bluuebunny/crossref_metadata_2025 huggingface dataset:
Quantum Yields of Crude Oils
Authors: Ralston Corie Y. , Wu Xu , Mullins Oliver C.
Published: August 2005

Fluorescence quantum yield measurements are reported for visible and UV excitation for neat and dilute crude oil solutions, extending earlier work with excitation in the long wavelength visible and the NIR. Large and monotonically increasing quantum yields are found with shorter wavelength excitation (to 325 nm), and all crude oils are shown to have nearly the same relative dependence of quantum yield on excitation wavelength. These observations are explained by the energy dependence of internal conversion. Dilute solutions of light crude oils exhibit higher quantum yields than those of heavy crude oils because of their lack of large chromophores. The fraction of fluorescence emission resulting from electronic energy transfer (with subsequent fluorescence emission) for neat crude oils was previously shown to vary from ∼100% for ultraviolet excitation to ∼0% for near-infrared excitation; this large variation correlates well with and is explained by the very large variation in quantum yields with excitation wavelength. Comparison of quantum yields from neat and dilute solutions shows that quenching is the other major process which occurs with chromophore interactions. The quantum yields of a maltene and resin are large and similar, while the asphaltene exhibits much smaller quantum yields because of its lack of small chromophores.
Wear-Induced Changes in the Raman, Infrared, and Fluorescence Spectra of Silicon Nitride Surfaces
Authors: Lauer James L.
Published: August 2005

Commercial α-silicon nitride plates and balls used in simulated sliding bearing tests were found to fluoresce under 514.5-nm argon-ion laser excitation after heating to above 350 °C in a stream of argon. Wear track areas fluoresced much more intensely than their surroundings. When small concentrations of ethylene or other carbonaceous gas were added to the argon stream, carbonaceous deposits formed primarily in the wear track in amounts roughly paralleling the fluorescence intensity. Some of the deposits were lubricating carbon and some nonlubricating silicon oxycarbide. Continuous high-temperature lubrication was possible by balancing deposit removal by wear with surface-chemical deposit formation rates. Raman, infrared, fluorescence, and other spectroscopies helped explain the process. Defect energy states within the large silicon nitride energy gap and dangling bonds appear to play a role.
In situ Diffusion Studies Using Spatially Resolved Infrared Microspectroscopy
Authors: Challa Sudarsana R. , Wang Shi-Qing , Koenig Jack L.
Published: August 2005

Spatially resolved infrared microspectroscopy is used in conjunction with the contact method to conduct in situ diffusion experiments of photocured polymer-dispersed liquid crystals (LCs). The system analyzed consists of a low-molecular-weight liquid crystal (E7) diffusing into a photopolymerizable monomer (NOA65). The measured concentration profiles were generated by monitoring the hydroxyl band of the monomer as a function of time and spatial position. The diffusion coefficients were calculated from least-squares fitting of the data. The system followed Fick's second law of diffusion. The diffusion coefficient for this system is (1.97 ± 0.2)(10−8) cm2/s. The morphology of the system after polymerization exhibited three distinct regions: nematic LC molecularly mixed in the cross-linked network of the polymer, nematic LC droplet gradient in the polymer matrix, and polymer fibers scattered in the continuous nematic LC.
ESR Study of Cu Centers Supported on Al-, Ti-, and Zr-Pillared Montmorillonite Clays
Authors: Bahranowski K. , Dula R. , Łabanowska M. , Serwicka E. M.
Published: August 2005

Cu-doped Al-, Ti-, and Zr-pillared montmorillonites obtained by various procedures have been investigated with the aid of electron spin resonance (ESR). The major species present in pillared montmorillonites exchanged with copper at low pH are physisorbed square planar tetraaquo-complexes [Cu(H2O)4]2+. Only at the surface of uncalcined Al pillars does a chemisorption of copper ions occur, giving an inner-sphere square planar complex [Cu(AlO) n (H2O)4- n] x. Calcination of the samples at 673 K brings about a significant change of the Cu2+ ion environment reflected in the change of ESR parameters. The most characteristic feature is the increased covalency of the Cu–O in-plane σ bonding due to the attachment of copper to lattice oxygens. The spectra show that cupric ions form links with the pillars rather than with the silicate sheet. In the case of Al- and Ti-pillared samples, copper species of different degrees of σ in-plane covalency are obtained depending on the preparative procedure. Catalytic tests with hydroxylation of phenol demonstrate that copper centers of higher covalency show superior catalytic performance. This effect is interpreted in terms of the higher in-plane σ covalency facilitating electron transfer between the donor and the acceptor sites at the catalyst surface. The ESR spectra of almost all copper-exchanged samples show, besides the isolated Cu2+ ions, a component due to the exchange-coupled clustered cupric ions.
129Xe NMR Linewidths as Indicators of Spatial Inhomogeneities in Zeolites
Authors: Rittner F. , Seidel A. , Sprang T. , Boddenberg B.
Published: August 2005

The widths of the 129Xe nuclear magnetic resonance (NMR) lines of xenon in zinc- and cadmium-exchanged zeolites NaY and HY were measured at ambient temperature as a function of the xenon gas equilibrium pressure. It is demonstrated that the observed values of the linewidths as well as their quite different dependence on pressure can be explained on the basis of a theoretical approach which traces back the origin of line broadening to inhomogeneous spatial distributions of transition metal cation sites interacting strongly with the encaged xenon atoms.
Determination of Major Compounds of Alcoholic Fermentation by Middle-Infrared Spectroscopy: Study of Temperature Effects and Calibration Methods
Authors: Fayolle Philippe , Picque Daniel , Perret Bruno , Latrille Eric , Corrieu Georges
Published: August 2005

The potential of Fourier transform middle-infrared spectroscopy has been demonstrated for the quantitative analysis of substrates (glucose and fructose) and metabolites (glycerol and ethanol) involved in alcoholic fermentation. Temperature variations between samples and water background reference caused changes in absorbance, and therefore the prediction of concentrations with partial least-squares (PLS) regressions was affected. The same temperatures for the calibration, validation, and prediction sets gave the smallest standard error of prediction (SEP): SEPglucose = 3.9 g L−1; SEPfructose = 4.3 g L−1; SEPglycerol = 0.5 g L−1; SEPethanol = 1.3 g L−1. In order to take different working temperatures (18, 25, and 35 °C) into account, an artificial neural network was used to create a nonlinear multivariate model. Compared to PLS regression, this method provided better results, especially for glycerol and ethanol, where SEP decreased by 0.3 g L−1 and 0.4 g L−1, respectively.
Quantitative Analysis of Cholesterol and Cholesterol Ester Mixtures Using Near-Infrared Fourier Transform Raman Spectroscopy
Authors: Le Cacheux P. , Menard G. , Quang H. Nguyen , Weinmann P. , Jouan M. , Dao Nguyen Quy
Published: August 2005

Near-infrared Fourier transform Raman spectroscopy is a rapid and nondestructive technique that can provide reliable qualitative in situ information about the chemistry of biological samples. We have combined this technique with partial least-squares (PLS) regression to perform a quantitative determination of free and esterified cholesterol in two synthetic sample series. In 66 ternary mixtures containing various proportions of cholesterol, cholesterol linoleate, and oleate, the standard errors of prediction were 1.27, 1.17, and 0.94%, respectively. For the second series of experiments concerning the sensitive problem of quantitative analysis of cholesterol palmitate and stearate mixtures, the standard error of prediction for 49 samples was 3.02%. It is also possible to extract quantitative information for a single component of the ternary mixtures independently. These results are of great importance when—as in the case of arterial samples—many chemical species are present. Comparison between Raman spectra of ternary mixtures and atherosclerotic rabbit aorta shows that many bands, assignable to free and esterified cholesterol, are easily observed in the aorta spectrum.
Near-IR Multiplex Bandpass Spectrometer Utilizing Polymer Filters
Authors: Fischer Michele R. , Hieftje Gary M.
Published: August 2005

A simple near-infrared spectrometer is described that utilizes ordinary polymer sheets as near-IR spectral filters. Examples of filter materials include polymethyl methacrylate, polyvinyl chloride (PVC), and organic solutions immobilized in a PVC matrix. The polymers were prepared by using solvent-molding techniques as well as with a thermoforming process. Each filter substance passes multiple bands of near-IR radiation. The performance of the spectrometer is demonstrated in selected quantitative and qualitative near-IR analytical applications. The applicability of the designed multiplex bandpass spectrometer in determining trace levels of water in methanol, dimethyl sulfoxide, and propylene glycol is examined. Additionally, the utility of the spectrometer in the determination of glucose concentration in aqueous solutions is studied.
Improved Curve Resolution of Highly Overlapping Bands by Comparison of Fourth-Derivative Curves
Authors: Fleissner Gerhard , Hage Wolfgang , Hallbrucker Andreas , Mayer Erwin
Published: August 2005

Curve fitting of highly overlapping bands can be improved by comparison of the fourth derivative of the experimental composite band profile with that of the sum of the curve-fitted component bands. Optimization is achieved with fixed values of one band parameter, aiming thereby for optimal correspondence between the fourth-derivative curves. FT-IR spectra of nitrate's v1 band region in ≈1 M glassy Ca(NO3)2 solution, and of its v2 band region in 10 M LiNO3 solution, in ≈0.5 M glassy Mg(NO3)2 solution and in 5 M Ca(NO3)2 solution, all with D2O as solvent, were used. As a general rule, reliable curve fitting of two overlapping bands of unknown band shape is possible only when separation of their peak maxima is larger than their average full width at half-height (FWHH). We show here that by comparison of fourth-derivative curves many more overlapped composite bands can be reliably resolved into their component bands, and, for the favorable case of 10 M LiNO3 solution, separation of two bands by only about a third of their average FWHH is sufficient for reliable curve fitting. This method requires data with very high signal-to-noise ratios. Improved curve fitting of highly overlapping bands is demonstrated for both a sum and a product of Gaussian and Lorentzian peak shapes, and a sort of recipe is given for both types of curve fitting. Synthetic spectra of two overlapping bands, where the degree of overlap and their relative intensity were varied in a systematic way, are given together with their fourth-derivative curves. This information will be of help for interpreting fourth-derivative curves of experimental highly overlapping two-band systems.
Multichannel Fourier Transform Raman Spectroscopy: Combining the Advantages of CCDs with Interferometry
Authors: Zhao Jun , McCreery Richard L.
Published: August 2005

A common-path (Sagnac) interferometer combined with a charge-coupled device (CCD) was evaluated for Raman spectroscopy in the near-infrared region. A spatial interferogram of the scattered light was projected onto the face of the CCD, and a Fourier transform of the intensity vs. pixel data yielded a Raman spectrum. This multichannel Fourier transform (MCFT) technique retains several advantages of FT spectroscopy, including high throughput, excellent frequency precision, and wide spectral coverage, while also retaining the multichannel, shot-noise-limited operation of the CCD. The signal-to-noise ratio (SNR) for the MCFT system was comparable to that for a dispersive spectrometer for the same laser power and integration time, and its frequency and intensity stability were excellent. Resolution is dictated by the number of CCD pixels, and was 25 cm−1 for the initial MCFT system. In addition to stability, a possibly important feature of the MCFT spectrometer is its large Ail product ( etendue), which results in a signal which is independent of laser beam diameter over the range of 60 μm to 1.3 mm.
Highly Sensitive Detection System Composed of a Thin, Long, Flow-Through Cell and a Semiconductor Laser for FIA Spectrophotometry and its Application to the Determination of Total Phosphorus in Water
Authors: Sun Fusheng , Korenaga Takashi
Published: August 2005

A highly sensitive detection system, which was composed of a thin, long, flow-through cell (TLFTC) and a semiconductor laser (SCL), for flow injection analysis (FIA) spectrophotometry has been developed. The new detection system was mainly composed of a thin, long, light path (100 mm x 1.4 mm i.d.), which was made of a polytetrafluoroethylene rod as an absorption cell, along with a GaAlAs semiconductor laser emitting at 780 nm (5 mW) as a light source. With the use of the detection system, the detection sensitivity was improved by about 10 times in comparison to FIA spectrophotometry with a normal flow cell. The detection system can be useful for determinations of many trace components in samples. The determination of total phosphorus in water, with the use of molybdenum-blue photometry, was one of its applications, and the relative standard deviation, detection limit (3σ), and linear range were 1.0%, 0.6, and 1.0–50 μg P/L, respectively. The determined results for the total phosphorus in the water samples by this method were almost coincident with those obtained by the official method. The detection system may also be useful for other flow-based analytical techniques such as liquid chromatography.
Two-Dimensional Gas-Phase Temperature Measurements Using Fluorescence Lifetime Imaging
Authors: Ni Tuqiang , Melton Lynn A.
Published: August 2005

Two-dimensional (2D) temperature images of turbulent hot nitrogen flows have been obtained by use of a novel technique involving fluorescence lifetime imaging. Nitrogen flows were doped with naphthalene vapor. The fluorescence lifetime of naphthalene decreases from 180 ns at 25 °C to 35 ns at 450 °C, and this temperature dependence can be used to calculate the temperature from the fluorescence lifetime in oxygen-free environments. With the current apparatus and with naphthalene as the fluorescent dopant, the error in the absolute temperature was estimated to be ±15 °C in the range of 25 to 450 °C. This application demonstrates that fluorescence lifetime imaging, which does not depend on the absolute concentration on the fluorescent dopant, may be useful in a variety of turbulence, temperature, and other combustion-related studies.
Nondestructive Measurement of the Subsurface Structure of Biological Material Having Cellular Structure by Using Near-Infrared Spectroscopy
Authors: Tsuchikawa Satoru , Hayashi Kazuo , Tsutsumi Shigeaki
Published: August 2005

Biological materials–wood is a typical example–are widely used in a state where not only the cellular structure but also its bulky shape is retained. NIRS (near-infrared spectroscopy) may be called for as a promising technique to analyze the physical state of such materials as well as the chemical composition. In this report, the effects of physical conditions found in wood on the absorption of NIR radiation are examined. In the experiments, conifers (Sitka spruce) that had various degrees of surface roughness and different orientations of fibers to the direction of incident light were used. Results of these measurements showed that the orientation of fibers and the surface roughness of wood were directly related to the absorbance. In addition, it became clear that the behavior of diffusely reflected light in wood could be expressed by Kubelka–Munk theory and fell into three categories according to the characteristic of the absorption and scattering coefficient. On the basis of these results, a new concept for the behavior of NIR light passing through material made of hollow fibers has been proposed.
Matrix Effects in the Detection of Pb and Ba in Soils Using Laser-Induced Breakdown Spectroscopy
Authors: Eppler Aaron S. , Cremers David A. , Hickmott Donald D. , Ferris Monty J. , Koskelo Aaron C.
Published: August 2005

With the use of laser-induced breakdown spectroscopy (LIBS), the effects of chemical speciation and matrix composition on Pb and Ba measurements have been investigated by using sand and soil matrices. A cylindrical lens was used to focus the laser pulses on the samples because it yielded higher measurement precision than a spherical lens for the experimental conditions used here. The detection limits for Pb and Ba spiked in a sand matrix were 17 and 76 ppm (w/w), respectively. In spiked soil, the detection limits were 57 and 42 ppm (w/w) for Pb and Ba, respectively. Measurement precision for five replicate measurements was typically 10% RSD or less. Two factors were found to influence emissions from Pb and Ba present in sand and soil matrices as crystalline compounds: (1) compound speciation, where Ba emission intensities varied in the order carbonate > oxide > sulfate > chloride > nitrate, and where Pb emission intensities varied in the order oxide > carbonate > chloride > sulfate > nitrate; and (2) the composition of the bulk sample matrix. Emissions from Ba(II) correlated inversely with the plasma electron density, which in turn was dependent upon the percent sand in a sand/soil mixture. The analytical results obtained here show that a field-screening instrument based on LIBS would be useful for the initial screening of soils contaminated with Pb and Ba.
Measurement of Single Moving Particle Temperatures with an FT-IR Spectrometer
Authors: Clausen Sønnik , Sørensen Lasse Holst
Published: August 2005

A conventional scanning FT-IR spectrometer is used to measure the blackbody radiation through a rapidly moving pinhole in an experiment simulating a flying hot particle. The effects and errors from source movements are analyzed and verified through experiments. The importance of the scanning velocity, phase-correction method, and temperature variations during scanning is investigated. It is shown that a calibration of the system at one temperature is sufficient for accurate spectral radiance and temperature measurements throughout a broad temperature range. The temperature errors are reduced by a factor of 2–10 compared with results from a typical two-color pyrometer. A novel method is presented for measuring emission spectra from single moving particles passing the field of view of the spectrometer in a random manner.
Infrared, Raman, and Nuclear Magnetic Resonance (1H, 13C, and 31P) Spectroscopy in the Study of Fractions of Peat Humic Acids
Authors: Francioso O. , Sanchez-Cortes S. , Tugnoli V. , Ciavatta C. , Sitti L. , Gessa C.
Published: August 2005

Fourier transform infrared spectroscopy (FT-IR), surface-enhanced Raman spectroscopy (SERS), and nuclear magnetic resonance (NMR) (1H, 13C, and 31P) have been applied to the study of fractions of humic acids in Irish peat. Owing to the high fluorescence of these materials, no Raman spectra have been obtained, up to now, for the characterization of humic acids. The SERS technique was employed for the first time in the study of these complex substances, demonstrating that very valuable information about the aromatic groups and the spacial conformation of these macromolecules in water solution can be obtained. The combined use of these techniques has evidenced an increase of oxygenated groups in those fractions containing humic acids with low molecular weight. The presence of a greater number of carboxylate and phenolic groups can explain the high concentration of metals and phosphate ions found in these fractions.
Optical Depth Profiling by Attenuated Total Reflection Fourier Transform Infrared Spectroscopy: A New Approach
Authors: Ekgasit Sanong , Ishida Hatsuo
Published: August 2005

A new analytical technique for depth profiling using multiple-angle attenuated total reflection Fourier transform infrared spectroscopy has been developed. The analysis does not require prior knowledge of the profile of the complex refractive indices with respect to depth from the surface for the depth profiling calculation. This depth profiling analysis consists of two steps. First, the estimated complex refractive index profile is obtained by solving a set of linear equations of absorptance. Second, the reflectances from experiment are non-linearly fitted with those from exact optical theory. The estimated complex refractive index profile from the first step is used as a trial profile for the fitting. The converged complex refractive index profile from the fitting is then defined as the reconstructed complex refractive index profile of the film. The noise-added reflectances are used as experimental data to show the applicability of the new analytical approach.
A Comparative Evaluation of Three Commercial Instruments for Field Measurements of Reinforcing Steel Corrosion Rates
Authors: Gepraegs OK , Hansson CM
Published: August 2005

In this study, a comparative evaluation was made of three instruments, designed for field monitoring of reinforcing steel corrosion rates. The electrochemical operating principles of each instrument were determined by monitoring the potential and current of each electrode during operation.

Corrosion current densities (icorr) of reinforcing steel bar (rebar) in concrete determined with the three different instruments varied by as much as 50 times. The average of the ratios of corrosion rates between any two of the instruments varied between four and 14 times. The size of the polarized area of a section of reinforcing steel is assumed by the configuration of each instrument's counter electrode and guard ring electrode. It was observed that the guard ring electrodes affected the polarization of the reinforcing steel and this effect, together with the different electrode materials, is considered the principal cause of the variations in measured corrosion rate.

Corrosion rates of embedded corrosion monitoring probes were also measured. The variation in icorr for measurements on probes was smaller than those on the reinforcing bar and, on average, corrosion rates varied between two and six times. The observation that corrosion monitoring of probes is more consistent than measurements on reinforcing bar suggests that the use of such embedded probes may provide more reliable values for service-life predictions. This consistency was attributed mainly to the known size of the polarized area.
Efforts to Determine the Relationship Between Corrosion Rate and Concrete Damage Using Acoustic Emission
Authors: Wheat HG , Thakar M
Published: August 2005

Over the past 20 years, the linear polarization resistance (LPR) technique has become one of the most popular techniques for determining the corrosion rate of steel in concrete. The results are then related to the amount of damage, and this parameter becomes very important in determining the amount of remaining service life of the concrete structure. Corrosion investigations that utilize polarization resistance (Rp), which is inversely related to the corrosion rate of the steel, are carried out with the knowledge that in laboratory specimens, and especially in field situations, the steel is not corroding uniformly, the changing conditions of the concrete play a major role in the corrosion rates determined, and the area over which polarization takes place is not well defined. All of these aspects become even more important when the concrete/reinforcement system is changed because the choice of the metallic material changes or the concrete changes due to the addition of admixtures. These factors will be discussed based on an investigation in which LPR was used in combination with Acoustic Emission (AE), which can offer more direct information about the extent of damage. The goal is to be able to provide insight into the complicated relationship between the corrosion rate of the metal reinforcement, the damage to the surrounding concrete, and the remaining life of the concrete structure.
Structural Reliability Analysis of Railroad Tank Cars Subjected to Fatigue and Corrosion
Authors: Zhao W , Sutton MA
Published: August 2005

Reliability analysis of tank car structures undergoing fatigue crack growth and general corrosion (tank wall thinning) is illustrated to support informed decision-making and planning for reliability-centered maintenance. Two specific mechanisms that contribute to tank car deterioration are considered: (1) corrosion with negligible fatigue crack growth; and (2) corrosion-accelerated fatigue crack growth. Reliability analysis of corrosion-accelerated fatigue crack growth is performed with a time-dependent tank wall thickness reduction and a fatigue crack growth model that incorporates a three-degrees-of-freedom surface crack obeying Walker crack growth law under tank car spectrum loading. System reliability problems involving multiple corrosion sites are considered to illustrate important features of failure probability for a series system in relation to failure probability of individual corrosion sites.
Load History Effects Resulting from Compression Precracking
Authors: James MA , Forth SC , Newman JA
Published: August 2005

Compression precracking (CPC) has seen renewed interest as a possible alternative procedure for generating fatigue crack growth threshold data with minimal load history effects, but recent testing confirms results from the literature that compression precracking does induce load history effects through residual stresses that influence subsequent fatigue crack growth test data. Using the CPC method, specimens are precracked with both maximum and minimum compressive loads. Compressive yielding occurs at the crack-starter notch, resulting in a local tensile residual stress field through which the fatigue crack must propagate. Although the tensile residual stress field contributes to the driving force for precracking, it also introduces the possibility of history effects that may affect subsequent fatigue crack growth. The tensile residual stress field elevates the local driving force at the crack tip, promoting higher crack growth rates than would be expected from the applied loading. This paper presents three-dimensional finite element results and experimental data for compact tension specimens that characterize the load history effects induced by compression precracking. The analysis results indicate that for low tensile loading levels near the threshold region, the residual stresses cause the calculated crack tip driving force to increase from the applied driving force by 25% or more. In addition, significant crack growth of about two times the estimated plastic zone size is needed to grow away from the residual stress field and reduce the calculated crack tip driving force to within 5% of the applied driving force. Experimental results show that growth of about two to three times the estimated plastic zone size is necessary to establish steady growth rates under constant ΔK loading for the materials and loading levels evaluated. Constant ΔK testing following compression precracking will demonstrate when residual stress effects are no longer significant and will ensure consistent growth rates.
Mechanical Properties of Cubic Silicon Carbide after Neutron Irradiation at Elevated Temperatures
Authors: Katoh Y , Snead LL
Published: August 2005

Mechanical properties of high-purity polycrystalline cubic SiC was characterized after neutron irradiation. Bar samples were irradiated in target position capsules in the High Flux Isotope Reactor (HFIR, Oak Ridge, Tennessee) to nominal fluence levels up to 7.7 dpa at temperatures of 300, 500, and 800°C. A decrease in Young's modulus was observed after irradiation, and its irradiation temperature dependence qualitatively agreed with the calculated modulus change due to point defect swelling. Irradiation caused a significant modification of statistical flexural strength but caused only minor increase in nano-indentation hardness. The irradiation effect on fracture initiation through an enhanced cleavage resistance likely is primarily responsible for the major change in flexural strength properties.
Radiation Resistance of Advanced Ferritic-Martensitic Steel HCM12A
Authors: Allen TR , Tan L , Tucker JD , Gan J , Gupta G , Was GS , Shutthanandan S , Thevuthasan S
Published: August 2005

HCM12A is an advanced 12 Cr ferritic-martensitic steel designed for higher temperature operation than could be achieved using earlier generation steels such as HT9. HCM12A is one of the advanced alloys under consideration for application in core components in Generation IV nuclear energy systems, and is of particular interest to the supercritical water reactor, sodium fast reactor, and lead fast reactor designs. The radiation resistance of HCM12A has not previously been studied. This work provides information on the hardening and microstructural changes in HCM12A after irradiation using 2.0 MeV protons at 400°C to 10 dpa and 5 MeV Ni-ions at 500°C to 50 dpa. Following irradiation, changes in hardness were measured using Vickers hardness indentation, changes in microstructure and phase stability were studied using transmission electron microscopy, and changes in microchemistry were measured using scanning Auger microscopy. The hardness increases by roughly 70 % and saturates by roughly 5 dpa. The changes to the microstructure contributing to this hardness increase are primarily due to the formation of precipitate phases, with some contribution from changes in dislocation density. Chromium is enriched at grain boundaries prior to irradiation, likely due to grain boundary carbides, and increases further during the irradiation.
Effects of Neutron Irradiation on Precipitation in Reactor Pressure Vessel Steels
Authors: Faulkner RG , Lu Z , Ellis D , Williams TJ
Published: August 2005

Several MnMoNi pressure vessel steels with varying Ni, Cu, and Mo contents have been investigated in the irradiated and unirradiated condition. Examination using analytical transmission electron microscopy was performed in order to understand more fully the nature of both the inter- and intra-granular precipitation in these alloys. In particular, attention has been paid to the carbide population, which exists in the material in addition to the copper precipitates, which have received detailed study elsewhere. The most dramatic revelations concern the discovery that fine, intra-granular (10 nm diameter) Fe3C particles are present in these steels, in addition to the normally expected copper-rich precipitates of a similar size. Neutron irradiation increases the volume fractions of inter- and intra-granular precipitation of all phases (Fe3C, Cu-rich, and Mo2C). Neutron irradiation has the least effect in increasing volume fraction in high Ni; high Cu alloys (WV). The effects of neutron irradiation on precipitation rates are greatest in low Ni; high Cu alloys (SG (SH)). Inter-granular precipitation is most prevalent in the high Ni; low Cu material (WF). It is significant that this material contains the least intra-granular fine-scale precipitation. This is probably because the Cu precipitation is minimal. Mo and C have an important influence on the amount of Mo2C phase formed, with large amounts being observed in high Mo-C, irradiated material (SH) (0.48 % Mo). These results are discussed in terms of various models for inter-and intra-granular precipitate nucleation and growth.
Radiation- and Thermally-Induced Phosphorus Inter-Granular Segregation in Pressure Vessel Steels
Authors: Lu Z , Faulkner RG , Jones RB , Flewitt PEJ
Published: August 2005

A survey of neutron- and thermally-induced phosphorus inter-granular segregation behavior in C-Mn welds, LWR plates, LWR HAZ materials, and VVER steels is described in this paper. The materials were irradiated up to doses of 0.13 dpa (fast neutron energy > 1 MeV), with dose rates ranging from 1.75 × 10−8 dpa/s to 10−12 dpa/s, at temperatures between 190°C and 400°C. Irradiation-induced P inter-granular segregation has been found in LWR and VVER materials at high doses (generally 10–130 mdpa) but is absent in all Magnox C-Mn submerged-arc welds at lower doses (1.5–13 mdpa). The dose sensitivity of the irradiation-induced P monolayer coverage depends on the material examined, being highest for VVER plates and weld, lower for the LWR materials, and zero for the C-Mn welds. There are high initial P segregations (arising from pre-heat-treatment) in C-Mn weld and LWR HAZ materials and low initial P segregation in LWR and VVER steels. Comparisons of the experimental data with model predictions are made. The amount of phosphorus segregation is shown via site competition models to be related to free carbon concentration. The model results show a good agreement with experimental measurements.
The Effect of Duplex Cladding Outer Component Tin Content on Corrosion, Hydrogen Pick-up, and Hydride Distribution at Very High Burnup
Authors: Arborelius J , Dahlbäck M , Hallstadius L , Jourdain P , Andersson T , Lisdat R , Hahn M , Toscano EH
Published: August 2005

The performance of two types of Duplex claddings irradiated to very high burnup in a German high duty pressurized water reactor (PWR) has been studied. Four fuel rods with Duplex cladding were moved from two discharged assemblies to a low-burnt assembly for further irradiation. These rods were finally unloaded after reaching a rod average burnup close to 70 MWd/kgU. The performance of these rods has been examined through pool-side inspection. Two of these rods have been studied further in a hot-cell post irradiation examination (PIE). The results of destructive and nondestructive examinations consistently show good corrosion resistance and low hydrogen pick-up for both Duplex variants. The hot-cell measurements reveal peak values of the oxide thickness of around 30 μm for both types of Duplex. Consequently, the claddings show low levels of absorbed hydrogen in the order of 300 ppm, as is indicated by metallographic cross-sections and the low axial growth of the rods. During the development of Duplex claddings, it was observed that the Sn content in the two components should not differ by more than about 0.7 wt%. A limited difference in Sn concentration implies that the two components have similar recrystallization temperatures. More important, hydriding studies of unirradiated Duplex claddings have shown that, by limiting the difference in Sn content, the amount of hydrides in the boundary zone between the inner component and the Duplex layer is reduced. There is a significant difference in the Sn concentration in the outer component of the two studied Duplex types. The effect of difference in Sn concentration on hydride distribution observed from studies of unirradiated claddings has, however, not been confirmed by the hot-cell studies presented here.
Influence of Structure—Phase State of Nb Containing Zr Alloys on Irradiation-Induced Growth
Authors: Shishov VN , Peregud MM , Nikulina AV , Pimenov YV , Kobylyansky GP , Novoselov AE , Ostrovsky ZE , Obukhov AV
Published: August 2005

On account of the search for the optimal composition and structure-phase state of Zr alloys much attention is paid to upgrade the E110 (Zr-1 %Nb) and E635 (Zr-1 %Nb-0.35 %Fe-1.2 %Sn) alloys that have proved well in terms of irradiation-induced creep and growth, high strength characteristics, and corrosion. The difference between the alloy properties is determined by their states related to their compositions. The structure-phase state of the Zr-Nb and Zr-Nb-Fe-Sn systems has been studied after heat treatment in the α-- and α + β- regions and its influence on the irradiation-induced growth (IIG) during BOR-60 irradiation at T =315–350 °C was investigated. A substantial difference has been shown in the deformation effected by IIG of those alloys, it is less for Zr-Nb-Fe-Sn alloys in dissimilar structure-phase states. The incubation period of the accelerated growth stage is determined by the α-matrix composition, the phase state and the initial dislocation structure. Neutron irradiation leads to a redistribution of alloying elements between the matrix and the precipitates, and to changes in the α-solid solution composition. These changes affect accumulation and mobility of irradiation defects, anisotropy and formation of vacancy c-component dislocation loops. The appearance of c-loops usually correlates with an axial direction acceleration of the IIG of tubes conforming to their texture. The basic regularities of the phase transformation have been established: a) β-Nb precipitates in Zr-Nb alloys are altered in composition to reduce the Nb content from 85–90 % to ∼ 50 %, fine precipitates likely enriched in Nb are formed; b) β-Zr precipitates are subject to irradiation-stimulated decomposition; c) Laves phase precipitates change composition (the content of Fe decreases) and crystal structure, HCP to BCC (β-Nb); d) (Zr,Nb)2Fe precipitates having the FCC lattice retain their composition and crystal structure; e) no amorphization of any secondary phase precipitates is observable under the given conditions of irradiation (T = 315–350 °C). Based on the dpa, the results were compared pertaining to Zr-alloy IIG deformation vs. fluence in various reactors at different energies of fast neutrons. The presented graphs enable comparison between the results of numerous experiments and enable predictions of Zr-material behavior in long-term operation and at high burn-up in commercial reactors.
Fretting-Wear Behavior of Zircaloy-4, OPTIN™, and ZIRLO™ Fuel Rods and Grid Supports Under Various Autoclave and Hydraulic Loop Endurance Test Conditions
Authors: King SJ , Young MY , Guérout FM , Fisher NJ
Published: August 2005

High fuel duty, eighteen-month and longer cycle lengths, and higher burnups have put increased demands on pressurized water reactor (PWR) fuel during recent years. As a result of these demanding operating conditions, the fretting-wear performance of PWR fuel rods against structural grid supports is being challenged. To understand the in-reactor fretting-wear performance of PWR fuel, Westinghouse Electric Company (W) and Atomic Energy of Canada Limited (AECL) have performed investigations to study the fretting-wear behavior of zirconium alloy nuclear fuel rods and grid supports. Experimental work was carried out at the AECL Chalk River Laboratories (Canada) in autoclave impact fretting-wear test machines and at the W Columbia, South Carolina (USA) plant in the Westinghouse — Vibration Investigation Pressure-Drop Experimental Research (VIPER) hydraulic test loop.

Autoclave impact fretting-wear tests were conducted for several grid-support/fuel-rod designs using either ZIRLO™, Zircaloy-4, and/or OPTIN™ materials. Rod-to-grid relative displacements and contact forces were measured throughout each test. The wear volumes of each fret mark on the fuel rod specimens were measured via surface profilometry at the end of each test. From these wear volumes, wear rates and wear coefficients for the fuel rod in contact with either springs or dimples were determined.

The VIPER loop is used for full-scale nuclear fuel assembly vibration and wear testing. Endurance tests were performed with severe flow conditions to induce fuel fretting-wear for different grid support and assembly designs using either all ZIRLO™ or all Zircaloy-4 materials. The wear volumes of the most severe fret marks on the fuel rods were measured via surface profilometry at the end of each test. From the profilometry of each fret mark, and using the fretting-wear coefficient derived from autoclave wear tests, the available energy (i.e., work-rate) to cause the fretting-wear damage was determined.

Fretting-wear scars on ZIRLO™, Zircaloy-4, and/or OPTIN™ fuel rods from the autoclave impact fretting-wear tests and the VIPER hydraulic tests were examined using scanning electron microscopy (SEM) to compare the fretting-wear mechanisms for different grid-support designs. Fretting-wear mechanisms from both types of tests were shown to be comparable and related to the grid-support design. For a given material (i.e., ZIRLO™, Zircaloy-4, or OPTIN™) under similar test conditions, there was no difference in the fretting-wear performance.
Adhesive Characterization & Durability of Self-Adhered Flashings
Authors: Katsaros JD
Published: August 2005

Self-adhered flashing products can very effectively maintain a durable moisture-tight seal at the window-wall interface, which is highly vulnerable to moisture intrusion. However, it is essential that these products be installed under conditions where adequate adhesion to the substrate is achieved. Also, the self-adhered flashing products must have thermal durability and dimensional stability to maintain their performance at the high temperatures that can exist behind siding. This study gives a preliminary adhesion characterization assessment of six self-adhered flashing products, three with modified-asphalt based adhesives and three with butyl based adhesives, onto several common building substrates and installed at a range of temperatures, including moist and dusty conditions. What is found is that the butyl based adhesive systems have a broader window of installation surface conditions and temperatures where “adequate adhesion” is achieved without the use of a primer than the modifiedasphalt based adhesive products. Also, a thermal aging study shows that the butyl based adhesive products are more thermally stable than the modified-asphalt based products at typical temperatures behind siding. Also, film topsheets are more prone to deformation and curling after thermal aging than nonwovens composite or foil laminate based topsheets.
A Review of Climate Loads Relevant to Assessing the Watertightness Performance of Walls, Windows, and Wall-Window Interfaces
Authors: Cornick SM , Lacasse MA
Published: August 2005

When assessing a wall assembly's ability to manage rainwater and control rain penetration, the two key climatic elements to consider are wind speed and rainfall intensity. However, of significance to rain penetration is the effect of wind-driven rain on the building cladding — that is wind coincident with rainfall. When water is present at openings in the cladding, water is driven into the layers of the assembly by the action of wind. Paths providing a direct line from openings in the cladding to inside the assembly offer particularly vulnerable points for water entry. Performance testing helps determine the location of vulnerable locations in a wall assembly and the test loads at which penetration occurs, and it possibly relates the amount of entry to specific details and simulated climate effects. Undertaking watertightness performance tests requires knowledge of extremes in wind-driven rain or specifically the occurrence and level of extreme rainfall events for locations of interest. A review of climate information on wind-driven rain is provided, and its relevance to assessing the watertightness performance of walls, windows, and wall-window interfaces is discussed. Values of rainfall intensity, duration, and frequency or occurrence are given, emphasizing the level of significance of these variables to different North American climates.
Influence of Oxygen Content on the Mechanical Properties of Titanium-35Niobium-7Zirconium-5Tantalum Beta Titanium Alloy
Authors: Jablokov VR , Murray NGD , Rack HJ , Freese HL
Published: August 2005

Titanium-35Niobium-7Zirconium-5Tantalum beta titanium alloy (also known as TiOsteum® beta titanium alloy) is a new metallic biomaterial that was designed to have outstanding osseointegratabilty, good mechanical strength, improved ductility, very low elastic modulus, and good hot and cold workability [1]. In this study, mechanical property data are presented from several TiOsteum alloy production lots with ingot oxygen contents ranging from 0.05 to 0.68 %. Additionally, mill annealed mechanical property data collected over the last 10 to 15 years for the more common alpha, alpha-beta, and beta titanium alloys are presented as a function of oxygen content and compared to TiOsteum alloy. The influence of oxygen as an interstitial strengthening element is well established in titanium alloys. This study examines this effect over a broad range of oxygen values, and has significance for the application of the new TiOsteum alloy and other beta titanium alloys being considered for use in medical and surgical devices.
Metallurgical Attachment of a Porous Tantalum Foam to a Titanium Substrate for Orthopedic Applications
Authors: Medlin DJ , Scrafton J , Shetty R
Published: August 2005

A porous tantalum foam (Trabecular Metal™) has been successfully attached to a titanium substrate for an orthopedic acetabular cup application by two different methods: sintered powder processing and diffusion bond processing. A metallurgical evaluation of the interfaces between the tantalum foam and the titanium substrates has been performed, as well as long-term corrosion immersion tests to evaluate the susceptibility of the materials and design to crevice corrosion attack. The sintered powder attachment method used sprayed titanium powder at the interface between the tantalum foam and the titanium substrate. The assembly is sintered at high temperature to form a metallurgical bond between the sintered titanium powder and the titanium substrate and a predominately mechanical interlock between the sintered powder and the tantalum foam. The diffusion bond attachment process used time, pressure, and temperature to form a metallurgical bond between the tantalum foam and the titanium substrate by solid state diffusion. Both methods formed acceptable bond strengths with no evidence of corrosion attack from the corrosion immersion tests.
Photo Thermal Micro-Spectroscopy — A New Method for Infared Analysis of Materials
Authors: Slough CG , Hammiche A , Reading M , Pollock HM
Published: August 2005

Many modern materials are composite structures with complex morphologies that play a large role in determining the material function. The ability to investigate the relationship between structure and property on a microscopic scale can play a crucial role in material development. Micro-Thermal Analysis (μTA)™ is a unique set of analytical techniques for characterizing materials on a micrometer and nanometer scale. Micro-TA combines the imaging power of atomic force microscopy with the ability to analyze physical, mechanical, thermal, and chemical characteristics at a specific point of interest on the surface of a material. At the heart of the technique is a miniaturized thermal probe. In a new technique termed Photo Thermal Micro-Spectroscopy (PTMS), this thermal probe is used to detect temperature fluctuations in samples that have been irradiated by IR radiation. A Fourier Transform Infrared (FT-IR) spectrum can be constructed from this information. This paper describes the PTMS technique and discusses recent applications.