Characterisation of the Residual Stresses in HVOF WC-Co Coatings and Substrates

Residual strains and stresses associated with the processing steps of the industrial high-velocity oxygen-fuel (HVOF) thermal spray technique, was non-destructively characterised in both the coatings and substrates. A range of substrates, having coefficients of thermal expansion different to that of the as-coated WC-Co material, have been considered to assess the potential role of the thermal misfit associated with the coating procedure. Surface and depth resolved studies of the in-plane and normal components of residual strains have been investigated by exploiting the penetrating capabilities of high energy synchrotron X-rays in conjunction with micron sized gauge volumes to enable strain gradient determination with high positional resolution. Results reveal the presence of large residual strain/stress mismatches at the interface region in all the substrate materials, whereas the strains/stresses in the as-coated material are small, seemingly independent of the substrate material. The different contributions due to the HVOF process are qualitatively assessed in terms of an eigenstrains (plastic deformation) approach.

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Validation of materials-informed digital twin: Mapping residual strains in HSLA steel weldment using high energy X-rays

Journal of Manufacturing Processes ◽

10.1016/j.jmapro.2021.11.057 ◽

2022 ◽

Vol 74 ◽

pp. 75-87

Author(s):

Charles R. Fisher ◽

Kelly E. Nygren ◽

Armand J. Beaudoin

Keyword(s):

Hsla Steel ◽

High Energy ◽

X Rays ◽

Steel Weldment ◽

Digital Twin ◽

Residual Strains

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In Situ Synchrotron Measurements of Oxide Growth Strains

Materials Science Forum ◽

10.4028/www.scientific.net/msf.490-491.287 ◽

2005 ◽

Vol 490-491 ◽

pp. 287-293 ◽

Cited By ~ 2

Author(s):

Jonathan Almer ◽

Geoffrey A. Swift ◽

John A. Nychka ◽

Ersan Üstündag ◽

David R. Clarke

Keyword(s):

Strain Relaxation ◽

Relaxation Mechanism ◽

High Energy ◽

Oxide Growth ◽

X Rays ◽

Pure Alumina ◽

Transmission Geometry ◽

Residual Strains

Synchrotron x-rays are used for in situ determination of oxide strain, during oxide formation on a Kanthal A1 FeCrAlZr substrate at 1160°C. The measurements rely on use of high-energy (~80keV) x-rays and transmission geometry, and the methodology of the strain measurements is presented. Oxide growth strains at elevated temperature, relative to pure alumina, were seen to be small, while temperature excursions induced significant strains. Furthermore, significant strain relaxation was observed during isothermal holds, suggesting oxide creep as a major relaxation mechanism. Upon cooling to room temperature, significant residual strains developed, with a corresponding in-plane residual stress of -3.7 GPa.

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Neutron Surface Residual Stress Scanning Using Optimisation of a Si Bent Perfect Crystal Monochromator for Minimising Spurious Strains

Materials Science Forum ◽

10.4028/www.scientific.net/msf.681.399 ◽

2011 ◽

Vol 681 ◽

pp. 399-404 ◽

Cited By ~ 1

Author(s):

Joana Rebelo-Kornmeier ◽

Jens Gibmeier ◽

Michael Hofmann ◽

Robert C. Wimpory

Keyword(s):

Residual Stress ◽

Stress Analysis ◽

Surface Effect ◽

Stress Gradient ◽

High Energy ◽

Surface Strain ◽

X Rays ◽

Surface Residual Stress ◽

Gauge Volume ◽

Residual Strains

For non destructive stress analysis of surface treated steel samples the application of laboratory X rays or high energy synchrotron radiation in reflection mode covers the region from some micrometers up to a depth of about 150 - 200 µm. To access depth regions deeper than 200 µm the incremental layer removal technique in combination with the repeated application of X‑ray stress analysis for the newly generated surfaces can be used. However, this procedure is destructive, laborious and furthermore, it has to be checked whether corrections have to be applied due to stress relaxation. By using neutron radiation penetration depths generally up to several millimetres can be achieved non destructively [1]. However neutron measurements are critical at the surface. When scanning a sample surface, aberration peak shifts caused by so called spurious strains arise due to the fact that the gauge volume defined by the primary and secondary optics is partially outside of the sample. These aberration peak shifts can be of the same order of magnitude as the peak shifts related to residual strains [2-6]. In this exemplary study it will be demonstrated that, by optimising the bending radius of a Si (400) monochromator, the spurious surface strains can be strongly reduced when compared to the values obtained with a traditional Ge (311) mosaic monochromator, even when the gauge volume is mainly out of the surface. The objective of the experiments is to find the optimal monochromator settings for the Si (400) monochromator at the STRESS-SPEC instrument at the research reactor FRM II, Munich, Germany. For the parametric studies a stress free steel sample of the fine grained construction steel, S690QL was used. The optimised conditions for the Si (400) monochromator that resulted from the systematic studies were applied to a shot peened plate of steel SAE 4140. The residual stress distribution is analysed by means of through surface strain scanning. The residual stress gradient obtained is in very good agreement with the well characterised residual stress depth profile obtained within a round robin test in the scope of the BRITE-EURAM-project ENSPED (European Network of Surface and Prestress Engineering and Design) [7]. The results indicated that surface residual stress profiles can be measured with neutrons up to 200 µm underneath the surface without time consuming and laborious surface effect corrections.

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Inter-Granular Residual Stresses in Polycrystalline Aggregates: Finite Element Modelling and Diffraction Post-Processing

Materials Science Forum ◽

10.4028/www.scientific.net/msf.571-572.271 ◽

2008 ◽

Vol 571-572 ◽

pp. 271-276 ◽

Cited By ~ 1

Author(s):

Xu Song ◽

Shu Yan Zhang ◽

Daniele Dini ◽

Alexander M. Korsunsky

Keyword(s):

Stress State ◽

Residual Stresses ◽

Elastic Anisotropy ◽

Fatigue Crack Initiation ◽

Grain Morphology ◽

High Energy ◽

External Loading ◽

X Rays ◽

Micro Scale ◽

Residual Strains

Most models based on continuum mechanics do not account for inhomogeneities at the micro-scale. This can be achieved by considering a representative volume of material and using (poly)crystal elasto-plastic deformation theory to model the effects of grain morphology and crystallographic orientation. In this way, the relationship between the macroscopic stress state and the stress state at the grain level can be investigated in detail. In addition, this approach enables the determination of the inhomogeneous fields of plastic strain, the identification of regions of localised plasticity (persistent slip bands), grain level shakedown, and the prediction of fatigue crack initiation using energy dissipation at the micro-scale. Elastic anisotropy is known to promote earlier onset of yielding, and to increase the magnitude of intergranular residual stresses. The effect of hardening behaviour of different slip systems on intergranular residual stresses is more subtle, as discussed in the text. The present study focuses on the analysis average intergranular residual strains and stresses that arise within the polycrystal aggregate following the application of single or cyclic external loading. These residual strains can also be evaluated experimentally using diffraction of penetrating radiation, e.g. neutrons or high energy X-rays, allowing comparisons with the model predictions to be made.

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The Role of Ground-Based Robotic Observatories in Satellite Projects

Advances in Astronomy ◽

10.1155/2010/594854 ◽

2010 ◽

Vol 2010 ◽

pp. 1-10

Author(s):

R. Hudec

Keyword(s):

Gamma Rays ◽

Large Fraction ◽

High Energy ◽

Photometric Data ◽

X Rays ◽

High Energy Astrophysics ◽

Robotic Telescopes ◽

Optical Wavelengths ◽

Multispectral Analysis

We discuss the role of robotic telescopes in satellite projects, as well as related strategies. Most satellite projects in space astrophysics focus on high-energy astrophysics from X-rays to gamma-rays. A large fraction of objects of high-energy astrophysics emit also optical light, which is, in many cases, variable. The observation of these sources at optical wavelengths can provide valuable inputs for multispectral analysis of various categories of celestial high-energy (HE) sources. As the magnitudes of numerous objects are bright and can be hence accessed by robotic ground-based observatories, these observations can contribute to investigations and analyses of HE sources. We discuss in detail this possible contribution, with emphasis on the ESAINTEGRALmission. In addition to this, there are also satellite projects outside the high-energy astronomy, in which the robotic telescopes can also play an important role. We will illustrate this on the example of the ESA satelliteGaia. In this project, robotic telescopes are expected not only to verify the triggers detected by satellite (such as transients and flares) but also to provide additional (mostly photometric) data for better scientific cases.

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Digital x-ray mapping of nanometer-size supported bimetallic catalysts

Proceedings, annual meeting, Electron Microscopy Society of America ◽

10.1017/s0424820100104716 ◽

1988 ◽

Vol 46 ◽

pp. 530-531

Author(s):

L. T. Germinario

Keyword(s):

Background Radiation ◽

Metal Cluster ◽

Single Element ◽

Beam Diameter ◽

X Rays ◽

X Ray ◽

Major Interest ◽

Induced Changes

Understanding the role of metal cluster composition in determining catalytic selectivity and activity is of major interest in heterogeneous catalysis. The electron microscope is well established as a powerful tool for ultrastructural and compositional characterization of support and catalyst. Because the spatial resolution of x-ray microanalysis is defined by the smallest beam diameter into which the required number of electrons can be focused, the dedicated STEM with FEG is the instrument of choice. The main sources of errors in energy dispersive x-ray analysis (EDS) are: (1) beam-induced changes in specimen composition, (2) specimen drift, (3) instrumental factors which produce background radiation, and (4) basic statistical limitations which result in the detection of a finite number of x-ray photons. Digital beam techniques have been described for supported single-element metal clusters with spatial resolutions of about 10 nm. However, the detection of spurious characteristic x-rays away from catalyst particles produced images requiring several image processing steps.

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The Basic Physical Principles of Ion, Electron, and X-Ray Detectors and Their Application to Microanalysis

Proceedings, annual meeting, Electron Microscopy Society of America ◽

10.1017/s0424820100117777 ◽

1985 ◽

Vol 43 ◽

pp. 154-157

Author(s):

A.J. Tousimis

Keyword(s):

Ion Beam ◽

Depth Resolution ◽

Sample Surface ◽

High Energy ◽

X Rays ◽

X Ray ◽

Electrons And Ions ◽

Spatial Depth ◽

Minimum Surface Area ◽

Physical Principles

An integral and of prime importance of any microtopography and microanalysis instrument system is its electron, x-ray and ion detector(s). The resolution and sensitivity of the electron microscope (TEM, SEM, STEM) and microanalyzers (SIMS and electron probe x-ray microanalyzers) are closely related to those of the sensing and recording devices incorporated with them.Table I lists characteristic sensitivities, minimum surface area and depth analyzed by various methods. Smaller ion, electron and x-ray beam diameters than those listed, are possible with currently available electromagnetic or electrostatic columns. Therefore, improvements in sensitivity and spatial/depth resolution of microanalysis will follow that of the detectors. In most of these methods, the sample surface is subjected to a stationary, line or raster scanning photon, electron or ion beam. The resultant radiation: photons (low energy) or high energy (x-rays), electrons and ions are detected and analyzed.

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Fundamentality

10.1093/oso/9780198714057.003.0013 ◽

2017 ◽

Author(s):

Richard Healey

Keyword(s):

Quantum Theory ◽

High Energy Physics ◽

Physical Property ◽

Natural World ◽

High Energy ◽

Quantum Field Theories ◽

Fundamental Physics ◽

The World ◽

Energy Physics

The metaphor that fundamental physics is concerned to say what the natural world is like at the deepest level may be cashed out in terms of entities, properties, or laws. The role of quantum field theories in the Standard Model of high-energy physics suggests that fundamental entities, properties, and laws are to be sought in these theories. But the contextual ontology proposed in Chapter 12 would support no unified compositional structure for the world; a quantum state assignment specifies no physical property distribution sufficient even to determine all physical facts; and quantum theory posits no fundamental laws of time evolution, whether deterministic or stochastic. Quantum theory has made a revolutionary contribution to fundamental physics because its principles have permitted tremendous unification of science through the successful application of models constructed in conformity to them: but these models do not say what the world is like at the deepest level.

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Pannexins and Connexins: Their Relevance for Oocyte Developmental Competence

International Journal of Molecular Sciences ◽

10.3390/ijms22115918 ◽

2021 ◽

Vol 22 (11) ◽

pp. 5918

Author(s):

Paweł Kordowitzki ◽

Gabriela Sokołowska ◽

Marta Wasielak-Politowska ◽

Agnieszka Skowronska ◽

Mariusz T. Skowronski

Keyword(s):

Assisted Reproductive Technologies ◽

Mammalian Species ◽

Atp Release ◽

Reproductive Technologies ◽

High Energy ◽

Developmental Competence ◽

Physiological Processes ◽

Protein Group ◽

Multicellular Organisms

The oocyte is the major determinant of embryo developmental competence in all mammalian species. Although fundamental advances have been generated in the field of reproductive medicine and assisted reproductive technologies in the past three decades, researchers and clinicians are still trying to elucidate molecular factors and pathways, which could be pivotal for the oocyte’s developmental competence. The cell-to-cell and cell-to-matrix communications are crucial not only for oocytes but also for multicellular organisms in general. This latter mentioned communication is among others possibly due to the Connexin and Pannexin families of large-pore forming channels. Pannexins belong to a protein group of ATP-release channels, therefore of high importance for the oocyte due to its requirements of high energy supply. An increasing body of studies on Pannexins provided evidence that these channels not only play a role during physiological processes of an oocyte but also during pathological circumstances which could lead to the development of diseases or infertility. Connexins are proteins that form membrane channels and gap-junctions, and more precisely, these proteins enable the exchange of some ions and molecules, and therefore they do play a fundamental role in the communication between the oocyte and accompanying cells. Herein, the role of Pannexins and Connexins for the processes of oogenesis, folliculogenesis, oocyte maturation and fertilization will be discussed and, at the end of this review, Pannexin and Connexin related pathologies and their impact on the developmental competence of oocytes will be provided.

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