Masao Kimura

Masao Kimura
High Energy Accelerator Research Organization | KEK · Institute of Materials Structure Science

Doctor of Engineering

About

139
Publications
13,627
Reads
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1,267
Citations
Introduction
Techniques: Microscopic spectroscopy, Imaging, In situ observation, Synchrotron radiation Materials: Metal, Carbon fiber reinforced plastic (CFRP), Battery, Catalyst
Additional affiliations
October 2013 - present
High Energy Accelerator Research Organization
Position
  • Professor
October 2012 - September 2013
Nippon Steel & Sumitomo Metal
Position
  • Principal Investigator
October 1995 - September 2012
Nippon Steel Co.
Position
  • Senior Researcher

Publications

Publications (139)
Article
Nanoscale fracture mechanism in CFRPs is still debated owing to the considerable difficulty in determining the three-dimensional mechanism of fracture using conventional techniques such as optical and/or electron microscopy relying on side-surface- and fracture-surface-based observation. In this study, microscopic damages such as fiber/matrix debon...
Article
Chemical-state imaging of materials using X-ray microscopes has been developed and applied to various materials such as composites, batteries, ceramics and so on. In this article, after features of X-ray microscopy are discussed, analytical approaches for chemical-state imaging are reviewed by showing typical application to materials : scanning tra...
Article
To effectively control the mechanical properties of structural materials and design their safety margins, understanding the properties of metal fracture is essential. However, it is difficult to experimentally investigate the atomic structures at the moment of fracture; therefore, the detailed fracture mechanism remains an active area of research....
Article
Full-text available
Solid lubricants are used to lubricate the mechanical equipment of various spacecraft and launch vehicles. Tungsten disulfide (WS2) is one of the solid lubricants that can be used in a variety of applications at elevated temperatures in outer space. In this study, WS2 coatings on a metal disc were applied via the shot peening method using WS2 powde...
Article
X-ray microscopy and time-resolved observation using synchrotron radiation are reviewed based on recent reports on in situ observation of cracking and degradation of structural materials. X-ray microscopy can provide three-dimensional images of microstructures and chemical states with a high spatial resolution down to 50 nm. In situ observation usi...
Article
Full-text available
To investigate the performance of the size measurement by asymmetric flow field-flow fractionation (AF4), the measurement results of gold nanoparticles were compared among AF4, transmission electron microscopy (TEM), and small-angle X-ray scattering (SAXS) in terms of the average size and full width at half maximum (FWHM) of the size distribution....
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Reduction behavior of various multi-component calcium ferrites at 900°C were investigated by using in situ X-ray diffraction (XRD) and X-ray absorption spectroscopy. Intermediate components were determined by XRD, and change in X-ray absorption spectra of Fe and Ca K-edges were analyzed to determine reaction rate constants. SFCA-I (Ca3(Ca,Fe)(Fe,Al...
Article
Full-text available
The mass fraction of each crystalline phase in inorganic materials can be investigated using the Rietveld refinement of the X-ray diffraction (XRD) patterns. For quantitative analysis, differences in the values of the linear absorption coefficient, μ, among the crystalline phases must be considered when certain X-ray sources are used, because such...
Article
The kinetics of phase transformation in the Fe–C system during cooling are of great importance for controlling its microstructure and mechanical properties. However, real-time observation of the phase transformation has been a challenging task because of experimental difficulties. Here, we developed an analytical technique for time-resolved observa...
Article
A simple and easy surface sensitive spectroscopic method using hard X-rays has been developed and applied to observe the surface oxide reduction reaction. The method named TREXS, Total REflection X-ray Spectroscopy, records the total reflection of incident X-rays at sample surfaces. The surface reduction reaction of Co oxide (Co3O4) to Co metal was...
Article
Full-text available
The mass fraction of each crystalline phase in inorganic materials can be investigated using the Rietveld refinement of the X-ray diffraction (XRD) patterns. For quantitative analysis, differences in the values of the linear absorption coefficient, µ, among the crystalline phases must be considered when certain X-ray sources are used, because such...
Article
Full-text available
In this study, an azimuthal-rotation sample holder compatible with scanning transmission X-ray microscopy was developed. This holder exhibits improvement in the accuracy of rotation angles and reduces the displacement of the rotation axes during azimuthal rotation by using a crossed roller bearing. To evaluate the performance of the holder, the aut...
Article
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The mechanical properties of carbon fibers (CFs) can be controlled by their internal structures such as the distribution of π-orbital-oriented domains, as well as the diameter and cross-sectional shape of the fiber. In this study, we investigated the carbon chemical structure maps of commercial polyacrylonitrile (PAN)- and pitch-based CFs using sca...
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The crack initiation and propagation under the application of opening load were analyzed in situ using nondestructive synchrotron radiation X-ray computed tomography (nanoscopic SR X-CT) with a spatial resolution of ∼50 nm. The results show that the voids and cracks initiation are not only the result of local stresses but also are due to two compet...
Article
Full-text available
Crack initiation and propagation in carbon fiber-reinforced plastic (CFRP) was observed in situ under the application of an opening load using nondestructive synchrotron radiation X-ray computed tomography (nanoscopic SR X-CT) at a high spatial resolution of ∼50 nm. Two datasets of reconstructed and segmented images were produced in typical regions...
Article
A pulse stretcher providing a 5.2 keV quasi-continuous beam has been developed for use with a pulsed slow-positron beam generated by an electron linear accelerator operated with a repetition frequency of 50 Hz. Pulses of positrons, of width 1.2 µs, were trapped in a Penning-Malmberg trap and then gradually released downstream, stretching the pulse...
Article
Full-text available
To investigate the performance of the size measurement by asymmetric flow field-flow fractionation (AF4), the measurement results of gold nanoparticles were compared among AF4, transmission electron microscopy (TEM), and small-angle X-ray scattering (SAXS) in terms of the average size and full width at half maximum (FWHM) of the size distribution....
Article
Full-text available
Voids and cracks can fatally degrade structural materials such as metals and ceramics but are tolerated in carbon fibre-reinforced plastic (CFRP) composites if monitored to prevent their growth to a critical size. Thus, the use of CFRPs as aeronautical structural materials requires an understanding of microscopic crack formation. However, this crac...
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Full-text available
The mechanism of recrystallization texture development of cold-rolled metal and steel largely depends on the material chemical composition, cold-rolling reduction, and annealing treatment conditions. To clarify the mechanism, it is important to identify the locations where recrystallization starts and progresses within cold-rolled materials. Using...
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Plastic deformation of polycrystalline materials under shock wave loading is a critical characteristic in material science and engineering. However, owing to the nanosecond time scale of the shock-induced deformation process, we currently have a poor mechanistic understanding of the structural changes from atomic scale to mesoscale. Here, we observ...
Article
A void formation at nanoscale and a crack initiation at micrometer scale in CFRP during a tensile test were investigated by means of positron annihilation and X-ray computed tomography (X-CT). Free volumes in bisphenol-A epoxy resin in CFRP were probed, and a mean diameter of free volumes at room temperature was determined to be 0.49 nm. The crack...
Article
X‐ray absorption fine structure (XAFS) spectroscopy is one of the most widely used methods at synchrotron radiation facilities. XAFS gives us information on chemical states and local structures. Fundamentally, XAFS is bulk sensitive, not surface sensitive. If a surface sensitive XAFS method was available, surface chemical reactions can be observed...
Article
Macroscopic properties of carbon fiber‐reinforced plastic (CFRP) and environmental barrier coating (EBC), widely used for airplanes, can be deteriorated by local cracks or degradation (“trigger sites”). We have tried to find these trigger sites using x‐ray microscopy (XM), which can provide the 2D or 3D images of the chemical states and microstruct...
Article
A novel in situ cell was developed for simultaneous X-ray absorption fine structure and X-ray diffraction (XAFS/XRD) measurements at high temperatures up to 1773 K in a gas atmosphere such as air containing reactive oxygen, in which typical heat-resistant or environmental-barrier materials are used. This new cell can provide multimodal information...
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Full-text available
The thermodynamic model of a silico-ferrites of calcium and aluminum solution, SFCA phase (Ca2(Fe, Ca)6Oct(Fe, Al, Si)6TetO20) was newly developed in the framework of the Compound Energy Formalism (CEF). Preferred substitution of Al atoms to tetrahedral sites in the SFCA solution was verified by X-ray absorption near edge structure (XANES) analysis...
Conference Paper
We have developed hard X-ray spectromicroscopes at various scales using synchrotron radiation to elucidate the origin of the function of materials at Photon Factory (PF), Institute of Materials Structure Science (IMSS), High Energy Accelerator Research Organization (KEK) in Japan. One is a 2D scanning X-ray microscope with ∼20-µm spatial resolution...
Conference Paper
The Materials Chemistry Group of the Institute of Materials Structure Science, KEK, aims to clarify irreversible reaction processes such as structural changes of materials induced by laser shock or temperature. We have developed an experimental system using dispersive X-ray absorption fine structure (DXAFS) spectroscopy and a laser to observe these...
Conference Paper
We have developed a type of surface sensitive x-ray spectroscopy, which is called total reflection x-ray spectroscopy (TREXS). As x-ray absorption fine structure (XAFS) spectroscopy is used to study many materials, TREXS provides structural and electronic information with the surface sensitivity of ~2–3 nm, and will be a powerful method to study su...
Article
Materials Chemistry Group of Institute of Materials Structure Science, KEK, researches to clarify irreversible reaction processes such as structural change of materials induced by laser shock and temperature. To observe these processes in real time, we have developed an experimental system using DXAFS and a laser. We have used a simple sample excha...
Article
3D Spectromicroscopic Observation of Yb-Silicate Ceramics Using XAFS-CT - Volume 24 Supplement - Yasuo Takeichi, Toshiki Watanabe, Yasuhiro Niwa, Satoshi Kitaoka, Masao Kimura
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Full-text available
In situ XRM Observation of Cracking in CFRP during Nanomechanical Testing - Volume 24 Supplement - Toshiki Watanabe, Yasuo Takeichi, Yasuhiro Niwa, Masao Kimura
Article
Full-text available
Non-Empirical Identification of Trigger Sites in Image Data using Persistent Homology: Crack Formation during Heterogeneous Reduction of Iron-Ore Sinters - Volume 24 Supplement - M. Kimura, I. Obayashi, Y. Takeichi, R. Murao, Y. Hiraoka
Article
Full-text available
Round robin studies have been used across fields of science for quality control testing and to investigate laboratory dependencies and cross-platform inconsistencies as well as to drive forward the improvement of understanding of experimental systems, systematic effects and theoretical limitations. Here, following the Q2XAFS Workshop and Satellite...
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Full-text available
The present state of XAFS databases, particularly in Japan, and proposals for future directions are presented. International collaboration is important for enlarging the database for further development of XAFS spectroscopy.
Article
The initial stage of degradation process of yttria partially stabilized zirconia thermal barrier coatings during heating at 1000–1450 K were observed in situ by transmission electron microscopy. The observation directly demonstrated that the formation of several kinds of oxides and resulting void growth started above 1000 K in the bond-coat layer n...
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Full-text available
Persistence diagrams have been widely recognized as a compact descriptor for characterizing multiscale topological features in data. When many datasets are available, statistical features embedded in those persistence diagrams can be extracted by applying machine learnings. In particular, the ability for explicitly analyzing the inverse in the orig...
Article
Full-text available
Analysis techniques for quantifying crystal structures of mineral phases and their fractions in iron ore sinters have been developed using the Rietveld analysis of X-ray diffraction patterns and applied to iron ore sinters of different mechanical strength, which were prepared by laboratory-scale sinter pot testing. The Rietveld analysis successfull...
Article
Full-text available
Macroscopic phenomena, such as fracture, corrosion, and degradation of materials, are associated with various reactions which progress heterogeneously. Thus, material properties are generally determined not by their averaged characteristics but by specific features in heterogeneity (or 'trigger sites') of phases, chemical states, etc., where the ke...
Article
Full-text available
The thermodynamic model of a silico-ferrites of calcium and aluminum solution, SFCA phase (Ca2 (Fe,Ca)6Oct (Fe,Al,Si)T6etO20 ) was newly developed in the framework of the Compound Energy Formalism (CEF). Preferred substitution of Al atoms to tetrahedral sites in the SFCA solution was verified by X-ray absorption near edge structure (XANES) analysis...
Article
To clarify the nature of the transformation in liquid iodine, which is reported to occur at around 4 GPa, we have conducted x-ray absorption fine structure (XAFS) and x-ray diffraction (XRD) measurements up to 9 GPa. In the XAFS spectra, the oscillation attributable to the molecular bond persisted to 9 GPa but showed a significant decay above 4–5 G...
Article
Full-text available
The sub-micron spatial distribution of chemical states of carbon fiber (CF) and the interface between CF and resin must affect physical properties of carbon-fiber-reinforced plastic (CFRP). In order to evaluate scanning transmission X-ray microscopy (STXM) techniques for application to the chemical-state analysis of CFRP, we performed STXM measurem...
Article
Full-text available
Iron ore sinter constitutes the major component of the iron-bearing burden in blast furnaces, and its reduction mechanism is one of the keys to improving the productivity of ironmaking. Iron ore sinter is composed of multiple iron oxide phases and calcium ferrites (CFs), and their heterogeneous reduction was investigated in terms of changes in iron...
Article
Full-text available
Sub-micron spatial distribution of chemical states of carbon fiber (CF) and the interface between CF and resin should affect physical properties (e.g. tensile strength and elastic modulus) of carbon fiber reinforced plastic (CFRP). In order to evaluate scanning transmission X-ray microscopy (STXM) techniques for application to the chemical state an...
Article
Full-text available
To obtain the best possible performance from engineering materials, it is necessary to optimize their intrinsic properties, the processing involved in their production, and their performance in actual applications. To this end, the concept of the “materials science tetrahedron” was proposed [1 Committee on the Survey of Materials Science and Engine...
Article
Full-text available
Quantification techniques of mineral phases in iron ore sinter has been developed by using Rietveld analysis of X-ray diffraction patterns and applied to iron ore sinters made by the sinter pot test in a laboratory. Rietveld refinements successfully determined phase fractions and structural parameters in co-existing phases such as hematite (α-Fe2O3...
Article
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Recent results at the Slow Positron Facility (SPF), Institute of Materials Structure Science (IMSS), KEK are reported. Studies using the total-reflection high-energy positron diffraction (TRHEPD) station revealed the structures of rutile-TiO2(110) (1×2), graphene on Cu (111) and Co (0001), and germanene on Al (111). First observations of the shape...
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Application of X-ray Absorption Spectroscopy (XAS) to observation of various reactions is reviewed. XAS is a unique tool for studying the local structure around a selected element at atomic scale. XAS can be applied to materials such as crystals, amorphous systems, and liquids, which are situated in various conditions (in gas, at high temperature,...
Article
Full-text available
X-ray analyzer-based phase-contrast imaging is combined with computed laminography for imaging regions of interest in laterally extended flat specimens of weak absorption contrast. The optics discussed here consist of an asymmetrically cut collimator crystal and a symmetrically cut analyzer crystal arranged in a nondispersive (+, −) diffraction geo...
Article
We report a single-shot nanosecond time-resolved dispersive XAFS measurement of copper foil under laser-induced shock compression. Obtained EXAFS results indicated clearly the structural evolution, though XANES spectra showed that the laser irradiation does not affect the copper electronic state. The nearest (ca. 0.22 nm) and longer (ca. 0.44 nm) C...
Conference Paper
Full-text available
BL-15A is a new x-ray undulator beamline at the Photon Factory. It will be dedicated to two independent research activities, simultaneous XAFS/XRF/XRD experiments, and SAXS/WAXS/GI-SAXS studies. In order to supply a choice of micro-focus, low-divergence and collimated beams, a double surface bimorph mirror was recently developed. To achieve further...
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Full-text available
LabDCT derives 3D crystallographic information via diffraction contrast tomography (DCT) within a commercial laboratory X-ray microscope (ZEISS Xradia 520 Versa) that uses a synchrotron-style detection system for tomography. The establishment of DCT into a laboratory setting opens the way for routine, non-destructive, time-evolution studies of grai...
Article
Full-text available
Iron-ore sinters constitute the major component of the iron-bearing burden in blast furnaces, and the mechanism of their reduction is one of the key processes in iron making. The heterogeneous reduction of sintered oxides was investigated by the combination of X-ray fluorescence and absorption fine structure, X-ray diffraction, and computed tomogra...
Article
A gritty surface sample holder has been invented to obtain correct XAFS spectra for concentrated samples by fluorescence yield (FY). Materials are usually mixed with boron nitride (BN) to prepare proper concentrations to measure XAFS spectra. Some materials, however, couldn't be mixed with BN, and would be measured in too concentrated conditions to...