Most of the alloys used as bonding matrix in diamond tools show a high content of cobalt -which is undesirable due to a series of reasons. In the last decade, some attempts were made towards the reduction of the Co content in these alloys. NEXT100J alloy (50wt%Cu-25wt%Fe-25wt%Co) by Eurotungstene is an example of it.This study aims to characterize the structure, microstructure and some mechanical properties of the NEXT100 -this is an comercial alloy widely used as bonding matrix for diamonds in cutting tools, and the informations about its properties are very scarce in the literature.The NEXT100 powder was hot pressed in a graphite matrix at 35MPa/800 C/3 minutes. It was performed structural and microstructural analyses by x-ray diffraction and scanning electon microscopy, respectivelly. Wear resistance and hardness HRB tests were carried out -these are the most important mechanical tests for a diamond bonding matrix. It was demonstrated that the samples presented good mechanical properties, XRD analysis showed the presence of two phases, Cu (CFC) and the solid solution a-Fe (CCC). Microstructural aspects are high densification, homogeneous distribution of phases, and little presence of pores.
In search of the reuse of waste from civil construction, studies are presented as an alternative on the insertion of this waste into materials so that they become ecologically viable and at a lower cost. In this scope, there is the red ceramic waste (RCW), which is largely produced both in renovation works and in the stage of transporting construction components such as bricks, slabs, and floors. On the other hand, the use of cement is of great proportions, which raises concerns about the excessive consumption of non-renewable natural resources, especially in large-scale projects. Thus, the study aimed to evaluate the mechanical properties of compressive strength of concrete with partial replacement of cement by RCW and to verify the influence at different breakage ages (7, 14, 21, and 28 days). Five mixes were used, the first with 100% cement, and the others with crushed RCW to replace 5%, 10%, 15%, and 20% of the cement, and the resistance obtained according to percentages and ages was also verified of RCW through the uniaxial compression test. Thus, it was observed that for replacements of up to 15%, the strength losses were not significant, suggesting the feasibility of its use in works with high concrete demands, such as in dams.
Some diamond tools use iron in their composition, and it is known that iron is a strong catalyst for the graphitization of diamonds. This graphitization occurs mainly during the processing of composite materials – conventional sintering or hot pressing, and during cutting operations. This work studies the effect of TiC coating on diamond, on structure, microstructure and mechanical properties of the processed composites. Samples were prepared by mixing powders of Fe (˜40 μm) and diamond (˜425 μm), and subsequent hot pressing at 35 MPa/900 °C, during 3 minutes. Microstructural aspects were observed by scanning electron microscopy (SEM) and iron diffusion on diamond was studied by energy dispersive spectrometry (EDS). Structural analysis was performed by X‐ray diffraction and Raman spectroscopy. Compressive tests were carried out, as well as the wear resistance of the diamond composites. The importance of employing coated diamonds is stablished. It was observed that iron has not activated the graphitization of diamond crystals.
Some diamond tools use iron in their composition, and it is known that iron is a strong catalyst for the graphitization of diamonds. This graphitization occurs mainly during the processing of composite materials - conventional sintering or hot pressing, and during cutting operations. This work studies the influence of the behavior of the wear and adhesion, of iron-diamond composites, by considering the use of TiC coated diamonds. Samples were prepared by mixing powders of Fe (40 μm) and diamond (425 μm), and subsequent hot pressing at 35MPa/900°C, for a time of 3 minutes. It was evaluated the mechanism of wear, and the behavior of the samples during diametral compression test. It was used the cumulative times of 2, 6, 12 and 20 minutes during the testing of abrasion.
The growth of the urban population is currently a concern of the public power and population, since it generates an occupation at a fast pace, constantly carried out without planning. To do so, it is necessary to identify areas susceptible to geological risk, in order to protect the population from the occurrence of landslides, in addition to recovering and protecting spaces already occupied. The present study aims to develop an evaluation method with the aid of Geoprocessing software in Geographic Information Systems (GIS), which provides the mapping of areas susceptible to mass gravitational movements located in the urban areas of Teófilo Otoni. In order to do so, the study area was delimited, followed by the identification and qualification of danger areas to planar landslide gravitational movements and, finally, risk qualification in some of these areas. This time, thirty-five areas of danger to planar landslide processes were identified and qualified, and the risk areas present in three of the districts of the municipality were delineated and classified, demonstrating that the use of geoprocessing technologies in a GIS platform satisfactorily provided the mapping of risk areas in urban spaces.
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