure and an alternate banding, exhibited on the nano-/microscale, were identified by optical microscopy, SEM (scanning electron microscopy), and BSE (backscattered electron microscopy) imaging. These structures are typical for colloform sphalerite and suggest a genesis due to episodic precipitation. The spherical nano/micro-particles (nodules) are characteristic of the colloform sphalerite from Baia Sprie. Raman analysis indicates the presence of a colloform sphalerite with low iron content. The typical diffraction lines for sphalerite were identified in X-ray diffraction: 3.118 Å (111), 1.907 Å (220), 1.627 Å (311). Microprobe analysis certifies the presence of sphalerite with the stoichiometric formula close to ZnS. Iron content is low (0%–0.0613%), but Sb (0.7726%–2.6813%), Pb (0.56%–1.1718%), Bi (0%–0.1227%) are also present. The negative correlation between Zn and Sb suggests the simultaneous deposition from the same epithermal fluids. Valentinite and colloform sphalerite were formed at low temperatures (100–150 °C) at the end of the epithermal process.
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Lallouche, S., e M. Y. Debili. "Structural Properties of Al-Cu Thin Films after Heat Treatment". Materials Science Forum 609 (gennaio 2009): 87–93. http://dx.doi.org/10.4028/www.scientific.net/msf.609.87.
Abstract (sommario):
In this work we are interested by the decomposition behaviour after heat treatment at 500°C of nanostructured Al-Cu deposits, prepared by radio frequency (13.56MHz) magnetron sputtered from composite targets. The use of X-ray diffraction leads to the characterization of different structures and the estimation of grain size and dislocation density. The grain size of the films is found to increase with annealing. The dislocation density is observed to exhibit a decrease trend with annealing temperature which leads to a reduction in the concentration of lattice imperfections A specific thermal study of the Al-Cu deposits, by combined thermal analysis (TDA/TG) permit to follow the structural behavior of the deposits with heat treatment. For Al-7.21at%Cu deposit, the exothermic peak convolution may be due to the elimination of micro deformations present in the sample.
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Poroch-Seriţan, Maria, Igor Creţescu, Gheorghe Gutt, Marius Prelipceanu, Radu Fechet, Dragoş Vicoveanu, Otilia-Sanda Prelipceanu e Andrei Poroch-Seriţan. "Research on Obtaining and Characterizing Ni - W Electroplating Alloys for Micro-Electro Mechanics". BULETINUL INSTITUTULUI POLITEHNIC DIN IAȘI. Secția Matematica. Mecanică Teoretică. Fizică 68, n. 1 (1 marzo 2022): 21–34. http://dx.doi.org/10.2478/bipmf-2022-0002.
Abstract (sommario):
Abstract The present research aimed to electrodeposit and characterize Ni-W alloys for different technological parameters, being an example of “induced co-deposition”, in which a certain metal (for example: Mo, W) can be co-deposited as an alloy, but it cannot be measured in its pure state. The investigated characteristics were the efficiency current, the average thickness, and the structural properties of the obtained deposits. The current efficiency decreases with an increased applied current density, and the tungsten content remains constant at around 11% for different current densities (10 mA·cm−2 and 16 mA·cm−2, respectively). An increase in the temperature of the electrolyte leads to the inclusion of more tungsten. The deposit tungsten content and the current efficiency are directly related to pH. The deposit hardness directly relates to the alloy composition, deposit morphology, and coating thickness. The higher hardness, approximatively 100 HV were measured and the optimal brightness were observed for the alloys obtained at increased current density (i = 16 mA·cm−2, T = 50°C, pH = 8), or to a basic pH (i = 10 mA·cm−2, T = 50°C, pH = 9.23). The scanning electron microscopy (SEM) technique was used to analyze the surface morphology, and energy dispersive spectroscopy (EDS) analysis was carried out to determine the composition of the alloys. The metallic surface brightness (%) was evaluated using the miniature spectrometer, based on the reflection property of the electrodeposited metallic layer, scanning the all-wavelength range between 200-1100 nm.
17
El-Hasa, Tayel. "SYNCHROTRON BASED MICRO-MAPPING AND XAFS INVESTIGATION OF Fe-Mn AND EPIGENETIC INTERGROWTH WITHIN THE CAMBRIAN SHALLOW MANGANESE DEPOSITS, SOUTH JORDAN". Iraqi Geological Journal 53, n. 1A (31 gennaio 2020): 117–27. http://dx.doi.org/10.46717//igj.53.1a.r7.2020.01.28.
Abstract (sommario):
The current work investigates the Cambrian Manganese ore deposits from Wadi Dana at central Wadi Araba region. This investigation aims to unravel the chemistry and micro-textures of the mineral paragenetic sequence for these manganese ore deposits. Particularly the Fe–Mn intimate intergrowth micro texture and the epigenetic Mn mineralization associated with Cu minerals. The combination of the synchrotron-based X-ray fluorescence (syn-XRF) micro-mapping and X-ray absorption fine structure (XAFS) techniques were used. They provide a clear picture of the elemental distribution of Mn, Fe, Cu, and Pb and other elements presented within the ore micro textures. Besides, it determines the exact elemental speciation. The results obtained gave a better understanding of the elemental atomic structures and eventually the depositional environment. Particularly, the syn-XRF micro-mapping reveals the existing of many successive evolution stages in the Mn ores. Besides, the X-ray Absorption Near Edge Structure (XANES) results showed that the micro-rhythmic texture is changing from Mn+4 (Pyrolusite) into Fe+3 (Hematite). This is evidence for the role of Eh as the main controlling factor during the ore formation. Eventually, indicating tentatively the paleoceanography setting of the Mn deposits. This is related to the continuous transgression-regression on the sea level in a semi-closed sea.
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Fan, Hui, Zong Jun Tian, Y. H. Huang, Z. D. Liu e X. C. Wang. "Fundamental Experiment of Laminated Templates Electro-Deposition in Manufacturing Metal Part". Key Engineering Materials 392-394 (ottobre 2008): 189–94. http://dx.doi.org/10.4028/www.scientific.net/kem.392-394.189.
Abstract (sommario):
Laminated templates electro-deposition is an original manufacturing technology that is aimed at micro-scale metallic structures fabrication. Based on the discrete piling-up principal and electrodepositing method, it realizes a manufacturing simplification from the traditional machining to the repetition of template-assisted planar deposition in forming a three-dimensional complicated object. The ability to control the deposit surface nouniformity is a key to successful implementation for each planar depositing. Profile geometry and current configuration are alternated in experiment and thought as the major factors influencing deposit surface roughening. The results show that the surface of the deposits obtained by pulse electroforming has better performance in deposit thickness distribution and properties of the deposits. Optimized parameters have been obtained from the preliminary experiments in which 0.3millimeters-thick epoxy templates and 4~6A/dm2 current density were used at 40+ and a bulk of copper parts, section size 30mm×30mm and 7mm thick were produced and tested for their mechanical performance.
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Baek, Gyeong Yun, Gwang Yong Shin, Ki Yong Lee e Do Sik Shim. "Mechanical Properties of Tool Steels with High Wear Resistance via Directed Energy Deposition". Metals 9, n. 3 (1 marzo 2019): 282. http://dx.doi.org/10.3390/met9030282.
Abstract (sommario):
This study focused on the mechanical and metallurgical characteristics of high-wear-resistance steel (HWS) deposited using directed energy deposition (DED) for metal substrate hardfacing or repairing. As post-deposition heat treatment changes the metallurgical characteristics of deposits, the effect of post-deposition heat treatment on the mechanical properties was investigated via microstructure observation and by conducting hardness, wear, and impact tests. The obtained micro-images showed that the deposited HWS layers exhibit cellular and columnar dendrites, and the microstructure of heat-treated HWS (HT-HWS) transformed its phase during quenching and tempering. The hardness and wear resistance of the HT-HWS deposits were higher than those of the HWS deposited specimen, whereas the latter exhibited a higher fracture toughness. The matrix microstructure and carbide characteristics, which are characterized by the chemical composition of the materials, significantly influenced the mechanical properties.
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Wang, Xi Ran, Xin Gang Hu e Wei Yuan Li. "Effect of Bath Compositions on the Properties of Electroless Ni-Cu-P Alloys on Aluminum". Applied Mechanics and Materials 117-119 (ottobre 2011): 1276–79. http://dx.doi.org/10.4028/www.scientific.net/amm.117-119.1276.
Abstract (sommario):
In this work, the electroless plating Ni-Cu-P on aluminium is obtained successfully by direct Ni-Cu-P plating method. The effect of bath compositions on the electroless plating rate and the properties of the electroless Ni-Cu-P deposits was studied by orthogonal test. The corrosion resistance, hardness, surface morphology and components of the coating were studied by using electrochemical workstation, digital micro-hardness SEM and EDS. The optimum bath formula obtained is 0.6g/L copper sulfate, 30g/L nickel sulfate, 35g/L sodium citrate, 25 g/L sodium hypophosphite, 20g/L acetic anhydride and right amount of self-made additive. The deposition rate, hardness and corrosion resistance are all good. The adhesion between the deposits and the matrix is better. The deposits is smooth and uniformity, smooth by SEM. The deposit contains Ni 78.90%, Cu 8.65%, P 12.46% by the analyses of energy disperse X-ray.
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BANERJEE, SUJIT, RALLMING YANG e R. DANIEL HAYNES. "Aggregation of colloidal material in recycling process water". August 2009 8, n. 8 (1 settembre 2009): 19–23. http://dx.doi.org/10.32964/tj8.8.19.
Abstract (sommario):
The aggregation of microstickies and pitch in white water into larger particles and deposits was studied with particle size measurements. Microstickies can cycle in process water if their concentration is high enough. The particle size of the stable colloidal material is a balance between the attractive forces among micro-stickies and the disruption caused by shear. The effective measurement of micro-organic accumulation (EMMA) potential (a measure of size-fractionated colloidal material) can track the particles in the size range that leads to dep-osition. Pitch and microstickies destabilize each other, which explains why mixing mechanical and recycle pulps can cause unusually high deposit problems.
22
Morishita, Yuichi, Napoleon Q. Hammond, Kazunori Momii, Rimi Konagaya, Yuji Sano, Naoto Takahata e Hirotomo Ueno. "Invisible Gold in Pyrite from Epithermal, Banded-Iron-Formation-Hosted, and Sedimentary Gold Deposits: Evidence of Hydrothermal Influence". Minerals 9, n. 7 (19 luglio 2019): 447. http://dx.doi.org/10.3390/min9070447.
Abstract (sommario):
“Invisible gold” in pyrite is defined as an Au solid solution of the pyrite lattice, sub-microscopic Au nanoparticles (NPs) in the pyrite, or other chemisorption complexes of Au. Because the relationship between the Au and As concentrations in pyrite could indicate the genesis of the deposit, the purpose of this study is to assess the micro-analytical characteristics of the Au–As relationship in pyrite from epithermal and hydrothermally affected sedimentary Au deposits by secondary ion mass spectrometry. The Au and As concentrations in pyrite vary from 0.04 to 30 ppm and from 1 to 1000 ppm, respectively, in the high-sulfidation Nansatsu-type epithermal deposits; these concentrations are both lower than those of the low-sulfidation epithermal Hishikari deposit. The Au concentrations in pyrrhotite and pyrite reach 6 and 0.3 ppm, respectively, in the Kalahari Goldridge banded-iron-formation-hosted gold deposit, and Au in pyrrhotite may sometimes exist as NPs, whereas As concentrations in pyrrhotite and pyrite are both low and lie in a narrow range from 6 to 22 ppm. Whether Au is present as NPs is important in ore dressing. The Au and As concentrations in pyrite from the Witwatersrand gold field range from 0.02 to 1.1 ppm and from 8 to 4000 ppm, respectively. The shape of the pyrite grains might prove to be an indicator of the hydrothermal influence on deposits of sedimentary origin, which implies the genesis of the deposits.
23
Li, Xue Lei, Xiao Hang Liu, Hao Bin Tian e Wen Jing Yuan. "Experimental Research on Hard and Crack-Free Electrodeposited Chromium Coatings". Advanced Materials Research 1044-1045 (ottobre 2014): 47–52. http://dx.doi.org/10.4028/www.scientific.net/amr.1044-1045.47.
Abstract (sommario):
In order to eliminate cracks in the chromium coating, a novel method named flexible extrusion assisted chromium electroplating was proposed. The bright and crack-free chromium coatings were electrodeposited by using the perturbation and extrusion of hard and insulating particles. The prepared deposits were characterized by scanning electron microscope (SEM) and three-dimensional topography. The testing results showed that the surface was very smooth and there was no micro cracks in the coating. Micro hardness of the electrodeposited layer was also tested. It was confirmed that the chromium coating electrodeposited with rotating cathode in hard particles had high micro hardness as to 850HV and the micro hardness could be controlled by the process parameters. The rule of the micro hardness was concluded by analyzing current density and rotating speed. In addition the results of salt spray test and electrochemical polarization curve showed that the coating deposited by new method had higher corrosion resistance than that by traditional method.
24
Eddy, C. R., D. L. Youchison, B. D. Sartwell e K. S. Grabowski. "Deposition of diamond onto aluminum by electron cyclotron resonance microwave plasma-assisted CVD". Journal of Materials Research 7, n. 12 (dicembre 1992): 3255–59. http://dx.doi.org/10.1557/jmr.1992.3255.
Abstract (sommario):
Diamond crystallites and thin films have been deposited onto polycrystalline aluminum substrates utilizing an electron cyclotron resonance microwave plasma-assisted chemical vapor deposition (ECR-PACVD) method. For all depositions, the substrates were biased to +40 V dc with respect to ground and their temperature was maintained at 500 °C. Similar deposits were obtained from two different feedgas systems at a total pressure of 1.33 Pa (10 mTorr). The first system consisted of a carbon monoxide (CO) and hydrogen (H2) mixture (CO:H2 = 20:80), and the second was a methane (CH4), oxygen (O2), and hydrogen (H2) mixture (CH4:O2:H2 = 21:10:69). The deposits were subsequently characterized by scanning electron microscopy, micro-Raman spectroscopy, and x-ray diffraction. The results of these analyses indicate that polycrystalline diamond was deposited onto aluminum substrates, as both individual crystallites and continuous films.
25
Wang, Lin Wei, Wei Ya Xu e An Quan Xu. "Study on Mechanical Properties of Talus Deposit Based on Digital Image Processing Technology". Advanced Materials Research 327 (settembre 2011): 159–64. http://dx.doi.org/10.4028/www.scientific.net/amr.327.159.
Abstract (sommario):
Talus deposit is often seen in the hydropower projects in the southwest of China. Its mechanical properties are so complex that microstructure study is often used to reveal the essence of deformation and damage. The digital image processing technology (DIPT) is introduced to the simulation of talus deposits. Based on the study of DIPT, a Photo-To-Flac3D (PTF) auto-modeling program is developed. It is able to realize the whole process: analyzing and processing the digital image, acquiring the information and establishing the micro-model files. A new modeling method is developed for the mechanical behavior simulation of talus deposit. As an example, some talus deposit data of Gushui hydropower station is used, the micro-model of talus deposit can be established fast and correctly by the PTF from the digital photo on-site. The mechanical properties are studied by the numerical simulation of triaxial test. The results show that the talus deposit has the feature of bully in deformation while that of Unicom band under force.
26
Lekka, Maria, Alex Lanzutti, Caterina Zanella, Gabriel Zendron, Lorenzo Fedrizzi e Pier Luigi Bonora. "Resistance to localized corrosion of pure Ni, micro- and nano-SiC composite electrodeposits". Pure and Applied Chemistry 83, n. 2 (20 novembre 2010): 295–308. http://dx.doi.org/10.1351/pac-con-10-08-21.
Abstract (sommario):
The aim of this work was the production and characterization of composite Ni matrix electrodeposits. Pure Ni, micro- and nano-SiC Ni matrix composite deposits have been produced from a Watts’s-type electroplating bath under both direct (DC) and pulse current (PC) conditions. The obtained deposits have been characterized regarding their microstructure by scanning electron microscopy (SEM) observations on both top surface and cross-section and their SiC content by energy-dispersive X-ray spectrometry (EDXS) and glow discharge optical emission spectrometry (GDOES) analyses. The resistance to localized corrosion has been evaluated by exposing the samples in a salt spray cabinet and performing visual observation as well as electrochemical impedance spectroscopy (EIS) measurements every five days. Both the use of PC and the codeposition of the nanoparticles lead to a grain refinement of the Ni matrix. The use of the PC did not influence in a significant way the resistance of the pure Ni deposits to the localized corrosion. The incorporation of micro-SiC led to a decrease of the corrosion resistance for the deposits produced under DC, while the microcomposites produced under PC presented a corrosion resistance comparable to the pure Ni deposits. The nanocomposites presented the highest corrosion resistance due to the more compact and fine-grained microstructure. EIS revealed the presence of a localized corrosion attack earlier than the visual observation, giving useful information about the failure mechanism.
27
Toma, Stefan Lucian, Margareta Peneoasu, Costică Bejinariu, Diana Antonia Gheorghiu, Lucian Eva e Bogdan Toma. "The Increasing of Corrosion Resistance of Low Alloy Carbon Steels Used in Petroleum Industry through Coating with Alloys Based on Fe-Ni-Cr by Thermal Spray". Advanced Materials Research 1029 (settembre 2014): 158–63. http://dx.doi.org/10.4028/www.scientific.net/amr.1029.158.
Abstract (sommario):
The main objective of this paper is to evaluate the mechanical properties, chemical and corrosion resistance of four types of metallic coatings: FeCr, FeCoCr, and FeCoCrNi, FeCrNi sprayed through thermal spraying in electric arc on an anchor substrate type 95Ni5Al or 78.3Ni20Cr1. 4Si0.3Fe. The five layers tested were deposited on carbon steel support low alloyed and the obtained results have provided a picture regarding the possibilities of using of the deposits. Because these types of alloys are used to increase the wear resistance of tools, it is very important to know their behaviour is saline environment, because the contributions brought by this paper would increase the applicability domain of these materials (could be used to recondition by thermal spraying the tools used in naval and petroleum industry). The researches of the obtained deposits have been carried out through several methods to screen their performance. Therefore, there have been done investigations on the microstructural morphology of the deposit, by optical microscopy (OM) and scanning electron microscopy (SEM). The OM and SEM results have sought to determine the degree of uniformity of the deposits and the amount of pores and oxides in layer. The physical properties of coatings were also evaluated by adhesion and porosity quantification. The corrosion resistance was evaluated by exposing samples in saline fog chamber. The corrosion products formed on the surface layers were investigated by scanning electron microscopy (SEM) analysis of the SEM. The intermediate alloy 78.3Ni20Cr1.4Si0.3Fe used as anchoring layer allowed the reducing of the pores and micro cracks frequently found in the ordinary 95Ni5Al alloy. It has been observed that the deposits based on NiCrCo are good enough to be used as an efficient coating of carbon steel in aggressive marine environments.
28
Sun, Ao, Cui Ye, Chenyang Yao, Lifeng Zhang, Ji Mi e Wenjun Fang. "Morphological and Compositional Analysis on Thermal Deposition of Supercritical Aviation Kerosene in Micro Channels". Molecules 28, n. 11 (1 giugno 2023): 4508. http://dx.doi.org/10.3390/molecules28114508.
Abstract (sommario):
The integration of active cooling systems in super or hypersonic aircraft using endothermic hydrocarbon fuels is considered an effective way to relieve the thermal management issues caused by overheating. When the temperature of aviation kerosene exceeds 150 °C, the oxidation reaction of fuel is accelerated, forming insoluble deposits that could cause safety hazards. This work investigates the deposition characteristic as well as the morphology of the deposits formed by thermal-stressed Chinese RP-3 aviation kerosene. A microchannel heat transfer simulation device is used to simulate the heat transfer process of aviation kerosene under various conditions. The temperature distribution of the reaction tube was monitored by an infrared thermal camera. The properties and morphology of the deposition were analyzed by scanning electron microscopy and Raman spectroscopy. The mass of the deposits was measured using the temperature-programmed oxidation method. It is observed that the deposition of RP-3 is highly related to dissolved oxygen content (DOC) and temperature. When the outlet temperature increased to 527 °C, the fuel underwent violent cracking reactions, and the structure and morphology of deposition were significantly different from those caused by oxidation. Specifically, this study reveals that the structure of the deposits caused by short-to-medium term oxidation are dense, which is different from long-term oxidative deposits.
29
Šumanovac, Franjo, Josipa Kapuralić, Ivica Pavičić e Luka Perković. "Assessment of Near-Surface Geophysical Methods Used to Discover Karst Bauxite Deposits in the Dinarides Using the Example of Posušje Area, Bosnia and Herzegovina". Minerals 14, n. 4 (3 aprile 2024): 378. http://dx.doi.org/10.3390/min14040378.
Abstract (sommario):
Geophysical exploration of bauxite deposits has been carried out in the area of Posušje in Bosnia and Herzegovina, which were formed on an Upper Cretaceous carbonate substrate, whereas the hanging wall rocks can be Paleogene limestones and sedimentary clastic rocks. Karst terrains are demanding for geophysical exploration due to the relatively complex geological relationships and exceptional near-surface inhomogeneities that generate large noises and challenging conditions for taking field measurements. The fundamental question is whether geophysical research can detect exceptionally irregular karst bauxite deposits with relatively small dimensions. The basic idea is to combine several geophysical methods and a joint interpretation of several data sets to increase the efficiency of geophysical surveying in detecting complex bauxite deposits in karst terrains. Therefore, fundamental near-surface research methods, electrical tomography and seismic refraction are used. In addition, magnetometry was used to examine whether bauxite deposits yield potential magnetic anomalies that could help in detecting them. Research undertaken in the area of Posušje was carried out in the first step on already discovered and known bauxite deposits to determine whether geophysical responses correlate with the occurrence of bauxite deposits and to evaluate the effectiveness of each of the applied surface geophysical methods. Measurements were taken at several locations, and results for two micro-locations, Krstače and Mratnjača, are shown. Geophysical measurements were firstly performed on discovered bauxite deposits in order to reliably determine the possibility of identifying deposits in geophysical inverse models. Bauxite deposits were clearly recognised as characteristic geophysical responses in inversion models using both methods, electrical tomography and seismic refraction. Although the response of bauxite deposits is expressed in both models, resistivity and velocity, it is much more evident in resistivity models. The characteristic resistivity response was confirmed by the discovery of a new deposit. Therefore, the conclusion is that electrical resistivity tomography should be considered a basic method for exploring karst bauxite deposits. Seismic refraction provides a better characterisation of deposits and reduces the interpretation ambiguity. This solution can generally be applied to the problem of researching bauxite deposits in the Dinarides and similar geological models in the Mediterranean. Magnetometric measurements have shown that no magnetic anomalies could be associated with bauxite deposits, and only magnetometry was not successful in discovering bauxite deposits.
30
Rizk, N., N. Ait-Mouheb, G. Bourrié, B. Molle e N. Roche. "Parameters controlling chemical deposits in micro-irrigation with treated wastewater". Journal of Water Supply: Research and Technology - Aqua 66, n. 8 (6 settembre 2017): 587–97. http://dx.doi.org/10.2166/aqua.2017.065.
31
Petersson, P., H. Bergsåker, G. Possnert, J. P. Coad, S. Koivuranta e J. Likonen. "Ion beam micro analysis of deposits at tokamak divertor surfaces". Nuclear Instruments and Methods in Physics Research Section B: Beam Interactions with Materials and Atoms 268, n. 11-12 (giugno 2010): 1838–41. http://dx.doi.org/10.1016/j.nimb.2010.02.025.
32
Criddle, Alan J., Hardeep Tamana, John Spratt, Karen J. Reeson, David Vaughan e Geoff Grime. "Micro-PIXE analysis of platinum group minerals from placer deposits". Nuclear Instruments and Methods in Physics Research Section B: Beam Interactions with Materials and Atoms 77, n. 1-4 (maggio 1993): 444–49. http://dx.doi.org/10.1016/0168-583x(93)95578-s.
33
Nesbitt, Jake A., Jared M. Robertson, Lawrence A. Swerhone e Matthew B. J. Lindsay. "Nickel geochemistry of oil sands fluid petroleum coke deposits, Alberta, Canada". FACETS 3, n. 1 (1 ottobre 2018): 469–86. http://dx.doi.org/10.1139/facets-2017-0115.
Abstract (sommario):
Nickel (Ni) leaching from oil sands petroleum coke can have toxicological effects on aquatic organisms. However, geochemical controls on Ni release, transport, and attenuation within coke deposits remains limited. We examined the geochemistry of fluid coke and associated pore waters from two deposits at an oil sands mine near Fort McMurray, Alberta, Canada. Synchrotron-based micro-X-ray fluorescence (μXRF) and micro-X-ray absorption near edge structure (μXANES) spectroscopy show that Ni(II)-porphyrin complexes dominate, but inorganic phases including Ni(II)-sulfide and Ni(II)-oxide comprise a minor component of fluid coke. Sequential chemical extractions suggested that sorption–desorption reactions may influence Ni mobility within fluid coke deposits. Although only a small proportion of total Ni (<4%) is susceptible to leaching under environmentally relevant concentrations, dissolved Ni concentrations ( n = 65) range from 2 to 120 μg·L−1 (median 7.8 μg·L−1) within the two deposits and generally decrease with depth below the water table. Pore water Ni concentrations are negatively correlated with pH, but not with dissolved sulfate, bicarbonate, or chloride. Overall, our findings suggest that pore water pH and sorption–desorption reactions are principal controls on dissolved Ni concentrations within oil sands fluid petroleum coke deposits.
34
Mason, R. H., C. Chou, C. S. McCluskey, E. J. T. Levin, C. L. Schiller, T. C. J. Hill, J. A. Huffman, P. J. DeMott e A. K. Bertram. "The micro-orifice uniform deposit impactor–droplet freezing technique (MOUDI-DFT) for measuring concentrations of ice nucleating particles as a function of size: improvements and initial validation". Atmospheric Measurement Techniques 8, n. 6 (15 giugno 2015): 2449–62. http://dx.doi.org/10.5194/amt-8-2449-2015.
Abstract (sommario):
Abstract. The micro-orifice uniform deposit impactor–droplet freezing technique (MOUDI-DFT) combines particle collection by inertial impaction (via the MOUDI) and a microscope-based immersion freezing apparatus (the DFT) to measure atmospheric concentrations of ice nucleating particles (INPs) as a function of size and temperature. In the first part of this study we improved upon this recently introduced technique. Using optical microscopy, we investigated the non-uniformity of MOUDI aerosol deposits at spatial resolutions of 1, 0.25 mm, and for some stages when necessary 0.10 mm. The results from these measurements show that at a spatial resolution of 1 mm and less, the concentration of particles along the MOUDI aerosol deposits can vary by an order of magnitude or more. Since the total area of a MOUDI aerosol deposit ranges from 425 to 605 mm2 and the area analyzed by the DFT is approximately 1.2 mm2, this non-uniformity needs to be taken into account when using the MOUDI-DFT to determine atmospheric concentrations of INPs. Measurements of the non-uniformity of the MOUDI aerosol deposits were used to select positions on the deposits that had relatively small variations in particle concentration and to build substrate holders for the different MOUDI stages. These substrate holders improve reproducibility by holding the substrate in the same location for each measurement and ensure that DFT analysis is only performed on substrate regions with relatively small variations in particle concentration. In addition, the deposit non-uniformity was used to determine correction factors that take the non-uniformity into account when determining atmospheric concentrations of INPs. In the second part of this study, the MOUDI-DFT utilizing the new substrate holders was compared to the continuous flow diffusion chamber (CFDC) technique of Colorado State University. The intercomparison was done using INP concentrations found by the two instruments during ambient measurements of continental aerosols. Results from two sampling periods were compared, and the INP concentrations determined by the two techniques agreed within experimental uncertainty. The agreement observed here is commensurate with the level of agreement found in other studies where CFDC results were compared to INP concentrations measured with other methods.
35
Nikolova, Maria P., Stefan Valkov, Stoyan Parshorov, Emil Yankov e Peter Petrov. "Biomineralization of Titanium Alloy with Surface Micro - and Nanoscaled Modifications". Key Engineering Materials 813 (luglio 2019): 165–70. http://dx.doi.org/10.4028/www.scientific.net/kem.813.165.
Abstract (sommario):
The aim of the present study was to characterize two kinds of TiN/TiO2 coatings in terms of topography, composition, and electrochemical stability after immersion in simulated body fluid (SBF). Micropatterning of the substrate (Ti-5Al-4V alloy) was done by using electron beam modification (EBM) by scanning electron beam while nanostructured TiN/TiO2 films were deposited over EBM Ti5Al4V substrates using two physical vapor deposition techniques: 1) magnetron sputtering, and 2) cathodic arc and glow-discharge methods. When immersed for 7 and 14 days in SBF at static conditions (37±0.05 °C, pH 7.4), Ca/P ratio of the apatite deposits increased from approximately 1.5 up to near stoichiometric (1.67), respectively. After the initial decrease, the pH of the solution during soaking increased gradually reaching values close to 7.7 for both coatings. However, the weight gain of the samples with Arc coatings after the immersion period in SBF was nearly three times more than those with magnetron deposited coating. The electrochemical potentiodynamic tests performed in SBF indicated a shift in the corrosion potentials towards nobler direction after 7 and 14 days of immersion compared to non-immersed samples, whereas the corrosion current density was slightly increased.
36
Aizawa, Tatsuhiko, Hiroki Naka, Takeshi Nasu e Yoshiro Nogami. "Robust Packaging of Vertically Aligned Graphite Substrate by Copper Micro-Rib Structuring". C 8, n. 4 (28 novembre 2022): 70. http://dx.doi.org/10.3390/c8040070.
Abstract (sommario):
Vertically aligned graphite substrate (VGS)-copper packaging was renowned for improving the robustness against the thermal gradient loading by using micro texturing. The micro-groove array with a line width of 50 μm and a pitch of 100 μm was formed into the VGS by controlling the line depth with the use of fast-rate oxygen plasma etching. Three micro-grooved VGS specimens were wet-plated to fill these microgrooves with copper deposits and to cover the VGS surfaces. The nearly full-deposited VGS-Copper specimens were subjected to a severe thermal transient loading test. The simply Cu-covered package and shallow rib-structured VGS-Cu packages were damaged to delaminate at their interfaces. The VGS-Cu package with the copper rib structure with a height of 50 μm experienced no delamination. This rib-structured VGS-copper package with high rib height had sufficient robustness against the severe thermal transients even with the proof of homogeneous thermal spreading capacity.
37
Misnikov, Oleg. "Effect of Hydro-Physical Properties of Peat on Regulation of Peatland Drainage Systems". E3S Web of Conferences 105 (2019): 01010. http://dx.doi.org/10.1051/e3sconf/201910501010.
Abstract (sommario):
The paper analyzes changes in the hydro-physical properties of peat micro- and macrosystems in the process of drainage. Maximum moisture-holding capacity of peat is used as the main characteristic. With a full drying cycle and subsequent moistening of peat, there are three stages associated with the coagulative structure formation in the system. The boundary of the transition from the state «peat in water» to the state «water in peat» is moisture content equal to one. It divides the period of structure formation into two periods, due to the predominating action of van der Waals interactions or hydrogen bonds. In the state «water in pear» the peat system loses the ability to recover its original hydro-physical properties. Scaling up the research results on peat deposits (marshes) makes it possible to classify them according to the degree of drainage of the deposit. A new approach to the use of the term «surface water body» for peat deposits is proposed.
38
Munir, Badrul, Vika Rizkia, Johny W. Soedarsono, Bambang Suharno e Andi Rustandi. "Growth of Anodized Layer and Cerium Sealing on Al7xxx/SiC Composite". Advanced Materials Research 1119 (luglio 2015): 212–17. http://dx.doi.org/10.4028/www.scientific.net/amr.1119.212.
Abstract (sommario):
Anodizing process conducted in Al7xxx/SiC produced non-uniform thickness of porous anodic film with cavities, micro-pores and micro-cracks. Cerium sealing was chosen as a post treatment to remedy the poor anodic film by providing a composite layer in order to further enhance the corrosion resistance in aggressive environment. In this study, anodizing process was conducted in H2SO4solution at current density values of 15, 20, and 25 mA/cm2at room temperature, 0°C and-25°C for 30 minutes. Subsequently, electroless sealing was conducted in CeCl3.6H2O + H2O2solution at room temperature and pH 9 for 30 minutes. Integrated protection composed of anodizing at 0°C and cerium sealing process in Al7xxx/SiC produced cerium rich deposits in the diameter of 64 nm (± 3nm) on the surface of anodic oxide layer. These spherical deposits covered the entire surface of anodic oxide layer in accordance with the morphology of the oxide layer. Otherwise, almost no cerium deposit formed on the surface of the oxide layer by conducted integrated protection at room temperature and-25°C. The integrated process conducted at anodizing temperature of 0°C presented a highest protection degree. The cerium protective layer which leads to the decreasing of corrosion rate and current density up to 99,99% or four orders magnifications than that of bare composite.
39
Mitrani Viggiano, Alejandro, José Luis Ruvalcaba Sil, Mayra D. Manrique Ortega e Victoria Corregidor Berdasco. "Non-Destructive Micro-Chemical and Micro-Luminescence Characterization of Jadeite". Microscopy and Microanalysis 22, n. 6 (dicembre 2016): 1304–15. http://dx.doi.org/10.1017/s1431927616012010.
Abstract (sommario):
AbstractJadeite was greatly appreciated by pre-Hispanic cultures in Mesoamerica. Despite its importance, knowledge of its mining sources was lost after the Spanish conquest. In the 1950s the only confirmed jadeite deposits in Mesoamerica were found in the Motagua River Fault (MRF), Guatemala. The aim of this study is to present a methodology that is appropriate for the study of archeological jadeite objects using non-destructive spectroscopic and micro-ion beam analysis techniques. This methodology has been applied to perform mineral, elemental, and luminescence characterization of five jadeite samples from the MRF, with white, lilac, and green colors. Fourier-transformed infrared spectroscopy and X-ray diffraction analysis confirmed the presence of jadeite, albite, and omphacite as the main mineral phases in the samples. Elemental maps using particle-induced X-ray emission (PIXE) with a nuclear microprobe and elemental concentration analysis from individual mineral grains using micro-PIXE coupled with micro-ionoluminescence (IL) allowed the detection of minor feldspar, titanite, and grossular mineral contents. Distinctive features from the mineral, elemental, and luminescence characterization have been found that allow the identification of these five jadeite samples.
40
Shi, Chong, e Jinzhou Bai. "Compositional Effects and Mechanical Parametric Analysis of Outwash Deposits Based on the Randomised Generation of Stone Blocks". Advances in Materials Science and Engineering 2015 (2015): 1–13. http://dx.doi.org/10.1155/2015/863915.
Abstract (sommario):
Based on the distribution of the stone blocks in outwash deposits, the paper present a modeling method for the random structure of outwash deposits, in which the long axis of the stone blocks is supposed obeying a lognormal distribution. Then numerical experiments of biaxial compression using the granular discrete element method are used in the macro- and micro parametric analysis. The influences of strength of the cementation, the sizes of stone blocks, and the content of stone blocks on the peak compressive and shear strength are discussed. The micromechanical parameters of the outwash deposits are also analyzed. The proposed method offers a supplement to the mechanical characterization of outwash deposits and accounts for the limitation that indoor experiments cannot consider large stone blocks.
41
Vasilatos, Charalampos, Evdokia E. Kampouroglou, Ifigeneia Megremi e Maria Economou-Eliopoulos. "Bio-Geochemical Processes: Insights from Fe-Mn Mineralization in the Aegean Sea (Greece)". Minerals 12, n. 10 (16 ottobre 2022): 1303. http://dx.doi.org/10.3390/min12101303.
Abstract (sommario):
In this study, we have compiled new and existing mineralogical and geochemical data on Fe-Mn mineralization from the Aegean region [Attica (Grammatiko, Legrena, and Varnavas), Evia and Milos islands], aiming to provide new insights on the genesis of Fe-Mn mineralization in that region and its potential environmental implications. A common feature of those deposits is the relatively low Cr, Co, V, Ni, Mo, and Cd content, whereas Ba, As, W, Cu, Pb, and Zn show remarkably variable values. The Mn-Fe deposits from Milos exhibit the highest tungsten content, while a positive trend between MnO and W, combined with a negative trend between MnO and Fe2O3 suggests the preference of W to Mn-minerals. The occurrence of bacterio-morphic Fe-Mn-oxides/hydroxides within Mn-Fe mineralizations in the studied region, indicates the important role of micro-organisms into redox reactions. Moreover, the presence of micro-organisms in the Fe-Mn-deposits, reflecting the presence of organic matter confirms a shallow marine environment for their deposition. A salient feature of the Varnavas and Milos Mn-Fe ores is the presence of sodium chloride coated fossilized micro-organisms, suggesting development from a solution containing relatively high Na and Cl concentrations. Furthermore, from an environmental point of view, consideration is given to the bioavailability of elements such as As, Pb, and W, related to the above-mentioned mineralizations. The high bio-accumulation factor for W (Wplant/Wsoil × 100) recorded in the Neogene sedimentary basins of Attica, related to the Grammatiko Fe-Mn mineralization, reflects the high W mobility under alkaline conditions and the potential environmental impact of similar deposits with elevated W content.
42
Mason, R. H., C. Chou, C. S. McCluskey, E. J. T. Levin, C. L. Schiller, T. C. J. Hill, J. A. Huffman, P. J. DeMott e A. K. Bertram. "The micro-orifice uniform deposit impactor-droplet freezing technique (MOUDI-DFT) for measuring concentrations of ice nucleating particles as a function of size: improvements and initial validation". Atmospheric Measurement Techniques Discussions 8, n. 2 (27 febbraio 2015): 2223–61. http://dx.doi.org/10.5194/amtd-8-2223-2015.
Abstract (sommario):
Abstract. The micro-orifice uniform deposit impactor-droplet freezing technique (MOUDI-DFT) combines particle collection by inertial impaction (via the MOUDI) and a microscope-based immersion freezing apparatus (the DFT) to measure atmospheric concentrations of ice nucleating particles (INPs) as a function of size and temperature. In the first part of this study we improved upon this recently introduced technique. Using optical microscopy, we investigated the non-uniformity of MOUDI aerosol deposits at spatial resolutions of 1, 0.25 mm, and for some stages when necessary 0.10 mm. The results from these measurements show that at a spatial resolution of 1 mm and less, the concentration of particles along the MOUDI aerosol deposit can vary by an order of magnitude or more. Since the total area of a MOUDI aerosol deposit ranges from 425 to 605 mm2 and the area analyzed by the DFT is approximately 1.2 mm2, this non-uniformity needs to be taken into account when using the MOUDI-DFT to determine atmospheric concentrations of INPs. Measurements of the non-uniformity of the MOUDI aerosol deposits were used to select positions on the deposits that had relatively small variations in particle concentration and to build substrate holders for the different MOUDI stages. These substrate holders improve reproducibility by holding the substrate in the same location for each measurement and ensure that DFT analysis is only performed on substrate regions with relatively small variations in particle concentration. In addition, the deposit non-uniformity was used to determine correction factors that take the non-uniformity into account when determining atmospheric concentrations of INPs. In the second part of this study, the MOUDI-DFT utilizing the new substrate holders was compared to the continuous flow diffusion chamber (CFDC) technique of Colorado State University. The intercomparison was done using INP concentrations found by the two instruments during ambient measurements of continental aerosols. Results from two sampling periods were compared and the INP concentrations determined by the two techniques agreed within experimental uncertainty. The agreement observed here is commensurate with the level of agreement found in other studies where CFDC results were compared to INP concentrations measured with other methods.
43
Benedicto, Antonio, Maher Abdelrazek, Patrick Ledru, Cameron MacKay e Dwayne Kinar. "Structural Controls of Uranium Mineralization in the Basement of the Athabasca Basin, Saskatchewan, Canada". Geofluids 2021 (24 febbraio 2021): 1–30. http://dx.doi.org/10.1155/2021/3853468.
Abstract (sommario):
The occurrence of unconformity-related uranium mineralization requires the combination of three components: fluids with the right composition, geochemical traps with the right agents that produce precipitation, and structural traps with the right geometry. In the Athabasca Basin unconformity-related uranium deposits, while basinal brines are commonly accepted as the principal mineralized fluids and graphite and gases (CH4, CO2, and H2S) are well known as the reductants, only few case studies describing structural traps are published. A number of recent works, including numerical modelling, have improved the understanding of the role of inherited shear zones on fluid flow and the development of uranium deposits at a micro- and regional-scale. Nevertheless, there is still a lack of knowledge about the meso- or deposit-scale structural controls that lead to the present (and potentially predictive) localization of uranium deposits along a given shear zone. The present work examines new structural data from drill holes and deals with (i) the identification of mesoscale structural traps that lead to the formation of the Athabasca unconformity-related uranium deposits hosted within the basement and (ii) with the understanding of the role and mode of reactivation of the inherited shear zones. The Sue deposits (McClean Project), the Tri-Island showing (Martin Lake Project) in the Eastern Athabasca, and the Spitfire prospect (Hook Lake Project) in the Western Athabasca have been selected for a detailed analysis of structures and related uranium mineralization. The structural analysis performed brings new insights about the mesoscale structural controls, the role the inherited ductile fabric had on the mode of brittle reactivation and to trap mineralization, and the tectonic regime to which basement-hosted uranium deposits may be associated in the Athabasca Basin.
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Rudmin, Maxim, Igor Reva, Ella Sokol, Elshan Abdullayev, Aleksey Ruban, Andrey Kudryavtsev, Oleg Tolkachev e Aleksey Mazurov. "Minerals of Rare Earth Elements in High-Phosphorus Ooidal Ironstones of the Western Siberia and Turgai Depression". Minerals 10, n. 1 (21 dicembre 2019): 11. http://dx.doi.org/10.3390/min10010011.
Abstract (sommario):
The aim of this research was to study the rare earth (REE) minerals in ooidal ironstone deposits of the West Siberian basin and the Turgai depression. Authigenic minerals (monazite and cerite) were described, and their main mineral form was identified as light rare earth element phosphate (LREE-phosphate) in this study. LREE-phosphate is included in ferruginous ooids, peloids, and oncoids and forms a consistent mineral association with Fe-hydroxides (goethite and its hydrated amorphous derivatives) and Fe-rich layered silicates (Fe-illite-smectite, chamosite, berthierine). The constancy of the mineral association in two deposits of different ages indicates a general mechanism behind the formation of these minerals. LREE-phosphates (authigenic monazite) are characterized by microscopic sizes (up to 24 μm), diverse morphology (mainly spherical or xenomorphic), and occupy spaces between the micro-cortex in ferruginous spheroids. This mineral can be found in other deposits of ooidal ironstone. According to its mineralogical and chemical characteristics, LREE-phosphate mainly belongs to the authigenic (nodular or “gray”) monazite. However, the incomplete (not 100%) correspondence of Kikuchi bands with the reference monazite does not allow its reliable identification. Based on its small size, chemical leaching or bacterial interaction is recommended to extract REE from ooidal ironstone while predicting the associated removal of phosphorus from iron ore due to its dominant phosphate mineral form. Ooidal ironstone should be considered a complex deposit and an unconventional natural type of REE ores as an example of the largest Bakchar and Lisakovsk deposits.
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Kwena, Irene Atsiech, Thomas Githui e Allan Kihara. "Capital Structure and Financial Performance of Micro-Finance Institutions in Kenya". International Journal of Finance 8, n. 4 (18 agosto 2023): 50–76. http://dx.doi.org/10.47941/ijf.1408.
Abstract (sommario):
Purpose: This research was envisioned to assess the influence of the capital structure on ROE of Micro-financial institutions in Kenya. The research was in search for resolving the following problem; is there a connection between the composition of capital (loan, shareholder’s equity, retained earnings and deposits) and the viability of MFIs? If the firm size has an influence on ROE? The study was motivated by the following capital structure theories, which are the theory of pecking order, Trade-off theory and the theory of Marketing timing.
Methodology: To define the independent variable, the researcher used a correlation research design. The target demographic of the research was all 14 successful microfinance companies as recognized by the Kenya Microfinance Act as of 2020. The research therefore represented a census survey with a period of 5 years (from 2016-2020). The study's research model consisted of the independent variable loans, shareholder’s equity, retained earnings and deposits and the size of the firm as a moderating variable, determined by the firm’s total asset value, and the following ratios as dependent variables: return on equity. To analyze the results, EViews was used. There was descriptive and inferential statistics execution. Diagnostic results were computed before the data analysis.
Findings: The results were presented in the form of tables. The inferential statistics with the moderating variable revealed that loan financing has statistical negligible sway on the financial return of MFIs (p=0.9832>0.05). Shareholders equity financing was found to have a statistically significant influence on financial performance of MFIs (p=0.0047<0.05). Retained earnings financing was found to have a statistically significant influence on financial performance of MFIs (p=0.0016<0.05). Deposit financing was found to have a statistically insignificant influence on financial performance of MFIs (p=0.2168>0.05).in this study.
Unique contribution to theory, practice and policy: The study suggested that MFIs should strike a balance benefits and costs of debt arising thereof in line with the Trade-off theory, fast growing MFIs to utilize more retained earnings in capital structure, more profitable businesses use less shareholder’s equity in capital structure mix and finally positive correlation on deposits indicating similar correlation is likely to exist with financing capital structure. Thus MFIs may consider reviewing these measures so as to enhance performance to serve the low-income earners better in improving the economy. Further studies can be done based on other performance measures like ROA, EPS,Net Interest Margin. The study used a correlation research design for five-year period from 2016 to 2020. Therefore, this study can be replicated using a different methodology and covering a longer period like ten year.
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Gerasimova, Larisa Vladimirovna, e Konstantin Petrovich Ivanov. "Assessment of Quality of Sapropel Deposits of Lake Kubalah in Central Yakutia". Interactive science, n. 11 (45) (20 novembre 2019): 55–58. http://dx.doi.org/10.21661/r-508675.
Abstract (sommario):
The paper presents the content analysis of macro- and micro-elements in the sapropel deposits of Lake Kubalah, which will allow us to evaluate the quality of sapropel and its utilization efficiency as a valuable organo-mineral material. The authors of the article define relevance and novelty of the paper. The detailed analysis of sapropel deposits of Lake Kubalah, situated in terrace above the flood-plain of (Magan) flat cryolitic zone of Central Yakutia.
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Pi-Puig, Teresa, Jesús Solé e Leticia Alba-Aldave. "Uranium in Fluorite, a Case Study: The La Azul Fluorspar Deposit, Taxco, Guerrero, Mexico". Minerals 13, n. 12 (29 novembre 2023): 1495. http://dx.doi.org/10.3390/min13121495.
Abstract (sommario):
Uranium can be found in the Earth’s crust in different reservoirs, with igneous rocks being the primary source of this element from which many types of secondary deposits are formed. Fluorspar deposits generally do not contain uranium, but in some cases, fluorite can carry both uranium in solid solutions and inclusions of uranium minerals. We studied the concentration (ICP-MS), composition (electronic microprobe), and spatial distribution (microscopy and auto-radiography) of elemental uranium and uranium minerals at different scales (microscopy and auto-radiography in fluorite from the La Azul fluorspar deposit (Taxco, Mexico) to assess the origin of uranium and its significance in this ore deposit. Auto-radiography images with the CR-39 detector were found to be impressive in their ability to elucidate uranium distribution at the millimeter scale. The limit between the solid solution of elemental uranium in natural fluorite and the appearance of uranium oxides as inclusions appeared to be between 20 μg g−1 and 40 μg g−1 bulk uranium concentration in this fluorspar ore. The maximum concentration of U in fluorite from the La Azul deposit was about 100 μg g−1. Using Raman spectroscopy and microprobe analysis, we identified the micro-inclusions of uranium minerals as uraninite (of the pitchblende variety); its composition suggested a hydrothermal origin for this fluorspar deposit. We also calculated a chemical age that can be compared with the previously published regional geology and isotopic (U-Th-Sm)/He ages in fluorite. Micro-thermometric studies of fluid inclusions were carried out in different samples of uranium-rich fluorite to identify the nature and origin of the mineralizing fluid and the precipitation mechanisms of uranium minerals. We concluded that the uranium-rich fluorite precipitated in the initial phases of mineralization from a reducing fluid, with low salinity (<8% NaCl eq.) and an intermediate temperature (110–230 °C), and that the presence of organic compounds and sulfides (mainly pyrite) favored the simultaneous precipitation of uraninite (pitchblende variety) and fluorite.
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James Ese IGHOROJE (PhD) e Emmanuel Othuke AKPOKERERE (PhD). "MICROFINANCE BANKS’ CREDIT ACCESSIBILITY AND POVERTY REDUCTION IN NIGERIA". Finance & Accounting Research Journal 4, n. 4 (9 novembre 2022): 162–68. http://dx.doi.org/10.51594/farj.v4i4.396.
Abstract (sommario):
The study investigated the effect of access to microfinance banks’ credit accessibility (MCA) on poverty reduction in Nigeria. The regressand is poverty reduction proxied by GDP per capita growth rate as a measure of standards of living, while the regressors are deposits (DEP), micro-loans and advances (LAD). The study gathered (sourced) from the annual bulletin of the Central Bank of Nigeria (CBN) for 16 years from 2000 to 2021. The Ordinary Least Square regression technique was employed for data analyses. The results showed that Loans and advances of microfinance banks have insignificant negative effect poverty reduction. Microfinance banks’ deposits have increased poverty minimally. The study thus concluded that Microfinance banks intermediation is not effective for poverty reduction/alleviation in Nigeria. Keywords: Micro Financing, Poverty Reduction, Bank Intermediation, Nigeria.
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Fuchs, S., W. J. Przybylowicz e A. E. Williams-Jones. "Elemental imaging of organic matter and associated metals in ore deposits using micro PIXE and micro-EBS". Nuclear Instruments and Methods in Physics Research Section B: Beam Interactions with Materials and Atoms 318 (gennaio 2014): 157–62. http://dx.doi.org/10.1016/j.nimb.2013.06.055.
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Yartsev, E. I., I. V. Vikentyev e N. I. Eremin. "Isotopic composition and geochemical features of ores of Dzhusa pyrite-polymetallic deposit (South Urals)". Moscow University Bulletin. Series 4. Geology, n. 4 (28 agosto 2019): 78–83. http://dx.doi.org/10.33623/0579-9406-2019-4-78-83.
Abstract (sommario):
The sulfur isotopic composition was studied for the main morphological types and generation of sulfides composing the ore of the Dzhusinsky deposit, and the content of trace elements was analyzed using the highly sensitive method of mass spectrometry with inductively coupled plasma and laser sampling (LA-ICP-MS). Both types of studies were performed for ore deposits for the first time. According to the geochemistry of sulfur isotopes, its deep magmatic source was reconstructed, which made a predominant contribution to the ore-forming fluid. Using the modules of the STATISTICA, correlations were calculated and the patterns of distribution of micro impurities in sulfide minerals were revealed.