Estudo da viabilidade do processo de reciclagem do material descartado do sistema Zirkonzanh® de produção de próteses dentárias

At present, the material of choice for performing aesthetic dental prosthetic work is in the ceramic. Among them, the ceramic base of stabilized zirconia with 3% yttria (3Y - TZP) stand out for having excellent physical and mechanical properties. During the machining of blocks of zirconia in the laboratory to prepare the various types of prostheses, much of the material is given off in the form of powder, which is subsequently discarded. The waste of this material results in financial loss, reflecting higher final cost treatment for patients, as well as damage to the environment, thanks to the processes involved in the manufacture and disposal of the ceramic. This research, pioneered the recycling of zirconium oxide powder obtained during milling of dental crowns and bridges, we highlight the social and environmental aspects and aims to establish a protocol for the reuse of waste (powder of zirconia Zirkonzahn® system) discarded to obtain a new block of compacted zirconia to maintain the same mechanical and microstructural properties of commercial high-cost imported material. To compare with the commercial material, samples were uniaxially (20 MPa) and isostatically (100 MPa), and its mechanical and microstructural characterization was performed through tests of density, porosity, dilatometry, X-ray diffraction (XRD), hardness, fracture toughness, resistance to fracture electron microscopy (SEM) and analysis of grain size. The results observed in the samples were isostatically pressed similiares those obtained with samples from the commercial material demonstrating the viability of the process

Efeito da velocidade de aquecimento nas propriedades de produtos da cerâmica estrutural

Heating rate is one of the main variables that determine a fire cycle. In industrial processes that use high temperatures, greater fire great can reduce the cost of production and increase productivity. The use of faster and more efficient fire cycles has been little investigated by the structural ceramic industry in Brazil. However, one of the possibilities that aims at modernizing the sector is the use of roller kilns and the inclusion of natural gas as fuel. Thus, the purpose of this study is to investigate the effect of heating rate on the technological properties of structural ceramic products. Clay raw materials from the main ceramic industries in the state of Rio Grande do Norte were characterized. Some of the raw materials characterized were formulated to obtain the best physical and mechanical properties. Next, raw materials and formulations were selected to study the influence of heating rate on the final properties of the ceramic materials. The samples were shaped by pressing and extrusion and submitted to rates of 1 °C/min, 10 °C/min and 20 °C/min, with final temperatures of 850 °C, 950 °C and 1050 °C. Discontinuous cycles with rates of 10 °C/min or 15 °C/min up to 600 °C and a rate of 20 °C/min up to final temperature were also investigated. Technological properties were determined for all the samples and microstructural analysis was carried out under a number of fire conditions. Results indicate that faster and more efficient fire cycles than those currently in practice could be used, limiting only some clay doughs to certain fire conditions. The best results were obtained for the samples submitted to slow cycles up to 600 °C and fast fire sinterization up to 950 °C. This paper presents for the first time the use of a fast fire rate for raw materials and clay formulations and seeks to determine ideal dough and processing conditions for using shorter fire times, thus enabling the use of roller kilns and natural gas in structural ceramic industries

Alternativas de ultimação de resíduo plástico termofixo

In the present work it was developed originals alternatives of enveronmentally safe and economically viable destination of thermoset plastic residue from a button factory, which at presnte stores such residue tempor and in a way that is inconvenient to the atmosphere, a waiting safe solutions. As the residue is not recycleab and its burning leberates strongly aggressive gases, safe alternatives were researched. Inicially, ghe residue in incineration was performed in cement ovens with precise control ofe emission of gases, but it was proved inviable due to its low calorific power, as well as the liberation of free lead in the ashes. An original and feasible option was the residue confinemente in soil-ciment blocks, lohich resulted in blocks highly resistant to simple compression with structural block, and also a significant increase in thermal resistence. Was got up other options of original and important composites as: making of blocks for pré-moulded flagstone, internal coating of walls with plaster being obtained good texture results, replenish of ceramic blocks and blocks with cement, also implying in increase of thermal resistance. Besides these original and scientific contributions, the it was technologically contribution of defreadation with suggestions of the material using torch of thermal plasm; for this was projected, built, characterized and tested a torch to it shapes it being obtained exciting results for the development of this technology come back for ending destruction from all the types of inconvenient garbage to the atmosphere

Aplicação da metodologia de planejamento de experimentos para formulação de massas cerâmicas para telhas

Rio Grande do Norte State stands out as one great producer of structural clay of the brazilian northeastern. The Valley Assu ceramic tiles production stands out obtained from ilitics ball clays that abound in the region under study. Ceramics formulation and the design of experiments with mixture approach, has been applied for researchers, come as an important aid to decrease the number of experiments necessary to the optimization. In this context, the objective of this work is to evaluate the effects of the formulation, temperature and heating rate in the physical-mechanical properties of the red ceramic body used for roofing tile fabrication of the Valley Assu, using design of mixture experiments. Four clays samples used in two ceramics industry of the region were use as raw material and characterized by X-ray diffraction, chemical composition, differential thermal analysis (DTA), thermogravimetric analysis (TGA), particle size distribution analysis and plasticity techniques. Afterwards, they were defined initial molded bodies and made specimens were then prepared by uniaxial pressing at 25 MPa before firing at 850, 950 and 1050 ºC in a laboratory furnace, with heating rate in the proportions of 5, 10 e 15 ºC/min. The following tecnologicals properties were evaluated: linear firing shrinkage, water absorption and flexural strength. Results show that the temperature 1050 ºC and heating rate of 5 ºC/min was the best condition, therefore presented significance in all physical-mechanical properties. The model was accepted as valid based of the production of three new formulations with fractions mass diferents of the initial molded bodies and heated with temperature at 1050 ºC and heating rate of 5 ºC/min. Considering the formulation, temperature and heating rate as variables of the equations, another model was suggested, where from the aplication of design of experiments with mixtures was possible to get a best formulation, whose experimental error is the minor in relation to the too much formulations

Estudo de Matérias-Primas do Rio Grande do Norte para Uso em Revestimento Poroso: Influência do teor de dolomita e temperatura de calcinação nas propriedades físico-mecânicas

The state of Rio Grande do Norte presents a great potentiality for the production of ceramic tiles because of having natural raw material in quantity and quality making its economical exploration possible, beyond the great energetic differential of the state, the natural gás. This works aims to study the influence of the dolomite and granulometry concentration and calcinations temperature in the obtaining of formulations for porous coverings which have to be coherent to the project,s specifications. The experiments have involved the physical-chemical and mineralogical characterizations of raw materials and mechanical tests in the dry and burnt proof bodies preceding a mixture experiment planning with the use of the response surface methodology, in order to get the best raw materials combinations to produce a ceramic mass with specific properties. The twelve ceramic masses studied in this work were prepared by the via dry process, characterized, shaped by uniaxial pressing and sinterized in the temperatures of 940ºC, 1000ºC, 1060ºC, 1120ºC and 1180ºC, using a fast burning cycle. The crystalline phases formed during the sintering in the temperatures in study have revealed the presence of anorthite and diopside beyond quartz with a remaining phase. These phases were the main responsible ones by the physical- mechanical properties of the sinterized proof bodies. The proof bodies after the sintering stage have presented water absorption higher than 10% and a good dimensional stability in all studied temperatures. However, the flexural breaking strength results in the temperatures of 940ºC, 1000ºC and 1060ºC, under the temperature zone of the vitrification of ceramic whiteware do not reach the flexural breaking strength specific for the porous wall tile (15 MPa), but in the temperature of 1120ºC next to the vitrification temperature zone, some whiteware ceramic (formulations) has reached the specified value for the porous wall tile. The results of this work have showed that the studied raw materials have great importance for used in the production of porous wall tiles (BIII)

Sinterização de matrizes cerâmicas à base de alumina reforçadas por carbetos a partir de precursores poliméricos

Ceramic composites produced with polymerics precursors have been studied for many years, due to the facility of obtaining a complex shape, at low temperature and reduces cost. The main objective of this work is to study the process of sintering of composites of ceramic base consisting of Al2O3 and silicates, reinforced for NbC, through the technique of processing AFCOP, as well as the influence of the addition of LZSA, ICZ and Al as materials infiltration in the physical and mechanical properties of the ceramic composite. Were produced ceramic matrix composites based SiCxOy e Al2O3 reinforced with NbC, by hidrosilylation reaction between D4Vi and D1107 mixtured with Al2O3 as inert filler, Nb and Al as reactive filler. The specimens produced were pyrolised at 1200, 1250 and 1400°C and infiltred with Al, ICZ and LZSA, respectively. Density, porosity, flexural mechanical strength and fracture surface by scanning electron microscopy were evaluated. The microstructure of the composites was investigated by X-ray diffraction to identify the presence of crystalline phases. The composites presented apparent porosity varying of 31 up to 49% and mechanical flexural strength of 14 up to 34 MPa. The infiltration process improviment of the densification and reduction of the porosity, as well as increased the values of mechanical flexural strength. The obtained phases had been identified as being Al3Nb, NbSi2, Nb5S3, Nb3Si and NbC. The samples that were submitted the infiltration process presented a layer next surface with reduced pores number in relation to the total volume

Influência da adição de gres porcelanato no comportamento mecânico e microestrutural em pastas de cimento portland para cimentação de poços de petróleo

Cementation operation consists in an extremely important work for the phases of perforation and completion of oil wells, causing a great impact on the well productivity. Several problems can occur with the cement during the primary cementation, as well as throughout the productive period. The corrective operations are frequent, but they are expensive and demands production time. Besides the direct cost, prejudices from the interruption of oil and gas production till the implementation of a corrective operation must be also taken into account. The purpose of this work is the development of an alternative cement paste constituted of Portland cement and porcelainized stoneware residue produced by ceramic industry in order to achieve characteristics as low permeability, high tenacity, and high mechanical resistance, capable of supporting various operations as production or oil wells recuperation. Four different concentration measures of hydrated paste were evaluated: a reference paste, and three additional ones with ceramic residue in concentrations of the order of 10%, 20% and 30% in relation to cement dough. High resistance and low permeability were found in high concentration of residues, as well as it was proved the pozolanic reactivity of the residue in relation to Portland cement, which was characterized through x-ray and thermogravimetry assays. It was evident the decrease of calcium hydroxide content, once it was substituted by formation of new hydrated products as it was added ceramic residue

Protótipo de um microgerador termoelétrico de estado sólido: cogeração a gás

The thermoelectric energy conversion can be performed directly on generators without moving parts, using the principle of SEEBECK effect, obtained in junctions of drivers' thermocouples and most recently in semiconductor junctions type p-n which have increased efficiency of conversion. When termogenerators are exposed to the temperature difference (thermal gradient) eletromotriz a force is generated inducing the appearance of an electric current in the circuit. Thus, it is possible to convert the heat of combustion of a gas through a burner in power, being a thermoelectric generator. The development of infrared burners, using porous ceramic plate, is possible to improve the efficiency of heating, and reduce harmful emissions such as CO, CO2, NOx, etc.. In recent years the meliorate of thermoelectric modules semiconductor (TEG's) has stimulated the development of devices generating and recovery of thermal irreversibility of thermal machines and processes, improving energy efficiency and exergy these systems, especially processes that enable the cogeneration of energy. This work is based on the construction and evaluation of a prototype in a pilot scale, for energy generation to specific applications. The unit uses a fuel gas (LPG) as a primary energy source. The prototype consists of a porous plate burner infrared, an adapter to the module generator, a set of semiconductor modules purchased from Hi-Z Inc. and a heat exchanger to be used as cold source. The prototype was mounted on a test bench, using a system of acquisition of temperature, a system of application of load and instrumentation to assess its functioning and performance. The prototype had an efficiency of chemical conversion of 0.31% for electrical and heat recovery for cogeneration of about 33.2%, resulting in an overall efficiency of 33.51%. The efficiency of energy exergy next shows that the use of primary energy to useful fuel was satisfactory, although the proposed mechanism has also has a low performance due to underuse of the area heated by the small number of modules, as well as a thermal gradient below the ideal informed by the manufacturer, and other factors. The test methodology adopted proved to be suitable for evaluating the prototype

Análise do desempenho de um queimador infravermelho funcionando com gás liquefeito de petróleo e glicerina

The use of infrared burners in industrial applications has many advantages in terms of technical-operational, for example, uniformity in the heat supply in the form of radiation and convection, with greater control of emissions due to the passage of exhaust gases through a macro-porous ceramic bed. This paper presents an infrared burner commercial, which was adapted an experimental ejector, capable of promoting a mixture of liquefied petroleum gas (LPG) and glycerin. By varying the percentage of dual-fuel, it was evaluated the performance of the infrared burner by performing an energy balance and atmospheric emissions. It was introduced a temperature controller with thermocouple modulating two-stage (low heat / high heat), using solenoid valves for each fuel. The infrared burner has been tested and tests by varying the amount of glycerin inserted by a gravity feed system. The method of thermodynamic analysis to estimate the load was used an aluminum plate located at the exit of combustion gases and the distribution of temperatures measured by a data acquisition system which recorded real-time measurements of the thermocouples attached. The burner had a stable combustion at levels of 15, 20 and 25% of adding glycerin in mass ratio of LPG gas, increasing the supply of heat to the plate. According to data obtained showed that there was an improvement in the efficiency of the 1st Law of infrared burner with increasing addition of glycerin. The emission levels of greenhouse gases produced by combustion (CO, NOx, SO2 and HC) met the environmental limits set by resolution No. 382/2006 of CONAMA

Incorporação de resíduo cerâmico para prevenção da retrogressão da resistência de cimentos de poços de petróleo submetidos à injeção de vapor

Steam injection is the most used thermal recovery method of oil nowadays because of the high degree of development of the technique that allows high recovery factors. However, injection of superheated steam into the reservoir affects the entire structure of the well, including the cemented layer that presents a retrogression of compressive strength and increases the permeability due to formation of more crystalline and denser phases at temperatures above 110 °C. These changes result in failures in the cement that favor the entrance of formation fluids into the annulus space resulting in unsafe operations and restrictions in the economic life of the well. But the strength retrogression can be prevented by partial replacement of cement by silica-based materials that reduce the CaO/SiO2 ratio of cement slurries changing the trajectory of the reactions, converting those deleterious phases in phases with satisfactory mechanical strength and permeability. The aim of this study was to evaluate the behavior of a ceramic waste material rich in silica in partial and total substitution of a mineral additive used to fight the strength retrogression of cement slurries subjected to high temperatures. The evaluation was made by compression, X-ray diffraction (XRD) and thermogravimetry (TG/DTG). The samples were submitted to a cycle of low temperature (38 °C) for 28 days and a cycle of low temperature followed by exposure to 280 ºC and 1000 psi by 3 days. The results showed that slurries with additions of up to 30% of the waste material are not enough to prevent the strength retrogression, while slurries with additions of the waste material combined with silica flour in various proportions produced hydrated products of low Ca/Si ratios that maintained the compressive strength at satisfactory levels

Análise de um queimador infravermelho funcionando com combustível híbrido : GLP/Bio-óleo

Biomass is considered the largest renewable energy source that can be used in an environmentally sustainable. From the pyrolysis of biomass is possible to obtain products with higher energy density and better use properties. The liquid resultant of this process is traditionally called bio-oil. The use of infrared burners in industrial applications has many advantages in terms of technical-operational, for example, uniformity in the heat supply in the form of radiation and convection, with a greater control of emissions due to the passage of exhaust gases through a macroporous ceramic bed. This paper presents a commercial infrared burner adapted with an ejector proposed able to burn a hybrid configuration of liquefied petroleum gas (LPG) and bio-oil diluted. The dilution of bio-oil with absolute ethanol aimed to decrease the viscosity of the fluid, and improving the stability and atomization. It was introduced a temperature controller with thermocouple modulating two stages (low heat / high heat), and solenoid valves for fuels supply. The infrared burner has been tested, being the diluted bio-oil atomized, and evaluated its performance by conducting energy balance. The method of thermodynamic analysis to estimate the load was used an aluminum plate located at the exit of combustion gases and the distribution of temperatures measured by thermocouples. The dilution reduced the viscosity of the bio-oil in 75.4% and increased by 11% the lower heating value (LHV) of the same, providing a stable combustion to the burner through the atomizing with compressed air and burns combined with LPG. Injecting the hybrid fuel there was increase in the heat transfer from the plate to the environment in 21.6% and gain useful benefit of 26.7%, due to the improved in the efficiency of the 1st Law of Thermodynamics of infrared burner

Evolução diagenética e caracterização dos reservatórios da seção devoniana na Bacia do Rio do Peixe-Nordeste do Brasil

The Rio do Peixe Basin represents a main basin of northeastern Brazil and pioneering work positioned the rocks of this basin in the Early Cretaceous. However, a recent study, based on integrated pollen analysis from three wells, found an unprecedented siliciclastic sedimentary section, in the region, of early Devonian age. Therefore, the present study aims a detailed petrographic and petrological analysis of this devonian section, in the Rio do Peixe Basin and proposes a diagenetic evolution, to understand the characteristics of the porous system, identify the main reservoir petrofacies with the main factors impacting on the quality of these rocks as reservoirs and a quick study on the provenance of this section. The petrographic study was based on samples obtained from subsurface and surface. The diagenetic evolution of petrofacies and its identification were based only on subsurface samples and the study of provenance was based on surface samples. The thin sections were prepared from sandstones, pelites and sandstones intercalated with pelites. The original detrital composition for this section is arcosean and the main diagenetic processes that affected these rocks occur in various depths and different conditions, which resulted in extensive diagenetic variety. The following processes were identified: early fracture and healing of grains; albitization of K-feldspar and plagioclase; siderite; precipitation of silica and feldspar; mechanical infiltration of clay and its transformation to illite/esmectite and illite; autigenesis of analcime; dissolution; autigenesis of chlorite; dolomite/ferrous dolomite/anquerite; apatite; calcite; pyrite; titanium minerals and iron oxide-hidroxide. The occurrence of a recently discovered volcanism, in the Rio do Peixe Basin, may have influenced the diagenetic evolution of this section. Three diagenetic stages affected the Devonian section: eo, meso and telodiagenesis. This section is compositionally quite feldspathic, indicating provenance from continental blocks, between transitional continental and uplift of the basement. From this study, we observed a wide heterogeneity in the role of the studied sandstones as reservoirs. Seven petrofacies were identified, taking into account the main diagenetic constituent responsible for the reduction of porosity. It is possible that the loss of original porosity was influenced by intense diagenesis in these rocks, where the main constituent for the loss of porosity are clays minerals, oxides and carbonate cement (calcite and dolomite)

Estudo do perfil térmico de fornos do tipo "caipira" utilizados pelo setor de cerâmica vermelha em parelhas na região Seridó-RN

The present study aimed to characterize the thermal profile of wood fired oven used by the red ceramic industry in Parelhas, in the Seridó region/RN, aiming to propose structural interventions that can contribute to increasing productivity and product quality, optimize wood consumption and mitigate existing losses during the burning process. The study was conducted at Cerâmica Esperança in the city of Parelhas -RN, Brazil, during the period from August 2012 to September 2013. Four treatments were performed with three replicates, ie, with, a total of 12 experimental units (burnings). In the first stage 4 treatments were performed with three replicates, totaling 12 experimental units (firings). In the second stage 2 treatments were performed with three replications, totaling 6 experimental units (firings). The physical characteristics of the wood were analyzed using standard NBR 11941 and NBR 7190 for basic density and moisture, respectively. The clay was used as a reference parameter for distinguishing treatments. For both the analysis and characterization was carried out using techniques of fluorescence X (XRF) rays, X-ray diffraction (XRD) analysis, particle size analysis (FA). In the first and second stages were monitored: the time during the firing process, the amount of wood used at each firing, the number of parts enfornadas for subsequent determination of the percentages of losses, but also product quality. To characterize the thermal profile of the oven, we measured the temperature at 15 points scored in the surface charge put into the oven. Measurements were taken every 30 minutes from preheat until the end of burning, using a pyrometer laser sight sighting from preheating until the end of burning. In the second step 12 metal cylinders distributed on the oven walls, and the cylinder end walls 8 of the furnace 2 and rollers on each side walls are installed equidistant to 17 cm from the soil and the surface 30 of the wall are installed. The cylinders distributed on the front were placed 50 cm above the furnace, and the base of the oven 20 cm distant from the ground. 10 also thermocouples were installed, and five thermocouples distributed 1.77 cm above the combustion chambers, and one thermocouple on each side, and three thermocouples in front of the oven. We carried out the measurements of the temperatures every 1 hour during the burning two hours in cooling the cylinders with a pyrometer and thermocouples for dattaloger. These were fixed with depth of 30 cm from the wall. After statistical analysis it was found that: the thermal profile of the furnace surface and at different heights was heterogeneous; and the ranges of density and moisture content of wood are within recommended for use as an energy source standards. We conclude that even at low temperatures reached during firing there was a significant production of good quality products, this is due to high concentrations of iron oxide and potassium oxide found in clay, which lowers the melting point of the piece. The average burn time for each step varied 650-2100 minutes wood consumption was on average 20 m3, product quality was on average 16% of first quality, 70% second, third and 5% to 10% loss . The distance between the wire and the surface of the oven was a significant parameter for all treatments, but with different variations, meaning that the wire should not be so generic and unique form, used as a criterion for completion of the burn process. The central part of the furnace was the area that reached higher temperature, and in a unified manner, with the highest concentration of top quality products. The ideal temperature curve, which provided the highest quality of ceramic products was achieved in the central part of the furnace

Desenvolvimento, pobreza e meio ambiente no seridó potiguar: um estudo centrado nas micro-regiões do seridó oriental e ocidental

This research work intends to carry out a study focused on the dynamic between development, poverty reduction and conservation of natural resources. To consider this relationship to the region chosen was the micro-region of Eastern and Western Seridó in the state of Rio Grande do Norte. In recent years, several studies (Araújo, 2011; BASTOS, 2009) have pointed out that after a period of economic crisis in its tripodproductive, formed by the activities of farming, cotton farming, mining and faced in the eighties, this region of the State of Rio Grande do Norte, has not only shown signs of economic recovery but also improve their social indicators. On the other hand, studies of desertification as the view of the state of RN (produced in cooperation between the Government of RN and research institutions) and the Sustainable Development Plan of Seridó (ADES, 2000), indicate that there is an ongoing French process of degradation of natural resources that is capable of compromising the ability of sustaining such a system. To verify this reality and likely finding this relationship, this work is adopted for this study, the analysis of evolution of secondary data from official bodies such as the IBGE on HDI, per capita income and other social indicators between 2000 and 2009. Here is another time of the survey analysis of qualitative data collected from interviews with institutions of academic intervention in nature, researchers at the Federal University of Rio Grande do Norte (UFRN) State agencies that address the issue of the Middle Environment in Seridó: Institute for Sustainable Development of the NB (IDEMA) and the Brazilian Institute of Environment and the Amazon (IBAMA) and institutions of direct intervention in the region, as the Agency's Sustainable Development Seridó (adhesive) and the Joint Semi-Arid (ASA). After crossing data from quantitative and qualitative, it was found that the dynamics of the region's economic Seridó Potiguar partially answers the improvement of social indicators of poverty. Contribution by the State in this shared stock transfer income. Regarding the influence of productive restructuring in the region on issues of environment, it is noted that the ceramic tile industry, responsible for the absorption percentage of the population with limited ingress into the urban economy, given the low education, accounts for the increase of susceptibility to the ongoing process of desertification in North Seridó Rio Grande. We conclude finally that the guarantee of increased income, freedom and conservation of natural resources ensures primarily by changing the beliefs and values, especially on the part of the business sector, which use natural resources so predatory, aimed at maintaining their rates of return on investment. And concomitantly, the synchronization between technological change, through the use of new energy sources, and institutional change.

Desenvolvimento (in) sustentável das indústrias cerâmicas da microrregião do Vale-do-Açu/RN

A great discussion of this work refers to development that is related to the common census of economic growth, in addition, another component of this discussion is related to socio-cultural and environmental impacts of this conception of progress. Giving economic progress is not necessary, since the development in its fullness, that progress depends, but what is sought is a harmony between capital accumulation and environmental limits and social interactions between men and between them and nature. The presence or absence of this harmonious relationship can be observed in various industrial activities, more punctual can cite the example of the developed ceramic activity in the meso-Valley-Acu in Rio Grande do Norte where such activity has great economic representativeness for the region, but that does not have good relations with social and environmental issues and is more focused on the accumulation of capital by increasing its level of industrial activity. Given this debate, the present paper aims to present the profile of a ceramic tile Valley-of-Acu and impacts, ecosocioambientais generated as a result of this activity as well. Methodologically the research will be conducted through literature research papers in books and other work carried out on the same theme, the second time will be held the empirical part of the research through interviews with managers of industries (selected through sample with the criteria set later ) as well as with employees working on the factory floor and city managers in the region under analysis and other agencies responsible for regulation and control of activity potter in the state