scholarly journals The Scanning Electron Microscope As A Precision Instrument

1996 ◽  
Vol 4 (6) ◽  
pp. 30-34
Author(s):  
Douglas Hansen
Keyword(s):  
Diffraction Gratings ◽  
Stray Field ◽  
X Ray Diffraction ◽  
Precision Instrument ◽  
X Ray ◽  
Electron Microscopes ◽  
Scanning Electron Microscopes ◽  
The University ◽  
Straight Lines ◽  
Scanning Electron

I began using scanning electron microscopes to solve problems encountered in the fabrication of x-ray diffraction gratings. Since these diffraction gratings consist of very regular lines and spaces, and produce high contrast images from the SEM. my microscopy work often points out problems with the microscope.One time, for example, I went to the university SEM lab I often use, and was advised that the microscope was down that day due to major field problems. This lab often had problems with stray fields for reasons no one could explain. Usually I was the only one to complain about stray field distortions since they are most obvious when imaging straight lines at high magnification, but on this occasion, the problem was serious and obvious to all.The microscope had just been serviced and as the lens coils had been replaced, they were expected to be the cause. The service technician was called in and determined that neither the coils nor the microscope electronics were the problem.

Analysis on Microstructure of Laser Brazing Diamond Grits with a Ni-Based Filler Alloy

2010 ◽  
Vol 97-101 ◽  
pp. 3879-3883 ◽  
Author(s):  
Zhi Bo Yang ◽  
Jiu Hua Xu ◽  
Ai Ju Liu
Keyword(s):  
Active Element ◽  
Steel Substrate ◽  
Parameters Optimization ◽  
Interfacial Region ◽  
Filler Alloy ◽  
X Ray Diffraction ◽  
X Ray ◽  
Cross Diffusion ◽  
Electron Microscopes ◽  
Scanning Electron Microscopes

Brazing diamond grits onto steel substrate using a Ni-based filler alloy was carried out via laser beam in an argon atmosphere. The microstructure of the interfacial region among the Diamond grits and the filler layer were investigated by means of scanning electron microscopes (SEM), X-ray diffraction (XRD) and energy dispersive X-ray spectroscopy (EDS). Meanwhile, the formation mechanism of carbide layers was discussed. All the results indicated that the active element chromium in the Ni-based alloy concentrated preferentially to the surface of the grits to form a chromium-rich layer, and the hard joint between the alloy and the steel substrate is established through a cross-diffusion of iron and Ni-based alloy through parameters optimization.

scholarly journals Creep Failure of Reformer Tubes in a Petrochemical Plant

Metals ◽  
2019 ◽  
Vol 9 (10) ◽  
pp. 1026 ◽  
Author(s):  
Abbas Bahrami ◽  
Peyman Taheri
Keyword(s):  
High Temperature ◽  
Void Coalescence ◽  
Petrochemical Plant ◽  
Creep Failure ◽  
X Ray ◽  
Carbide Phases ◽  
Electron Microscopes ◽  
Reformer Tubes ◽  
Scanning Electron Microscopes ◽  
Scanning Electron

This paper investigates a failure in HP-Mod radiant tubes in a petrochemical plant. Tubes fail after 90,000 h of working at 950 °C. Observed failure is in the form of excessive bulging and longitudinal cracking in reformer tubes. Cracks are also largely branched. The microstructure of service-exposed tubes was evaluated using optical and scanning electron microscopes (SEM). Energy-dispersive X-ray spectroscopy (EDS) was used to analyze and characterize different phases in the microstructure. The results of this study showed that carbides are coarsened at both the inner and the outer surface due to the long exposure to a carburizing environment. Metallography examinations also revealed that there are many creep voids that are nucleated on carbide phases and scattered in between dendrites. Cracks appeared to form as a result of creep void coalescence. Failure is therefore attributed to creep due to a long exposure to a high temperature.

Otosclerotic Stapes: Morphological and Microchemical Correlates

1977 ◽  
Vol 86 (4) ◽  
pp. 525-540 ◽  
Author(s):  
David J. Lim ◽  
William H. Saunders
Keyword(s):  
Calcium Salt ◽  
Mineral Deposit ◽  
Ground Substance ◽  
X Ray Diffraction ◽  
Typical Pattern ◽  
X Ray ◽  
Initial Stage ◽  
Electron Microscopes ◽  
Sclerotic Lesions ◽  
Scanning Electron Microscopes

A total of 32 otosclerotic stapes is thin-sectioned without decalcification and examined using transmission and scanning electron microscopes, with a nondispersive x-ray analyzer attached to the latter. These otosclerotic stapes are classified as spongiotic, sclerotic, or preotosclerotic, according to their pathologic characteristics and state of mineralization. Either diffuse or patchy demineralization in the ground substance appears to be the initial stage of otosclerosis, and this area coincides with preotosclerotic lesions (also known as blue mantle) in light microscopy. Therefore, it is interpreted that demineralization precedes the destruction of ground substance in the preotosclerotic lesion. Bone mineral deposits in new otosclerotic bone appear to be related to the collagen fibrils that are embedded in the ground substance. No mineral deposit could be seen without the ground substance deposition; therefore, it is suggested that this ground substance is the single most important factor in the poor mineralization of the otosclerosis. The sclerotic lesions are well mineralized and show a typical pattern of hydroxyapatite by x-ray diffraction study. We could not confirm the notion that the sclerotic lesion is hypermineralized as compared to the normal stapes. The spongiotic lesions are poorly mineralized, with low calcium salt. Using the Ca/P ratio and x-ray diffraction pattern as criteria, it was determined that spongiotic lesions belong to unstable, immature bone.

Mini-Scanning Electron Miscroscope Concept

1974 ◽  
Vol 32 ◽  
pp. 406-407
Author(s):  
Donald J. Evins ◽  
Robert J. Engle
Keyword(s):  
Electron Microscope ◽  
Depth Of Field ◽  
X Ray ◽  
Rapid Scan ◽  
Operational Characteristics ◽  
Electron Microscopes ◽  
The Cost ◽  
Scanning Electron Microscopes ◽  
Large Research ◽  
Scanning Electron

The scanning electron microscope has already established itself as one of the most useful instrument developments in recent years. The SEM provides 20 times greater useful magnifications and up to 500 times greater depth of-field than the best optical microscopes. Until the introduction of the Mini-SEM concept, the cost and complexity of SEM's has limited their use primarily to large research oriented laboratories.Design features, specifications, and operational characteristics will be reviewed. The Mini-Rapid Scan with resolution of 750Å will be described, along with the Mini-SEM with resolution of 150 to 200Å. Both of these are table top scanning electron microscopes. Various specimen stage options will be illustrated. Other accessories extending the SEM's versatility will be described, such as the energy dispersive x-ray system

scholarly journals Practical Issues for Quantitative X-ray Microanalysis in SEM at Low kV

2006 ◽  
Vol 14 (1) ◽  
pp. 30-33 ◽  
Author(s):  
Peter Statham
Keyword(s):  
Quantitative Analysis ◽  
Atomic Number ◽  
Beam Current ◽  
Research Groups ◽  
X Ray ◽  
Time Scanning ◽  
Electron Microscopes ◽  
Scanning Electron Microscopes ◽  
Scanning Electron

In the three decades following Castaing's seminal thesis [1] x-ray analysis received widespread attention from research groups. By 1980, the methods and correction procedures for quantitative analysis of elements with atomic number 11 and above, using accelerating voltages between 15kV and 25kV, were well established and available in commercial instrumentation. At the time, scanning electron microscopes (SEMs) could rarely deliver high and stable beam current at much lower kV, and x-ray spectrometers had poor efficiency below lkeV so that low kV analysis received comparatively little attention.

Take-off Angle Imaging: A New Image Mode for Scanning Electron Microscopy

2013 ◽  
Vol 21 (3) ◽  
pp. 22-25
Author(s):  
Nicholas C. Barbi ◽  
Richard B. Mott
Keyword(s):  
Electrical Current ◽  
Avalanche Photodiode ◽  
Si Substrate ◽  
Silicon Photomultiplier ◽  
Silicon Photomultipliers ◽  
X Ray ◽  
Backscattered Electron ◽  
Electron Microscopes ◽  
Scanning Electron Microscopes ◽  
Scanning Electron

Traditional electron detectors for scanning electron microscopes (SEMs) are the Everhart-Thornley detector located on one side of the specimen and the overhead backscattered electron detector (BSED), usually mounted under the final lens. In 2011 PulseTor introduced an efficient BSED based on scintillator/silicon photomultipler technology that is small enough to be mounted on the tip of an X-ray detector. The scintillator converts the electron signal to light, which is in turn converted to an electrical current in the silicon photomultiplier (SiPM). Silicon photomultipliers were initially developed in Russia in the 1990s. The review article by Dolgoshein et al. cites much of the historical development. Following the recent work of Piemonte and others, the SiPM consists of an array of many identical and independent detecting elements (microcells) connected in parallel on a common Si substrate. Each microcell is an avalanche photodiode only tens of micrometers in size.

Laser Welding of AISI 316 Steel: Microstructural and Stress Analysis

2013 ◽  
Vol 135 (3) ◽  
Author(s):  
B. S. Yilbas ◽  
Sohail Akhtar
Keyword(s):  
Residual Stress ◽  
Base Material ◽  
Element Model ◽  
X Ray Diffraction ◽  
X Ray ◽  
Cooling Period ◽  
Thermal Stress Field ◽  
Electron Microscopes ◽  
Aisi 316 ◽  
Scanning Electron Microscopes

Thermal-stress field in the welded region was modeled incorporating the finite element model. Temperature and stress fields were predicted at different cooling periods. The morphological and metallurgical changes in the welded region were examined using optical and scanning electron microscopes, energy dispersive spectroscopy and X-ray diffraction. The residual stress formed at the surface vicinity of the weld was determined using the X-ray diffraction technique. It was found that the residual stress predicted agreed well with the experimental data. The solidification cracking did not occur in the weld section during the cooling period. The microhardness in the weld cross-section was almost 1.4 times the base material hardness.

scholarly journals Sensitivity Analysis of X-ray Spectra from Scanning Electron Microscopes

2014 ◽  
Author(s):  
Thomas Martin Miller ◽  
Bruce W. Patton ◽  
Charles F. Weber ◽  
Kursat B. Bekar
Keyword(s):  
Sensitivity Analysis ◽  
X Ray ◽  
Electron Microscopes ◽  
Scanning Electron Microscopes ◽  
Scanning Electron

scholarly journals Preparation and properties of nanocrystalline Ni/graphene composite coatings deposited by electrochemical method

2018 ◽  
Vol 20 (1) ◽  
pp. 29-34 ◽  
Author(s):  
Grzegorz Cieślak ◽  
Maria Trzaska
Keyword(s):  
Steel Substrate ◽  
Composite Coatings ◽  
X Ray Diffraction ◽  
Dispersion Phase ◽  
X Ray ◽  
Graphene Layers ◽  
Nano Crystalline ◽  
Graphene Flakes ◽  
Electron Microscopes ◽  
Scanning Electron Microscopes

Abstract The paper presents results of studies of composite nickel/graphene coatings produced by electrodeposition method on a steel substrate. The method of producing composite coatings with nanocrystalline nickel matrix and dispersion phase in the form of graphene is presented. For comparative purposes, the study also includes nano-crystalline Ni coatings produced by electrochemical reduction without built-in graphene flakes. Graphene was characterized by Raman spectroscopy, transmission and scanning electron microscopes. Results of studies on the structure and morphology of Ni and Ni/graphene layers produced in a bath containing different amounts of graphene are presented. Material of the coatings was characterized by SEM, light microscopy, X-ray diffraction. The microhardness of the coatings was examined by Knoop measurements. The adhesion of the coatings with the substrate was tested using a scratchtester. The influence of graphene on the structure and properties of composite coatings deposited from a bath with different graphene contents was determined.

Importance of the relative x-ray line intensities

1992 ◽  
Vol 50 (2) ◽  
pp. 1636-1637
Author(s):  
János L. Lábár ◽  
Charles E. Fiori ◽  
Robert L. Myklebust
Keyword(s):  
Rare Earth ◽  
Energy Dispersive Spectrometry ◽  
X Ray ◽  
Line Intensities ◽  
Elemental Concentrations ◽  
Wavelength Dispersive Spectrometry ◽  
Electron Microscopes ◽  
Scanning Electron Microscopes ◽  
Standardless Analysis ◽  
Scanning Electron

Relative intensities of the non-analytical lines of an element (as compared to the analytical X-ray line of the same element) directly affect the accuracy of quantitative X-ray microanalysis. Correct spectral deconvolution can only be based on the knowledge of these relative intensities. Not even wavelength dispersive spectrometry (WDS) is free from spectral overlaps, making deconvolution of the X-ray lines necessary. A typical example for such a serious overlap can be the L line series of different rare-earth elements simultaneously present in the same sample. Energy dispersive spectrometry (EDS) is even more affected. Many EDS systems are equipped on scanning electron microscopes (SEM). Quick standardless analysis is frequently in use in these systems. Starting approximation of the elemental concentrations are based on computed "standard intensities" in contrast to measured ones in full quantitative analysis. Computation of the generated standard intensities directly contain the relative intensities of other lines too.

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