bluuebunny/crossref_metadata_2025_split huggingface dataset:
In‐situ monitoring of fibre and matrix deformation in fibre/polymer composites
Authors: FAVRE J.‐P. , AUVRAY M.‐H. , SIGETY P. , LÉVĚQUE D. , BRIANÇON C. 
Published: August 2011

SummaryThree methods, namely microphotoelasticimetry, Raman spectroscopy and surface microgrids, are currently used at ONERA on fibre‐reinforced polymers to measure the in‐situ fibre or matrix deformation. They provide the materials scientist with valuable indications on the early damage growth. Recent results are given and information about the limitations of the methods are indicated.
The effect of microstructure on flow promotion in resin transfer moulding reinforcement fabrics
Authors: GRIFFIN P. R. , GROVE S. M. , GUILD F. J. , RUSSELL P. , SUMMERSCALES J. 
Published: August 2011

SummaryThe resin transfer moulding (RTM) process is becoming increasingly important for the manufacture of continuous fibre‐reinforced thermosetting resin matrix composites. The RTM process is a closed mould technique which reduces volatile emissions relative to traditional hand lay‐up methods. The fibres, generally as several layers of fabric, are prepared as a preform and laid in the closed mould. The resin is injected, at one or more points, and flows through the mould to form the finished product. In the manufacture of high‐performance composite structures, the flow of resin is constrained by the high volume fraction of reinforcement fibres required to achieve the performance. Commercial fabrics are becoming available which are woven with specially designed mesoscale architecture to promote flow of the resin. The flow rates in a series of such fabrics have been studied. The microstructures of the resulting composites have been examined using brightfield optical microscopy. A Quantimet image analyser was used to quantify the structures on both the mesoscale and the microscale. The flow rate has been shown to be related to the presence of both large and more modest sized pore space in the reinforcement architecture.
The microstructure of experimental SiC fibre‐reinforced yttrium magnesium aluminosilicate (SiCf‐YMAS) materials
Authors: VICENS J. , DOREAU F. , CHERMANT J. L. 
Published: August 2011

SummaryTwo experimental SiC fibre‐reinforced yttrium magnesium aluminosilicate (SiCf‐YMAS)‐type ceramic‐matrix composite (CMC) materials fabricated (i) by the glass process and (ii) by chemical precursor infiltration have been studied by light microscopy, transmission electron microscopy (TEM), high‐resolution electron microscopy (HREM) and energy‐dispersive X‐ray spectroscopy (EDS). The distribution of the fibres inside the composite as well as the average diameter of fibres have been determined by image analysis. The microstructure of the YMAS matrices has been characterized by TEM observations. YMAS matrices are formed of two main phases, cordierite and β‐yttrium silicate (Y2Si2O7). Two minor phases (mullite and spinel) have been found to crystallize inside the cordierite and the yttrium silicate crystals. Fibre‐matrix interfaces have been observed in HREM. A thin turbostratic carbon layer (20–30 nm) has been imaged in both composites at the fibre‐matrix interface. It crystallizes along the matrix interface and grows inside the fibre, forming a diffuse interphase. The carbon layer is believed to be the consequence of reaction between oxygen in the matrix and SiC nanocrystals of the Nicalon fibres.
Nanostructure of interlayers in different Nicalon fibre/glass matrix composites and their effect on mechanical properties
Authors: HÄHNEL A. , PIPPEL E. , WOLTERSDORF J. 
Published: August 2011

SummaryInterlayer phenomena, revealed by high‐voltage electron microscopy (HVEM) and high‐resolution electron microscopy (HREM), are presented as they occur in various SiC(Nicalon) fibre‐reinforced Duran glass composites (differing in the specific sol‐gel supported production processes). Their dependence on the production parameters and their influence on the materials properties are discussed, taking into account the results of scanning electron microscope (SEM) in situ tensile tests.Besides graphitic carbon, textured to a variable degree and influencing the tensile behaviour, oxycarbide formation is indicated.A reactive matrix additive, such as, e.g. TiO2, resulted in a decrease in strength and a brittle behaviour, while the addition of ZrO2 markedly improves the mechanical properties.
Surface characteristics of Zirfon® composite ultrafiltration membranes
Authors: KUYPERS S. , GENNÉ I. , LEYSEN R. 
Published: August 2011

SummaryThis paper presents the first high‐resolution field emission scanning electron micrographs of the skin layers of a series of Zirfon® ultrafiltration membranes. The flux through these polymer‐based composite membranes is known to be proportional to the inorganic‐filler content. Image analysis of skin surface micrographs revealed the skin surface pore characteristics to be almost unchanged over a wide range of compositions. The inorganic filler was found to be present in the skin layer, where it modifies the polymer network and locally reduces the skin thickness. This latter effect might be able to account for the observed flux behaviour.
Microstructural investigation of colloidal silver embedded in glass
Authors: HOFMEISTER H. , DUBIEL M. , GOJ H. , THIEL S. 
Published: August 2011

SummaryNanoparticulate composites consisting of very small silver particles embedded in near‐surface regions of glass were obtained by sodium–silver ion exchange. Colloidal silver is formed by reduction of silver ions and aggregation of silver atoms in the glass matrix at elevated temperatures. Owing to absorption bands in the visible region, the silver particles cause a coloration of the glass that depends on their size and depth distribution. From high‐resolution electron microscopy imaging of lattice plane fringes of the silver particles, size‐dependent lattice contractions are deduced that are larger than those reported in the literature for supported particles not interacting with a matrix. This effect is the more pronounced the higher the annealing temperature is during the particle formation. The increased lattice contraction is attributed to compressive stresses that arise during the ion exchange process as well as during cooling after annealing.
Microstructure and fracture behaviour of particle‐reinforced metal–matrix composites
Authors: DERBY B. 
Published: August 2011

SummaryThe fracture behaviour of particle‐reinforced metal‐matrix composites is shown to be controlled by a period of damage nucleation and evolution prior to final failure. The nucleation of damage can be by reinforcement fracture or decohesion and the mode of damage is shown to be controlled by the size of the reinforcement and segregation of alloying elements from the matrix. The nucleation and growth of damage can be monitored by a number of techniques. Acoustic emission and tomography are used here and the results are found to be consistent with simple models of void growth.
Microstructure of a spray‐formed Al/SiC composite
Authors: VERMAUT P. , RUTERANA P. 
Published: August 2011

SummaryThe microstructure of an Al–6Cu–2Mn–0·45 Mg–1(Ag, Ti, V, Zr, Cr) alloy, reinforced with 13 vol.% SiC particles, made by spray deposition has been investigated by transmission electron microscopy, high‐resolution electron microscopy and electron diffraction X‐ray spectroscopy. Particular attention was focused on the influence of the reinforcement on the precipitation sequence. Instead of the expectedprecipitation sequence due to the high Cu/Mg ratio, there is an additional σ precipitate which was previously observed in A1 alloys containing silicon. This precipitate becomes predominant at the T6 temper. The new precipitation sequence for this reinforced alloy is thereforeThe precipitation of σ phase is believed to be due to the presence of SiC particles, and seems to be correlated with the occurrence of large Mn‐rich particles. Although expected, no S phase precipitation is found to occur in the matrix grains. At the matrix grain boundaries, small Al2Cu (θ) and Al2CuMg (S), as well as Mn‐rich precipitates are found. At the SiC particle surfaces, preferentially orientated Ag‐rich and Mg‐rich intermetallic precipitates are found. They can coexist with amorphous patches containing oxygen enclosed in an irregularly shaped Al2Cu (θ) phase remaining from large crystalline areas which did not go into solution.
X‐ray microtomographic studies of metal matrix composites using laboratory X‐ray sources
Authors: MUMMERY P. M. , DERBY B. , ANDERSON P. , DAVIS G. R. , ELLIOTT J. C. 
Published: August 2011

SummaryX‐ray microtomography (XMT) is a non‐destructive technique that allows the internal structure of a material to be imaged by the spatial distribution of its linear X‐ray absorption coefficients. This paper demonstrates the use of XMT to investigate: (1) the distribution of TiB2 reinforcement in composites formed by powder processing; (2) the local void volume fraction as a function of position in highly deformed regions of failed tensile specimens of SiC‐reinforced material allowing a valid damage parameter to be defined at high strains; (3) absorption coefficients measured at different energies simultaneously using a multichannel analyser which can sometimes be used to separate linear absorption changes due to (a) density variations and (b) compositional variations in individual voxels; and (4) the use of sequential sections to provide a three‐dimensional representation of the failed specimens.
The use of a single fibre test technique to investigate interfacial phenomena in SiC/Ti3Al‐based composites
Authors: BRISSET F. , VASSEL A. 
Published: August 2011

SummaryA study of the chemical compatibility of a Ti3 Al‐based alloy (Ti–24Al–10Nb, at.%) with two silicon carbide continuous fibres (SCS‐6, SM 1240) has been conducted. Owing to the difficulty in processing intermetallic matrix composites, this type of material has been simulated in the present work by sputtering a thin titanium aluminide layer onto fibres and heat treating at temperatures representative of fabrication conditions. The degradation of the fibre strength due to its interaction with the matrix was correlated with analytical studies of the fibre/matrix interface using a combination of SEM, TEM, EELS and a submicrometre ion probe.
Atomic force microscopy under liquid: A comparative study of three different AC mode operations
Authors: WONG T. M. H. , DESCOUTS P. 
Published: August 2011

SummaryThe image contrast mechanism of three newly proposed AC mode operations under liquid in three different frequency ranges is presented. They all rely on a strong repulsive force to damp the cantilever and the tip still ‘touches’ the sample surface. A direct comparison of the three different modes of operation with the conventional DC mode technique using the same gold sample under isopropanol was conducted. It was found that all the three AC modes exerted a much smaller lateral force than the DC mode although the normal loads were of the same order of magnitude. The suitability of such techniques in imaging physisorbed systems on hard substrates (such as soft biological samples) and the prospect of a true non‐contact repulsive mode operation are discussed.
Monitoring cutting forces with an instrumented histological microtome
Authors: WILLIS A. , VINCENT J. F. V. 
Published: August 2011

SummaryA modification to the knife mounting of a histological microtome is described which can sense the load on the knife when a section is being cut. The performance of this microtome is described in general terms. The variation in force on the knife can be used to give information about the texture of the sample being cut.
The biological reality of the interlacunar network in the embryonic, cartilaginous, skeleton: A thiazine dye/absolute ethanol/LR White resin protocol for visualizing the network with minimal tissue shrinkage
Authors: LAWTON D. M. , OSWALDs W. B. , MCCLURE J. 
Published: August 2011

SummaryThird toe phalanges of chicks aged 8–13 days in ovo and 7‐day post‐natal rat femoral growth plate were examined to determine whether the interlacunar network (IN), a structure with no lipoprotein membrane component or cytoplasmic organelles, is a genuine component of young growth cartilage. In chick phalanges dehydrated by 70% (v/v) ethanol and LR White resin, variable metachromatic staining of the interlacunar network by toluidine blue and red staining by picro‐Sirius red indicate the presence of glycosaminoglycans and collagen. The network in phalanges dehydrated by 80% (v/v) ethanol appears little different; however, the network is much less widely detectable in phalanges dehydrated by 90% (v/v) ethanol and, after dehydration by absolute ethanol, is almost completely undetectable. In contrast, when the young cartilage is permeated by a thiazine dye such as toluidine blue, using a solution of dye in the aldehyde fixative, the network is widely detectable, following dehydration by absolute ethanol, both in chick phalanges and in rat growth plate. Comparison of projected areas shows that the extent to which whole chick feet are found to have shrunk, by the time that they are photographed under LR White resin, is determined principally by the extent of dehydration, by 70% (v/v) or absolute ethanol; post‐shrinkage areas are 33% or 35% of areas measured in buffer for 70% (v/v) ethanol/LR White resin and 71% or 75% for absolute ethanol/LR White resin (the higher value in each is for the toluidine blue treatment). The network is thus present in radically shrunk tissue, but, significantly, is also fully represented in tissue shrunk by only a conventional margin and is therefore not produced as an artefact by exceptional tissue shrinkage as has been suggested.
Mechanism of image formation for thick biological specimens: exit wavefront reconstruction and electron energy‐loss spectroscopic imaging
Authors: HAN K. F. , SEDAT J. W. , AGARD D. A. 
Published: August 2011

SUMMARYWith increasing frequency, cellular organelles and nuclear structures are being investigated at high resolution using electron microscopic tomography of thick sections (0·3–1·0 μm). In order to reconstruct the structures in three dimensions accurately from the observed image intensities, it is essential to understand the relationship between the image intensity and the specimen mass density. The imaging of thick specimens is complicated by the large fraction of multiple scattering which gives rise to incoherent and partially coherent image components. Here we investigate the mechanism of image formation for thick biological specimens at 200 and 300 keV in order to resolve the coherent scattering component from the incoherent (multiple scattering) components.Two techniques were used: electron energy‐loss spectroscopic imaging (ESI) and exit wavefront reconstruction using a through‐focus series. Although it is commonly assumed that image formation of thick specimens is dominated by amplitude (absorption) contrast, we have found that for conventionally stained biological specimens phase contrast contributes significantly, and that at resolutions better than ∼10 nm, superposed phase contrast dominates. It is shown that the decrease in coherent scattering with specimen thickness is directly related to the increase in multiple scattering. It is further shown that exit wavefront reconstruction can exclude the microscope aberrations as well as the multiple scattering component from the image formation. Since most of the inelastic scattering with these thick specimens is actually multiple inelastic scattering, it is demonstrated that exit wavefront reconstruction can act as a partial energy filter. By virtue of excluding the multiple scattering, the ‘restored’ images display enhanced contrast and resolution.These findings have direct implications for the three‐dimensional reconstruction of thick biological specimens, where a simple direct relationship between image intensity and mass density was assumed, and the aberrations were left uncorrected.
V(Z) curve formation of solid spherical microparticles in scanning acoustic microscopy
Authors: MASLOV K. I. , ZININ P. V. , LOBKIS O. I. , KUNDU T. 
Published: August 2011

SUMMARYInformation about the properties of materials in acoustic microscopy can be obtained in the form of the V(Z) curves. The purpose of this paper is to present the theoretical and experimental study of the V(Z) curve formation for solid spheres. It is shown that an investigation of the position of different peaks in the V(Z) curves is useful to determine the size and acoustical properties of a spherical particle.
An ion microprobe study of the microchemistry of Ni‐base superalloy‐Al2O3 metal‐matrix composites
Authors: SONI K. K. , TSENG M. W. , WILLIAMS D. B. , CHABALA J. M. , LI JIANWEI , LEVI‐SETTI R. , BAMPTON C. C. 
Published: August 2011

SUMMARYThe chemical microstructure of Ni‐base superalloy/Al2O3 metal‐matrix composites (MMCs) has been studied by scanning ion microprobe microanalysis, using the secondary ion mass spectrometry (SIMS) technique. The MMCs were fabricated using the transient‐liquid‐phase bonding (TLP) process, with B‐doped superalloy powder as an interlayer. Boron was found to diffuse rapidly throughout the matrix to form boride phases, mostly at the grain boundaries in the matrix. These borides contain excess Cr (also Mo, Si, W) in comparison with the Ni alloy‐matrix, but are depleted in Ni (also in Al and Co). Carbides form at the grain boundaries as thin platelets and inside the grains as fine particles. Chemical reaction occurs between the sapphire fibre and the matrix; formation of NiAl2O4 spinel at the interface is suggested. This interface reaction layer is friable and parts of it peel off during consolidation to become inclusions in the matrix near the fibre/matrix interface.
Estimation of individual feature surface area with the vertical spatial grid
Authors: CRUZ‐ORIVE L. M. , HOWARD C. V. 
Published: August 2011

SUMMARYThe area of an individual bounded surface (e.g. the boundary of a properly sampled cell) can be estimated from an isotropic uniform random stack of parallel sections, or of non‐invasive planar scans, using the well‐known spatial grid. A standing problem was to estimate the area of an individual bounded surface with an arbitrary degree of accuracy from a vertical (i.e. not isotropic) stack of sections or scans. A new tool to do this, called the ‘vertical spatial grid’, is presented.
Computer‐assisted method for simultaneous three‐dimensional reconstruction of highly magnified nerve endings and low‐magnification contours of the spinal cord
Authors: LISS A. G. 
Published: August 2011

SUMMARYThree‐dimensional reconstructions of biological structures can be obtained by the use of serial sections, tomography, confocal microscopy techniques and X‐ray crystallography. The earliest reconstructions were achieved manually, but semi‐automatic and automatic techniques are now available. Tissue studied by microscopy contains structures of greatly varying dimensions. When producing a three‐dimensional reconstruction of the contours of the spinal cord and its white and grey matter, greater magnification of the fine nerve endings may provide additional information. However, reconstruction at different magnifications of the structures of interest cannot be achieved automatically, but requires manual delineation of the structures. A method is described in which a commercial program was used to provide a wire‐frame reconstruction which had been drawn by hand. The data were processed further to obtain a realistic image which could be rotated to provide details of the three‐dimensional relationships of the spinal cord structures. This technique is useful when relationships and details are otherwise difficult to comprehend due to large size differences.
A system for aligning video‐recorded visual data and high‐quality multichannel recordings of simultaneously occurring signals
Authors: LUMSDON T. , DICKSON M. , GLADDEN M. H. 
Published: August 2011

SUMMARYAn electronic circuit is described which provides a unique number for each video frame, and which is superimposed on the frame as a 4‐digit light‐emitting diode display using a second camera and videomixer. The number is also encoded as a simple voltage waveform which is recorded separately together with electrical signals giving information about events related to, and coincident with, the visual data, for example nerve spike trains. Sophisticated computer analysis of signals can thus be related accurately to microscopical visual information processed by video analysis.
A low‐cost digitized microscope stage for linear measurements
Authors: ROHITHA B. H. 
Published: August 2011

SUMMARYA low‐cost device for making fine, but repetitive linear measurements under the binocular microscope is described. Linear displacement is coupled on to digital callipers which read the measurements in numerical values. The accuracy of the measurements was such that their 95% confidence interval was within 0·01 mm when read through the apparatus. The data were assimilated on a computer and then transmitted into a PC for analysis.
The secondary fluorescence correction for X‐ray microanalysis in the analytical electron microscope
Authors: ANDERSON I. M. , BENTLEY J. , CARTER C. B. 
Published: August 2011

SUMMARYA general formulation for the secondary fluorescence correction is presented. It is intended to give an intuitive appreciation for the various factors that influence the magnitude of the secondary fluorescence correction, the specimen geometry in particular, and to serve as a starting point for the derivation of quantitative correction formulae. This formulation is primarily intended for the X‐ray microanalysis of electron‐transparent specimens in the analytical electron microscope (AEM).The fluoresced intensity, IYX, is expressed relative to the primary intensity of the fluorescing element, IY, rather than to that of the fluoresced element, IX, as has been customary for microanalysis. The importance of this choice of IY as a reference intensity for the electron‐transparent specimens examined in the AEM is discussed. The various factors entering the secondary fluorescence correction are grouped into three factors, representing the dependencies of the correction on specimen composition, X‐ray fluorescence probability and specimen geometry. In principle, an additional factor should be appended to account for the difference in detection efficiencies of the fluoresced and fluorescing X‐rays; however, this factor is shown to be within a few per cent of unity for practical applications of the secondary fluorescence correction. The absorption of secondary X‐rays leaving the specimen en route to the detector is also accounted for through a single parameter.In the limit that the absorption of secondary X‐rays is negligible, the geometric factor has the simple physical interpretation as the fractional solid angle subtended by the fluoresced volume from the perspective of the analysed volume. Studies of secondary fluorescence in the published literature are compared with this physical interpretation. It is shown to be qualitatively consistent with Reed's expression for secondary fluorescence in the electron probe microanalyser and with the specimen‐thickness dependence of the Nockolds expression for the parallel‐sided thin foil. This interpretation is also used to show that the ‘sec α’ dependence on specimen tilt in the latter expression is erroneous and should be omitted. The extent to which extrapolation methods can be used to correct for secondary fluorescence is also discussed. The notion that extrapolation methods, by themselves, can be used to correct for secondary fluorescence is refuted. However, extrapolation methods greatly facilitate secondary fluorescence correction for wedge‐shaped specimens when used in conjunction with correction formulae.