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Construction and demolition waste (CDW) has become one of the most important environmental problems in large and medium-sized cities around the world. Classification and segregation of CDW particles constitute the main difficulties for their recycling. The present paper proposes a methodology for morphological classification of particles of recycled sands from CDW that consists in a typical supervised classification procedure. It uses size, shape and texture description parameters to discriminate between CDW particles from mortar, ceramic and concrete observed with scanning electron microscopy technique. The classification system reaches a reasonable success. The total success rate obtained is 73.96% and the success rates for mortar and ceramic are greater than 80%. The main limitation is the recognition of the concrete particles; the best result obtained for its success rate is 56.30%. [ABSTRACT FROM AUTHOR]

A methodology for quantitative microstructural characterization of iron ore sinters is proposed. Sinter samples with ≈3 cm diameter were mounted in resin, ground and polished. For each sample, mosaic images covering the entire sample were acquired (5x objective lens). An automatic image analysis routine was employed to measure the area fraction of each phase, including pores. In addition, more than I .500 images were also acquired and analyzed in higher resolution (20x objective). The results obtained from different resolutions are very similar for hematite, magnetite and ferrites. However, there is a wide variation - about 40% - in silicates fractions. Likewise, X-ray diffraction results are consistent with the measurements carried out by image analysis, except for silicates. [ABSTRACT FROM AUTHOR]

Varistors are very complex polycrystalline ceramic systems containing several dopants and their electrical properties are directly dependent on the chemical composition and on microstructural characteristics, such as grain size, porosity, twins and phase distribution. The aim of this work is to evaluate, using image analysis tools, the microstructural characteristics of varistor ceramics. The microstructural characterization was made by scanning electron microscopy and energy dispersive X-ray spectroscopy. Microstructural and morphological parameters were obtained by means image analysis techniques based on appropriate filters. Segmentation and binarization methods were used to differentiate grain and grain boundaries properties, as well phase structures. In this study, image processing and measurements have been developed in order to extract the relevant microstructural parameters on the varistor ceramics. It was developed an appropriate filtering and segmentation method for analysis of varistor ceramics to obtain grain and grain boundaries structural and morphological informations. In the case of zinc oxide-based varistors doped with rare-earth oxides it was determined the influence of the intergranular layer former material on the densification degree, the average thickness of the intergranular layers and the average percentage of area occupied by secondary phases. [ABSTRACT FROM AUTHOR]

In this work, a simple methodology was developed for the quantitative evaluation of the microstructure of spheroidized steels. In the first part, the decarburization of these steels was analyzed and now, methodology for the determination of the spheroidization degree was developed, as the available industrial norms are restricted to the use of qualitative standards for determining the mean spheroidization degree. The SAE 1095 steel was studied in the spheroidized annealed condition. The parameter circularity was applied to scanning electron micrographs, enabling the quantification of the carbides distribution according to their spheroidization degree. [ABSTRACT FROM AUTHOR]

In this work, simple methodology was developed for the quantitative evaluation of the microstructure of spheroidized steels. In this first part, the decarburization of these steels was analyzed and, sequentially, the determination of the spheroidization degree will be analized, as the available industrial norms are restricted to the comparison with perlitic micrographic standards, in the case of the decarburization degree and with qualitative standards, in the case of the spheroidization degree. The AISI 1095 steel was studied in the hot-rolled and spheroidized-annealed condition. Using stereologic methods and scanning electron microscopy it is possible to quantify, from the volumetric fraction of carbides, decarburization profiles of spheroidized products with a spatial depth resolution of circa 5 μm. [ABSTRACT FROM AUTHOR]

Despite progress in Scanning Electron Microscopy (SEM) automatic instruments, these systems are not capable of performing the identification and discrimination of major iron ore minerals (hematite and magnetite). On the other hand, Reflected Light Microscopy (RLM) can easily distinguish these iron oxides by their reflectancies, but it cannot discriminate quartz and epoxy resin, which presents similar color on images. Therefore, iron ore quantitative microstructural characterization is still a challenge. In the present work, a Co-Site Microscopy methodology that combines images obtained by RLM and SEM is applied to perform a quantitative characterization of an itabiritic iron ore. The so-called RLM-SEM Co-site Microscopy can discriminate phases that are not distinguishable with either RLM (epoxy resin and quartz) or SEM (hematite and magnetite) through this multimodal approach, allowing the subsequent mineralogical quantification. The applied methodology employs an automatic routine based on Image Analysis and Pattern Recognition techniques. The mineralogical quantification computed by image analysis was consistent with independently obtained results based on the Rietveld technique. [ABSTRACT FROM AUTHOR]