Microstructure microscopic examination

All commercially available polishing pads are relatively complex composite materials, as evidenced in photomicrographic cross sections of the major pad types illustrated in Figs. 5-7. The signature structural characteristics of each class of pads (Table I) are readily apparent. The impact of manufacturing process on microstructure is sufficiently strong that the manufacturing process used to produce an unknown pad sample can be readily determined from microscopic examination. 

The obtained PSZ-SUS 304 gradient green specimens were measined as 30 mm in diameter and approximately 4 to 20 mm in height. The green specimens were dried at 373 K, and then sintered without pressures for 1 hour at 1623 K in a vacuum. The relative density and the linear shrinkage of monolithic sintered specimens were measured. The microstructure of monolithic and multilayer sintered specimens was microscopically examined. The gradient distribution was examined by an X-ray line analysis of Fe and Zr. 

Changes in the microstructure of reinforced plastics can be observed under scanning electron microscope examination. When debonding is ex-... 

Finally, microscopical examination alone may not provide sufficient answers to the questions of clinker microstructure or a cement s inferior performance. Cement particle size distribution, variations in crystal chemistry, mineral and chemical admixtures, as well as the effectiveness of the set-controlling material (normally gypsum or similar minerals), may have stronger effects on cement hydration than the clinker production problems inferred by routine microscopy. Some clinker and cement problems, however, are simple and easily solved others require the analysis of a tangled set of multiple causes and effects. Microscopy should be one of the first steps in that analysis. 

For ceramic materials that are not extremely hard (e.g., stabilized zirconium oxide or multiphase materials), surface relief can be created within a few minutes by means of final polishing with colloidal silica on a chemicaUy resistant, short-napped fiber cloth. Because removal is dependent on the grain orientation and the type of phase, it is possible to distinguish between grains of a single phase and between different phases during microscopic examination. Application of the DIC method makes it possible to use even poorly defined reUef to display microstructure under the optical microscope. A brief final polishing step with very fine alumina (0.05 pm) will help reveal the spinel phase in aluminum oxide materials, for example. 

Avoidance of these artifacts will make it easier to use microscopic methods to distinguish between pores, pull-outs, phases, and smearing. This requires preparation techniques which are well-matched to material in question, especially with respect to its microstructure and manufacture. It is always necessary to perform microscopic examinations of the section after the individual process steps, so that the preparation... 

This microstructure has been investigated by up-to-date methods especially the scanning electron microscope examination proved the presence of fractures, cavities and matrix porosities wich, in reservoir engineers opinion, deciding determine the transmissibility of methane (the permeability of coal). It is true, that commercial gas production to date has been hampered by the low permeabilities of coal seams. For example the permeability of a good porous sandstone reservoir is between 0.1-0.5 pm just then a coal seam has only 5-20.10-3 permeability but there are coals with permeability between 10- >-10 pm. As it will be discussed in point 4 the low permeability is indeed the greatest problem of methane recovery from coal seams. 

Quality control of plastic molded parts can use optical techniques. In this procedure thin slices of the material are cut from the part and microscopically examined under polarized light transmitted through the sample. Study of the microstructure by this technique enables rapid examination of quality-affecting properties. This kind of approach can provide the molder with information for failure analysis, part and mold design, and processing optimization [12]. 

Hatchfield, P. B., Koestler, R. J. (1987). Scanning electron microscopic examination of archaeological wood microstructure altered by consolidation treatments. Scanning Microscopy, 7(3), 1059-1069. 

Microscopic examination is an extremely useful tool in the study and characterization of materials. Several important applications of microstructural examinations are as follows to ensure that the associations between the properties and structure (and defects) are properly understood, to predict the properties of materials once these relationships have been established, to design alloys with new property combinations, to determine whether a material has been correctly heat-treated, and to ascertain the mode of mechanical fracture. Several techniques that are commonly used in such investigations are discussed next. 

Microscopic examination of refractories can range from simple hand lens examination to the use of sophisticated scanning or transmission electron microscopes with magnification in the order of many thousands of times. The purpose of examination is to increase the knowledge of microstructural properties of the... 

Typical information that can be obtained firom microscopic examination of refractories are parameters such as grain size, grain distribution, and mineralogy. However, many parameters are subjective in nature and therefore need to be examined in comparison with similar materials. Considerable experience is required if microstructures are to be correctly and objectively interpreted. 

Microstructures were examined by reflected light with a Zeiss Universal Microscope and an ETEC U-1 Scanning Electron Microscope. 

In order to observe cell morphology, the extruded samples were immersed into liquid nitrogen and fractured in brittle manner. The fractured smface was coated with a thin layer of platinum, and the microstructure was examined using a scanning electron microscope, SEM (JSM-6060, JEOL). 

Other instruments which have been devised for microstructure examination include the X-ray microscope, with greater resolving power than the EM (Ref 41), and the electron microprobe, capable of indicating subtle changes in composition over small specimen areas (Refs 57 62)... 

Thanks to the increased sensitivity of detectors, good reflectance spectra can be obtained for small samples such as those examined under an optical microscope. Focusing the beam down to almost the exact size (a few pm) allows the composition of samples that have a microstructure. The instrument includes a spectrometer coupled to an optical microscope (Fig. 10.21). 

Further evidence in favour of the amorpho-crystalline texture was recently provided by Ranby [46]. In a series of his papers several questions connected with the microstructure of cellulose are made clear. Cellulose to be examined in an electron microscope was initially dispersed by means of ultrasonic waves. In this way Ranby has isolated elementary thread-like micelles of about 70 A dia. Any dimension characterizing the length of the micelle is however missing. 

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