油气集输管道腐蚀失效分析

利用X-射线衍射、电子探针、化学组成和夹杂物分析等方法系统分析了中国石油化工股份有限公司中原油田分公司某采油厂油气集输管道的失效机理,从而为集输系统腐蚀的有效防护提供了理论依据。     

RECIST Applied to Realistic Tumor Models

RECIST (Response Evaluation Criteria in Solid Tumors) is a linear measure intended to predict tumor size in medical computed tomography (CT). In this work, using purely geometrical considerations, we estimate how well RECIST can predict the volume of randomly-oriented tumor models, each composed of the union of ellipsoids. The principal conclusion is that RECIST is likely to work less well for realistic tumors than for ellipsoids.     

The detection of low-intensity peaks in energy dispersive x-ray spectra from particles

A critical step in the processing of energy dispersive (EDS) x-ray spectra from the automated scanning electron microscopy (ASEM) analysis of particles is the detection and identification of elemental peaks. Since there are often several hundred to several thousand spectra for each ASEM analysis, it is important that this step operate rapidly and with a minimum of interaction between analyst and the program. For peaks with large peak-to-background (P/B) ratios, most peak-find or peak-fitting methods do a reasonable job even when the spectra have low signal-to-noise (S/N) ratios. The detection of peaks with small P/B ratios is much more problematical. Peak identification and fitting procedures may not work well on low-intensity peaks, particularly in spectra with low S/N ratios. In this study, three procedures for identifying x-ray peaks, with small P/B ratios in spectra with varying S/N ratios, were evaluated. The first procedure was the identification of peaks by human analysts. The results from the analysts were then used to set a benchmark for the performance of two computer-based procedures that included three different qualitative peak identification methods, and one quantitative analysis procedure. The success of the qualitative methods in finding small peaks varied widely. In general, the quantitative analysis procedure performed as well as the best human analysts and was better than the qualitative methods.     

High-energy X-ray diffraction and topography investigation of CdZnTe

High-energy transmission x-ray diffraction techniques have been applied to investigate the crystal quality of CdZnTe (CZT). CdZnTe has shown excellent performance in hard x-ray and gamma detection; unfortunately, bulk nonuniformities still limit spectroscopic properties of CZT detectors. Collimated high-energy x-rays, produced by a superconducting wiggler at the National Synchrotron Light Source’s X17B1 beamline, allow for a nondestructive characterization of thick CZT samples (2–3 mm). In order to have complete information about the defect distribution and strains in the crystals, two series of experiments have been performed. First, a monochromatic 67 keV x-ray beam with the size of 300×300 μm² was used to measure the rocking curves of CZT crystals supplied by different material growers. A raster scan of a few square centimeter area allowed us to measure the full-width at half-maximum (FWHM) and shift in the peak position across the crystal. The rocking curve peak position and its FWHM can be correlated with local stoichiometry variations and other local defects. Typically, the FWHM values ranging from 8.3 arcsec to 14.7 arcsec were measured with the best crystal used in these measurements. Second, transmission white beam x-ray topography (WBXT) was performed by using a 22 mm×200 μm beam in the energy range of 50 keV to 200 keV. These types of measurements allowed for large area, high-resolution (50 μm) scans of the samples. Usually, this technique is used to visualize growth and process-induced defects, such as dislocations, twins, domains, inclusions, etc. the difference in contrast shows different parts of the crystal that could not be shown otherwise. In topography, good contrast is indicative of a high quality of the sample, while blurred gray shows the presence of defects. Correlation with other techniques (e.g., infrared (IR) mapping and gamma mapping) was also attempted. Our characterization techniques, which use highly penetrating x-rays, are valid for in-situ measurements, even after electrical contacts have been formed on the crystal in a working device. Thus, these studies may lead to understanding the effects of the defects on the device performance and ultimately to improving the quality of CZT material required for device fabrication. It is important to study crystals from different ingot positions (bottom, center, and top); consequently, more systematic studies involving scans from center to border are planned.     

High Count Rate Electron Probe Microanalysis

Reducing the measurement uncertainty of quantitative analyses made using electron probe microanalyzers (EPMA) requires a careful study of the individual uncertainties from each definable step of the measurement. Those steps include measuring the incident electron beam current and voltage, knowing the angle between the electron beam and the sample (takeoff angle), collecting the emitted x rays from the sample, comparing the emitted x-ray flux to known standards (to determine the k-ratio) and transformation of the k-ratio to concentration using algorithms which includes, as a minimum, the atomic number, absorption, and fluorescence corrections.This paper discusses the collection and counting of the emitted x rays, which are diffracted into the gas flow or sealed proportional x-ray detectors. The representation of the uncertainty in the number of collected x rays collected reduces as the number of counts increase. The uncertainty of the collected signal is fully described by Poisson statistics. Increasing the number of x rays collected involves either counting longer or at a higher counting rate. Counting longer means the analysis time increases and may become excessive to get to the desired uncertainty. Instrument drift also becomes an issue. Counting at higher rates has its limitations, which are a function of the detector physics and the detecting electronics.Since the beginning of EPMA analysis, analog electronics have been used to amplify and discriminate the x-ray induced ionizations within the proportional counter. This paper will discuss the use of digital electronics for this purpose. These electronics are similar to that used for energy dispersive analysis of x rays with either Si(Li) or Ge(Li) detectors except that the shaping time constants are much smaller.     

Effects of solid-state annealing on the interfacial intermetallics between tin-lead solders and copper

The interfacial intermetallics between Cu and solder were studied for four Sn-Pb compositions at the annealing temperatures of 125°C, 150°C, and 175°C for up to 30 days. The η-phase (Cu₆Sn₅) layer formed during reflow continues to grow during annealing. An additional layer of ɛ-phase (Cu₃Sn) forms at the η/Cu interface after an incubation annealing time. The thickness results fit a power-law relationship against time with average exponents 0.69 and 0.44 for the η phase and the ɛ phase, respectively. On prolonged annealing, the proportions of the individual phases in the total layer reach a steady state.     

In-situ spectroscopic study of the As and Te on the Si (112) surface for high-quality epitaxial layers

A detailed analysis of the As-exposed Si (112) and subsequent Te exposure was performed. X-ray photoelectron spectroscopy shows that the Te- and As-exposed Si (112) surface had 70% As and 27% Te coverage, respectively. Direct surface coverage measurement with ion scattering spectroscopy (ISS) shows that the Si (111) surface is completely covered by As, and that of the Si (112) had about 78% and 20% coverage of As and Te, respectively. Finally, using ISS shadowing effects, it was found that the Te atoms were positioned mainly on the step edges.     

Fundamental Parameters Line Profile Fitting in Laboratory Diffractometers

The fundamental parameters approach to line profile fitting uses physically based models to generate the line profile shapes. Fundamental parameters profile fitting (FPPF) has been used to synthesize and fit data from both parallel beam and divergent beam diffractometers. The refined parameters are determined by the diffractometer configuration. In a divergent beam diffractometer these include the angular aperture of the divergence slit, the width and axial length of the receiving slit, the angular apertures of the axial Soller slits, the length and projected width of the x-ray source, the absorption coefficient and axial length of the sample. In a parallel beam system the principal parameters are the angular aperture of the equatorial analyser/Soller slits and the angular apertures of the axial Soller slits. The presence of a monochromator in the beam path is normally accommodated by modifying the wavelength spectrum and/or by changing one or more of the axial divergence parameters. Flat analyzer crystals have been incorporated into FPPF as a Lorentzian shaped angular acceptance function. One of the intrinsic benefits of the fundamental parameters approach is its adaptability any laboratory diffractometer. Good fits can normally be obtained over the whole 20 range without refinement using the known properties of the diffractometer, such as the slit sizes and diffractometer radius, and emission profile.     

Effect of hydrogen annealing on hot-carrier instability of X-Ray irradiated CMOS devices

In the very large scale integration (VLSI) technology, the need for high density and high performance integrated circuit (IC) chip demands advanced processing techniques that often result in the generation of high energy particles and photons. Frequently, the radiation damage are introduced by these energetic particles and photons during device processing. The radiation damage created by x-ray irradiation, which can often occur during metal sputtering process, has been shown to potentially enhance hot-carrier instability if the neutral traps which act as electron or hole traps in the silicon dioxide is not annealed out. In this paper, we investigate the effects of annealing using different hydrogen contents and temperatures on the device characteristics and hot carrier instability of 0.5 μm CMOS devices after 1500 mJ/cm² synchrotron x-ray irradiation. Three different annealing conditions were employed; 400° C H₂, 450° C H₂, and 400° C H₂ + N₂. It is found that for all three different hydrogen anneals the normal characteristics of irradiated CMOS devices can be effectively recovered. The hot-carrier instability of bothp- andn-channel MOSFETs are significantly enhanced after x-ray irradiation due to the creation of neutral traps and positively charged oxide traps. After high H₂ (100%) concentration anneals at 450° C, the hot-carrier instability in irradiatedn-channel devices is greatly reduced and comparable to the non-irradiated devices. Although the hot-carrier instability inp-channel devices is also significantly reduced after annealing, the threshold voltage shifts are still enhanced as compared to the devices without exposure to x-ray irradiation during maximum gate current stress. For those non-irradiated, but hydrogen-annealedp-channel devices, the hot-carrier instability was observed to be worse than the non-irradiated device without hydrogen annealing.     

Influence of the structural state on mechanical behavior of tin babbit

Phase constituents of tin babbit have been specified by experimental methods. It has been established that β-phase exerts an influence on elongation, ultimate strength, yield strength, and other mechanical properties of the alloy. The significant distinction in deformation behavior between the cast alloy and the rolled one is attributed to processes of failure of cast structure, its recovery, and recrystallization.