Grain-size characterization of reworked fine-grained aeolian deposits

2018 ◽  
Vol 177 ◽  
pp. 43-52 ◽  
Author(s):  
J. Vandenberghe ◽  
Y. Sun ◽  
X. Wang ◽  
H.A. Abels ◽  
X. Liu
Keyword(s):  
Grain Size ◽  
Fine Grained ◽  
Aeolian Deposits ◽  
Size Characterization

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.

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.

Grain-size distribution of Italian raw materials for building clay products: a reappraisal of the Winkler diagram

Clay Minerals ◽  
1998 ◽  
Vol 33 (3) ◽  
pp. 435-442 ◽  
Author(s):  
M. Dondi ◽  
B. Fabbri ◽  
G. Guarini
Keyword(s):  
Grain Size ◽  
Size Distribution ◽  
Grain Size Distribution ◽  
Raw Materials ◽  
New Classification ◽  
X Ray ◽  
Size Characterization ◽  
Good Behaviour ◽  
Hollow Bricks

AbstractThe grain size of raw materials influences their behaviour during the technological process and affects many properties of building clay products. Over the last few years, brickworks have been technologically updated and grain size requirements have been modified to ensure good behaviour during shaping and drying. Therefore, the reference schemes used to assess the suitability of clays, such as the classic Winkler diagram, should be updated.For this purpose, the grain-size distribution of 350 clays currently used in ~240 Italian plants was determined by X-ray monitoring of gravity sedimentation. Raw materials are basically represented by silty clays and clayey silts, while bodies present a narrower grain-size range. With reference to the Winkler diagram, most of the Italian bodies fall within the field of ‘thin-walled hollow bricks’, with no significant differentiation among the various product types.In order to improve the grain-size characterization of bodies, a new classification scheme for Italian raw materials is proposed, based on three ranges: >10 µm, 2-10 µm and <2 µm, respectively. It allows distinction of specific grain-size features of bodies for (a) facing bricks; (b) roofing tiles; and (c) lightweight blocks, paving bricks and hollow slabs.

scholarly journals Grain Size Characterization of Ceramic Matrix Composites

2021 ◽  
Vol 11 (4) ◽  
pp. 317-322
Author(s):  
Gao Xiang ◽  
◽  
Tan Rong ◽  
Guanghui Li ◽  
Leijiang Yao
Keyword(s):  
Grain Size ◽  
Materials Science ◽  
Image Data ◽  
Ceramic Matrix Composites ◽  
Ceramic Matrix ◽  
Matrix Composites ◽  
Bounding Box ◽  
Size Characterization ◽  
Bounding Boxes

In the field of materials science, the mesoscopic geometry of materials is of great significance for the research and development of materials and materials. This paper mainly focuses on the image data of existing ceramic matrix composites, and studies the characterization method of grain image of ceramic matrix, which realizes the accurate characterization of grain size. It has important practical research on the mesostructure of ceramic matrix composites. Value. Taking the SEM grain image of 5μm resolution of self-toughening silicon nitride (Si3N4) ceramic as an example, the grain image is segmented by median filtering, image binarization and watershed algorithm, and then used to directional bounding box (Oriented). The Bounding Boxes, OBB) algorithm finds the rectangular outline bounding box of the grain, enabling accurate measurement and statistics of the grain size.

scholarly journals Dislocation Mechanics Pile-Up and Thermal Activation Roles in Metal Plasticity and Fracturing

Metals ◽  
2019 ◽  
Vol 9 (2) ◽  
pp. 154 ◽  
Author(s):  
Ronald Armstrong
Keyword(s):  
Grain Size ◽  
Thermal Activation ◽  
Crack Size ◽  
Dislocation Model ◽  
Square Root ◽  
Steel Material ◽  
Dislocation Mechanics ◽  
Pile Up ◽  
Size Characterization

Dislocation pile-up and thermal activation influences on the deformation and fracturing behaviors of polycrystalline metals are briefly reviewed, as examples of dislocation mechanics applications to understanding mechanical properties. To start, a reciprocal square root of grain size dependence was demonstrated for historical hardness measurements reported for cartridge brass, in line with a similar Hall-Petch grain size characterization of stress-strain measurements made on conventional grain size and nano-polycrystalline copper, nickel, and aluminum materials. Additional influences of loading rate (and temperature) were shown to be included in a dislocation model thermal activation basis, for calculated deformation shapes of impacted solid cylinders of copper and Armco iron materials. Connection was established for such grain size, temperature, and strain rate influences on the brittle fracturing transition exhibited by steel and other related metals. Lastly, for AISI 1040 steel material, a fracture mechanics based failure stress dependence on the inverse square root of crack size was shown to approach the yield stress at a very small crack size, also in line with a Hall-Petch dependence of the stress intensity on polycrystal grain size.

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