Titanium is used in the manufacture of AISI 316L austenitic stainless steel as a deoxidizer. Titanium is considered a residual element, and limits are often not specified. As a residual element, titanium most often appears in complex oxide inclusions, usually in conjunction with aluminum and other deoxidizers. Titanium-bearing inclusions have been found to initiate pitting during electropolishing. The present work was performed to evaluate the acceptable upper limit for titanium as a residual element in AISI 316L.

Metallographic specimens were prepared from seven commercial heats of AISI 316L (Table 1) with titanium contents varying from 0.003 % to 0.014 %. A quantitative metallographic analysis of each specimen was performed using an SEM/EDS system with an automated stage. Operating parameters are given in Table 2. Data was obtained with the system in the backscatter (BS) mode, producing a high-contrast image based on differences in chemical composition. Once each inclusion was identified by its difference in gray scale, it was also analyzed by EDS for elements present.

This paper addresses the microanalysis techniques used to characterize thermal sprayed Ti coatings on concrete surfaces as anodes in impressed current cathodic protection (ICCP) systems. Thermal sprayed Ti anodes on concrete were electrochemically aged in laboratory studies of anode performance and service life. A thermal sprayed catalyzed Ti anode was installed on the Depoe Bay Bridge on the Oregon Coast in a field demonstration of the ICCP system. Both air and N were used as the atomizing gases during the study. Thermal sprayed Ti coatings are typically applied in an inert atmosphere or vacuum using shrouds or chambers to prevent reactions with the atmosphere. This was not possible with a structure as large as a bridge.

Microanalysis of Ti and N together is difficult and the effects of O add to the complexity of the analysis. The ternary Ti-O-N system has not be well studied.

The layer sequence of multi-layered white and off-white paint chips usually encountered by the forensic scientist in cases involving structural and/or maintenance paint is sometimes difficult to discern when utilizing commonly employed microscopical methods. This layer sequence information becomes vitally important when comparing a questioned paint sample to a paint sample of known origin. Techniques such as reflected light microscopy, fluorescence microscopy, and scanning electron microscopy (SEM) coupled with energy dispersive x-ray spectroscopy (EDS) may not provide the needed discrimination. Also, binder information may not be available for comparison since the thinness of the layers the difficulty in detecting individual layers, and the abundance of the extender pigments may preclude analysis by infrared microspectrophotometry.

Cathodoluminescence microscopy (CLM) may provide the needed layer sequence information and discrimination when analyzing and comparing multi-layered white and off-white paint samples. Cathodoluminescence (CL) is the emission of radiation from the sample in the visible light region and neighboring wavelengths during excitation by electrons generated from a cathode electron gun.

Microscopy is of vital importance in the real world of the forensic scientist. In today's society, physical evidence is critical to the criminal justice system for the detection, investigation and prosecution of criminal acts. A trail of microscopic fibers led investigators in Atlanta to the conviction of the serial killer, Wayne Williams. Flecks of paint on a hit-run victim, analyzed microscopically, can be compared with the paint on a suspect vehicle to exclude or match it to the crime. The forensic firearms examiner compares the microscopic striations on a bullet to match it to the gun it was fired from. Microscopes are used throughout the modern forensic laboratory. They are essential in searching for evidence. They aid the examiner in identifying and comparing trace evidence. As the scales of justice symbolize forensic science, microscopes symbolize the trace evidence examiner.

Because of the variety of physical evidence, forensic scientists use several types of microscopes in their investigations.

Focused Ion Beam or FIB systems have been used in integrated circuit production for some time. The ability to combine rapid, precision focused ion beam sputtering or gas-assisted ion etching with focused ion beam deposition allows for rapid-prototyping of circuit modifications and failure analysis of defects even if they are buried deep within the chip's architecture. Inevitably, creative TEM researchers reasoned that a FIB could be used to produce site specific parallel-sided, electron transparent regions, thus bringing about the rather unique situation wherein the specimen preparation device often was worth as much as the TEM itself.

More recently, FIB manufacturers have concentrated on improving the resolution and imaging characteristics of these instruments, resulting in a more general-purpose characterization tool. The Micrion 2500 FIB system used in this study is capable of 4 nm imaging resolution using either secondary electron or secondary ions, both generated by a 50 kV liquid metal gallium ion source.

Photographs of x-ray transmission images by x-ray films have been used for observing the inside nondestructively. Further, Imaging Plates(IP) are used for precise measurements of x-ray diffraction patterns. But, these integrating area detectors are not suitable for real time nor time resolved measurements. For real time and time resolved measurements, the X-Ray Image Intensifier(XRII, a large image tube that converts an x-ray image into a visible image) is used for biological x-ray TV systems, x-ray nondestructive inspection systems etc. These TV x-ray image systems require high energy x-rays, x-ray tube voltage of 30 to 150 kV, and show faint contrast for x-ray images of light element substances owing to its low absorption coefficients. However, light elements have intense x-ray absorption coefficients in a low energy x-ray region, x-ray tube voltage of 5 to 20 kV, and give fine contrast for x-ray images of light element substances.

Exploratory synthetic strategies may yield limited quantities of sample. Characterization of such limited-quantity samples is facilitated by the use of sensitive analytical methods and smart sample preparation. Polymers may be analyzed by mass spectrometry for molecular weight distributions, structural information (such as endgroups), and impurities. However, polymer research using mass spectrometry has not focused on detection limits; in some work the amount of polymer used is not even mentioned. Studies to determine detection limits of polymers and studies that characterize sample preparation techniques can provide valuable information.

Examination of the sample surface on a probe tip, generated by the use of an aerospray technique for sample deposition, was accomplished by scanning electron microscopy (SEM). Aerospraying the polymer and matrix solutions allowed signal averaging of mass spectra from up to 400 shots on the same sample spot. SEM images showed the surface of the probe to have a fairly uniform coating of the sample and matrix.

Transport, cleanup, and bioremediation properties of polychlorinated biphenyls (PCBs) bound to sediments depend on the specific components to which the PCBs are bound. Analysis of the sediment from Contaminant Cove on the St. Lawrence River by gas chromatography with an electron capture detector shows that the sediment contains 600 ppm PCBs. Previous work showed that there were both weak and strong binding of PCBs to sediment components, but gave no indication of which components were responsible for the binding.2 The average content of PCBs is below the limit of detectability by energy-dispersive x-ray microanalysis (EDX) for CI, but constituents which bind large quantities of PCBs could be detected. Sediment which is not contaminated with PCBs contains no detectable chlorine.

EDX analysis was performed on a JEOL JEM-4000FX, using a cryo-stage (operated at -160° C) and a Tracor TN5500 system.

Protection of public health requires routine monitoring of environmental waters for fecal contamination, especially waters serving as drinking supplies. Municipalities typically rely on assays of indicator microorganisms to detect fecal contamination. Ideally, indicators and pathogens share a common origin. However, the indicators should have higher numbers, survive longer, and be easier to detect and quantify in the laboratory than pathogens. Coliform bacteria are the standard microbial indicator currently used in the United States. Enteric viruses are smaller and survive longer than coliform bacteria, therefore they are inadequate indicators of enteric viruses. Enteric bacteriophages, viruses infecting bacteria, may be a more reliable indicator for human viral pathogens. However, there are several taxonomic groups of enteric bacteriophages, all of which may not be good virus indicators. This project examines the ecology of coliphages, bacteriophages infecting Escherichia coli, in a ground water aquifer which serves as a municipal water supply.

Volcanic eruptions inject tons of silicic material into the atmosphere. Large, dense material falls out within a few hours whereas fine size fractions, < 10 μm radius ash, may remain airborne for weeks to months. Protection of human population centers and aircraft requires predictive atmospheric transport models. Many of these models assume the ash particles are spherical but abundant qualitative studies of ash particles demonstrate irregular shapes ranging from parachute-like bubble-wall shards to polygonal shaped mineral grains. These non-spherical shapes increase atmospheric drag. The accuracy of transport models may be improved with a better understanding of the actual shapes found in fine ash particles. Therefore, the objective of this study is to accurately determine three-dimensional shape measurements via stereoscopic methods using the scanning electron microscope.

The scanning electron microscope is an ideal imaging platform for collection of stereo pairs because of its utility in stereoscopic height measurement.

It has long been known that carbons have order at the microcrystalline level. Soots have been characterized as having a turbostratic structure and chars have been described as crumpled sheets. The value of electron microscopy in studying the morphology of such materials has been well established although only a few attempts have been made toward quantification.

The Methodology is based upon High Resolution Transmission Electron Microscopy (HRTEM) and further image analysis. The HRTEM image of each sample is recorded, digitized and processed with an image analysis software. Computer generated diffractograms are produced through Fourier Transformation and subsequent reverse transformation yields two color ‘extracted structures’ (Figure 1). The extracted structure is then undergoes statistical analysis. The analysis is aimed at identifying quantifiable structural parameters. Currently the following parameters are studied: circularity (C), elongation (E), and length of fringes (La) orientation of the fringes (cti), the inter-layer spacing (d002), and the fractional coverage of the extracted pattern (F).

Micro-Raman spectrometry and Mossbauer spectroscopy have been used to identify the corrosion products on a steel coupon exposed in an industrial environment for 16 years. The Raman analysis was performed on a polished metallographic cross-section in order to map the oxides across the thickness of the coating. The spectra were recorded using a LabRam Micro-Raman spectrograph incorporating a 17 mW HeNe laser (attenuated to 1 mW to prevent oxide transformation), focused to 1 μm spot size, and 1800 g/mm grating. The confocal line-scan imaging enabled 100 spectra to be recorded in one scan at 0.5 um intervals across the thickness of the coating. The Mossbauer analysis was performed using in-situ scattering Mossbauer spectroscopy on the attached corrosion coating and transmission Mossbauer spectroscopy at 300K and 77K on the removed coating, to measure the fraction of each oxide present. Micro-Raman spectrometry showed that the corrosion products had formed in distinct layers as shown in Figure 1.

In previous work with the Raman microprobe, we have examined the fluorescence emissions of rareearth (RE) bearing glasses to study the phenomena of structural resonances in the spectra of glass microspheres and the energy upconversion processes for RE ions in such glasses that give rise to anti- Stokes fluorescence emission. Presently, we are revisiting these same fluorescent glasses to study their laser excited emissions as potential radiometric sources for the calibration of Raman spectral intensities. Many of the rare earth ions produce interesting fluorescence spectra on laser excitation depending on the type of ordered or disordered (solid) host matrix. These fluorescence spectra, depending on RE concentration and quenching effects, can be intense and may consist of either narrow-band (or line) emissions or broad-band spectra covering a wide spectral range. These spectra, acquired at laser wavelengths from the ultraviolet (UV) to the near-infrared (NIR), provide a practical means for the calibration of Raman instrumentation for both Raman frequency and intensity.

Al films have been deposited on the inside of the Color Display Tube (CDT) panel on which black matrix carbon and RGB phosphors were coated to improve brightness with the prevention of voltage down and less ion impact to phosphors. The characteristics of Al films have a close relationship with the deposition variables such as base pressure and deposition rate causing changes in Al film microstructures and differences in the reflectance. It is generally known that the reflectance is affected by the thickness, grain size, and surface roughness of the Al film: The grain size of the Al film tends to decrease when base pressure is poor due to the presence of residual gas. The reflectance of Al alloys was reported to be increased with the larger grain size.

The purpose of this study is to understand the relationship between the reflectance and the microstructures of Al films as a function of base pressure in a CDT manufacturing to optimize deposition conditions for improved reflection properties.

319 aluminum (6.5-8.5% Si, 3.0-4.0%Cu, 0.2-0.45%Mg, 0.8%max.Fe, 0.5%max.Mn) is utilized by the automobile industry for engine block and cylinder head applications. Detailed understanding of the solidification behavior is critical to optimizing the “as-cast” microstructure and the physical properties of this alloy. Samples were generated by allowing a 50 gram sample of molten alloy to partially solidify at a slow cooling rate (0.34 °C/sec). During cooling, the temperature of the alloy was monitored by a thermocouple in the center of the sample to generate a cooling curve (Fig. 1). At various locations along this cooling curve the normal cooling was interrupted by plunging the cup into an iced- brine quench. In addition to optical and SEM examination, detailed TEM analysis was performed on three quenched samples as well as one sample allowed to cool uninterrupted to room temperature. TEM sample preparation consisted of standard grinding and dimpling procedures followed by ion milling at liquid nitrogen temperature using a gun voltage of 4keV.

319 Al (7.2-7.7wt% Si, 3.3-3.7%Cu, 0.25-0.35%Mg, 0.4%max.Fe, 0.2-0.3%Mn, 0.25%max Zn, 0.25%max Ti) is utilized by the automotive industry for engine blocks and cylinder heads. Detailed understanding of the age hardening behavior of these types of alloys is important to optimize the processing of these components to yield the desired physical properties. Age hardening curves for temperatures between 100 and 305°C have been determined for a commercial grade 319 Al alloy having a dendrite arm spacing of 30(im. Samples for TEM were prepared by conventional grinding and dimpling followed by ion milling at 4keV at liquid nitrogen temperatures. The phases formed within the primary aluminum dendrites during age hardening were characterized by JEOL 2000FX and an OXFORD ISIS microanalysis system.

Age hardening curves for Al-Cu alloys are characterized by multiple hardening stages as shown by Silcock, et al. Figure 1 shows an example of a 150°C age hardening curve for 319 Al.

Optical, video and scanning electron microscopic observations show fractographic features that are used to determine the crack propagation direction and crack origin in thermally stressed single crystal sapphire hemispherical shells. These features have been typically identified in materials with symmetrically applied stresses and simple geometries. This fractographic evaluation of sapphire is unusual because of the hemispherical geometry and complex mechanical and thermal stress conditions. Computer models predict the thermal stress response of the sapphire from fast acting asymmetrical heating patterns generated during controlled laboratory testing. These experimental tests are conducted to validate the computer model predictions. When an experimental structure fails to meet the survival limits predicted by the computer model, a fractographic evaluation is conducted to determine fracture mode and to locate the crack initiation site.

Fractured pieces are examined and photographed using a low magnification, binocular optical microscope and a high resolution video camera with digitizing capabilities.

Stress corrosion cracking has been a problem in aluminum alloys exposed to an aggressive environment under high static residual tensile stress. This work is concerned with the application of electron microscopy to investigate possible causes that led to failure through stress corrosion cracking in the aluminum alloy 5182. This alloy is commonly used for making carbonated beverage containers. The containers in this study did not experience any problem at the time of the filling. However, after humid storage periods going from a few days to a few weeks, leakage at the can ends was reported in many of them. These leaks developed from a failure referred to as aluminum can end blow out.

Figure la shows an SEM micrograph of a cross section of the score imposed on the top of the can during manufacturing. The unscored metal below the score is broken when the ring or tab is pulled out during opening.

The SEM/EDS is a valuable tool in the pharmaceutical industry for aiding in the identification of isolated particles. It is a part of our systematic approach which proceeds from lower magnification techniques, e.g., stereomicroscope, to higher magnification techniques, eg., polarized light microscopy, and finally to the high magnification of SEM/EDS. Particles associated with pharmaceutical product rejects are due to a variety of sources, often due to the ubiquitous use of some materials, e.g., stainless steel alloys, in the manufacturing arena. Our particles of interest range in size from submicron to ≥ 50 μm (visible with the unaided eye), appearing in numerous shapes and/or colors. Any particles contained in a drug product or associated with the package are objectionable. Detection during production operations and/or during the terminal 100% inspection prior to market release will cause product rejection. In any case, foreign particles are not tolerated. Their identification leads to their source and thus proper corrective action.

The evolution of scanning tunneling microscopy (STM) into atomic force microscopy (AFM) have led to a family of scanning probe techniques which are widely applied in fundamental research and in industry. Visualization of the atomic- and molecular-scale structures and the possibility of modifying these structures using a sharp probe were demonstrated with the techniques on many materials. These unique capabilities initiated the further development of AFM and related methods generalized as scanning probe microscopy (SPM). The first STM experiments were performed in the clean conditions of ultra-high vacuum and on well-defined conducting or semi-conducting surfaces. These conditions restrict SPM applications to the real world that requires ambient-condition operation on the samples, many of which are insulators. AFM, which is based on the detection of forces between a tiny cantilever carrying a sharp tip and a sample surface, was introduced to satisfy these requirements. High lateral resolution and unique vertical resolution (angstrom scale) are essential AFM features.