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Synthesis And Characterization Of Monoacetylferrocene Added Sulfonated Polystyrene IonomersBuyukyagci, Arzu 01 January 2004 (has links) (PDF)
Incorporation of monoacetylferrocene to the sulfonated polystyrene
ionomers imparted some changes in the properties of sulfonated polystyrene.
Sulfonation was carried out by acetic anhydride and concentrated sulphuric acid.
The sulfonation reaction and the degree of sulfonation were determined by
analytical titration and adiabatic bomb calorimeter .
For this purpose, sulfonated polystyrene (SPS) samples with varying
percentages of sulfonation were prepared between 0.85% and 6.51%. Monoacetyl
ferrocene was used in equivalent amount of sulfonation through addition
procedure.
FTIR Spectroscopy was one of the major techniques used to support the
successful addition of AcFe to the SPS samples. Altering the sulfonation degree
did not change the characteristic peak positions, but increased the peak intensities
with increasing the degrees of sulfonation.
Mechanical properties of resultant polymers were investigated. As a result,
elastic modulus of polymers decreased by the amount of monoacetylferrocene.
Thermal characteristic were found by Differential Scanning Calorimeter
(DSC). Thermal analysis revealed that sulfonated polystyrene samples after
addition of monoacetylferrocene displayed lower values of Tg.
Microscopic analysis were made by Scanning Electron Microscopy (SEM)
and single phase for each sample was observed. Besides, energy dispersed micro
analysis showed an increase in the intensity of the iron (II) peaks that is related to
the amount of monoacetylferrocene added to the SPS samples.
Flame retardancy for each polymer was also examined and found that
addition of monoacetylferrocene to sulfonated polystyrene does not change the
Limiting Oxygen Index value (LOI)(17). However, LOI value for polystyrene is
18.
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Efeito do ambiente de sinterização na resistência de união de cerâmicas a ligas de níquel-cromo, cobalto-cromo e titânio comercialmente puro / Effect of firing atmosphere on metal ceramic bond strength of nickelchromium, cobalt-chromium and commercially pure titaniumMilena Teixeira da Rocha 23 November 2012 (has links)
O objetivo deste trabalho foi avaliar o efeito do ambiente de sinterização vácuo e argônio na resistência de união (RUMC) de cerâmicas às ligas de Ni-Cr (Fit Cast SB), Co-Cr (Star Loy C) e titânio comercialmente puro (Tritan). A partir de uma matriz de teflon, foram obtidos 60 padrões de resina/cera em forma de cilindro, com 8 mm de comprimento e 5 mm de diâmetro. Os padrões foram incluídos e os anéis foram levados ao forno e submetidos a ciclos térmicos para a expansão do revestimento. Em seguida, os anéis para fundição em Ni-Cr e Co-Cr foram levados à máquina de fundição por indução eletrônica. Os anéis referentes ao titânio foram levados à máquina de fundição por arco voltaico. Após resfriamento dos anéis, as fundições foram desincluídas e jateadas com óxido de alumínio (100 μm). Depois de recortados dos canais de alimentação, os cilindros metálicos foram preparados para aplicação da cerâmica. Em seguida, foi realizada a aplicação e sinterização da cerâmica à vácuo ou em argônio. Para as ligas alternativas, foi utilizada a cerâmica IPS Classic V e para o titânio, a Triceram. Na sequência, os cilindros compostos pelo metal e disco cerâmico (5 mm de diâmetro e 2 mm de espessura) (n=10) foram submetidos aos ensaios de RUMC por cisalhamento na máquina de ensaios universais com célula de carga de 500 Kg e velocidade do travessão móvel de 0,5 mm/min. Após os ensaios, foram realizadas análises das fraturas por meio de microscopia óptica (MO) (15X) e microscopia eletrônica de varredura (MEV). Os dados de RUMC (MPa) obtidos foram analisados estatisticamente pelos testes ANOVA e Tukey (α=0,05). Os resultados demonstraram que a sinterização à vácuo propiciou obtenção de maiores valores (MPa) de RUMC (76,58) que a sinterização em argônio (51,31). Quanto às ligas avaliadas, as de Ni-Cr e Co-Cr apresentaram maiores valores de RUMC (71,32 e 71,28, respectivamente) que o titânio cp (49,23); sendo que entre elas não houve diferença estatística. Não houve interação entre os fatores avaliados. De acordo com a MO, houve predomínio de fraturas mistas. Segundo a MEV, os espécimes de Ni-Cr e titânio sinterizados a vácuo apresentaram maior rugosidade de superfície do que os sinterizados em argônio. Para a liga de Co-Cr não houve diferença na topografia de superfície. A sinterização em argônio influenciou negativamente a RUMC dos pares metalocerâmicos analisados. / The aim of this study was to evaluate the effect of firing atmospheres: vacuum and argon on the bond strength of ceramic to Ni-Cr (Fit Cast SB), Co-Cr (Star Loy C) and commercially pure titanium (Tritan) alloys. 60 wax/acrylic resin cylinder patterns (8 mm high and 5 mm in diameter) were prepared on a plastic custom mold for metalceramic bond strength (MCBS) test. The patterns were invested in phosphated investment and manipulated on vacuum. The rings were placed in a furnace to burn out patterns and thermally expand the molds. Then, the rings of Ni-Cr and Co-Cr were placed in an electronic machine to cast. The rings related to titanium were positioned in the casting machine with a voltaic arc. After the rings have cooled, the castings were divested manually and abraded with aluminum oxide particles (100 μm). Then, the cylinders were prepared for applying of the ceramic veneering disks. The ceramic was applied and fired in vacuum and argon atmospheres. IPS-Classic ceramic was used for alternative alloys and for titanium, Triceram ceramic. Then, the cylinders composed of metal and ceramic disk (5 mm diameter and 2 mm height) (n=10) were submitted to metal-ceramic bond strength (MCBS) shear tests on an universal testing machine with load cell of 500 Kg at a crosshead speed of 0.5 mm/min. After the tests, there were made fracture analysis by optic microscopy (OM) and scanning electron microscopy (SEM). The MCBS data (MPa) were statistically analyzed by the ANOVA and Tukey test (α=0.05). The results indicated that the vacuum firing (76.58) promoted higher MCBS values than argon firing (51.31). Among the metals, Ni-Cr and Co-Cr alloys presented higher MCBS (71.32 e 71.28, respectively) than titanium (49.23); between two base alloys there was no statistical difference. There was no interaction between the evaluated factors. According to MO analysis, there was predominance of mixed fractures. According SEM, the Ni-Cr and titanium specimens submitted to vacuum presented higher surface roughness than the specimens submitted to argon. For Co-Cr, there was no difference of surface topography. The argon firing influenced negatively the MCBS of metal-ceramic evaluated pairs.
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An investigation into the effect of different types of antiscalant on desalination reverse osmosis (Ro) membrane fluxShames, Elhashmi Adel January 2012 (has links)
Thesis (MTech (Chemical Engineering))--Cape Peninsula University of Technology, 2012. / Recently much research and development has been done into the creation of desalination
systems in South Africa, with particular emphasis on the commercialisation of desalination
plants that serve local communities. This has been successful - there are currently plants
running at Bitlerfontien, Bushmans River Mouth and Robben Island - although membrane
fouling and scaling remains a problem associated with membrane desalination, as it does
worldwide
The aim of this study was to Investigate the performance of different type of antiscalants
on artificially scaled membranes which we prepared inside the lab as well as on scaled
membranes which were used in pilot plant. We used two type of anti-sealants in our
research: Vitec 3000 and Zinc ions. The effects of these anti-sealants on the membrane
were determind and the RO performances of the treated and untreated membrane
compared.
A suitable autopsy procedure was established and was then used to autopsy the XLE
4040 membranes. The autopsied membranes were characterized by scanning electron
microscopy (SEM) and optical microscopy (OM). The SEM and OM results clearly showed
that scaling had taken place: deposits were observed for both the shell and core samples,
which were not present in the images of the untreated membrane, especially when
looking at high SEM images magnification.
Results also showed that the anti-sealants reduced the fouling and scaling on the
membrane surface. As a result, the membrane rejection improved. Rejection and flux
results indicated that commercial anti-sealant was more effective in preventing scaling
than the Zinc ions. For Vitec anti-sealant case, the flux was in steady state at 36.8 Imh
(5% less) after 5 hours compared to around 35 Imh (8% less) for zinc ions case. In
addition; SEM images showed that less deposited particles are formed when the
membrane was treated with commercial anti-sealant.
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Desenvolvimento de teste in-situ de deformação a alta temperatura no MEV e sua aplicação no estudo do fenomeno de fratura por queda de ductilidade em ligas de niquel / Development of SEM in-situ high temperature-deformation test and its application to the study to the study of ductility dip cracking phenomemon on Ni-base alloysTorres Lopez, Edwar Andres 25 February 2008 (has links)
Orientadores: Antonio Jose Ramirez, Rubens Caram Junior / Dissertação (mestrado) - Universidade Estadual de Campinas, Faculdade de Engenharia Mecanica / Made available in DSpace on 2018-08-11T13:06:54Z (GMT). No. of bitstreams: 1
TorresLopez_EdwarAndres_M.pdf: 39783627 bytes, checksum: 03310e12f2969671a1edcad6da907e3b (MD5)
Previous issue date: 2008 / Resumo: Foi desenvolvido um experimento para estudo in-situ dos processos de deformação a alta temperatura no interior do microscópio eletrônico de varredura, permitindo assim o estudo do fenômeno de trincamento a alta temperatura, denominado fratura por queda de ductilidade. Este experimento teve como finalidade o estudo específico das ligas de níquel AWS A5.14 ERNiCrFe-7 e ERNiCr-3AWS empregadas como metal de aporte para a soldagem de ligas de Ni. Instrumentação cientifica dedicada foi desenvolvida e modificada de modo a superar os desafios impostos pelas condições experimentais adversas associadas as elevadas temperaturas necessárias, à compatibilização do experimento com o nível de vácuo necessário na câmera do microscópio e finalmente, à estabilidade mecânica necessária para o acompanhamento do processo de deformação em escala micrométrica juntamente com os processos de aquecimento e de aplicação de forças elevadas. Utilizando esta instrumentação foram definidas as condições e procedimentos adequados para o acompanhamento do processo de deformação das ligas de Ni AWS A5.14 ERNiCrFe-7 e ERNiCr-3 em temperaturas entre 700 e 1000 °C, de forma a estudar as condições de inicio da fratura por queda de ductilidade nestes materiais. Porém, a instrumentação desenvolvida permite não apenas estudar o fenômeno de fratura por queda de ductilidade e avaliar o desempenho de ligas experimentais, mas também o estudo tanto qualitativo como quantitativo de diversos outros fenômenos de fratura e transformação de fase / Abstract: An in-situ high temperature deformation experiment was developed and adapted be performed within the vacuum chamber of a scanning electron microscope in order to study the high temperature cracking phenomenon known as ductility-dip cracking. This experiment was specifically applied to the study of Ni-base alloys AWS A5.14 ERNiCrFe-7 e ERNiCr-3, which are commonly used as filler metal to weld Ni- and Fe- based alloys. Dedicated scientific instrumentation was developed and modified to overcome the challenges imposed by the severe experimental conditions as elevated temperatures and forces, the compatibleness with the microscope vacuum chamber, and the required mechanical stability to track deformation processes at the micro scale. Using this instrumentation were defined and optimized the conditions to study the deformation of Ni-base alloys AWS A5.14 ERNiCrFe-7 e ERNiCr-3 alloys between 700 and 1000 °C and therefore, helps to elucidate the causes of ductility-dip cracking phenomenon . However, the developed instrumentation is a powerful tool to perform several other qualitative and quantitative studies of deformation, cracking phenomena and phase transformations in different materials / Mestrado / Materiais e Processos de Fabricação / Mestre em Engenharia Mecânica
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A systematic appraisal of the Eriophyoidea (Acari Prostigmata)Craemer, Charnie 18 October 2011 (has links)
The diversity of the Eriophyoidea is largely unknown and their systematic study mostly entails alpha-taxonomy which is critically important for these mites. Eriophyoid morphology is almost exclusively studied on slide-mounted specimens, and truly permanent specimen slides cannot be prepared and are eventually lost. Shortcomings in taxon descriptions are persistent, and too few morphological characters are available for systematic use, particularly for phylogenetic studies. The fragile, simplified and minute eriophyoid bodies, and the inadequacy of study methods and technology, including preparation and light microscopy, contribute to these problems. The present eriophyoid classification is widely accepted, relatively stable and useful. The major part of the classification, however, is probably artificial, and some taxon delimitations and identifications are becoming increasingly difficult. Scanning electron microscopy (SEM) is only sporadically used to supplement conventional descriptions of eriophyoid mites, and their phylogeny has hardly been studied. In the present study some aspects of eriophyoid systematics and its improvements by incorporating SEM for morphological study and phylogenetic analyses for testing and improving the naturalness of the present eriophyoid classification, are used and appraised. The morphology of about 64 species, mostly from South Africa, was studied with low-temperature (cryo) SEM. The specimens remained turgid and the shape of the mites largely unaltered. A general overview of the contribution of the SEM study towards systematic morphology of the Eriophyoidea is presented. Discrepancies between species descriptions from slide-mounted specimens and the SEM images were found. These include body form, interpretation of structures, resolution and information on minute morphology, and the presence of secretions. Some of these differences were caused by artefacts introduced with slide-mounting of specimens. The SEM study includes a comparative morphological study of the gnathosoma, including a review and appraisal of characters presently used in eriophyoid systematics. New morphological information was found, including new characters that may be of systematic use. Morphology studied with SEM should be routinely incorporated into eriophyoid descriptions, which is not presently the case. The phylogeny of the Eriophyoidea was studied at genus level, using morphological data, to test the monophyly of the present suprageneric taxa. Three data matrices with 66, 60 and 27 informative characters of 316 (including most Diptilomiopus spp.), 64 and 17 eriophyoid ingroup species respectively were analyzed with parsimony analyses, and trees were searched under different parameters. This was done to find different hypotheses regarding the taxon relationships, to roughly assess the robustness of the tree groups, and to use different approaches: a very comprehensive taxon sample, but with low ratio of characters to taxa; an exemplar species sample to improve the ratio between characters to taxa; and a very small taxon sample with a good ratio between characters and taxa, but very little inclusion of variation found in the Eriophyoidea. Most groups found were supported only by homoplasy, but many made biological sense and various potentially monophyletic groups, additional to taxa in the present classification, are proposed for further study. The robustness and convergence of these groups on monophyly are discussed. The Phytoptidae was found to be polyphyletic. Part of the Nalepellinae is probably positioned outside the remainder of the Eriophyoidea, while the rest of the Phytoptidae were positioned in smaller subgroups among the Eriophyidae. The Phytoptinae and Sierraphytoptinae, including Pentasetacus, may group together. The Eriophyidae never grouped together with much support, and the family is both polyphyletic and paraphyletic. The Diptilomiopidae was largely found to be monophyletic, with a relatively strong phylogenetic structure. The Rhyncaphytoptinae is mainly paraphyletic, and the Diptilomiopinae polyphyletic, but part of the Diptilomiopinae may be monophyletic. Three new Diptilomiopus spp. from South Africa are described as part of the study: D. faurius sp. nov. from Faurea rochetiana (A. Rich.) Pic. Serm. (Proteaceae); D. apobrevus sp. nov. and D. apolongus sp. nov. from Apodytes dimidiata E. Mey. ex Arn. (Icacinaceae). They were leaf vagrants not causing any observable symptoms. / Thesis (PhD)--University of Pretoria, 2011. / Zoology and Entomology / unrestricted
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[en] THE EFFECT OF SURFACE ON NITI FILES SUBJECTED TO TORSION LOADING / [pt] EFEITO DO TRATAMENTO SUPERFICIAL EM LIMAS DE NITI SUBMETIDOS A CARREGAMENTO EM TORÇÃOJULIO CESAR DE AZEVEDO CARVALHAL 10 February 2005 (has links)
[pt] Limas de NiTi Profile® 25/.04 após sua usinagem não
recebem tratamento superficial de polimento gerando pontos
concentradores de tensão conseqüente áreas de trinca e
fraturas. Avaliou-se o efeito de diferentes condições
superficiais de limas endodônticas na resistência à
torção. Foram avaliadas e caracterizadas por Microscopia
Eletrônica de Varredura dezoito limas rotatórias de NiTi
Profile® 25/.04. Utilizou-se 6 limas que não foram
submetidas a tratamento químico (Grupo I), 6 limas
tratadas com Ácido Nítrico 8% e Ácido Fluorídrico 4% em
solução durante 2 minutos (Grupo II) e 6 limas tratadas
com a mesma solução porém em tempo de 2 minutos e trinta
segundos (Grupo III). Analisaram-se as limas com e sem
tratamento superficial carregadas em ensaio de torção e
suas fractografias em Microscopia Eletrônica de Varredura.
As variáveis avaliadas foram torque aplicado no momento da
fratura e ângulo máximo de rotação até a fratura. Os
valores obtidos nos ensaios mecânicos referentes ao ângulo
máximo de rotação e torque máximo foram analisados
estatisticamente através do teste estatístico T-student.
Os resultados obtidos permitem concluir que houve
diferença estatisticamente significante quanto aos valores
de torque máximo entre o Grupo II e Grupo III e ângulo
máximo entre os Grupos I e III. / [en] NiTi Profile® 25/.04 files do not undergo surface
polishing treatments after machining, and therefore
exhibit local stress concentrators and, consequently,
areas of cracking and fractures. The effect of different
surface conditions on the torsional strength of endodontic
files were evaluated. 18 NiTi Profile® 25/.04 rotary files
were examined by scanning electron. A group of 6 files
(Group I) were not subjected to any chemical treatment,
another group of 6 (Group II) were treated for 2 minutes
using a solution of 8% Nitric Acid, 4% Flouridic Acid, and
a further 6 (Group III) were treated with the same
solution fot 2.5 minutes. All the file, with and without
treatment, were loaded in a torsion test and fractography
of the samples was undertaken by scanning electron
microscopy. The variables investigated were, torque at
fracture and maximum angle of rotation at fracture. The
results obtained in these mechanical tests were subjected
to a statistical analysis utilizing the T-Student test. It
can be concluded from these results that there was a
statistically significant difference between the maximum
torque results for groups II and III, and between the
maximum angle results for groups I and III.
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Povrchová analýza nanokompozitu xGnP/PEI / Surface analysis of xGnP/PEI nanocompositeČervenka, Jiří January 2012 (has links)
Tato Diplomová práce se zabývá povrchovou analýzou nanokompozitní folie polyetherimidu (PEI) vyztuženého exfoliovanými grafitickými nanodestičkami (xGnP). Analyzovány byly take vzorky nevyztužené PEI folie a samostatné nanodestičky. Vzorky nanokompozitu a PEI folie byly plazmaticky leptány s využitím argonového plazmatu po dobu 1, 3 a 10 hod. Skenovací elektronová mikroskopie (SEM) byla použita pro charakterizaci samostatných nanodestiček rozptýlených na křemíkovém substrátu, původních či leptaných vzorků PEI folie a nanokompozitu. Nanodestičky byly identifikovány při povrchu leptané nanokompozitní folie. Mikroskopie atomárních sil (AFM) byla použita pro zobrazení povrchové topografie separovaných nanodestiček a odkrytých destiček při povrchu leptaného kompozitu. Povrchová drsnost (střední kvadratická hodnota, vzdálenost nejnižšího a nejvyššího bodu) leptaného nanokompozitu narůstala s prodlužující se dobou leptání. Akustická mikroskopie atomárních sil (AFAM) byla použita pro charakterizaci elastické anizotropie leptaných kompozitních vzorků. Nanoindentační měření umožnila charakterizaci lokálních mechanických vlastností PEI a nanokompozitních folií.
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Bacterial Growth on Metal and Non-metal Surfaces in a Static BioreactorLiong, Rolan Yuk Loong 01 March 2013 (has links) (PDF)
Research was conducted to observe bacterial growth on the surface of metals in a static bioreactor. Metal and non-metal samples were subjected to bacterial exposure (1 day and 9 days). The metal samples were surface treated prior to bacterial exposure. The microstructures of the surface treated samples were analyzed by optical microscopy. After exposure, the microstructures of the samples were analyzed by scanning electron microscopy (SEM). The analysis suggested that microbial attachment on the surface was related to the underlying microstructure of steel. The preferential attachment of microbes could potentially be influenced by cathodic and anodic regions created by the electrolytic cells.
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In Situ Nanoindentation at Elevated HumiditiesTadayon, Kian, Bar-On, Benny, Günther, Björn, Vogel, Cordula, Zlotnikov, Igor 17 September 2024 (has links)
Nanoindentation is one of the most widespread methods to measure the mechanical performance of complex materials systems. As it allows for local characterization of composite architectures with sub-micron spatial features and a large range of properties, nanoindentation is commonly used to measure the properties of biological materials. In situ nanoindentation, a further development of the approach, is a powerful tool for the analysis of plastic deformation and failure of materials. Here, samples can be mechanically manipulated using the indenter, while their behavior is monitored with the resolution of a scanning electron microscope (SEM). Indeed, numerous studies demonstrate the potential of this approach for studying the most fundamental material characteristics. However, so far, these measurements are performed in high-vacuum conditions inherent to the conventional electron microscopy method, which are irrelevant when studying biological structures that evolved to perform in hydrated conditions. In this work, the ability to conduct nanoindentation experiments under controlled humidity and temperature inside an environmental SEM is developed. This technique has the potential to become crucial for materials design and characterization in many domains where humidity has a significant impact on performance. These include organic/polymer systems, microelectronic and optoelectronic devices, materials for catalysis, batteries, and many more.
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Development and Implementation of an Automated SEM-EDX Routine for Characterizing Respirable Coal Mine DustJohann, Victoria Anne 02 November 2016 (has links)
This thesis describes the development and use of a computer-automated microscopy routine for characterization of respirable dust particles from coal mines. Respirable dust in underground coal mining environments has long been known to pose an occupational health hazard for miners. Typically following years of exposure, coal workers' pneumoconiosis (CWP) and silicosis are the most common disease diagnoses. Although dramatic reductions in CWP and silicosis cases were achieved across the US between about 1970-1999 through a combination of regulatory dust exposure limits, improved ventilation and dust abatement practices, a resurgence in disease incidence has been noted more recently – particularly in parts of Appalachia. To shed light on this alarming trend and allow for better understanding of the role of respirable dust in development of disease, more must be learned about the specific characteristics of dust particles and occupational exposures.
This work first sought to develop an automated routine for the characterization of respirable dust using scanning electron microscopy with energy dispersive x-ray (SEM-EDX). SEM-EDX is a powerful tool that allows determination of the size, shape, and chemistry of individual particles, but manual operation of the instrument is very time consuming and has the potential to introduce user bias. The automated method developed here provides for much more efficient analysis – with a data capture rate that is typically 25 times faster than that of the manual method on which it was based – and also eliminates bias between users. Moreover, due to its efficiency and broader coverage of a dust sample, it allows for characterization of a larger and more representative number of particles per sample. The routine was verified using respirable dust samples generated from known materials commonly observed in underground coal mines in the central Appalachian region, as well as field samples collected in this region. This effort demonstrated that particles between about 1-9μm were accurately classified with respect to defined chemical categories, and suggested that analysis of 500 particles across a large area of a sample filter generally provides representative results.
The automated SEM-EDX routine was then used to characterize a total of 210 respirable dust samples collected in eight Appalachian coal mines. The mines were located in three distinct regions (i.e., northern, mid-central and south-central Appalachia), which differed in terms of primary mining method, coal seam thickness and mining height, and coal and/or rock mineralogy. Results were analyzed to determine whether number distributions of particle size, aspect ratio, and chemistry classification vary between and within distinct mine regions, and by general sampling location categories (i.e., intake, feeder, production, return). Key findings include:
1) Northern Appalachian mines have relatively higher fractions of coal, carbonate, and heavy mineral particles than the two central Appalachian regions, whereas central Appalachian mines have higher fractions of quartz and alumino-silicate particles.
2) Central Appalachian mines tended to have more mine-to-mine variations in size, shape, and chemistry distributions than northern Appalachian mines.
3) With respect to particle size, samples collected in locations in the production and return categories have the highest percentages of very small particles (i.e., 0.94-2.0μm), followed by the feeder and then the intake locations.
4) With respect to particle shape, samples collected in locations in the production and return categories have higher fractions of particles with moderate (i.e., length is 1.5 to 3x width) to relatively high aspect ratios (i.e., length is greater than 3x width) compared to feeder and intake samples.
5) Samples with relatively high fractions of alumino-silicates have higher fractions of particles with moderate aspect ratios than samples with low alumino-silicate fractions.
6) Samples with relatively high fractions of quartz particles have higher fractions of particles with moderate aspect ratios and higher percentages of very small particles than samples with no identified quartz particles.
7) Samples with high fractions of carbonates have higher percentages of particles with relatively low aspect ratios (i.e., length and width are similar) than samples with no identified carbonate particles. / Master of Science / This thesis describes the development and use of a computer-automated microscopy routine for characterization of respirable dust particles from coal mines. Overexposure to respirable dust has long been known to pose an occupational health hazard for miners, leading to the development of lung diseases such as coal workers’ pneumoconiosis (CWP, commonly called “black lung”) and silicosis. Incidence of such diseases amongst US coal miners declined for many years following regulation and development of mining best practices. However, a recent resurgence in disease incidence, particularly in parts of Appalachia, demonstrates a real need for greater understanding of the respirable dust in underground coal mines.
This work first sought to develop an automated routine for characterizing coal mine dust using scanning electron microscopy with energy dispersive x-ray (SEM-EDX). SEM-EDX is a powerful tool that allows the size, shape and chemistry of individual particles to be determined. The developed routine is not only much faster than an analogous manual method, but it also reduces the possibility of user bias and provides for more representative results by examining more particles across a wider area of a sample. The method was verified using laboratorygenerated dust samples from known materials commonly observed in underground coal mines, as well as field samples collected in central Appalachia. This effort indicated that the method produces accurate and representative results.
Next, the automated SEM-EDX method was used to scan 210 respirable dust samples. These were collected in eight mines in three different regions of Appalachia (i.e., northern, midcentral and south-central Appalachia), which differed by primary mining method, coal seam thickness and mining height, and coal and/or rock mineralogy. Results were analyzed to determine whether particle size, shape, and chemistry number distributions vary between and within distinct mine regions, and by general sampling location categories (i.e., intake, feeder, production, return). Key findings include:
1) Northern Appalachian mines have relatively higher fractions of coal, carbonate, and heavy mineral particles than the two central Appalachian regions, whereas central Appalachian mines have higher fractions of quartz and alumino-silicate particles.
2) Central Appalachian mines tended to have more mine-to-mine variations in size, shape, and chemistry distributions than northern Appalachian mines.
3) With respect to particle size, samples collected in locations in the production and return categories have the highest percentages of very small particles (i.e., 0.94-2.0μm), followed by the feeder and then the intake locations.
4) With respect to particle shape, samples collected in locations in the production and return categories have higher fractions of particles with moderate (i.e., length is 1.5 to 3x width) to relatively high aspect ratios (i.e., length is greater than 3x width) compared to feeder and intake samples.
5) Samples with relatively high fractions of alumino-silicates have higher fractions of particles with moderate aspect ratios than samples with low alumino-silicate fractions.
6) Samples with relatively high fractions of quartz particles have higher fractions of particles with moderate aspect ratios and higher percentages of very small particles than samples with no identified quartz particles.
7) Samples with high fractions of carbonates have higher percentages of particles with relatively low aspect ratios (i.e., length and width are similar) than samples with no identified carbonate particles.
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