Desgaste corrosivo-cavitativo-erosivo de um aço-carbono em meio aquoso com frações de sal (NaCl), CO2 e particulados sólidos (SiO2)

A batch of eighty-four coupons of low carbon steel were investigated at laboratory conditions under a corrosive, cavitative-corrosive (CO2) and corrosive-erosive (SiO2 + CO2) in an aqueous salt solution and two levels of temperature. The following measurements were made on Vickers (HV0,05, HV0,10, HV0,20) Microhardness tests at three levels of subsurface layer. A turbulent flow collided on the cylindrical sample, with and without mechanical stirring and gas bubbling, with and without fluid contamination by solid particles of SiO2, at two temperatures. Surface Roughness and Waviness, under two conditions "as received, after machining" and "after worn out", as well as gravimetric and electrochemical parameter were measured on the two opposite generatrices of each cylindrical sample, on the flow upstream (0°) and downstream (180°) by Profilometry, Mass Variation and Linear Polarization Resistance (LPR). The results of the Microhardness and Surface Texture of all coupons were subjected to statistical comparison, using the software Statgraphics® Centurion XVI, 95% statistical certainty, and significant differences were observed in some arrays of measurements. The corrosive wear rate measured by LPR and mass variation shown to be sensitive to the presence of bubbles and hydrodynamic fluctuations inside the cell, considering the temperature and contamination of corrosive fluid by solid particles. The main results of visual inspection relative to some topologies of the surface damages involving different mechanisms that were seen to give explanation for some fluctuations in wear rates of the steel experimentally investigated

Desenvolvimento e teste de um protótipo de reator de plasma com gaiola catódica rotatória para nitretação em lote de pequenas peças

The technique of ion nitriding, despite being fully consolidated in the industry, has great limitations when applied to the treatment of small parts. This is because effects that occur due to non-uniformity of the electric field, generate localized heating in parts, damaging the uniformity of nitrided layer. In addition, because the samples are treated static parts thereof are untreated. To expand the use of plasma nitriding, this work presents the development, assembly and testing of a prototype plasma reactor with rotatory cathodic cage [patent pending], able to meet these needs, giving the material a uniform treatment and opening doors to industrial scale production. The samples tested with hexagonal nuts are 6.0 mm in diameter, made of stainless steel AISI 304 nitrided at a pressure of 1 mbar in an atmosphere of 20% H2 + 80% N2 for 1 h. After treatment, testing visual inspection, optical microscopy and microhardness were carried out to check the effectiveness of the process for uniformity and hardness of the parts. All samples exhibited uniform color, and matte brownish, unlike the untreated samples, silver color and gloss. The hardness of the surface (top and sides) was 65% and even higher than the original hardness. The nitrided layer showed great uniformity in microstructure and thickness. It is concluded, therefore, that the unit was effective constructed for the purposes for which it was designed

Um estudo das condições de percolação e estabilidade em barragens de terra mediante métodos geofísicos: caso do dique de Sant Llorenç de Montgai - Espanha

The monitoring of Earth dam makes use of visual inspection and instrumentation to identify and characterize the deterioration that compromises the security of earth dams and associated structures. The visual inspection is subjective and can lead to misinterpretation or omission of important information and, some problems are detected too late. The instrumentation are efficient but certain technical or operational issues can cause restrictions. Thereby, visual inspections and instrumentation can lead to a lack of information. Geophysics offers consolidated, low-cost methods that are non-invasive, non-destructive and low cost. They have a strong potential and can be used assisting instrumentation. In the case that a visual inspection and strumentation does not provide all the necessary information, geophysical methods would provide more complete and relevant information. In order to test these theories, geophysical acquisitions were performed using Georadar (GPR), Electric resistivity, Seismic refraction, and Refraction Microtremor (ReMi) on the dike of the dam in Sant Llorenç de Montgai, located in the province of Lleida, 145 km from Barcelona, Catalonia. The results confirmed that the geophysical methods used each responded satisfactorily to the conditions of the earth dike, the anomalies present and the geological features found, such as alluvium and carbonate and evaporite rocks. It has also been confirmed that these methods, when used in an integrated manner, are able to reduce the ambiguities in individual interpretations. They facilitate improved imaging of the interior dikes and of major geological features, thus inspecting the massif and its foundation. Consequently, the results obtained in this study demonstrated that these geophysical methods are sufficiently effective for inspecting earth dams and they are an important tool in the instrumentation and visual inspection of the security of the dams

A inserção da família no processo socioeducativo de adolescentes em privação de liberdade

This master thesis has the main goal investigate how families are inserted in the socioeducational process of teenagers who are undergoing social measures of liberty deprivation. The specific objectives are: to characterize the family´s living together of adolescents deprived of their freedom and their families, from the actions and routines of the socio-educational system; to assess the professional working links in the context of socio-education, in order to care and strengthening families of the adolescents; to investigate how families evaluate the operation of socio-educational process in which adolescents are met. Method: to achieve the proposed objectives, data collection occurred in complementary steps: the first phase took place from visits to socioeducational units of liberty deprivation of RN, and dialogues with professionals working in socio-education. Subsequently, action research stage was carried out, from the insertion of the researcher in the extension project Family and the struggle for the effectiveness of the National Socio Service System, that aimed to strengthen monitoring the adolescents socio-education by their families, and had as methodology the conversation circles and thematic workshops. Lastly, were performed reading and analysis of the references to the family in the Individual Care Plans (PIAs) for adolescents. The information gathered was recorded in field diaries and subjected to thematic content analysis. This research was guided by the Marxist theoretical framework, structured on the understanding of the involvement of adolescents with illegal acts as a development and expression of the social question. From this theoretical framework, the prevailing view in the capitalist society of adolescents in conflict with the law as individuals who are treated by means of repression and segregation and the weakness of social policies is questioned, both in the execution of their own socioeducational measures as the articulation of network services for adolescent protection and strengthening your family. Results: in relation to the operation of the socioeducational system in RN in general, it was observed a state of unhealthy physical spaces and institutional practices that violate human rights, idleness and lack of access to social rights, and criminalization and institutionalization of poor young people and their families. With regard to family´s living together, it was noticed great distance between principles and guidelines recommended by the SINASE, about acquaintanceship and family strengthening, and every day practices of socio-education in RN: serious violations were observed that undermine the family´s living together, as the distance between the socio-educational units of deprivation of liberty and the cities where families live; absence, irregularity and poor conditions in carrying out the family visits; lack of conjugal visits; restricted and unarticulated actions for the care and strengthening of the families of adolescents, most of whom live in poverty or extreme poverty. Finally, it was found a number of blamefully and punishments to the family, including practices such as inward inspection (visual inspection while naked and squant), plus a series of violence and omissions care that sick family members and weaken the links between adolescents and their families.