scholarly journals Characterization of glacial silt and clay using automated mineralogy

2019 ◽  
Vol 60 (80) ◽  
pp. 49-65
Author(s):  
Jeff W. Crompton ◽  
Gwenn E. Flowers ◽  
Brendan Dyck
Keyword(s):  
Grain Size ◽  
Size Composition ◽  
Rock Properties ◽  
Fine Grained ◽  
Rock Fragments ◽  
Grain Sizes ◽  
Automated Mineralogy ◽  
Log Normal ◽  
Discrete Populations

AbstractGlacial erosion produces vast quantities of fine-grained sediment that has a far-reaching impact on Earth surface processes. To gain a better understanding of the production of glacial silt and clay, we use automated mineralogy to quantify the microstructure and mineralogy of rock and sediment samples from 20 basins in the St. Elias Mountains, Yukon, Canada. Sediments were collected from proglacial streams, while rock samples were collected from ice marginal outcrops and fragmented using electrical pulse disaggregation. For both rock fragments and sediments, we observe a log-normal distribution of grain sizes and a sub-micrometer terminal grain size. We find that the abrasion of silt and clay results in both rounding and the exploitation of through-going fractures. The abundance of inter- versus intragranular fractures depends on mineralogy and size. Unlike the relatively larger grains, where crushing and abrasion are thought to exploit and produce discrete populations of grain sizes, the comminution of fines leads to a grain size, composition and rounding that is continuously distributed across size, and highly dependent on source-rock properties.

Synthesis and Characterization of Plasma Synthesized Nanostructured Magnesia-Yttria Based Nanocomposites

2007 ◽  
Vol 1056 ◽  
Author(s):  
Jafar F. Al-Sharab ◽  
Rajendra Sadangi ◽  
Vijay Shukla ◽  
Bernard Kear
Keyword(s):  
Electron Microscopy ◽  
Transmission Electron Microscopy ◽  
Grain Size ◽  
Chemical Mapping ◽  
X Ray Diffraction ◽  
Fine Grained ◽  
Transmission Electron ◽  
Spray Method ◽  
Average Grain Size

ABSTRACTPolycrystalline Y2O3 is the material of choice for IR windows since it has excellent optical properties in the visible, and near infra-red band. However, current processing methods yield polycrystalline Y2O3 with large grain size (> 100 μm), which limits the hardness and erosion resistance attainable. One way to improve strength is to develop an ultra-fine grained material with acceptable optical transmission properties. To realize a fine-grained ceramic, one approach is to develop a composite structure, in which one phase inhibits the growth of the other phase during processing. In this study, Y2O3-MgO nanocomposite with various MgO content (20, 50 and 80 mol%) were synthesized using plasma spray method. Extensive characterization techniques including x-ray diffraction, scanning electron microscopy (SEM), Transmission electron microscopy (TEM) and Energy Dispersive spectrometry (EDS) were employed to study the synthesized powder as well as the consolidated sample. Transmission Electron Microscopy, as well as EDS chemical mapping, revealed that the consolidated sample have bi-continuous MgO-Y2O3 nanostructure with an average grain size of 200 nm.

Thermal and mechanical characterization of polymer composites filled with dispersed zeolite and oil shale

2010 ◽  
Vol 45 (11) ◽  
pp. 1209-1216 ◽  
Author(s):  
A.M. Zihlif ◽  
Ziad Elimat ◽  
G. Ragosta
Keyword(s):  
Thermal Conductivity ◽  
Grain Size ◽  
Yield Stress ◽  
Oil Shale ◽  
Activation Volume ◽  
Filler Concentration ◽  
Grain Sizes ◽  
Eyring Theory ◽  
Zeolite Composite

The thermal, viscoelastic, mechanical behavior of polymers filled with dispersed zeolite and oil shale is studied as a function of temperature, grain size, and filler concentration. It was found that the thermal conductivity of epoxy—zeolite composite increases with different zeolite grain sizes and takes a higher value in case of the 63 μm grain size composite. The observed enhancement in the thermal conductivity of zeolite composites correlates well with that of the electrical conductivity. The thermodynamic results exhibit a slight increase in the glass transition temperature of the polystyrene/oil shale composites, and shift in the observed relaxation peaks with increasing the oil shale content. The plastic deformation of PS/oil shale composites shows that the elastic modulus increases and the compressive yield stress decreases with oil shale content. The Eyring theory of yielding could predict the dependence of the yield stress on the applied strain rate. The predicted activation volume and activation energy showed dependence on the oil shale grains sizes and content.

Structural Characterization of FeAl28Cr5 Alloy Deformed in the Hot Torsion Process

2016 ◽  
Vol 246 ◽  
pp. 43-46 ◽  
Author(s):  
Iwona Bednarczyk ◽  
Magdalena Jabłońska
Keyword(s):  
Plastic Deformation ◽  
Grain Size ◽  
Structural Changes ◽  
Al Alloys ◽  
Dynamic Processes ◽  
Fine Grained ◽  
Average Grain Size ◽  
Fine Grained Structure ◽  
Hot Torsion

Current research in the field of iron aluminides are directed towards to understand the structural phenomena occurring during plastic deformation of these alloys. The obtained results of the study and collected informations will be used to determine the description of the structural changes taking place during hot deformation of Fe ̶Al alloys. The article presents the results of the study of the alloy FeAl28Cr5 deformed by hot torsion in temperature range of 800÷1100°C and a strain rate of 0.1 s-1. The analysis of the structure of the alloy FeAl28Cr5 allowed to reveal changes caused by dynamic processes of deformation. The results of torsion tests show the possibility to obtain a fine-grained structure with of parameters of the processes (T=1000°C, 1100°C) and strain of ε=40. After deformation at strain of (ε=40) the structure consists of fine grains with a misorientation angle higher than 15°, and the average grain size diameter D=28.5 micrometers. Deformation at a temperature of T=1000°C and 1100°C is accompanied by superplastic flow effect.

Studies with the intraruminal selenium pellet. 2. The effect of grain size of selenium on the functional life of pellets in sheep

1981 ◽  
Vol 32 (6) ◽  
pp. 935 ◽  
Author(s):  
DR Hudson ◽  
RA Hunter ◽  
DW Peter
Keyword(s):  
Grain Size ◽  
Progressive Increase ◽  
Coarse Grained ◽  
Elemental Selenium ◽  
Average Composition ◽  
Plasma Selenium ◽  
Iron Selenide ◽  
Fine Grained ◽  
Grain Sizes

Grain size of elemental selenium is a major factor controlling the long-term effectiveness of intraruminal selenium pellets. Microscope studies of polished sections of new and used selenium pellets showed that two commercially manufactured pellets contained selenium with average grain sizes about 4 and 40 �m respectively. Plasma selenium concentrations in sheep treated with pellets containing the coarse-grained selenium were maintained at higher levels over longer periods of time than those measured for sheep treated with pellets with fine-grained selenium. Pellets removed from sheep after 2, 4, 8, 16 and 28 days showed a progressive increase in the degree of alteration of selenium to a compound of average composition (g/100 g) iron, 33.7; selenium, 51.3 ; oxygen, 15.0. After 28 days only a small percentage of elemental selenium remained in pellets with fine-grained selenium, whereas about 50% remained in pellets with coarse-grained selenium. CSIRO prototype pellets, for which long-term effectiveness had been established, also contained coarse-grained selenium, and remnants of selenium were found in pellets that had been in sheep for periods up to 3 years. Selenium, administered in gelatin capsules or as sachets containing glass-selenium mixtures, was stable under the pH-Eh conditions of the rumen, but was rendered unstable in selenium pellets or iron-selenium mixtures by the presence of iron. It is probable that the most rapid release of selenium to the sheep occurs as a result of a chemical reaction involving the oxidation of iron and concomitant alteration of elemental selenium to iron selenide.

Effect of Grain Size on Mechanical Properties of Dual Phase Steels Composed of Ferrite and Martensite

MRS Advances ◽  
2016 ◽  
Vol 1 (12) ◽  
pp. 811-816 ◽  
Author(s):  
Myeong-heom Park ◽  
Akinobu Shibata ◽  
Nobuhiro Tsuji
Keyword(s):  
Mechanical Properties ◽  
Heat Treatment ◽  
Grain Size ◽  
Tensile Test ◽  
Coarse Grained ◽  
Dual Phase ◽  
Fine Grained ◽  
Grain Sizes ◽  
Dp Structure ◽  
Dp Steels

ABSTRACTIt is well-known that dual phase (DP) steels composed of ferrite and martensite have good ductility and plasticity as well as high strength. Due to their excellent mechanical properties, DP steels are widely used in the industrial field. The mechanical properties of DP steels strongly depend on several factors such as fraction, distribution and grain size of each phase. In this study, the grain size effect on mechanical properties of DP steels was investigated. In order to obtain DP structures with different grain sizes, intercritical heat treatment in ferrite + austenite two-phase region was carried out for ferrite-pearlite structures having coarse and fine ferrite grain sizes. These ferrite-pearlite structures with coarse and fine grains were fabricated by two types of heat treatments; austenitizing heat treatment and repetitive heat treatment. Ferrite grain sizes of the specimens heat-treated by austenitizing and repetitive heat treatment were 47.5 µm (coarse grain) and 4.5 µm (fine grain), respectively. The ferrite grain sizes in the final DP structures fabricated from the coarse-grained and fine-grained ferrite-pearlite structures were 58.3 µm and 4.1µm, respectively. The mechanical behavior of the DP structures with different grain sizes was evaluated by an uniaxial tensile test at room temperature. The local strain distribution in the specimens during tensile test was obtained by a digital image correlation (DIC) technique. Results of the tensile test showed that the fine-grained DP structure had higher strength and larger elongation than the coarse-grained DP structure. It was found by the DIC analysis that the fine-grained DP structure showed homogeneous deformation compared with the coarse-grained DP structure.

Advanced Identification and Quantification of In-Bearing Minerals by Scanning Electron Microscope-Based Image Analysis

2017 ◽  
Vol 23 (3) ◽  
pp. 527-537 ◽  
Author(s):  
Kai Bachmann ◽  
Max Frenzel ◽  
Joachim Krause ◽  
Jens Gutzmer
Keyword(s):  
Base Metal ◽  
Metal Sulfide ◽  
Massive Sulfide ◽  
Sulfide Ores ◽  
Grain Sizes ◽  
Mineral Assemblages ◽  
New Strategy ◽  
Automated Mineralogy ◽  
Liberation Analysis

AbstractThe identification and accurate characterization of discrete grains of rare minerals in sulfide base-metal ores is usually a cumbersome procedure due to the small grain sizes (typically <10 μm) and complex mineral assemblages in the material. In this article, a new strategy for finding and identifying indium minerals, and quantifying their composition and abundance is presented, making use of mineral liberation analysis (MLA) and electron probe microanalysis (EPMA). The method was successfully applied to polymetallic massive sulfide ores from the Neves-Corvo deposit in Portugal. The presence of roquesite and sakuraiite could be systematically detected, their concentration quantified by MLA measurements, and their identity later confirmed by EPMA analyses. Based on these results, an almost complete indium deportment could be obtained for the studied samples. This validates the approach taken, combining automated mineralogy data with electron microprobe analysis. A similar approach could be used to find minerals of other common minor and trace elements in complex base-metal sulfide ores, for example Se, Ge, Sb, or Ag, thus permitting the targeted development of resource technologies suitable for by-product recovery.

Grain Size Dependence of the Flow Stress of TWIP Steel

2010 ◽  
Vol 654-656 ◽  
pp. 294-297 ◽  
Author(s):  
Ghasem Dini ◽  
Rintaro Ueji ◽  
Abbas Najafizadeh
Keyword(s):  
Grain Size ◽  
Flow Stress ◽  
Twip Steel ◽  
Strengthening Mechanism ◽  
Mechanical Twinning ◽  
Coarse Grained ◽  
Strengthening Effect ◽  
Fine Grained ◽  
Hardening Behavior ◽  
Grain Sizes

The effect of grain size on the flow stress in TWinning Induced Plasticity (TWIP) steel was investigated via the X-ray diffraction (XRD) measurements of dislocation density. The results indicated that the hardening behavior of fine grained samples (mean grain sizes in the range of 2.1-3.8μm) can be described as typical dislocation interactions. However in coarse grained samples (mean grain sizes in the range of 4.7-38.5μm) where extensive mechanical twinning occurs, another strengthening mechanism is required. Consequently, the effect of grain size on the flow stress parameters of the proposed equation was considered and it was found that in the fine grained samples, the Holloman analysis can describe the hardening behavior. However, in coarse grained samples, a second hardening term due to the strengthening effect of mechanical twin boundaries needs to be added to the Holloman equation.

Polarization Mechanism of Fine-Grained BaTiO3 Ceramics at High Temperature Region

2013 ◽  
Vol 566 ◽  
pp. 12-15
Author(s):  
Takahiro Yamazaki ◽  
Takuya Hoshina ◽  
Hiroaki Takeda ◽  
Takaaki Tsurumi
Keyword(s):  
Grain Size ◽  
High Temperature ◽  
Barium Titanate ◽  
Boundary Effect ◽  
High Temperature Region ◽  
Fine Grained ◽  
Grain Sizes ◽  
Polarization Mechanism ◽  
Sintering Method ◽  
Grain Boundary Effect

Pure Barium titanate (BaTiO3) ceramics with grain sizes of 0.6, 1.5, and 18 μm on average were prepared by using a two-step sintering method. The wideband dielectric spectra in the range from kHz to THz were measured at 25 and 150 °C to understand the polarization mechanism of fine-grained BaTiO3ceramics. It was revealed that the dipole and ionic polarizations decreased with decreasing grain size at 25 and 150 °C when the grain size was smaller than 1 μm. These mechanisms were interpreted as a grain boundary effect.

Fine Grained AZ31 by Conventional Thermo-Mechanical Processing

2009 ◽  
Vol 618-619 ◽  
pp. 239-244
Author(s):  
Nicole Stanford
Keyword(s):  
Grain Size ◽  
Yield Strength ◽  
Fine Grained ◽  
Specific Strength ◽  
Magnesium Alloy Az31 ◽  
Grain Sizes ◽  
Processed Material ◽  
Property Space ◽  
Rolled Condition ◽  
Strength And Ductility

The magnesium alloy AZ31 was processed by severe hot rolling and annealing. This processing was optimised to produce recrystallised grain sizes as small as 2.2μm. Specimens in the as-rolled condition had a grain size of 0.5μm, and exhibited a yield strength in excess of 350MPa. In the fully recrystallised condition, with a grain size of 2.2μm, the material had a yield strength of 260MPa which is almost twice that of the as-received plate. The ductility of the annealed specimens was also increased compared to the as-received condition. The combination of specific strength and ductility brings this newly processed material into a new property space compared to the other light metals.

scholarly journals Challenging Ultra Grain Refinement of Ferrite in Low-C Steel Only by Heat Treatment

2020 ◽  
Vol 7 ◽  
Author(s):  
Myeong-heom Park ◽  
Akinobu Shibata ◽  
Nobuhiro Tsuji
Keyword(s):  
Heat Treatment ◽  
Plastic Deformation ◽  
Grain Size ◽  
Severe Plastic Deformation ◽  
Cyclic Heat Treatment ◽  
Austenite Grain Size ◽  
Fine Grained ◽  
Grain Sizes ◽  
Austenite Grain ◽  
Cyclic Heat

It is well-known that grain refinement is one of the most effective ways to improve strength of metals without addition of alloying elements. In order to obtain bulky metals having ultrafine grained (UFG) microstructures with average grain sizes smaller than 1 μm, severe plastic deformation (SPD) processes have made a great success. However, there are still big barriers to realize UFG metallic materials, especially UFG steels, in large scale industries, since severe plastic deformation processes usually need special techniques and equipment, and large deformation forces are required for heavy plastic deformations. Cyclic heat treatments to repeat martensitic transformation and austenitization have been known as a simple way to fabricate fine-grained austenitic structures in steels. In the present study, we tried to make final ferrite microstructures ultrafine in a low-C steel by means of the cyclic heat treatment. Evolution of microstructures during the cyclic heat treatment was systematically investigated, putting stress on the change of grain sizes of austenite and ferrite. The austenite grain size decreased with increasing the number of heat treatment cycles, and the minimum average austenite grain size obtained was 11 μm. By having furnace-cooling from austenite states with various grain sizes, ferrite microstructures with different mean grain sizes were fabricated. We could successfully obtain a fine-grained ferrite structure with a mean grain size of 4.5 μm and nearly a random texture through the heat treatment without deformation. Microstructural features and mechanical properties of the obtained fine-grained ferritic structures were investigated by scanning electron microscope/electron back-scattering diffraction measurements and a tensile test at room temperature. The specimens with ferrite + pearlite microstructure with the smallest average ferrite grain size of 4.5 μm managed both high strength (yield strength of 375 MPa and tensile strength of 500 MPa) and large tensile ductility (uniform elongation of 20% and total elongation of 39%) in the simple 2Mn-0.1C steel.

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