971 resultados para Resistência à flexão


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The world market of Kaolin has been growing as new investments for better quality of materials have been applied. This market produces amounts of dross that are put in the environment in a wrong way, causing damages to it. Trying to reduce these damages, researches have been done in an attempt to use kaolin dross in ceramic. The disposal of kaolin dross in the environment by the industries of the states of Rio Grande do Norte and Paraiba have great impact in society. Usually this dross is disposed clandestinely in places like roads, river banks and lands of small cities. The present work shows the characteristics of the kaolin produced by the mining company in Junco do Seridó, Paraiba state, western Seridó, 300 km from Natal, in the border of both states. After that, researches were done to study its physical and the chemistry characteristics, trying to see if it can be used in white ceramic. The samples got were bolted in fabric of 325# . The technological characteristics tried to use it as a product in white ceramic. For that, it was made a haracterization of the subject matter through enlargement analyses, ATG and ATD, elaborating three formulations that were burned in four different temperatures, 1175, 1200, 1250 and 1300 degrees centigrade up to 30 minutes. After the burning, the subjects were submitted to water absorbing tests, linear retreating, apparent porosity, apparent specific mass, resistance to flexibility and MEV. For one of the mixtures it was obtained demanded properties for a semi porous material

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The marble and granite waste come from the process of mining of those ornamental rocks for use in the building industry. Brazil is one of the largest producers of blocks or finished products of ornamental rocks, extracting about 5.2 tons / year. The largest national producers are the states of Espírito Santo, Minas Gerais and Bahia which account for 80% of the Brazilian production. However, the waste total amount during processing of these blocks reaches 40% of the total. The use of the waste produced by this industry in white ceramics could be a form of disposition, because these materials, are thrownasa mud directly at decantation ponds, wastelands or in rivers, without any treatment. The present work has as main purpose to study the influence that reject of the ornamental rocks on the physical and mechanical properties of white ceramics. X-Ray characterizations of raw materials by were performed X-Ray fluorescence, X-Ray diffraction, granulometric, thermogravimetric and thermodiferencial analysis, five formulations were made (0, 10, 20, 30, 40% in granite weight) wich were burned at three temperatures: 1100°C, 1150°C and 1200ºC with 60 minutes of sorling time. After sintering, the samples were submitted to different analyser absorption of water, linear retraction, apparent porosity, apparent specific mass, flexival stronght, and scanning were obtained microscopy. Compatible technological properties within the limits demanded for the production of porcelainized stoneware

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The State of Rio Grande do Norte, Brazil, possess major deposits of feldspar, clay, kaolin and talc, all raw materials used in the production of porcelainized stoneware tiles. Conversely, state industries manufacture only low added value red ceramics. Porcelainized stoneware tiles is one of the noblest ceramics, depicting low water absorption (typically below of 0,5%), in addition to excellent staining resistance and mechanical strength. The present work aims at investigating the potential of local raw materials for the production of porcelainized stoneware tiles. To that end, these materials were characterized by X-ray fluorescence, X-ray diffraction, particle size analysis, thermal gravimetric analysis and thermal differential analysis. Admixtures containing different compositions were prepared and fired at three temperatures, 1150, 1200 and 1250°C for 30 min. After firing, tests samples were characterized by water absorption tests, linear retraction, dilatometric analysis, apparent porosity, apparent specific mass, flexural strength, and microstructural analysis by XRD and SEM. The results revealed that ceramics with porcelainized stoneware tiles characteristics could be produced from raw materials originated in the State of Rio Grande do Norte

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The State Bahia, Brazil, presents different geological sites it with a very expressive variety minerals. It is situated among the very important States which produces minerals for industries, such as pointed aggregate, ornamentals stones and ceramics raw materials. Nowadays only four companies producting ceramics tiles. Porcelainized stoneware tiles is one of the noblest ceramics, depicting low water absorption (typically below of 0,5%), in addition to excellent staining resistance and mechanical strength. The present work aims at investigating the potential of local raw materials for the production of porcelainized stoneware tiles. For this purpose, these materials were characterized by X-ray fluorescence, X-ray diffraction, particle size analysis, thermal gravimetric analysis, thermal differential analysis and dilatometric analysis. Admixtures containing different compositions were prepared and fired at four temperatures, 1100 ºC, 1150 ºC, 1200 ºC and 1250 ºC with isotherm for 60 minute and heathing rate of 5 oC/min. After firing the samples, they were characterized by water absorption tests, linear retraction, analysis, apparent porosity, apparent specific mass, flexural strength, and microstructural analysis by X-ray diffraction and scanning electron microscopy . The results revealed three ceramics with porcelainized stoneware tiles characteristics and porcelain tile will be produce from raw materials originated in the State of Bahia

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Brazil is the world s leading coffee producer. In 2008, 45.99 million of 60 kg bags of benefited coffee were produced. In the process of improvement 50% is grain and 50% is husk, thus, 1.38 million tons of coffee husk are produced annually. The husk is used as combustible in the drying and improvement ovens in the coffee farms, generating ash as residue. These ashes contain a high concentration of alkaline metals and earth metals, mainly K2O and CaO. This work studies the use of this residue in the ceramic tiles industry, as fluxing agents in substitution to the feldspar. Ten mixtures with equal ratios of clay and kaolin, proceeding from Bahia and the residue (varying from 30 to 5%) were defined and produced in uniaxial tool die of 60x20mm with approximately 5 mm of thickness and 45MPa compacting pressure. The samples were fired in four different temperatures: 1100 °C, 1150 °C, 1185 °C and 1200 °C during 60 minutes and characterized by means of X-ray fluorescence, X-ray diffraction, gravimetric thermal analysis and differential thermal analysis. The results of water absorption, apparent porosity, linear shrinkage, XRD, dilatometry, flexural strength and SEM were also analysed. The test specimen with addition of 10% of ash fired in 1200 °C resulted in 0.18% water absorption and 40.77 MPa flexural strength, being classified as porcelain stoneware tiles according to ABNT, UNI and ISO norms

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With the objective to promote sustainable development, the fibres found in nature in abundance, which are biodegradable, of low cost in comparison to synthetic fibres are being used in the manufacture of composites. The mechanical behavior of the curauá and pineapple leaf fibre (PALF) composites in different proportions, 25% x 75% (P1), 50% x 50% (P2) e 75% x 25% (P3) were respectively studied, being initially treated with a 2% aqueous solution of sodium hydroxide. Mechanical analyses indicated that with respect to studies of traction, for the combination of P1 and P3, better results of 22.17 MPa and 16.98 MPa, were obtained respectively, which are higher than that of the combination P2. The results of the same pattern were obtained for analysis of bending resistance where P1 is 1.21% and P3 represents 0.96%. In the case of resistance to bending, best results were obtained for the combination P1 at 49.07 MPa. However, when Young's modulus values were calculated, the values were different to the pattern of the results of other tests, where the combination P2 with the value of 4.06 GPa is greater than the other combinations. This shows that the PALF had a greater influence in relation to curauá fibre. The analysis of the results generally shows that in combinations of two vegetable fibers of cellulosic origin, the fiber which shows higher percentage (75%) is the best option than to the composition of 50%/50%. In the meantime, according to the results obtained in this study, in the case where the application should withstand bending loads, the better composition would be 50%/50%

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This research presents an approach to the addition of curauá fibers and licuri fibers in a polypropylene resin matrix, such as an alternative proposal to reinforce the polymeric composites. Fiber content of 0 %, 5 %, 10 %, and 20% were analyzed for verification of their mechanical properties comparing them, inclusive with the properties of polypropylene. The grainulated biocomposites had been prepared in an extrusora. The test bodies had been molded by injection and submitted to the mechanical essays uniaxial traction, flexion on three points, impact, in addition to thermal tests (HDT). These biocomposites had been also subjected the essay physicist-chemistry index of fluidity (IF). It was observed that the biocomposites of PP with 20% curauá, obtained bigger increase in the modulus of elasticity and a bigger reduction in the resistance to the impact. In the mechanical behavior, for all the biocomposites, these were increases in values of the limit of drainage and tension of rupture, when tested by uniaxial traction, as they added the fibers. Another important point was the increase of the resistance the flexion. It was also noted that the addition of fibers reduced the thermal degradation of the mixture natural fibers / polypropylene.

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Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

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Pós-graduação em Agronomia (Energia na Agricultura) - FCA

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Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)

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Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)

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Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)