Estudo da adição de resíduo de scheelita em matriz cerâmica: formulação, propriedades físicas e microestrutura

Extractivism mineral is considered an activity highly degrading, due to the large volume of material that he moves in the form of ore and residues. The vast majority of mining companies do not show any technology or economically viable application that will allow the recycling of mineral residue, these being launched in areas receiving located the "open skies" degrade the environment. In Rio Grande do Norte to the production of ceramic red restricts their activities to the production of products such as: solid bricks, ceramic blocks, tiles, among others. Seeking to unite experiences and technical information that favor sustainable development, with important benefits to the construction sector and civil society in general, the present work studies the incorporation of the residue of scheelite in ceramic matrix kaolinitic, coming from the municipality of Boa Saúde - RN, in percentage of 5 %, 10 %, 20 %, 30% 40% and 50 %, by evaluating its microstructure, physical properties and formulation. The raw materials were characterized through the trials of X ray fluorescence, Diffraction of X rays, Differential Thermal Analysis and Termogravimetric Analysis. The samples were formed and fired at temperatures of 850o, 900o, 1000o, 1050o, 1100o, 1150o and 1200 oC, with isotherm of 1 hour and heating rate of 10 oC/min. Assays were performed technological of loss to fire, Water Absorption, Apparent Porosity, Apparent Density, Mass Loss in Fire and Bending Resistance; in addition to the Scanning Electron Microscopy, analyzing their physical and mechanical properties. The use of residue of scheelite in ceramic mass kaolinitic provided a final product with technological properties that meet the technical standards for the production of bricks and roofing tiles, with the percentage of 20% of waste that showed the best results

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 rejeitos cerâmicos nas propriedades de cerâmica vermelha da região do Recôncavo Baiano

The study of the physical and mechanic properties is an analysis of unquestioned importance on the production of the ceramic materials. In the region of the Recôncavo Baiano, there are ceramic and small brick factories, that still use rudimentary techniques, where the necessity of characterization of raw materials is denounced by the quality of the final product. The present work has for objective to study the behavior of the clay proceeding from the region of the Recôncavo, between the cities of Candeias and Camaçari/Ba, with addition of 5, 10 and 15% by weight of brick scraps, trying to optimize the physic and mechanical properties of the final product, aiming a better possibility of being manufactured, mechanic resistance, low linear retraction and water absorption. The brick scraps and the clay were characterized by FRX, DRX, TG, ATD and the granulometric analysis. Samples for testing where prepared by uniaxial pressing at 25Mpa, in 60x20x5mm size. The evaluated technological properties were: linear retraction, water absorption, apparent porosity and flexural strength. The samples were burned in electric oven in the temperatures of 850º, 950º and 1050ºC and compared its mechanical properties and the gresification. With addition of 15% by weight of brick scraps and burning at 900º-1000ºC the samples showed properties superior to that clay

Anodização para obtenção de membranas cerâmicas

This a study on the achievement of alumina membranes by the method of anodizing. From this method got up a layer of aluminum oxide on the anodic metal, who presented the basic properties necessary for the application as a support for the production and acquisition of nanomaterials, such as porosity nano and resistance to high temperature, and other properties, as resistance to corrosion, and chemical, high ranking of the structure and pore size of the pores. The latter, ranging from 10 to 100nm depended on the electrolyte used, which in this study was the H2SO4. To remove all remaining aluminum, it is a bath of dissolution with HCl and CuCl where the residual aluminum has been withdrawn, and the deep pores were opened after chemical treatment with NaOH. After the dissolution, the membranes were calcined at temperatures of 300, 600 and 900° C, and sintered at temperatures of 1200 and 1300º C to win mechanical strength, porosity and observe the desired crystallization. Then went through analyses of composition through X-ray diffraction and morphology of the microstructure through a scanning electron microscope. The method was effective for obtaining alumine membranes applied in the processes of production of materials in nano

Caracterização de cerâmicas porosas de alumina reforçada com zircônia produzidas pelo método da réplica

Porous ceramics have many applications: thermal insulation, catalytic support, materials to fire protection, filters, and others. There are many techniques to production of ceramic filters. One technique to obtain ceramic filters is the replication method. This method consists in the impregnation of polymeric foam with ceramic slurry followed by a heating treatment that will burn out the organic elements and sintering of the material, resulting of a replication of the original foam. To perform their functions ceramic filters must satisfy mechanical requirements and permeability parameters (darcian k1 and no-darcian k2). The permeability and the strength of the ceramic material are dependent of the pore size and pore distribution. To the use at high temperatures the evaluation of mechanical properties in these temperatures is necessary. In this work the mechanical behavior of two commercial porous ceramics (10 and 40 poros per inch) was studied these materials were submitted to compression and four-point flexure test (room temperature, at 1000 °C, after thermal shock). Density and porosity measurements, permeability tests and microstructural analysis by scanning electronic microscopy (SEM) were realized. The Results showed that the decrease of mechanical strength of these materials, when submitted to thermal shock, occur for propagation of new cracks from cracks pre-existing and the permeability depends of the pore size

A influência da adição de caulim, quartzo e feldspato potássico na formulação de massas cerâmicas para telhas: Modelo estatístico

The production of roof tiles in the state of Rio Grande do Norte accounts for around 60% of the total of ceramic pieces produced. There is a need for investment to improve quality and productivity, thereby promoting technological innovations. Accordingly, the aim of this study is to determine the effect of kaolin, potassium feldspar and quartz in two standard formulations, as well as the effect of sintering temperature on the technological properties of linear firing shrinkage, water absorption and bending rupture stress, by fitting the statistical model and using multiple linear regression to assess the relationship between technological properties and independent variables. The raw materials were characterized using the following techniques: X-ray fluorescence (XRF), X-ray diffraction (XRF), rational analysis (RA), differential thermal analysis (DTA) and granulometric analysis (GA). The test specimens were compacted by uniaxial pressure (25 MPa), dried in a stove at 110 ºC for 24 hours and sinterized at 850 ºC, 950 ºC and 1050 ºC and held isothermal for 30 minutes. The results obtained indicate that the addition of kaolin to two standard formulations (M and R) promoted a reduction in water absorption values and an increase in bending rupture stress values. The sintering temperatures for group M that resulted in the lowest linear firing shrinkage and water absorption values were 850 ºC and 950 ºC, respectively, and the highest bending rupture stress values were reached at a temperature of 950 ºC. In the case of group R, the sintering temperature that obtained the lowest water absorption and linear firing shrinkage values was 850 ºC, and the highest bending rupture stress values were attained at a temperature of 1050 ºC. This work explains the statistical approach used to fit the model that describes the relationship between the technological properties and percentage of kaolin, quartz and feldspar, as well as the models that enable predictions, provided that the lower and upper limits of the percentage of clay minerals, flux and quartz used in this study are respected. Statistica 6 software was used and results were obtained by stepwise forward regression

Estudo da formulação de massas cerâmicas provenientes da região do Seridó-RN para fabricação de telhas

This work has for objective study compared the characteristics and technological properties of ceramic bodies from the region of Seridó-RN. The region under study has identified 23 cities where they were 80 ceramics industries. To define the universe of search, there was a survey of pottery that are part of APL Seridó next to the IEL. The characteristics and operating conditions of ceramics industries of the region were identified through a socio-economic questionnaire applied locally, which addressed issues such as: profiles of companies, production process etc. The analysis of information collected from 24 companies identified in seven cities shows that the vast majority of industries is small, with family structure, obsolete equipment and labo, little qualified. Most of the pottery works with low technical knowledge, poor control of the production process and product technology. The raw collected were submitted to analysis of X ray diffraction, chemical composition, termical analysis, particle size distribution and plasticity. Then were produced five formulations and made by uniaxial pressure at 25 MPa for firing in temperatures varying from 850 to 1050 °C. The firing technological properties evaluated were: mass loss to fire, lineal shrinkage, apparent density, apparent porosity, water absorption and flexural strength (3 points). The results indicated that the raw materials from the region have significant similarities in the composition chemical and mineralogical. Furthermore, it indicates the possibility of the use of cycles of firing faster and efficient than the current, limited to some clay mass burning of certain conditions

Caracterização de matérias-primas regionais e desenvolvimento de formulações de massas cerâmicas para porcelanato

Initially concentrated in some poles at the South and Southeast regions of Brazil, the ceramic tiles industry became wide during the 80 s decade, with a disconcentration industrial and regional pulverization. The competitiveness in the ceramic tiles internal and external consumers markets, it has debtor the industries to invest in sophisticated products each time more, either in design or the technology, but, mainly, in its final properties. Amongst the diverse types of ceramic coating, the porcelanato if has detached had to its process of technological production and excellent characteristics techniques. The Porcelanato is currently the material for coatings that presents the best technical and aesthetic features when compared with others ceramics found on the market. The chemical composition and the others raw materials characteristics have an importance that must to be ally to the inherent characteristics of fabrication process, essentially those related to the cycle of burning. This work had as purpose to develop formularizations of ceramic mass for production of porcelanato without glass coating, pertaining to the group BIa (text of absorption of water ≤ 0.5%) and with resistance superior mechanics 35MPa from raw materials characterized. The ceramic raw materials selected to the development of this study (A1 and A2 clays, feldspate, talc and quartz) were submitted to the following tests: X-ray fluorescence - chemical analysis determination; X-ray diffraction - Analysis of the stages mineralogics; Laser granulometry - size distribution of particles; and Differential thermal analysis - thermal behavior. Were performed tests of absorption of water, lineal retraction of it burns, apparent specific mass and rupture tension the flexing. The results had evidenced that the formularizations that had the A1 clay and talc on its composition were efficient for the porcelanato production remaining their technological characteristics inside of the intervals of variation desired by the Norms of the ABNT

Análise do comportamento mecânico de espumas cerâmicas a base de alumina obtidas pelo método da réplica

Ceramics with porous cellular structure, called ceramic foams, have a potential use in several applications, such as: thermal insulation, catalyst supports, filters, and others. Among these techniques to obtain porous ceramics the replication method is an important process. This method consists of impregnation of a sponge (usually polymer) with ceramic slurry, followed by a heat treatment, which will happen the decomposition of organic material and sintering the ceramic material, resulting in a ceramic structure which is a replica of impregnated sponge. Knowledge of the mechanical properties of these ceramics is important for these materials can be used commercially. Gibson and Ashby developed a mathematical model to describe the mechanical behavior of cellular solids. This model wasn´t for describing the ceramics behavior produced by the replica method, because it doesn´t consider the defects from this type of processing. In this study were researched mechanical behavior of porous alumina ceramics obtained by the replica method and proposed modifications to the model of Gibson and Ashby to accommodate this material. The polymer sponge used in processing was characterized by thermogravimetric analysis and scanning electron microscopy. The materials obtained after sintering were characterized by mechanical strength tests on 4-point bending and compression, density and porosity and by scanning electron microscopy. From these results it was evaluated the mechanical strength behavior compared to Gibson and Ashby model for solid cellular structure and was proposed a correction of this model through a factor related to struts integrity degree, which consider fissures present in the structure of these materials besides defects geometry within the struts

Incorporação de cinzas da casca de café na produção de placas cerâmicas para revestimento

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

Análise comparativa entre propriedades mecânicas, termofísicas e geométricas de tijolos produzidos pelos fornos caieira e abóbada

In the State of Rio Grande do Norte potteries are distributed in several counties in the four meso, which are: West Potiguar, Center Potiguar, Agreste Potiguar and East Portiguar. The ceramics, mostly, are responsible for products used in construction as bricks, tiles and white brick and wood used as fuel. This paper had a primary focus in the region of Seridó. The furnaces in this region, used to manufacture bricks are configured Caieira and Valt, in most of them using principles rustic, usually operated in an empirical way, using principles of control rather primitive, predominantly visual control. The focus of this study was to analyze the differences in the thermophysical, mechanical and geometric characteristics of bricks produced by Caieira and vault furnaces, using the NBR 15720 and the evaluation of energy efficiency in both furnaces. Thermophysical characteristics were analyzed through tests to determine the water absorption obtained from the difference between dry mass and wet mass of the sample and analysis of the thermal gradient, the mechanical characteristics from determination of the compressive strength of ceramic brick popularly known as bricks and also analyzed the geometrical characteristics of the bricks in order to verify the homogeneity of manufacturing. The tests showed that the energy difference of the two furnaces is not considered responsible for a significant difference in the properties of the products

Estudo de formulação de massa para aplicação em placas cerâmicas

The sector of civil construction is strongly related to the red ceramic industry. This sector uses clay as raw material for manufacturing of various products such as ceramic plates. In this study, two types of clay called clay 1 and clay 2 were collected on deposit in Ielmo Marinho city (RN) and then characterized by thermogravimetric analysis (TG/DTG), differential thermal analysis (DTA), X-ray diffraction (XRD), X-ray fluorescence (XRF), rational analysis and particle size distribution and dilatometric analyses. Ceramic plates were manufactured by uniaxial pressing and by extrusion. The plates obtained by pressing were produced from the four formulations called 1, 2, 3 and 4, which presented, respectively, the following proportions by mass: 66.5% clay 1 and 33.5% clay 2, 50% clay 1 and 50% clay 2, 33.5% clay 1 and 66.5% clay 2, 25% clay 1 and 75% clay 2. After firing at 850, 950 and 1050 °C with heating rate of 10 °C/min and soaking time of 30 minutes, the following technological properties were determined: linear firing shrinkage, water absorption, apparent porosity, apparent specific mass and tensile strength (3 points). The formulation containing 25% clay 1 produced plates with most satisfactory results of water absorption and mechanical resistance, because of that it was chosen for manufacturing plates by extrusion. A single firing cycle was established for these plates, which took place as follow: heating rate of 2 °C/min up to 600 ºC with soaking time of 60 minutes, followed by heating using the same rate up to 1050 ºC with soaking time of 30 minutes. After this cycle, the same technological properties investigated in the plates obtained by pressing were determined. The results indicate (according to NRB 13818/1997) that the plates obtained by pressing from the mixture containing 25 wt% clay 1, after firing at 1050 °C, reach the specifications for semi-porous coating (BIIb). On the other hand, the plates obtained by extrusion were classified as semi-stoneware (group AIIa)

Estudo da viabilidade técnica do uso das argilas da região do agreste potiguar para produção de peças cerâmicas: caracterização e formulação

In recent decades, ceramic products have become indispensable to the technological development of humanity, occupying important positions in scientific production and consequently in industrial production. One area of the economy that continues to absorb large amounts of the products of this sector is Construction. Among the branches of the ceramic industry, there are the red ceramic industry which is traditionally the basis of that economic sector. Among the reasons for which the red ceramic industry became popular in the country, and specifically in Rio Grande do Norte, is the abundance of this raw material, easily found throughout the national territory. However, it appears that the red ceramic industry has deficiencies in technology and skilled labor, resulting in the production of ceramic goods with low added value. Among the factors that determine the quality of the ceramic products red has the proper formulation of the ceramic mass, the conformation and the firing temperature. Thus, the overall goal of this work is to study the mineralogical and technological properties, two clays from the region of the Wasteland Potiguar industrial ceramist. Therefore, the raw materials were characterized by analysis of Xray diffraction (XRD) analysis, X-ray fluorescence (XRF), particle size analysis (FA), scanning electron microscopy (SEM), optical microscopy (OM ), plasticity index (PI), thermal gravimetric analysis (TGA) and differential thermal analysis (DTA). The technological properties of the material were analyzed by water absorption tests (AA%) porosity (% PA), the linear shrinkage (RT%), apparent density (MEA), loss on ignition (PF%) and flexural strength three points (TRF)