LOW FREQUENCY ACOUSTIC RESPONSE OF SURFACE CRACKS BY ATOM FORCE ACOUSTIC MICROSCOPY

2009 ◽  
Vol 16 (03) ◽  
pp. 449-453 ◽  
Author(s):  
WEI-TAO SU ◽  
BIN LI ◽  
DING-QUAN LIU ◽  
FENG-SHAN ZHANG
Keyword(s):  
Electron Microscopy ◽  
Scanning Electron Microscopy ◽  
Thermal Stress ◽  
Elastic Properties ◽  
Surface Crack ◽  
Low Frequency ◽  
Acoustic Microscopy ◽  
Surface Cracks ◽  
Acoustic Response ◽  
Scanning Electron

Surface crack of CeF 3 films generated by thermal stress were characterized by scanning electron microscopy and atom force acoustic microscopy (AFAM). Low frequency (8–18 kHz) acoustic response of films and cracks was measured by AFAM. The low frequency acoustic response is similar to what had been got at several MHz or even higher frequency. It was found that surface elastic properties of CeF 3 films can be easily qualitatively measured by low frequency AFAM.

Nondestructive Characterization of Beryllium Effects on Ni-Cr Dental Alloy Elastic Properties and Microstructure: Ultrasonics, X-Ray Diffractometry, Scanning Electron Microscopy and Wavelength Dispersive Spectrometry

1988 ◽  
Vol 142 ◽  
Author(s):  
Surendra Singh ◽  
J. Lawrence Katz ◽  
B. S. Rosenblatt
Keyword(s):  
Electron Microscopy ◽  
Scanning Electron Microscopy ◽  
Elastic Properties ◽  
Ultrasonic Pulse ◽  
Chemical Compositions ◽  
Transmission Method ◽  
Buoyant Force ◽  
X Ray ◽  
Wavelength Dispersive Spectrometry ◽  
Scanning Electron

AbstractKnowledge of structure-properties relationship is a key factor in the development and improvement of new and existing metal alloys through manipulation in their chemical-compositions. In this study, the elastic properties and microstructure of cast Ni-Cr-Be and Ni-Cr dental alloys were studied. The elastic properties, i.e., Young's, shear and bulk moduli and Poisson's ratios, were determined using measurements on the ultrasonic velocities and densities. Both the shear and the longitudinal (dilatational) velocities were measured using an ultrasonic pulse-through-transmission method; density was measured using a buoyant force method. In microstructure, crystallinity, porosity, particle-size and quantitative elemental compositions were studied using x-ray diffractometry (XRD), scanning electron microscopy (SEM) and wavelength dispersive spectrometry (WDS) respectively. These results show that: (1) the addition of Be increased significantly the alloy's elastic moduli and Poisson's ratio; and (2) the presence of Be in Ni-Cr alloy also significantly modified its microstructure by producing a second binary phase, Ni-Be, in eutectic areas.

Failure Analysis of the Entrance Elbow for Crude Oil Cracking Furnace

2012 ◽  
Vol 524-527 ◽  
pp. 1811-1815
Author(s):  
Cheng Xu ◽  
Xiao Tao Zheng ◽  
Jiu Yang Yu ◽  
Tao Yi ◽  
Wei Lin ◽  
...  
Keyword(s):  
Electron Microscopy ◽  
Scanning Electron Microscopy ◽  
Thermal Stress ◽  
Weld Metal ◽  
Crude Oil ◽  
Energy Dispersive Spectroscopy ◽  
Hardness Testing ◽  
Sulfide Corrosion ◽  
Oil Cracking ◽  
Scanning Electron

The weld cracking mechanism of the entrance elbow of crude oil cracking furnace served at 490°C was investigated. The performance and microstructure of failed elbow were characterized by hardness testing, optical microscopy, scanning electron microscopy (SEM) equipped with energy dispersive spectroscopy (EDS). The results showed that cracks are caused by the combination of sulfide corrosion, embrittlement of weld metal and thermal stress.

Scanning Electron-Acoustic Microscopy: Do You Know Its Capabilities?

MRS Bulletin ◽  
1996 ◽  
Vol 21 (10) ◽  
pp. 42-46 ◽  
Author(s):  
M. Urchulutegui
Keyword(s):  
Electron Microscopy ◽  
Scanning Electron Microscopy ◽  
Acoustic Waves ◽  
Material Characterization ◽  
Sample Surface ◽  
Acoustic Microscopy ◽  
Photoacoustic Microscopy ◽  
Characterization Methods ◽  
Electron Acoustic ◽  
Scanning Electron

Characterization of materials usually requires microscopy techniques. Some of the most useful are based on a scanning microscope and involve scanning the sample surface with a focused beam (e.g., photons, electrons, ions, etc.). For example, photoacoustic microscopy uses a laser beam, acoustic microscopy uses an ultrasound beam, and scanning electron microscopy uses an electron beam. The interaction between the material and the beam produces a signal that can be used to generate a two-dimensional image.In scanning photoacoustic microscopy (SPAM), an intensity-modulated light beam is used to produce oscillations in the surface temperature of the sample. These oscillations induce changes in the pressure of a fluid in the photoacoustic cell as a consequence of the periodic heat conduction from the surface to the cell fluid. Subsequently many material-characterization methods have employed the same philosophy as SPAM, using a modulated beam as an excitation probe. The breadth of such techniques is due to the large number of possible excitation sources and signal detectors that have been proposed to probe the specimen response. In particular, scanning electron-acoustic microscopy (SEAM), also referred to as thermal wave microscopy, is a technique based on the utilization of a scanning electron microscope developed in 1980 and applied in recent years to material characterization. It can be considered an additional mode of scanning electron microscopy (SEM), which uses the generation of acoustic waves in the sample. Most reviews have concentrated on the application of SEAM to metals and semiconductors. However many other possibilities exist.

Electron-Acoustic Microscopy of Polycrystalline Metals and Alloys

1981 ◽  
Vol 39 ◽  
pp. 390-391
Author(s):  
S. Cargill
Keyword(s):  
Electron Microscopy ◽  
Scanning Electron Microscopy ◽  
Electron Beam ◽  
Acoustic Microscopy ◽  
Scattered Electron ◽  
Near Surface ◽  
Ultrasonic Signals ◽  
Bending Resistance ◽  
Electron Acoustic ◽  
Scanning Electron

Electron-acoustic microscopy is a mode of ultrasonic imaging in scanning electron microscopy for which image contrast arises primarily from spatial variations in the elastic and thermal properties of a specimen, e.g., its resistance to bending, resistance to heat flow, and volume expansion on heating. Electron-acoustic (EA) microscopy differs from conventional scanning electron microscopy in that the electron beam is chopped at kHz or MHz rates, and a piezoelectric transducer bonded to the specimen is used to detect ultrasonic signals which are generated thermoelastically within the specimen. A scanned, magnified image of the specimen is formed using the rectified output of this transducer, in place of the usual secondary or back scattered electron signal. This technique provides near-surface and subsurface information which is not accessible in other modes of SEM imaging. The experiments described here were performed with a Cambridge Stereoscan S4-10 SEM in which the electron beam was chopped electrostatically by deflector plates located below the second condenser lens.

Thermal- and acoustic-wave techniques in scanning electron microscopy

1986 ◽  
Vol 64 (9) ◽  
pp. 1238-1246 ◽  
Author(s):  
Ludwig Josef Balk
Keyword(s):  
Electron Microscopy ◽  
Scanning Electron Microscopy ◽  
Electron Beam ◽  
Acoustic Wave ◽  
Three Dimensional ◽  
Acoustic Microscopy ◽  
Wave Form ◽  
Time Resolved ◽  
In Situ Experiments ◽  
Scanning Electron

Since their introduction in 1980, thermal- and acoustic-wave techniques utilizing electron-beam excitation, denoted in the following as scanning electron acoustic microscopy (SEAM), have developed to include methods in the realm of scanning electron microscopy (SEM), giving additional and important information on material parameters compared with other SEM techniques. However, the SEAM method still has shortcomings, both theoretically and experimentally. New theories have to consider various principal sound-generation mechanisms, especially for semiconductors, ceramics, and ferromagnets. Furthermore, they must include three-dimensional and time-resolved calculations. From experimental evidence there is obviously the need for additional consideration of nonlinear signal generation. The theoretical discussion has to be supported by experiments; both phase analysis of the SEAM signal with respect to the electron-beam wave form and evaluation of the temporal SEAM behaviour are important for revealing information about the specimen. With special detectors, in situ experiments can be carried out for varying process parameters, as shown for the investigation of steel sheets. The SEAM performance has to be compared to other SEM modes by simultaneous experiments, especially for applications to semiconductors. Finally, extension to gigahertz frequencies and use of tomographic methods should increase the importance of SEAM in future.

scholarly journals Investigation of Microdiamonds Obtained by the Oxygen-Acetylene Torch Method

2017 ◽  
Vol 19 (2) ◽  
pp. 163
Author(s):  
B. Mansurov ◽  
B. Medyanova ◽  
A. Kenzhegulov ◽  
G. Partizan ◽  
B. Zhumadilov ◽  
...  
Keyword(s):  
Electron Microscopy ◽  
Scanning Electron Microscopy ◽  
Raman Scattering ◽  
Low Frequency ◽  
Copper Film ◽  
Scattering Method ◽  
Copper Films ◽  
Experimental Conditions ◽  
Synthesis Time ◽  
Scanning Electron

The results of experiments on the synthesis of micro- and nano-diamonds by an oxy-acetylene torch on the surface of the pre-deposited copper thin films are presented in this article. The influence of thickness of a buffer copper film and the ratio of the concentrations of oxygen and acetylene on the structure of the deposited samples has been studied in the course of the conducted experiments. The studies by Raman scattering and scanning electron microscopy showed that the synthesis of micro- and nano-diamonds occurs under certain experimental conditions. From the results of the analysis of the obtained samples by the methods of Raman scattering and scanning electron microscopy, it was determined that the deposition time of the copper films and consequently its thickness mainly influence on the structure formation of diamond crystals. On copper films grown for 30 min, the Raman scattering method showed a shift of the diamond peak from the standard (1332 cm‒1) to the low-frequency band (1331.3 cm‒1), which may occur after the presence of stress in the crystals. The results of the investigation showed that with increasing of synthesis time take place smoothing of the facets of crystallites (scanning electron microscopy) and decrease in intensity of the diamond peaks (Raman scattering method).

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