Scanning Electron Microscopy Image Processing Research Articles

SEM Image Processing Assisted by Deep Learning to Quantify Mesoporous γ-Alumina Spatial Heterogeneity and Its Predicted Impact on Mass Transfer.

The pore network architecture of porous heterogeneous catalyst supports has a significant effect on the kinetics of mass transfer occurring within them. Therefore, characterizing and understanding structure-transport relationships is essential to guide new designs of heterogeneous catalysts with higher activity and selectivity and superior resistance to deactivation. This study combines classical characterization via N2 adsorption and desorption and mercury porosimetry with advanced scanning electron microscopy (SEM) imaging and processing approaches to quantify the spatial heterogeneity of γ-alumina (γ-Al2O3), a catalyst support of great industrial relevance. Based on this, a model is proposed for the spatial organization of γ-Al2O3, containing alumina inclusions of different porosities with respect to the alumina matrix. Using original, advanced SEM image analysis techniques, including deep learning semantic segmentation and porosity measurement under gray-level calibration, the inclusion volume fraction and interphase porosity difference were identified and quantified as the key parameters that served as input for effective tortuosity factor predictions using effective medium theory (EMT)-based models. For the studied aluminas, spatial porosity heterogeneity impact on the effective tortuosity factor was found to be negligible, yet it was proven to become significant for an inclusion content of at least 30% and an interphase porosity difference of over 20%. The proposed methodology based on machine-learning-supported image analysis, in conjunction with other analytical techniques, is a general platform that should have a broader impact on porous materials characterization.

Quantifying cracking and strain localisation in a cold spray chromium coating on a zirconium alloy substrate under tensile loading at room temperature

The mechanical and cracking behaviour of a Cr coating, deposited on an Optimized ZIRLOTM substrate using the Cold Spraying (CS) technique, was investigated by in-situ scanning electron microscopy (SEM) tensile testing at room temperature. To achieve this, curved micro-tensile samples were machined from cladding tubes, and a styrene-assisted gold remodelled pattern was applied on the coating surface. The macroscopic crack density of the coating with applied axial strain was quantified through automated SEM image processing, whilst the localisation of strain was monitored with High Resolution Digital Image Correlation (HRDIC). Like with most brittle thin films deposited on ductile substrates, under applied external stress, parallel crack channelling appeared on the coating surface, perpendicular to the loading direction. The first crack was captured at 0.5% axial strain, whilst saturation was observed at 1.5%. Single crack formation in the coating was found to cause relaxation of local strains and redistribution towards the uncracked segment's midpoint. The local fracture strain of the coating was found to increase with the decreasing crack spacing, whilst shear bands appeared on the coating's surface at 35° and 145° with respect to the loading direction, which is evidence of plastic deformation. The crack density of the curved sample geometry was correlated with the tubes using a modified shear-lag model, considering the residual stresses in the coating measured by X-ray Diffraction (XRD). The CS Cr coating showed high levels of bonding and mechanical interlocking with the substrate, even after 3% axial strain.

Study of the Macro and Micro Characteristics of and Their Relationships in Cemented Backfill Based on SEM

Nuclear magnetic resonance can only quantitatively obtain porosity and pore size distribution, but as a conventional microstructure observation technology, scanning electron microscope (SEM) can select different magnifications to observe the microstructure of backfill materials. However, the processing of SEM images is not deep enough. In this paper, Image-Pro Plus 6.0 software was used to extract the data from SEM images, and the parameters of the area, and the perimeter, aspect ratio and roundness of the pores in the SEM images were obtained. The fractal characteristics of the pores in the SEM image were obtained by using the slit island method fractal theory. The concretization and quantification analysis of the pores’ complexity were achieved. A functional relationship model for the strength and pore parameters was constructed; thus, the influence law of pore characteristics on strength was quantitatively analyzed. The conclusions included: (1) Pore parameters indicate that most pores in backfill are irregular, and only a few pores are regular—however, the whole structure has good fractal characteristics (R2 > 0.96). (2) The fractal dimension of pores is directly proportional to the roundness, the aspect ratio, and the pore content of pores—which indicates that the complexity of pores is related to both pore shape and pore content. (3) The strength had a linear inverse relationship with the roundness, aspect ratio, pore content, and fractal dimension—which indicates that all characteristics of pores have a certain influence on the strength.

Interfacial delamination of porous thermal barrier coatings based on SEM image processing in finite element model

Numerical analysis of interfacial delamination and the effect of microstructural pores and rough interfaces on the field variables in thermal barrier coatings (TBCs) based on a real scanning electron microscope (SEM) image is performed. The interfacial delamination is modelled by the utilization of cohesive zone method (CZM) in finite element (FE) analysis. The empirical TBC sample considered in this study is constructed via air plasma spray (APS) method and comprises ZrO27-8wt.%Y2O3 ceramic top coat (TC), thermally grown oxide (TGO) made of Al2O3 and NiCrAlY metallic bond coat (BC). A compatible geometry is provided by applying image processing technique to SEM image of the sample's cross-section. SEM image-based geometry imported into FE software to scrutinize the interplay effects of porosity and rough interfaces on temperature fields, thermal stresses and interfacial debonding of TC/TGO and TGO/BC interfaces of the TBC structure. FE analysis reveal that porosity distribution has a prominent role on the stress concentration zones at the sharp corners of pores especially adjacent to undulations of the TC/TGO interface, which is responsible for possible internal cracks and interfacial fracture, respectively. The main findings demonstrate that the porosity near the TC/TGO interface has detrimental effect as leads to aggravation in the TC/TGO interface damage, which causes an increment in TC/TGO interfacial crack length. While, the porosity within the BC has the ability to reduce the stress and damage level along the TGO/BC interface. In addition, considering creep for all layers leads to lower stress levels up to 24.82 % and consequently alleviates the TC/TGO interface damage.

Effect of curing pressure on the stability of bottom cemented paste backfill under different types of barricade

In this paper, a multi-physical field coupling curing experimental instrument was developed to study the effect of curing pressure on the stability of bottom cemented paste backfill (CPB) under two different barricades. The effect mechanism was analyzed by using 5TE, MPS-6 sensor, scanning electron microscope (SEM), and binary processing of SEM images. And then, the strength prediction model of CPB under different curing conditions was established. The findings show that the strength of CPB increases with curing pressure regardless of permeable or impermeable barricade, and the relationship between CPB strength and curing pressure conforms to the law of linear function, and the change law of strength grow rate can also be expressed by a linear function. The curing pressure will accelerate the hydration reaction rate and compress the internal pores of the CPB, making the structure of the CPB more denser, thus promoting the formation of strength. It is worth noting that after the curing pressure was increased to 600 kPa, the strength growth rate of CPB slowed down in the later period, and obvious cracks appeared in the bottom CPB during sampling. The results will be helpful to better consider setting different types of barricade at different stope heights

Mechanical properties and microscopic characterization of cement stabilized calcareous sand modified by nano SiO2

The accessible crushing property of calcareous sand leads to poor mechanical properties. Cement is usually used for solidification treatment in engineering. Nano-SiO2 (NS) can further improve the strength of cement-stabilized calcareous sand (CCS). In this study, the mechanical research of NS modified CCS is carried out through unconfined compression strength (UCS) test, split tensile strength (STS) test, and one-dimensional consolidation (ODC) test. The results show that when the CCS was solidified with 4.5‰ NS, the unconfined compressive strength reaches the maximum after 7–14 days of solidification, and the strengthening effect of NS is reflected in the early hydration stage. The addition of NS increased the splitting tensile strength at 7 days and 14 days by 100% and 48%,respectively. The ratio of splitting tensile strength to unconfined compressive strength was about 0.11, which was consistent with the curing law of solidified soil. Moreover, the addition of NS can reduce the compression coefficient of the sample, improve the compression modulus, and improve the compressive deformation resistance of CCS. The scanning electron microscopy (SEM) was used to study the microscopic mechanism. SEM test showed that the addition of NS produced more needle-like hydrates, and the nucleation effect of NS made the hydrates more tightly cemented. The porosity was obtained after the binary processing of SEM images, and the relationship model between the microstructure parameter porosity and UCS was established.

Measuring the randomness of micro- and nanostructure spatial distributions: Effects of scanning electron microscope image processing and analysis.

The quantitative characterisation of the degree of randomness and aggregation of surface micro- and nanostructures is critical to evaluate their effects on targeted functionalities. To this end, the methods of point pattern analysis (PPA), largely used in ecology and medical imaging, seem to provide a powerful toolset. However, the application of these techniques requires the extraction of the point pattern of nanostructures from their microscope images. In this work, we address the issue of the impact that Scanning Electron Microscope (SEM) image processing may have on the fundamental metric of PPA, that is, the Nearest Neighbour Index (NNI). Using typical SEM images of polymer micro- and nanostructures taken from secondary and backscattered electrons, we report the effects of the (a) noise filtering and (b) binarisation threshold on the value of NNI as well as the impact of the image finite size effects. Based on these results, we draw conclusions for the safe choice of SEM settings to provide accurate measurement of nanostructure randomness through NNI estimation.

Multiscale Fractal Characterization of Pore Structure for Coal in Different Rank Using Scanning Electron Microscopy and Mercury Intrusion Porosimetry

Multiscale fractal analysis of the pore system for coal is necessary to obtain more inner information. The techniques of Scanning Electron Microscopy (SEM) and Mercury Intrusion Porosimetry (MIP) are combined to characterize the pore structure of natural coal. A total of eight coal samples, of a different rank and coalification degree, are prepared for experiments. Methods of SEM image processing, piecewise curve-fitting and correction of intrusion data are adopted to obtain more useful results. According to the pore size range of the MIP probe, pores in coal are classified as seepage pore (pore size ≥ 1000 nm), transition pore (pore size ≥ 50 nm and <1000 nm) and mesopore (pore size < 50 nm). Variations of multi-scale fractal dimensions are studied from the perspective of coalification degree or coal rank. Fractal dimension from SEM data (D1) and fractal dimensions of seepage pore, transition pore and mesopore (D2, D′2 and D″2) from MIP data are calculated by fitting curves, and consequently correlations of those with volatile matter (Vdaf), pore volume and pore size are analyzed and discussed. The U-shape relationships between fractal dimensions (D1, D2 and D′2) and Vdaf are observed. Macropores are presented as the isolated clusters embedding in the network of smaller pores, and the difference of the order of magnitude of the pores’ size affects the connectivity between pores. Both the pore size and volume have a direct influence on multiscale fractal dimensions. Overall, multiscale fractal analysis is beneficial to explore the structure of natural coal.

Measuring the Randomness of Micro and Nanostructure Spatial Distributions: Effects of Scanning Electron Microscope Image Processing and Analysis

Measuring the Randomness of Micro and Nanostructure Spatial Distributions: Effects of Scanning Electron Microscope Image Processing and Analysis

Characterizing clay textures and their impact on the reservoir using deep learning and Lattice-Boltzmann simulation applied to SEM images

The presence of clays in hydrocarbon reservoirs challenges the producible amount of oil and gas significantly. Therefore, this study reports a detailed quantitative characterization of clays' specific properties from two fundamental aspects which include clays' type and amount, and their impact on reservoir's fluid flow. We used Scanning Electron Microscopy (SEM) images and respectively adopted deep learning for typing and quantifying clays, and the Lattice-Boltzmann Method (LBM) for flow simulations with and without the presence of clays. The trained deep learning model of the present study was translated into a MATLAB application that is a convenient tool for clay characterization by the future user. This model was trained using 2160 images of different clay minerals based on transfer learning using AlexNet and resulted in more than 95.4% accuracy while applied on the unforeseen images. Moreover, we established the technique of depth-slicing of 2D SEM images, which provides the possibility of 3D processing of the routine SEM images. The results from this technique proved that clays could reduce reservoir porosity and permeability by more than 30% and 400 mD, respectively. The introduced approach of the present study provides new insights into the detailed impacts of clay minerals on the reservoir's quality.

Numerical modeling of the thermal performance of soil containing microencapsulated PCM

Phase change material (PCM) can be used with soil as an alternative type of thermal regulation of the subgrade, since it has an ability to accumulate and generate heat during the phase change. This paper evaluates the position of PCM microcapsules in the soil by means of scanning electron microscopy (SEM) and X-ray photoelectron spectroscopy (XPS) analysis. The SEM image processing method includes an integrated approach to transferring a color pixel image into a numerical matrix, followed by noise removal and precise determination of the position and size of microcapsules. Based on these data, a macroscale model of the soil volumetric unit with the inclusion of the microencapsulated phase change material (mPCM) was created, which made it possible to estimate the temperature of the mixture at a changing external temperature, as well as the nature of the effect of mPCM on the soil temperature regime. Through the analysis of many points in the model, the following results were obtained: 1) mPCM not only reduces the peak temperatures of its own volume, but it also softens the peak temperatures of the surrounding soil, 2) with a decrease in the external temperature, there is a tendency to a decrease in the temperature change rate as the model temperature approaches the phase change temperature range, 3) in the second cycle of changing the outside temperature, the effect of mPCM on peak temperatures is greater than in the first cycle due to the cumulative effect of decreasing the temperature change from cycle to cycle. PCM materials release/absorb a large amount of latent heat during hardening/melting, which can be useful in solving problems associated with seasonal freezing and thawing of pavements.

Vertical distance from shading in the SEM

Vertical data collected by Scanning Electron Microscopy (SEM) are important for sample characterization, 3D reconstruction, and flex manipulation. Traditional methods are limited by the extent to which the probe obstructs the view of the sample along the vertical axis. Herein, we propose a novel SEM microprobe for measuring the vertical distance between the probe and substrate. To form a semi-transparent hole that is set as the objective regions in processing of the SEM images, an epoxy film was embedded in the through-hole at the tip of the microforce probe with 3D printing. The film can be modified with a focused ion beam (FIB) system. The motion of the modified probe along the vertical axis is controlled by a nanopositioner and the process is recorded by taking a real-time SEM video. The change in gray contrast caused by the semi-transparent epoxy is corrected during the SEM image processing of the video. By comparing the gray contrast with the nanopositioner motion data, we find that the change in gray contrast can provide feedback for adjusting the displacement between the probe and the substrate, and the resolution can be up to 100 nm. We propose a novel and simple method for measuring vertical distances in the SEM, which is useful for in-situ measurements and nanomanipulations.

Analysis of Mafic rocks Microstructure damage and failure Process under Compression Test Using Quantitative Scanning Electron Microscopy and Digital Images Processing

The micro-structures of rock govern meso- and macro-scale rock behaviours and their failure mechanisms. This paper applied the experimental study (uniaxial and triaxial compressive tests) and scanning electron microscope (SEM) method to illustrate the relationship between microscopic damage and mesoscopic fracture. Specifically, this study carried out that there are three main pre-existing micro-structures including heterogeneity (31%), micro-cracks (27%), and crystal lattice boundaries (25%). The pre-existing micro-cracks are investigated and classified as inter-granular cracks (37%), intra-granular cracks (36%), and trans-granular cracks (27%) based on morphological characteristics. According to the deformation types, the micro-cracks after test are divided as tensile crack (53%), shear crack (29%), and mixed shear and tensile crack (18%). Moreover, this paper provides a damage property parameter which is the ratio of tensile damage degree to shear damage degree based on the SEM image processing technique. This parameter could reveal the damage properties (tensile or shear) at different stages including initiating stage, propagation stage and failure stage, which could present the microscopic damage development process. Finally, compared with the fractures on two specimens from compressive tests, it could confirm that the meso-scale fracturing process is associated with the micro-scale damage development process.

Determination of the Elastic Properties at Aging of Medical Ti-6Al-4V ELI Alloy by Ultrasonic Velocity Measurements

In this paper, we report the experimental data of the elastic properties of the Young’s modulus and shear modulus based on the variation in the ultrasonic velocity parameter during the microstructural evolution in a Ti-6Al-4V alloy with two—bimodal and Widmanstatten—varying microstructures. The two different initial microstructures were treated thermally by aging at 515, 545, and 575°C at different times from 1 min to 576 h to induce a precipitation process. Ultrasonic measurements of shear and longitudinal wave velocities, scanning electron microscopy image processing, optical microscopy, and microhardness measurements were performed, establishing a direct correlation with the measurements of the ultrasonic velocity and the elastic properties developed during the thermal treatment by artificial aging. The results of the ultrasonic velocity show a very clear trend as the aging time progresses, which is affected by precipitation of Ti3Al particles inside the α phase. In this way, we can find, in a fast and efficient way, the elastic properties developed during the heat treatment by long-term aging, since the presence of these precipitates hardens the material microstructure, thus affecting the final mechanical properties.

Исследования островковых пленок нитрида галлия на сапфировых подложках методами растровой электронной микроскопии и спектральной эллипсометрии

Методами растровой электронной микроскопии (РЭМ) и спектральной эллипсометрии проведены исследования зародышевых слоев нитрида галлия (GaN) субстананометровой толщины, нанесенных при различных режимах в процессе атомно-слоевой эпитаксии (АСЭ) из триэтил галлия и аммиака на сапфировые подложки. Полученные зародышевые слои представляют собой островковые пленки с различной степенью покрытия поверхности подложек, состоящие из кристаллитов GaN, имеющих различные размеры и средние толщины в диапазоне 10–40 нм. Разработана программа обработки РЭМ-изображений, позволяющая проводить количественную оценку площади частиц, включений, фаз, присутствующих в пленках и на поверхности подложек. Показано, что методика обработки спектральных эллипсометрических измерений островковых пленок из кристаллитов GaN на сапфировых подложках по модели Максвелла–Гарнетта выявляет такую же тенденцию в площади покрытия подложек пленками, что и обработка РЭМ-изображений. Разработанные программа и методика позволили определить оптимальный режим АСЭ зародышевых слоев GaN на сапфировых подложках для формирования высококачественных HEMT-структур из шести реализованных режимов. Они могут быть также эффективно использованы при исследовании любых островковых пленок, слоев с включениями физических и химических фаз и систем коллоидных частиц, применяемых в процессе формирования микроэлектронных структур.

Identification of organic matter components and organic pore characteristics of marine shale: A case study of Wufeng-Longmaxi shale in southern Sichuan Basin, China

Abstract With the global success of the commercial exploration and development of shale oil and gas, research interest in the structure of shale pore, the gas and oil storage carrier, is increasing. However, current studies on shale organic pore are insufficient. Based on this, the basic parameters of Wufeng-Longmaxi shale in Sichuan Basin were tested and shale samples were observed using optical and electron microscopes. In the Changning and Weiyuan areas, CO2, N2 adsorption and mercury intrusion porosimetry (MIP) experiments were conducted on shale samples with different total organic carbon (TOC) content. In this study, we termed the organic matter (OM) with fixed form as formed OM, and the OM without fixed form as amorphous OM, rather than the amorphous OM in the conventional context, which only exists when the maturity of shale is less than 1.0%. The results showed that: (1) formed and amorphous OM can be distinguished under optical and electron microscopes. The formed OM was mainly graptolite, while the amorphous OM could be subdivided into bitumen and micrinite. Under reflected light, bitumen appeared gray-black, while micrinite exhibited certain fluorescence. Under the electron microscope, bitumen showed larger particles than micrinite; (2) there were abundant organic pores in graptolite and bitumen. The organic pores in graptolites were significantly smaller than those in bitumen. Due to the limitation associated with the scanning electron microscope (SEM) resolution, we did not observe organic pores in micrinite, which indicated that the organic pore size in micrinite is smaller than that in bitumen; (3) there were obvious differences in the development of organic pore. In different areas, the relationship between shale porosity and TOC content varied greatly, which was related to the shale gas preservation conditions. Microscopically, there were also several reasons for the developmental differences of organic pore. Among them, inorganic minerals contribute to the preservation of organic pore by filling these pores or forming rigid spatial skeletons, which is an important reason for the micro-difference of organic pore development; (4) The SEM image processing results showed that the organic pore of Wufeng-Longmaxi shale in the Sichuan Basin mainly occurs in the range of mesopore. By comparing the pore size distribution curves of shale samples in the Changning and Weiyuan areas, it is concluded that the organic pore size of shale in the Changning area is primarily 4–10 nm and that in the Weiyuan area it is primarily 2–20 nm.

INVESTIGATION OF GALLIUM NITRIDE ISLAND FILMS ON SAPPHIRE SUBSTRATES VIA SCANNING ELECTRON MICROSCOPY AND SPECTRAL ELLIPSOMETRY

Gallium nitride (GaN) seed sub 100 nm layers deposited from triethyl gallium and ammonia on sapphire substrates in different modes during atomic-layer epitaxy (ALE) have been studied via scanning electron microscopy (SEM) and spectral ellipsometry. The seed layers are island films with different degrees of substrate surface coating, which consist of GaN crystallites having different sizes and average thicknesses from 10 to 40 nm. A program for processing SEM images has been developed, which allows us to quantitatively estimate areas of particles, inclusions, and phases present in films and on the substrate surface. The technique of processing the results of spectral ellipsometric measurements of island films composed of GaN crystallites on sapphire substrates using the Maxwell–Garnett model reveals the same tendency in the area of substrates coated with the films as the processing of SEM images. The developed program and technique made it possible to determine the optimal mode (among six implemented) of ALE of GaN seed layers on sapphire substrates for preparation of high-quality HEMT structures. They can also be efficiently used for studying any island films, layers with inclusions of physical and chemical phases, and systems of colloidal particles used for formation of microelectronic structures.

ANALISIS UKURAN PARTIKEL SILIKA HASIL EKSTRAKSI DARI BATU PADAS ASAL KABUPATEN KETAPANG KALIMANTAN BARAT

Analysis of particle size of silica was extracted from rocks from Ketapang Regency, West Kalimantan based on characterization using scanning electron microscope (SEM) have been carried out. The analysis was performed to determine the particle size change in extraction silica without and with activation using acid solution. SEM image processing was performed on a 10 μm scale at 350x magnification through the image-J software to determine the particle size distribution. The results of the analysis showed that the area and diameter of the silica particle extracted from rocks were 3,935 μm2 and 3,147 μm (without activation) and 4,28 μm2 and 3,267 μm (activated) respectively.

Dynamic modeling of the formation damage and mud cake deposition using filtration theories coupled with SEM image processing

In the present paper, a dynamic modeling is presented for deposition of the mud solid particles over and through the porous sandstones during permeability plugging experiments. Scanning electron microscopy (SEM) coupled with image processing are utilized to find the porosity and pore size distribution of the mud cake. The structure of the porous rock as well as the mud cake are modeled via bundle of the curved tubes approach and deposition probability of the solid particles has been taken into the account through filtration theories. Four different sandstones in addition to four mud samples were utilized to measure and predict the volume of the expelled fluid during the 30 min of filtration through thin sections of the rock samples. The presented model is successful to predict the amount of expelled fluid with about 9.2% of relative error. The novelty of the present study, is quantitative utilization of the SEM images by applying the watershed segmentation algorithm to detect and measure the size of the mud cake pore spaces.

Performance of 3D Tissue Engineering Scaffolds of Nanocellulose/High Cationic Polymers Composite

Three- dimensional(3D) tissue engineering scaffolds were prepared by compounding nanocellulose with polyacrylic cationic polymer and polyethylene amine cationic polymer respectively.The structural morphology of the scaffolds was characterized by scanning electron microscopy(SEM).The influence of the relative molecular mass and dosages of the polymers on the pore structure of the scaffolds was investigated, while a new method for fast measuring the porosity of the scaffolds was established based on SEM image processing. The water retention value(WRV) of the scaffolds was also measured. Results show that the porosity of all the nanocellulose 3D tissue engineering scaffolds is larger than 90%. The porosity value obtained by the new image processing method is close to that measured according to Archimedes principle with a difference less than 5%, which indicated that this method was reliable. All the 3D scaffolds have high WRV(200%). Both the porosity and WRV of the 3D scaffolds can be adjusted by varying the species and dosage of polymers. Therewith the nanocellulose 3D tissue engineering scaffolds may optionally be prepared to meet the requirement for tissue and cell culture.