scholarly journals The Influence of Trace Elements on the Nature of the Nuclei of the Graphite in Ductile Iron

2018 ◽  
Vol 925 ◽  
pp. 78-85 ◽  
Author(s):  
Gorka Alonso ◽  
Doru Michael Ştefănescu ◽  
Esther de La Fuente ◽  
Pello Larrañaga ◽  
Ramón Suárez
Keyword(s):  
Trace Elements ◽  
Ductile Iron ◽  
Room Temperature ◽  
Active Role ◽  
Titanium Content ◽  
Titanium Nitrides ◽  
Minor Elements ◽  
Nucleation Sites ◽  
Nucleation Mechanisms ◽  
Detector Spectrum

Nucleation mechanisms and the effect of minor elements added with the inoculants are still a subject of extensive research in ductile iron. Oxides, sulfides, silicates and nitrides have been reported to be nuclei for graphite precipitation. Those compounds originate both from the nodulizing treatment and the inoculation process. Previous research works have shown that titanium nitrides or carbonitrides play an active role in graphite nucleation. In order to determine the efficiency and nature of nitrides that can act as nuclei for graphite, and the possible effect of the trace elements added with the inoculant, melts with titanium contents ranging from 0.007% to 0.036% were produced and poured into standard thermal analysis cups, with and without inoculation. Different inoculants rich in titanium, cerium, aluminum or zirconium were used. Two cups were produced with each inoculant, one cooled down to room temperature, and the other quenched in brine immediately after pouring. Nucleation sites were characterized through detector, spectrum, mapping and line scans of a FEG-SEM equipment. Most of the analyzed nuclei exhibited two or three different inclusions: magnesium sulfides or Mg-Ca oxy-sulfides, Mg or Al oxides, and Ti carbo-nitrides or Mg-Si-Al nitrides. The appearance of each type of nitrides is directly related to the titanium content in the base melt. When titanium was added in the inoculant, no titanium nitrides were noticeable. The zirconium added with the inoculant promoted more complex nitrides that appeared in higher amount. Cerium appears occasionally forming sulfides. Aluminum stimulates the formation of complex nitrides. No differences in the nature of the nuclei were observed between the samples quenched and the ones obtained at room temperature, which assures the methodology approach.

Physical Based Microstructure Modelling Coupled with Nucleation Theory during and after Hot Forming of AA5083

2010 ◽  
Vol 89-91 ◽  
pp. 509-514
Author(s):  
Pavel Sherstnev ◽  
Christof Sommitsch ◽  
Stefan Mitsche ◽  
Carsten Melzer
Keyword(s):  
Aluminium Alloy ◽  
Hot Rolling ◽  
Volume Fraction ◽  
Electron Backscatter Diffraction ◽  
Grain Structure ◽  
Nucleation Theory ◽  
Structure Evolution ◽  
Nucleation Sites ◽  
Nucleation Mechanisms ◽  
Backscatter Diffraction

A physical model based on three types of dislocations and three nucleation sites for recrystallized grain is applied to hot rolling simulation. This model was implemented into a commercial Finite Element (FE) analysis package FORGE 2008 to calculate both the structure evolution during and the recrystallized volume fraction after hot working of aluminium alloy 5083. It is shown that the main nucleation mechanisms in the aluminium alloy are the particle stimulated nucleation (PSN) and nucleation at grain boundaries. Hence the precipitation kinetics during homogenisation was investigated by use of the thermodynamic calculation software MatCalc. To validate the simulation results hot rolling experiments were performed by means of a laboratory mill. The grain structure evolution was analysed by electron backscatter diffraction (EBSD).

Effect of the Nucleation Layer on TiO2 Nanoflowers Growth via Solvothermal Synthesis

2012 ◽  
Vol 1479 ◽  
pp. 95-100
Author(s):  
Oscar A. Jaramillo ◽  
Reshmi Raman ◽  
Marina E. Rincón
Keyword(s):  
Solvothermal Synthesis ◽  
Room Temperature ◽  
Active Surface ◽  
Dip Coating ◽  
Fixed Number ◽  
Active Surface Area ◽  
Nucleation Layer ◽  
Sensing Properties ◽  
Nucleation Sites ◽  
Ethanol Sensing

ABSTRACTTiO2 nanoflowers were obtained on modified ITO substrates by solvothermal synthesis. Surface modification was achieved with a layer of TiO2 seeds/nucleus obtained by dip-coating at various pH and dip cycles. Field emission scanning electron microscopy results indicated that at all nucleation conditions there was a dual population of TiO2 nanoparticles and nanoflowers. For a particular pH, the effect of increasing the number of dips was to increase the size and number of the nanoflowers, whereas for a fixed number of dips, the increase in pH causes a decrease in nanoflower population. The comparison with solvothermal films obtained on unmodified substrates indicates that TiO2 nanoflowers grew up on the nucleation sites. These microstructural changes determine the active surface area and sensing properties of the solvothermal films. At room temperature, no evidence of superior ethanol sensing properties was found for TiO2 nanoflowers, which show larger resistivity than TiO2 nanoparticles.

High-yield synthesis of CsPbBr3 nanoparticles: Diphenylphosphine as a reducing agent and its effect in Pb-seeding nucleation and growth

2021 ◽  
Author(s):  
Eder Antonio Castillo-Ruiz ◽  
Diana Fabiola Garcia-Gutierrez ◽  
Domingo Ixcóatl Garcia-Gutierrez
Keyword(s):  
Nucleation And Growth ◽  
Reducing Agent ◽  
High Yield ◽  
Reaction Yield ◽  
High Quality ◽  
Stabilizing Agents ◽  
Nucleation Sites ◽  
Nucleation Mechanisms ◽  
Attractive Option ◽  
Mass Increment

Abstract Based on the reported nucleation mechanisms for CsPbX3 and II-VI/IV-VI quantum dots, CsPbBr3 nanoparticles with a high reaction-yield, up to 393% mass-increment, were synthesized by the hot-injection method. The introduction of diphenylphosphine (DPP) as a reducing agent improved nanoparticle nucleation and growth, giving out evidence for Pb-seeding in CsPbBr3 nanoparticles formation. Additionally, a clear influence of the DPP in a CsPbBr3-Cs4PbBr6 incomplete phase transformation was observed, marked by the appearance of several PbBr2 nanoparticles, indicating the need for an improved ratio between the stabilizing agents and the precursors, due to the increased number of nucleation sites produced by the DPP. The resulting CsPbBr3 nanoparticles showed high quality, as they displayed 70%-90% photoluminescence quantum yield (PLQY), narrow size distribution with an average nanoparticle size of ~10 nm and the characteristic cubic morphology reported in previous works. This increment in CsPbBr3 nanoparticles’ reaction yield will contribute to making them a more attractive option for different optoelectronic applications.

scholarly journals Assessment of Air Quality in School Environments in Hanoi, Vietnam: A Focus on Mass-Size Distribution and Elemental Composition of Indoor-Outdoor Ultrafine/Fine/Coarse Particles

Atmosphere ◽  
2020 ◽  
Vol 11 (5) ◽  
pp. 519
Author(s):  
Trinh Dinh Tran ◽  
Phuong Minh Nguyen ◽  
Dung Trung Nghiem ◽  
Tuyen Huu Le ◽  
Minh Binh Tu ◽  
...  
Keyword(s):  
Trace Elements ◽  
Elemental Composition ◽  
Size Distribution ◽  
World Health ◽  
Emission Sources ◽  
Mass Size Distribution ◽  
Minor Elements ◽  
Mass Size ◽  
Pm2.5 And Pm10 ◽  
Indoor And Outdoor

Indoor and outdoor ultrafine, accumulation mode, and coarse fractions collected at two preschools (S1 and S2) in Hanoi capital, Vietnam were characterized in terms of mass-size distribution and elemental composition to identify major emission sources. The sampling campaigns were performed simultaneously indoors and outdoors over four consecutive weeks at each school. Indoor average concentrations of CO2 and CO at both schools were below the limit values recommended by American Society of Heating, Refrigerating and Air-Conditioning Engineers (1000 ppm for CO2) and World Health Organization (7 mg/m3 for CO). Indoor concentrations of PM2.5 and PM10 at S1 and S2 were strongly influenced by the presence of children and their activities indoors. The indoor average concentrations of PM2.5 and PM10 were 49.4 µg/m3 and 59.7 µg/m3 at S1, while those values at S2 were 7.9 and 10.8 µg/m3, respectively. Mass-size distribution of indoor and outdoor particles presented similar patterns, in which ultrafine particles accounted for around 15–20% wt/wt while fine particles (PM2.5) made up almost 80% wt/wt of PM10. PM2.5–10 did not display regular shapes while smaller factions tended to aggregate to form clusters with fine structures. Oxygen (O) was the most abundant element in all fractions, followed by carbon (C) for indoor and outdoor particles. O accounted for 36.2% (PM0.5–1) to 42.4% wt/wt (PM0.1) of indoor particles, while those figures for C were in the range of 14.5% (for PM0.1) to 18.1% (for PM1–2.5). Apart from O and C, mass proportion of other major and minor elements (Al, Ca, Cr, Fe , K, Mg, Si, Ti) could make up to 50%, whereas trace elements (As, Bi, Cd, Co, Cr, Cu, La, Mn, Mo, Ni, Pb, Rb, Sb, Se, Sn, Sr, and Zn) accounted for less than 0.5% of indoor and outdoor airborne particles. There were no significant indoor emission sources of trace and minor elements. Traffic significantly contributed to major and trace elements at S1 and S2.

scholarly journals Thermal evolution of the morphology of Ni/Ge(111)-c(2 × 8) surface

2014 ◽  
Vol 32 (4) ◽  
pp. 641-647 ◽  
Author(s):  
Agnieszka Tomaszewska ◽  
Jhen-Hao Li ◽  
Xiao-Lan Huang ◽  
Tsu-Yi Fu
Keyword(s):  
Scanning Tunneling Microscopy ◽  
Room Temperature ◽  
Thermal Evolution ◽  
Scanning Tunneling ◽  
Tunneling Microscopy ◽  
Nucleation Sites ◽  
Dual Polarity ◽  
Stm Images

AbstractThe thermal evolution of the interface formed by room temperature (RT) deposition of Ni atoms (coverage 0.1, 0.5, 1.2 ML) onto a Ge(111)-c(2 × 8) surface has been studied with the use of scanning tunneling microscopy (STM). Atomically resolved STM images revealed that, at RT, the boundaries between the different c(2 × 8) domains acted as nucleation sites for Ni atoms. After annealing the surface with deposited material at 473 to 673 K the formation of nano-sized islands of NixGey compounds was observed. In addition, the occurrence of ring-like structures was recorded. Based on the dual-polarity images the latter were assigned to Ni atoms adsorbed on Ge adatoms.

Investigation of thermochemical boriding effect on wear behavior of a GGG 50 quality as-cast ductile iron

2016 ◽  
Vol 68 (4) ◽  
pp. 476-481 ◽  
Author(s):  
Harun Mindivan
Keyword(s):  
Wear Resistance ◽  
Abrasive Wear ◽  
Ductile Iron ◽  
Room Temperature ◽  
Wear Behavior ◽  
Surface Hardness ◽  
Wear Test ◽  
Content Type ◽  
Pin On Disc ◽  
Cast Ductile Iron

Purpose This study aims to investigate the microstructure and the abrasive wear features of the untreated and pack borided GGG 50 quality ductile iron under various working temperatures. Design/methodology/approach GGG 50 quality as-cast ductile iron samples were pack borided in Ekabor II powder at 900°C for 3 h, followed by furnace cooling. Structural characterization was made by optical microscopy. Mechanical characterization was made by hardness and pin-on-disc wear test. Pin-on-disc test was conducted on a 240-mesh Al2O3 abrasive paper at various temperatures in between 25 and 450°C. Findings Room temperature abrasive wear resistance of the borided ductile iron increased with an increase in its surface hardness. High-temperature abrasive wear resistances of the borided ductile iron linearly decreased with an increase in test temperature. However, the untreated ductile iron exhibited relatively high resistance to abrasion at a temperature of 150°C. Originality/value This study can be a practical reference and offers insight into the effects of boriding process on the increase of room temperature wear resistance. However, above 150°C, the untreated ductile iron exhibited similar abrasive wear performance as compared to the borided ductile iron.

The Influence of Boron on Structure and Mechanical Properties of Bainite Ductile Iron in the Step Austempering in Room Temperature Machine Oil

2010 ◽  
Vol 139-141 ◽  
pp. 235-238
Author(s):  
De Qiang Wei
Keyword(s):  
Mechanical Properties ◽  
Heat Treatment ◽  
Cast Iron ◽  
Impact Strength ◽  
Ductile Iron ◽  
Room Temperature ◽  
Solute Drag ◽  
Ductile Cast Iron ◽  
Treatment Technique ◽  
The Impact

In this paper, the low alloy bainite ductile cast iron has been obtained by a new heat treatment technique of the step austempering in room-temperature machine oil. The effects of element boron, manganese and copper on structure and mechanical properties of the bainite ductile cast Iron in above-mentioned process are investigated. The phenomenon, hardness lag of the alloyed bainite ductile cast Iron, has been discussed. It shows that after the step austempering in room-temperature machine oil, the hardness will increases with the time. It is found that boron and manganese can increase the hardness and reduce the impact strength while copper can increase the impact strength. The results show that reasonable alloyed elements can improve mechanical properties of the bainite ductile cast Iron. Essentially, hardness lag of the alloyed bainite ductile cast Iron is resulted from solute drag-like effect.

Element Distribution in Two Epidiorite Sills from the Central Grampian Highlands of Scotland

1965 ◽  
Vol 102 (2) ◽  
pp. 93-105 ◽  
Author(s):  
T. K. Ball
Keyword(s):  
Trace Elements ◽  
Element Distribution ◽  
The Other ◽  
Multiple Injection ◽  
Magmatic Differentiation ◽  
Minor Elements ◽  
Structural Significance

AbstractMagmatic differentiation is demonstrated in two epidiorite sills from the Grampian Highlands of Scotland, and the distribution of major and minor elements compared with data given for other intrusions, and for trace elements in the Whin Sill at High Cup Gill, Westmorland. The latter sill has Sr and Ba enriched towards the top. The element distribution for the epidiorite sills indicates that they are overturned. The data are conclusive for one sill but merely suggestive for the other, since such phenomena as multiple injection may also have affected the element distribution. The structural significance is briefly discussed.

scholarly journals ENVIRONMENTAL GEOCHEMICAL AND MINERALOGICAL STUDY OF THE PELLANA LIGNITE (PREFECTURE OF LAKONIA)

2004 ◽  
Vol 36 (1) ◽  
pp. 300
Author(s):  
Α. Χατζηαποστόλου ◽  
Σ. Καλαϊτζίδης ◽  
Σ. Παπαζησίμου ◽  
Κ. Χρηστάνης ◽  
Δ. Βάγιας
Keyword(s):  
Power Generation ◽  
Trace Elements ◽  
Major Elements ◽  
Geochemical Data ◽  
Element Mobility ◽  
Minor Elements ◽  
Mineral Phases ◽  
Wide Range ◽  
Mineralogical Study ◽  
Type Factor

The aim of this study is to estimate the environmental impacts in case of exploitation the Pellanalignites for power generation. The object of the study is to predict the element mobility during lignite combustion using mineralogical and geochemical data from bulk-lignite samples and their ashes of two cores from this area. The mineralogical determinations on the ashes revealed that quartz, K-feldspars and illitemicas are the major mineral phases contained in the lignite. The identification of anhydrite in ashes implies the presence of gypsum, althought neoformation of anhydrite from organic associated with Ca+2 and SO42 can not be excluded. These minerals correspond to primary phases. Oxides and hydroxides occur subordinately and probably represent minerals that do not correspond to primary phases. The results of the elemental analysis show that the major elements (>1000 ppm) are AI, Fe, Ca, Mg and Κ in the bulk samples of both cores. Minor elements (100-1000 ppm) are Na, Mn and Ba, while the concentrations of Be, Bi, Cd, Ce, Co, Cs, Cu, Eu, Ga, Hf, La, Li, Lu, Mo, Nb, Nd, Pb, Rb, Sb, Se, Sm, Sn, Sr, Tb, Te, Th, TI, U, Y, Yb and Zr do not exceed 100 ppm. The concentrations of many elements like As, Ba, Cr, Ni, V and Zn have a wide range among the bulk samples. In order to assess the geochemical affiliation of the studied elements, R-type factor analysis was applied on the element contents of bulk lignite and ash. The elements Ca, S, V, As, Μη, Mo, Na, Sb, Hf, Zr and U provide both organic and inorganic affiliations, while Se and Nb provide organic affiliations. To approach the mobility of each trace element, the relative enrichment factor (RE) was calculated. The most depleted trace elements according to RE mean (<0.5) are Hf and Sb, while the elements Se and Ba are moderately depleted (0.7>RE mean>0.5).

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