scholarly journals Photothermal frequency-domain depth profilometry of a discrete inhomogeneous surface layer on homogeneous substrate

1994 ◽  
Vol 04 (C7) ◽  
pp. C7-95-C7-98 ◽  
Author(s):  
F. Funak ◽  
A. Mandelis ◽  
M. Munidasa
Keyword(s):  
Surface Layer ◽  
Frequency Domain ◽  
Inhomogeneous Surface

scholarly journals Features of the Surface and Subsurface Waves Application for Ultrasonic Evaluation of Physicomechanical Properties of Solids. Part 2. Strenghtned Inhomogeneous Surface Layer

2019 ◽  
Vol 10 (1) ◽  
pp. 69-79
Author(s):  
A. R. Baev ◽  
A. L Mayorov ◽  
N. V. Levkovich ◽  
M. V. Asadchaya
Keyword(s):  
Experimental Data ◽  
Surface Layer ◽  
Spatial Distribution ◽  
Surface Wave ◽  
High Frequency ◽  
Hardened Layer ◽  
Gray Iron ◽  
Physicomechanical Properties ◽  
Inhomogeneous Surface ◽  
Ultrasonic Evaluation

The propagation of a pulsed signal of a surface wave over an object with a non-uniform surface layer, obtained, for example, as a result of surface hardening, with structural damage, is accompanied by the dispersion of the velocity of the wave carrying important information about the parameters of such a layer. The aim of the work is to study the relationship between the acoustic parameters of a pulsed acoustic signal of a surface and subsurface waves and the surface layer of steel specimens hardened by high-frequency hardening, and gray iron-chill. Features of the surface and subsurface waves application for ultrasonic evaluation of physicomechanical properties of solids. Strenghtned inhomogeneous surface layer.A brief analysis of the known works on determining the depth of hardened surface layers by various methods, including high-frequency hardening, cementation, etc., is carried out. Based on the Oulder integral expression. The dependence connecting the wave velocity, its frequency, the depth of the hardened layer and the spatial distribution of hardness represented as a step with a changing slope of its side surface simulating the transition zone of the hardened layer are calculated.Using the pulse method and low-aperture transducers with a frequency of 1−3.8 MHz, the dependences of the surface wave velocity on the cutting height of a layer hardened by HDTV hardening are obtained. A comparison of experimental data and calculations of the theoretical model showed a good qualitative correspondence between them, demonstrate a high «sensitivity» of the method in relation to the nature of the change in hardness over the depth of the hardened layer. It is shown that the proposed approach is promising for solving the inverse problem of restoring the spatial distribution of hardness based on experimental data.The goniometric method was approbated to determine the dependence between amplitude-angle characteristics and depth of the surface steel layers hardened by high-frequency hardening and depth of hardened gray iron specimens layer – with chill. It is shown that the optimal angle corresponding maximum of excited surface wave amplitude in steel specimens is decreasing up to 24–26'vs. hardened depth layer. But when the tested specimens from cast iron this angle decreasing is nearly of 6°. Recommendations on the use of research results in practice are given.

Thermal Radiation from a Microscopically Roughened Dielectric Surface

1972 ◽  
Vol 94 (1) ◽  
pp. 73-79 ◽  
Author(s):  
R. P. Caren ◽  
C. K. Liu
Keyword(s):  
Refractive Index ◽  
Surface Layer ◽  
Thermal Radiation ◽  
Spatial Variation ◽  
Riccati Equation ◽  
Radiant Energy ◽  
Dielectric Surface ◽  
Inhomogeneous Surface ◽  
Roughened Surface ◽  
Total Emittance

The emission of thermal radiation from a microscopically roughened dielectric surface is treated using a laminar-inhomogeneous layered model for a representation of the effective spatial variation in refractive index associated with a roughened surface layer. The Riccati equation is used to calculate the modification to the spectral angular transmittance of the surface due to the presence of this inhomogeneous surface layer. A consideration of the emission of radiant energy from the bulk dielectric through the surface layer permits the angular emittance to be determined. Total emittance values are obtained using the spectral angular emittance data.

scholarly journals Ellipsometric Diagnostics of a Transient Surface Layer in Optical Glass

2019 ◽  
Vol 64 (5) ◽  
pp. 442 ◽  
Author(s):  
O. V. Makarenko ◽  
L. V. Poperenko ◽  
O. I. Zavalistyi ◽  
A. L. Yampolskiy
Keyword(s):  
Optical Properties ◽  
Surface Layer ◽  
Layer Structure ◽  
Optical Glass ◽  
Target Function ◽  
Morphological Structure ◽  
Thin Layers ◽  
Inhomogeneous Surface ◽  
Interference Phenomenon ◽  
Near Surface

Optical properties of a transient layer with a broken structure that arises at the surface of optical glass at its treatment have been considered. Rather often, the surface of optical elements is considered to be perfect, although the actual inhomogeneous surface structure can have a significant effect for precision physical experiments or novel technological problems. Furthermore, the simulation of the surface layer structure and the corresponding optical characteristics, as well as the study of a possibility to determine those parameters from the results of optical researches, is also of theoretical interest, which is demonstrated in this work. Ellipsometric measurements of optical glass specimens with a broken surface layer are carried out. When modeling the angular dependences of the ellipsometric parameters tan ф and cos б, the near-surface specimen region is considered as a stack of 500 thin layers, and the matrix method of light reflection in this structure with regard for the interference phenomenon is used in calculations. Five models are tested for the optical profile of a nonuniform layer, whose parameters are fitted to achieve the minimum of the target function describing the discrepancy between the calculated and measured data. It is found that the theoretical models describe the optical properties of the specimens more accurately, if they make allowance for the inhomogeneous surface layer. Nevertheless, the solution of the inverse ellipsometric problem turns out ambiguous, so that additional measurements are required for the final choice of a model that would be adequate to the actual morphological structure of the broken layer to be made. However, the key advantage of the applied method consists in that it allows a direct registration of the optical response of the system.

Photoacoustic frequency‐domain depth profilometry of surface‐layer inhomogeneities: Application to laser processed steels

1992 ◽  
Vol 71 (12) ◽  
pp. 6029-6035 ◽  
Author(s):  
Tian‐Chi Ma ◽  
Mahendra Munidasa ◽  
Andreas Mandelis
Keyword(s):  
Surface Layer ◽  
Frequency Domain

The oxidation of Inconel alloy MA754 at low oxidation potential

1983 ◽  
Vol 41 ◽  
pp. 218-219
Author(s):  
D. N. Braski ◽  
P. D. Goodell ◽  
J. V. Cathcart ◽  
R. H. Kane
Keyword(s):  
Surface Layer ◽  
Oxidation Potential ◽  
Metal Interface ◽  
Elevated Temperature Strength ◽  
Surface Conditions ◽  
Inconel Alloy ◽  
Inco Alloy ◽  
Resistance To Oxidation ◽  
Oxide Particles ◽  
Cold Worked

It has been known for some time that the addition of small oxide particles to an 80 Ni—20 Cr alloy not only increases its elevated-temperature strength, but also markedly improves its resistance to oxidation. The mechanism by which the oxide dispersoid enhances the oxidation resistance is being studied collaboratively by ORNL and INCO Alloy Products Company.Initial experiments were performed using INCONEL alloy MA754, which is nominally: 78 Ni, 20 Cr, 0.05 C, 0.3 Al, 0.5 Ti, 1.0 Fe, and 0.6 Y2O3 (wt %).Small disks (3 mm diam × 0.38 mm thick) were cut from MA754 plate stock and prepared with two different surface conditions. The first was prepared by mechanically polishing one side of a disk through 0.5 μm diamond on a syntron polisher while the second used an additional sulfuric acid-methanol electropolishing treatment to remove the cold-worked surface layer. Disks having both surface treatments were oxidized in a radiantly heated furnace for 30 s at 1000°C. Three different environments were investigated: hydrogen with nominal dew points of 0°C, —25°C, and —55°C. The oxide particles and films were examined in TEM by using extraction replicas (carbon) and by backpolishing to the oxide/metal interface. The particles were analyzed by EDS and SAD.

Structural analysis of the surface-layer protein of spirillum serpens by high-resolution electron microscopy

1983 ◽  
Vol 41 ◽  
pp. 738-739
Author(s):  
W. H. Wu ◽  
R. M. Glaeser
Keyword(s):  
Electron Microscopy ◽  
Surface Layer ◽  
Structural Analysis ◽  
High Resolution ◽  
Low Dose ◽  
High Resolution Electron Microscopy ◽  
Optical Diffraction ◽  
Surface Layer Protein ◽  
Morphological Unit ◽  
Resolution Electron

Spirillum serpens possesses a surface layer protein which exhibits a regular hexagonal packing of the morphological subunits. A morphological model of the structure of the protein has been proposed at a resolution of about 25 Å, in which the morphological unit might be described as having the appearance of a flared-out, hollow cylinder with six ÅspokesÅ at the flared end. In order to understand the detailed association of the macromolecules, it is necessary to do a high resolution structural analysis. Large, single layered arrays of the surface layer protein have been obtained for this purpose by means of extensive heating in high CaCl2, a procedure derived from that of Buckmire and Murray. Low dose, low temperature electron microscopy has been applied to the large arrays.As a first step, the samples were negatively stained with neutralized phosphotungstic acid, and the specimens were imaged at 40,000 magnification by use of a high resolution cold stage on a JE0L 100B. Low dose images were recorded with exposures of 7-9 electrons/Å2. The micrographs obtained (Fig. 1) were examined by use of optical diffraction (Fig. 2) to tell what areas were especially well ordered.

Electron-Mirror Microscopic Aspects of Ferroelectric Domains of BaTiO3 And Ca2Sr (C2H5CO2)6

1970 ◽  
Vol 28 ◽  
pp. 478-479
Author(s):  
Teruo Someya ◽  
Jinzo Kobayashi
Keyword(s):  
Surface Layer ◽  
Electric Fields ◽  
Quantitative Study ◽  
Recent Progress ◽  
Ferroelectric Domain ◽  
Resolving Power ◽  
Surface Pattern ◽  
Crystal Surfaces ◽  
One Dimensional ◽  
Ferroelectric Domains

Recent progress in the electron-mirror microscopy (EMM), e.g., an improvement of its resolving power together with an increase of the magnification makes it useful for investigating the ferroelectric domain physics. English has recently observed the domain texture in the surface layer of BaTiO3. The present authors ) have developed a theory by which one can evaluate small one-dimensional electric fields and/or topographic step heights in the crystal surfaces from their EMM pictures. This theory was applied to a quantitative study of the surface pattern of BaTiO3).

Microstructure of Electro-Eroded Cemented Carbide Surfaces

1968 ◽  
Vol 26 ◽  
pp. 284-285
Author(s):  
V. N. Filimonenko ◽  
M. H. Richman ◽  
J. Gurland
Keyword(s):  
Surface Layer ◽  
Cobalt Content ◽  
Cemented Carbides ◽  
Face Centered Cubic ◽  
X Ray Diffraction ◽  
Metallographic Examination ◽  
Standard Procedures ◽  
Face Centered ◽  
Diamond Paste ◽  
Plastic Carbon

The high temperatures and pressures that are found in a spark gap during electrical discharging lead to a sharp phase transition and structural transformation in the surface layer of cemented carbides containing WC and cobalt. By means of X-ray diffraction both W2C and a high-temperature monocarbide of tungsten (face-centered cubic) were detected after electro-erosion. The W2C forms as a result of the peritectic reaction, WC → W2C+C. The existence and amount of the phases depend on both the energy of the electro-spark discharge and the cobalt content. In the case of a low-energy discharge (i.e. C=0.01μF, V = 300v), WC(f.c.c.) is generally formed in the surface layer. However, at high energies, (e.g. C=30μF, V = 300v), W2C is formed at the surface in preference to the monocarbide. The phase transformations in the surface layer are retarded by the presence of larger percentages of cobalt.Metallographic examination of the electro-eroded surfaces of cemented carbides was carried out on samples with 5-30% cobalt content. The specimens were first metallographically polished using diamond paste and standard procedures and then subjected to various electrical discharges on a Servomet spark machining device. The samples were then repolished and etched in a 3% NH4OH electrolyte at -0.5 amp/cm2. Two stage plastic-carbon replicas were then made and shadowed with chromium at 27°.

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