In the present work, the effect of variation in specimen orientation and heat treatment on the Stress Corrosion Cracking (SCC) susceptibility of 7050 aluminum alloy was investigated in 3,5% NaCl solution and under freely corroding conditions. For this purpose, Constant Extension Rate Tests (CERT) was performed on precracked Compact Tension (CT) specimens and the Direct Current Potential Drop technique was applied to measure the crack lengths. In addition to crack length versus time curves, the relationship between the crack growth rate and the stress intensity factor was determined. Fractographic analysis was utilized extensively to support the findings related with basic mechanisms of cracking. The alloy was found to be in the most susceptible state in the SL orientation, in which the crack propagation direction is parallel to the rolling direction. The resistance to SCC is higher in the TS but at maximum in LT orientation where the loading direction is parallel to the rolling direction. In the peak aging treatment, T651, alloy is susceptible to SCC in SL orientation. When the over aging treatment, T7651, is applied the resistance is increased and the two step over aging treatment, T73651, has resulted in an additional improvement in this orientation. On the other hand, the alloy showed higher resistance to SCC in TS and LT orientations in T651 condition compared to the T7651 and T73651 treatments. In these orientations, the alloy is less susceptible in T73651 condition than in T7651 treatment.

The aim of this study is to investigate the mechanical behavior and its relation with processing and microstructure of the silicon carbide particulate (SiCp) reinforced aluminum matrix composite. Aluminum 7075 alloy is chosen as matrix alloy, in which zinc is the main alloying element. Four different additions of SiCp were used and the weight fractions were 10%, 15%, 20% and 30%. Composites were processed by with squeeze casting and the applied pressure during casting was 80 MPa. The mould is specially designed to produce both specimens ready for tensile and three point bending tests. Both as-cast and heat treated aluminum composites were examined and T6 heat treatment was applied. Three point bending tests were performed to reveal the fracture strength of aluminum composites. 10wt% SiCp aluminum composites showed the maximum flexural strength in both as-cast and heat treated composites. The mechanical test results revealed that precipitated phases in heat treated composites, behaved like fine silicon carbide particulates and they acted as barriers to dislocation motion. Maximum flexural strength increased about 40 MPa (10%) in as-cast and 180 MPa (44%) in heat treated composites. Tensile testing was also conducted to verify the results of the three point bending tests. Hardness tests were done to find the effect of silicon carbide addition and to find the peak hardness in heat treatment. For as-cast specimens hardness values increased from 133 to 188 Vickers hardness (10 kg.) with increase in SiCp content from 0 to 30wt% and for heat treatment specimens hardness values increased from 171 to 221 Vickers hardness (10 kg.). The peak hardness values were obtained at 24 hours precipitation heat treatment. SEM studies were carried out to examine the heat treated composites, to take SEM photographs and to obtain a general elemental analysis. Theoretical volume percentage addition of SiCp was checked with Clemex Image Analyzer program. Distribution of SiCp was determined by mettalographic examination. Second phases that were formed during heat treatment was searched by x-ray analysis.

The quality and shelf-life of pressure processed (150, 200 and 250 MPa at 25 and 35&deg / C for 5, 10 and 15 minutes) orange, tomato and carrot juices were compared to fresh and thermally pasteurised (60&deg / C for 5, 10 and 15 minutes and 80&deg / C for 1 minute) juices. Treatments were capable of microbial inhibition of juices to non-detectable levels. The change in ascorbic acid content of HHP treated juices was not statistically significant (p&gt / 0.05). Both heat treatments at 60 and 80&deg / C, displayed a significant loss and induced a decrease in the free radical scavenging activity but was not affected by HHP treatments. Pressurization at 250 MPa at 35&deg / C for 15 minutes and thermal pasteurization at 80&deg / C for 1 minute and stored at 4 and 25&deg / C for shelf-life analysis. HHP treated juices showed a small loss of antioxidants (below 10%) at both storage temperatures whereas the loss is higher (about 30%) in the heat treated juices through shelf life (30 days). The pressurized juices, stored at 25&deg / C, contained ascorbic acid better than heat treated ones after 30 days. The total color changes were minor (&amp / #8710 / E=10) for all pressurized juices but for heat pasteurized samples, higher as a result of insufficient antioxidant activity. The pH of juices was not affected by treatment, storage temperature or time. HHP yielded a better product, regarding the studied parameters of the juices compared to the conventional pasteurization. Therefore, HHP treatment (250 MPa, 35&deg / C for 15 minutes) can be recommended for industrial production of fresh fruit and vegetables.

i ABSTRACT I investigated aspects of the management of subterranean termites in the field by evaluating the protective values of preservative treated softwoods and evaluating the potential of softwoods conditioned by decay fungi or heat to produce termite monitoring and aggregating devices. As part of the investigation, it was necessary to: · develop assay techniques suitable for research into the natural resistance of timbers, the efficacy of wood preservatives and termite biology and foraging behaviour; and quantify variation in termite responses to untreated softwoods in various situations in the field using these techniques. Field bioassays were conducted with two Australian Coptotermes species to determine protection of pine sapwood afforded by borate compounds (Chapter 2). Coptotermes lacteus (Froggatt) was examined in winter and C. acinaciformis (Froggatt) in winter, spring and summer at two localities in Queensland. Hoop-(Araucaria cunninghamii Ait ex D. Don) and slash-pine (Pinus elliottii Engelm.)-sapwood blocks were placed in plastic containers and attached to termite mounds or infested trees. Termite response was determined by mass losses over five weeks and modelled. Coptotermes lacteus was relatively benign in winter and for 1.0 and 2.5% mass losses of hoop-pine sapwood, borate retentions of 0.20 and 0.06% mass/mass (m/m) boric acid equivalent (BAE), respectively, were derived. With C. acinaciformis, for 1.0 and 5.0% mass losses of hoop-pine sapwood, borate retentions ranged from 0.49 and 0.25% BAE, respectively, in winter to 0.76 and 0.47% BAE, respectively, in late summer. For 1.0 and 5.0% mass losses of slash-pine sapwood in summer, borate retentions of 0.58 and 0.14% BAE, respectively, were derived for C. acinaciformis. These results support conclusions from earlier laboratory studies conducted elsewhere. Prevention of damage by field populations of termites was not achieved. Marked intercolony variation in response to borate compounds was demonstrated, highlighting the usefulness of this rapid technique. The need for long-term field exposure trials to calibrate the lunch-box technique and to facilitate technology transfer to industry, is indicated. For comparison, termite response to white cypress (Callitris glaucophylla Thompson and Johnson), a naturally termite resistant timber, is also reported. A field bioassay was conducted to evaluate responses of C. acinaciformis to untreated southern-yellow-pine (Pinus spp.), hoop-pine and slash-pine blocks (Chapter 3). Sapwood blocks were placed in plastic containers and attached to trees infested with the termites during summer. Containers with a test block of each of the timber species were prepared. These and other containers were exposed to termites for 10 weeks. Termite feeding response (“voracity”) was assessed for all blocks by determining the mass of wood consumed. Termite voracity differed among trees. Variation in termite responses to individual hoop-pine feeder-blocks within a container was appreciable and consistent between containers. Variation in termite responses to the test blocks was appreciable, with hoop pine being significantly more susceptible to termite attack than either slash pine or southern yellow pine. Southern yellow pine is a generic name for five species of pine which are difficult to separate reliably. Therefore, caution should be exercised when using “southern yellow pine” to ensure that samples are at least from the same species of pine and preferably from the same length of timber. The sensitivity of both the bioassay and the statistical tests was demonstrated. Of particular interest was the similar level of termite response to the test timbers in the two sections of the experiment. The usefulness of feeder-blocks to initiate reliable attack rather than to promote sustained attack, is worth further attention. Sapwood stakes of Australian-grown hoop pine, slash pine, radiata pine and North American-grown southern yellow pine were exposed to subterranean termite attack in an in-ground bioassay (Chapter 4). Stakes in bait containers and bare stakes were attacked by C. acinaciformis and Schedorhinotermes intermedius (Brauer). Susceptibility of these timbers was evaluated with regard to potential for termite monitoring and aggregation. Variation between timbers and difference between termite species are described. The relevance of these data to suppressing foraging populations of subterranean termites, in Australia, using insect growth regulators, is discussed. Four field bioassays were conducted using two species of Australian subterranean termites, C acinaciformis and C. lacteus (Chapter 5). Hoop-pine blocks decayed using 14 fungi for four weeks and for 10 weeks were subsequently conditioned using dry heating, freezing or moist heating, and then exposed to termites. Blocks decayed by Gloeophyllum abietinum [Persoon: Fries] Murrill, Trametes lilacino-gilva (Berkeley) Wright & Deschamps, Schizophyllum commune Fries and Rigidoporus undatus (Persoon) Donk and subsequently oven dried, were attacked the most. Oven drying generally enhanced termite feeding responses in these two field bioassays. In a third bioassay, blocks of five softwood timber species conditioned with two high temperature regimes were exposed to C. acinaciformis. Slash pine was attacked the least. Mean mass losses for hoop pine, Caribbean pine (Pinus caribaea Morelet), radiata pine and the interspecific F1 hybrid between Caribbean and slash pine were not significantly different. For C. lacteus, slash and hoop-pine blocks were attacked the least while radiata pine was attacked the most. Additional heating at 105°C increased the susceptibility of most timber species. Relationships between heating duration and the consumption of hoop-pine-sapwood blocks were determined using results from a fourth bioassay. Heating the timber increased feeding responses for both termite species. The selective and rapid response of the termites highlights the usefulness of this field technique for multiple-choice bioassays. The cyclodiene termiticides were withdrawn from use, in Australia, as from 30 June 1995. Implications for the management of subterranean termites in Queensland are discussed. Community perceptions of the use of chemical pesticides and cost do not favour the widespread use of preservative treated timber in buildings. An integrated pest management approach to termite control is the likely direction for the future in Australia. A range of building techniques, regular inspections, and attention to factors that predispose existing buildings to termite attack can reduce the risk of damage from termites, but do not eliminate that risk. There will be an increased need for reliable preventative and remedial treatments involving bait technology. Much more work is needed on termite biology, foraging behaviour and bait toxicants before a baiting system can be confidently commercialised in Australia. Directions for research in Queensland are discussed.

Diss. (sammanfattning) Uppsala : Sveriges lantbruksuniv., 2007. / Härtill 5 uppsatser.

Submitted by Johnny Rodrigues (johnnyrodrigues@ufcg.edu.br) on 2018-04-18T15:31:59Z No. of bitstreams: 1 VANUCIA SANTOS DIAS - DISSERTAÇÃO PPG-CEMat 2014..pdf: 3639913 bytes, checksum: 915ca6c2f3b8eced104eb3bd31c33dd3 (MD5) / Made available in DSpace on 2018-04-18T15:31:59Z (GMT). No. of bitstreams: 1 VANUCIA SANTOS DIAS - DISSERTAÇÃO PPG-CEMat 2014..pdf: 3639913 bytes, checksum: 915ca6c2f3b8eced104eb3bd31c33dd3 (MD5) Previous issue date: 2014-08-29 / Um dos grandes problemas sanitários está na disposição final dos resíduos gerados pela população e pelas indústrias. No estado da Paraíba, são coletados diariamente 2.754 toneladas de resíduos sólidos urbanos, destes 30,9% têm destinação final em aterros sanitários, 36,9% destinam-se para aterros controlados e 32,2% têm como destino final os lixões. O reaproveitamento do vidro indica 100% de reprocessamento. Além de ser 100% reciclável, o vidro, quando reaproveitado, resulta em redução do impacto ambiental e ainda contribui para diversificação da fabricação de produtos e para diminuição dos custos finais de sua produção. Este trabalho objetiva estudar o processo de recozimento de resíduos vítreos, visando contribuir para o desenvolvimento de uma tecnologia social de reciclagem de vidros para as trabalhadoras do CAVI - Associação de Catadores e Recicladores de Vidros e outros Materiais. Para isso foram utilizados resíduos de vidros planos e ocos submetidos a cinco processos de fusão e recozimento com diferentes níveis de temperatura, empregando técnicas de reciclagem de vidro a quente (vitrofusão e termoformado). Foram utilizados moldes de cerâmica para os estudos iniciais e de gesso para a confecção dos corpos de prova. A resistência após o recozimento foi analisada por meio de ensaios de impacto, em que pode ser constatado que as amostras submetidas ao tratamento térmico estudado apresentaram maior resistência ao impacto quando comparadas às amostras que não receberam tratamento térmico durante o processo de fusão. As fraturas obtidas após os ensaios foram analisadas macroscopicamente. / One of the major health problems is the disposal of waste generated by the population and industries. In the state of Paraíba, are collected daily 2,754 tons of municipal solid waste, 30.9% of these have final disposal in landfills, 36.9% intended to controlled landfills and 32.2% have a final destination landfills. Recycling of glass indicates 100% reprocessing. Besides being 100% recyclable glass, when reused, resulting in reduced environmental impact and still contributes to diversification of manufacturing products and to decrease the final cost of its production. This work aims to study the process of annealing of glassy waste, aiming to contribute to the social development of a recycling technology for glass workers CAVI - Association of Collectors and Recyclers of Glass and other Materials. For this waste flat glass and hollow undergone five mergers and annealing with different temperature levels were used, employing techniques of recycling glass hot (fusing and slumping). Ceramic molds for the initial studies and gypsum for the manufacture of test specimens were used. The resistance after annealing was examined by impact tests, it can be seen that the samples subjected to the heat treatment study had higher impact resistance compared to samples which received no heat treatment during the melting process. The fractures obtained after the tests were analyzed macroscopically.

Made available in DSpace on 2014-06-11T19:28:35Z (GMT). No. of bitstreams: 0 Previous issue date: 2006-12Bitstream added on 2014-06-13T19:37:18Z : No. of bitstreams: 1 furtado_ae_me_guara.pdf: 4157561 bytes, checksum: c59e496f189cae1f505585658dfe2da7 (MD5) / Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES) / Objetivando um maior compromisso com o meio ambiente, as montadoras ao redor do mundo passaram a investir em veículos menos poluentes e para tanto, um dos caminhos adotados foi a redução do peso para diminuir o consumo de combustível. Um dos meio para atingir esse objetivo foi a utilização dos materiais menos densos, com plástico e o alumínio. Essa política fez cair significativamente a proporção de utilização do aço nos projetos automotivos nos últimos vinte anos. Desta forma, a fim de manter seu volume de vendas no mercado automobilístico, grandes siderúrgicas ao redor do mundo se uniram com o intuito de provar a viabilidade da construção de carros utilizando o aço e ainda assim obter um produto final mais leve e barato. Esse estudo iniciou-se em 1994 e ficou conhecido por Consórcio ULSAB (Ultra Light Steel Auto Body). Esse trabalho tem como objetivos apresentar os projetos da família ULSAB, bem como realizar a análise de um componente da suspensão traseira de um veíclo do segmento popular produzido atualmente em grande escala no Brasil (e em outros países) baseado nesta filosofia. Desta forma, através de diferentes rotas de tratamento térmico, foram obtidas diferentes estruturas (temperada, temperada e revenida, normalizada e bifásicas) para o componente em questão. Foi realizada a análise microestrutual e mecânica dos corpos de prova para a definição de uma proposta de tratamento termicos alternativos para oo componente estudado. Dentre as estruturas obtidas pode-se concluir que os aços bifásicos foram os que apresentaram melhores resultados, ou seja resitência mecânica muito próxima ao nível de resistência atual da superfície temperado do componente,e alongamento ( por analogia, tenacidade) próximo aos níveis atuais atingidos no núcleo do componente. / The adoption of friendly environmental politics OEMs all over the world to invest in low emissions vehicles. A way to achieve this goal is mass reduction in order to improve fuel consumption. This mass recution can be achieved using lighter materials as plastics and aluminum. This politics caused and important reduction in the proportional use of steel in car projects in last twenty years. So, in order to maintain their market share in automotive new projects, thirty -five steel-makers from the five continents have a made a partnership which objective was to prove the viability to build lighter and cheaper steel intensive vehicles. Project team started working in 1994 andwas named ULSAB (Ultra-Light Steel Auto Body). This dissertation has a guidelinesthe presentation of ULSAB family programs and also analyzing a rear suspension part of a small size car produced in large scale in Brazil (and other countries too) base on this philosophy. Thus, using different thermal treatment, different structures(quenching and tempering and dual-phase steels) have been achieved for the component. Mechanical and micro-structural analyses of these different materials permitted to ptopose alternative treatments for the component. The best results among the achieved structures were reached by dual phase steels: mechanical strength very near from the quenched surface and elongation values almost the same as the non treated center of the component.

Made available in DSpace on 2014-12-17T14:07:11Z (GMT). No. of bitstreams: 1 QueremAFA_DISSERT.pdf: 6927049 bytes, checksum: 5fbf755901320194b71aa9dc0dc0b657 (MD5) Previous issue date: 2013-06-07 / Studies indicate that a variation in the degree of crystallinity of the components of a polymer blend influences the mechanical properties. This variation can be obtained by subjecting the blend to heat treatments that lead to changes in the spherulitic structure. The aim of this work is to analyze the influence of different heat treatments on the variation of the degree of crystallinity and to establish a relationship between this variation and the mechanical behavior of poly(methyl methacrylate)/poly(ethylene terephthalate) recycled (PMMA / PETrec) with and without the use of compatibilizer agent poly(methyl methacrylate-al-glycidyl methacrylate-al-ethyl acrylate) (MMAGMA- EA). All compositions were subjected to two heat treatments. T1 heat treatment the samples were treated at 130 ? C for 30 minutes and cooled in air. In T2, the samples were treated at 230 ? C for 5 minutes and cooled to approximately -10 ? C. The variation of the degree of crystallinity was determined by the proportional relationship between crystallinity and density, with the density measured by pycnometry. The mechanical behavior was verified by tensile tests with and without the presence of notches and pre-cracks, and by method of fracture toughness in plane strain (KIC). We used the scanning electron microscopy (SEM) to analyze the fracture surface of the samples. The compositions subjected to heat treatment T1, in general, showed an increase in the degree of crystallinity in tensile strength and a tendency to decrease in toughness, while compositions undergoing treatment T2 showed that the opposite behavior. Therefore, this work showed that heat treatment can give a polymer blend further diversity of its properties, this being caused by changes in the crystal structure / Estudos apontam que uma varia??o no grau de cristalinidade dos componentes de uma blenda polim?rica influencia nas suas propriedades mec?nicas. Essa varia??o pode ser obtida pela submiss?o da blenda a tratamentos t?rmicos que levam a modifica??es da estrutura esferul?tica. O objetivo desse trabalho ? analisar a influ?ncia de diferentes tratamentos t?rmicos na varia??o do grau de cristalinidade e estabelecer uma rela??o entre essa varia??o e o comportamento mec?nico da blenda poli(metacrilato de metila)/poli(tereftalato de etileno) reciclado (PMMA/PETrec) com e sem o uso do agente compatibilizante interfacial poli(metacrilato de metila-almetacrilato de glicidila-al-acrilato de etila) (MMA-GMA-EA). Todas as composi??es foram submetidas a dois tratamentos t?rmicos. No tratamento t?rmico T1 as amostras foram tratadas a 130 ?C por 30 minutos e resfriadas ao ar. No tratamento T2 as amostras foram tratadas a 230 ?C por 5 minutos e resfriadas a aproximadamente 10 ?C. A varia??o do grau de cristalinidade foi verificada pela rela??o de proporcionalidade existente entre cristalinidade e densidade, sendo a densidade medida por picnometria. O comportamento mec?nico foi verificado por ensaios de tra??o, com e sem a presen?a de entalhes e pr?-trincas, e pelo m?todo da tenacidade ? fratura em estado plano de deforma??o (KIC). Utilizou-se a microscopia eletr?nica de varredura (MEV) para analisar a superf?cie de fratura das amostras. As composi??es submetidas ao tratamento t?rmico T1, de uma forma geral, mostraram aumento no grau de cristalinidade, na resist?ncia ? tra??o e uma tend?ncia ? redu??o na tenacidade ? fratura, enquanto que as composi??es submetidas ao tratamento T2 mostraram um comportamento oposto a esse. Portanto, este trabalho mostrou que um tratamento t?rmico pode conferir a uma blenda polim?rica uma diversidade ainda maior de suas propriedades, sendo essa ocasionada pelas mudan?as na estrutura cristalina

High chromium ferritic steels such as Grade 91 and Grade 92 are extensively used in the power plant industry. Components made from these types of steels, including headers, steam pipes and tubes, are required to provide reliable service at high pressures (20-30 MPa) and temperatures (550-610°C) for several decades. However, in order to further improve the thermal efficiency of the power plant, the future operation temperature for the ferritic steels needs to be elevated to 650°C. Therefore, the current research project focuses on the examination of recently developed MarBN type steels (Martensitic steel strengthened by Boron and Nitrides) and four Grade 92 derivatives in order to evaluate their suitability for 650°C application, and also to assess their creep strength from a microstructural point of view.

Recrystallisation is an important topic in the metal industry since the process may drastically alter the properties of the materials subjected to it. By controlling the recrystallisation process, the material properties can be adjusted as desired, which could lead to stronger materials and hence lighter constructions, decreasing our material consumption. This is currently regulated using softening curves complied from tensile tests, a method which does not show the degree of recrystallisation of a metal. This thesis work therefore explores the possibility to characterise the recrystallisation process using in situ X-ray diffraction, XRD, during heating.The method proposed is using in situ heat treatments of aluminium samples combined with XRD measurements. The results show that it is possible to follow the recrystallisation process of rolled aluminium alloy AA3003 by using in situ XRD during heating, a discovery that could facilitate development and understanding of new materials. Nevertheless, further investigations of the subject is required before the method will be profitable. / Rekristallisation är ett viktigt ämne inom metallindustrin, detta eftersom materialegenskaper drastiskt kan förändras under rekristallisationsprocessen. Genom att kontrollera rekristallisationsprocessen kan materialegenskaper skräddarsys efter applikation. Även starkare material kan tillverkas och därav kan lättare strukturer konstrueras och på så vis minskar även materialåtgången. Idag regleras rekristallisation med hjälp av mjukningskurvor sammanställda genom dragprov, en metod som inte kan visa rekristallisationsgraden av en metall. Detta examensarbete utforskar möjligheten att karaktärisera rekristallisationsprocessen genom att använda in situ röntgendiffraktion, XRD, under värmningsprocessen.Den framtagna metoden inkluderar in situ värmebehandlingar av aluminiumprover i kombination med XRD-mätningar. De erhållna resultaten från experimenten visar på att det är fullt möjligt att följa rekristallisationsprocessen av aluminiumlegering AA3003 med in situ XRD, en upptäckt som kan komma att underlätta vid utveckling och förståelse av legeringar och nya material. Dock krävs fortsatta studier i ämnet innan metoden kan anses vara lönsam.