Efeito da adição de WC e Co na sinterização e propriedades mecânicas da alumina

Composites based on alumina (Al2O3), tungsten carbide (WC) and cobalt (Co) exhibit specific properties such as low density, high oxidation resistance, high melting point and high chemical inertia. That composite shows to be a promising material for application in various fields of engineering. In this work, the mechanical properties of the composite (Al2O3 – WC – Co), particularly density and hardness, were evaluated according to the effects of the variables of powder processing parameters, green compact and sintered. Powder composites with the composition of 80 wt% Al2O3, 18 wt% WC and 2 wt% Co were processed by high energy ball milling in a planetary mill for 50 hours as well as mixed by manual mixing in a glass vessel with the same proportion. Samples were collected (2, 10, 20, 30, 40 and 50 hours) during the milling process. Then, the powders were compacted in a cylindrical die with 5 mm in diameter in a uniaxial press with pressures of 200 and 400 MPa. The sintering was in two stages: first, the solid phase sintering was performed at 1126 and 1300 °C for 1 hour with a heating rate of 10 °C/min in a resistive furnace under argon atmosphere for green samples compacted in 200 and 400 MPa; the second sintering was performed on dilatometer in solid phase at 1300 °C for green sample compacted in 200 MPa, another sintering also was performed on dilatometer, this time in liquid phase at 1550 °C for green samples compacted in 200 and 400 MPa, with the same parameters used in resistive furnace. The raw materials were characterized by X – ray diffraction (XRD), X – ray fluorescence (XRF), scanning electron microscopy (SEM), energy dispersive spectroscopy (EDS) and laser particlemeter. The sintered samples were subjected to microhardness testing. The results showed that high energy milling achieved to the objectives regarding the particle size and the dispersion of composite phases. However, the hardness did not achieve to significant results, this is an indication that the composite has low fracture toughness.

Efeito da adição de WC e Co na sinterização e propriedades mecânicas da alumina

Composites based on alumina (Al2O3), tungsten carbide (WC) and cobalt (Co) exhibit specific properties such as low density, high oxidation resistance, high melting point and high chemical inertia. That composite shows to be a promising material for application in various fields of engineering. In this work, the mechanical properties of the composite (Al2O3 – WC – Co), particularly density and hardness, were evaluated according to the effects of the variables of powder processing parameters, green compact and sintered. Powder composites with the composition of 80 wt% Al2O3, 18 wt% WC and 2 wt% Co were processed by high energy ball milling in a planetary mill for 50 hours as well as mixed by manual mixing in a glass vessel with the same proportion. Samples were collected (2, 10, 20, 30, 40 and 50 hours) during the milling process. Then, the powders were compacted in a cylindrical die with 5 mm in diameter in a uniaxial press with pressures of 200 and 400 MPa. The sintering was in two stages: first, the solid phase sintering was performed at 1126 and 1300 °C for 1 hour with a heating rate of 10 °C/min in a resistive furnace under argon atmosphere for green samples compacted in 200 and 400 MPa; the second sintering was performed on dilatometer in solid phase at 1300 °C for green sample compacted in 200 MPa, another sintering also was performed on dilatometer, this time in liquid phase at 1550 °C for green samples compacted in 200 and 400 MPa, with the same parameters used in resistive furnace. The raw materials were characterized by X – ray diffraction (XRD), X – ray fluorescence (XRF), scanning electron microscopy (SEM), energy dispersive spectroscopy (EDS) and laser particlemeter. The sintered samples were subjected to microhardness testing. The results showed that high energy milling achieved to the objectives regarding the particle size and the dispersion of composite phases. However, the hardness did not achieve to significant results, this is an indication that the composite has low fracture toughness.

Estudo da incorporação de cinza e chamote gerado pela cerâmica vermelha ao próprio processo industrial

The ceramics industry generates waste at various stages of that process, defective products, waste from burning solid fuels, among others. This waste is dumped in landfills, garbage dumps or directly on roads, which has a negative environmental impact. This paper presents a study to incorporate the waste of algaroba wood and chamote (scrap pieces of ceramic already sintered), in to the ceramic material for making sealing blocks. The methodological procedures consist in the characterization of chemical and mineralogical residues, raw materials, and physical-mechanical of the formulations of mixes with clay, silt and waste. By pressing test pieces were produced using a pressure of 200 kgf/cm², varying compositions in the range of 0%, 5%, 10% and 15% by weight of residue. The sintering was performed in a muffle furnace, with the temperature levels of 850 ° C, 900 ° C, 950 ° C, 1000 ° C and 1050 ° C. The evaluated physical and mechanical properties were: Water Absorption, Linear Shrinkage Burning, Apparent Porosity, Apparent Density and Mechanical Resistance to Flexion. Analysis was carried out by Scanning Electron Microscopy on fracture surfaces of the specimens. Evaluation of linear shrinkage property drying and firing , water absorption and mechanical resistance to compression of the sealing blocks 5% wood ash residue, sintered at 900 °C hold temperature in the laboratory the products manufactured on an industrial scale. The main results, it was found on the viability of using the residues of algaroba wood and to confer refractory properties of the ceramic product. The main results, it was concluded feasibility of using the ash residues algaroba wood to impart refractory properties to the ceramic product and the residue of chamote, being derived from the own ceramic product not interfere with the properties, when used in a percentage of up to 5%.Since the residue of chamote being derived from the ceramic product itself had no effect on the properties. Studies in the laboratory have shown that the incorporation of up to 5% of these residues may be adopted as an alternative technology to reduce the environmental impact caused by the industrial sector, without compromising the final properties of the material, since the results on an industrial scale showed absorption values 11.66 and 11.74 of water and waste products respectively, within the parameters of NBR - 15,270, since the mechanical strength was 1.25 MPa and 0.94 MPa respectively for products with and without residue, lower than the minimum required by the technical standard that is 1.5 MPa.

Estudo da incorporação de cinza e chamote gerado pela cerâmica vermelha ao próprio processo industrial

The ceramics industry generates waste at various stages of that process, defective products, waste from burning solid fuels, among others. This waste is dumped in landfills, garbage dumps or directly on roads, which has a negative environmental impact. This paper presents a study to incorporate the waste of algaroba wood and chamote (scrap pieces of ceramic already sintered), in to the ceramic material for making sealing blocks. The methodological procedures consist in the characterization of chemical and mineralogical residues, raw materials, and physical-mechanical of the formulations of mixes with clay, silt and waste. By pressing test pieces were produced using a pressure of 200 kgf/cm², varying compositions in the range of 0%, 5%, 10% and 15% by weight of residue. The sintering was performed in a muffle furnace, with the temperature levels of 850 ° C, 900 ° C, 950 ° C, 1000 ° C and 1050 ° C. The evaluated physical and mechanical properties were: Water Absorption, Linear Shrinkage Burning, Apparent Porosity, Apparent Density and Mechanical Resistance to Flexion. Analysis was carried out by Scanning Electron Microscopy on fracture surfaces of the specimens. Evaluation of linear shrinkage property drying and firing , water absorption and mechanical resistance to compression of the sealing blocks 5% wood ash residue, sintered at 900 °C hold temperature in the laboratory the products manufactured on an industrial scale. The main results, it was found on the viability of using the residues of algaroba wood and to confer refractory properties of the ceramic product. The main results, it was concluded feasibility of using the ash residues algaroba wood to impart refractory properties to the ceramic product and the residue of chamote, being derived from the own ceramic product not interfere with the properties, when used in a percentage of up to 5%.Since the residue of chamote being derived from the ceramic product itself had no effect on the properties. Studies in the laboratory have shown that the incorporation of up to 5% of these residues may be adopted as an alternative technology to reduce the environmental impact caused by the industrial sector, without compromising the final properties of the material, since the results on an industrial scale showed absorption values 11.66 and 11.74 of water and waste products respectively, within the parameters of NBR - 15,270, since the mechanical strength was 1.25 MPa and 0.94 MPa respectively for products with and without residue, lower than the minimum required by the technical standard that is 1.5 MPa.

Concentração do óleo de girassol em compostos insaturados utilizando destilação molecular

Vegetable oils are characterized as important raw materials in the supplying of natural substances of interest pharmaceutical, food and cosmetic industry. Sunflower oil stands out for its important composition present in unsaturated fatty acids such as oleic acid (C18:1) and linoleic (C18:2), responsible for many health benefits. The main objective of this study is obtain enriched fractions in unsaturated compounds from refined sunflower oil. The oil used in this study was characterized by the determination of some properties, like iodine number, acid number and viscosity. A transesterification was done to transform the triglycerides into their corresponding methyl esters of fatty acids. These was submitted the molecular distillation process, for present as an efficient alternative to separation and purification of these substances, using high vacuum and low temperatures. Of the esters fractions that was obtained, were analyzed by gas chromatography. The experimental design technique was used to evaluate the influence of the temperature variation of evaporation and condensation system on the percentage obtained residue. The evaporator temperature proved to be the most influential variable on the studied response. The optimized conditions for the answer was studied at 100 °C for evaporator temperature and 10 °C for the condenser temperature. The graph of "split ratio" showed that for the lowest flow feed (1 mL/min) and higher evaporator temperature (110 °C) was obtained in the largest fraction of distillate. It also used the study of the influence of evaporator temperature on the concentration of unsaturated compounds. The best operating conditions for temperature was 90 °C reached 82.21 % of unsaturated compounds. Elimination curves of the unsaturated compounds present in the distillate stream were obtained. The simulation results of the molecular distillation process of sunflower oil showed the concentration profiles for three different feed flow rates. The speed, temperature and thickness profiles of the liquid film were obtained. The speed of the film increases as the fluid flows through the walls of the evaporator, reaching a maximum on length of 0.075 m. The film thickness decreases on the route, since many compounds are volatilized. The result of the temperature profile had to be consistent with the literature reproduced, being constant after reaching the maximum operating temperature in the length of 0.15 m. This study allowed characterizing and focusing, through experimental analysis, unsaturated compounds and observing the sunflower oil´s behavior through process simulation.

Concentração do óleo de girassol em compostos insaturados utilizando destilação molecular

Vegetable oils are characterized as important raw materials in the supplying of natural substances of interest pharmaceutical, food and cosmetic industry. Sunflower oil stands out for its important composition present in unsaturated fatty acids such as oleic acid (C18:1) and linoleic (C18:2), responsible for many health benefits. The main objective of this study is obtain enriched fractions in unsaturated compounds from refined sunflower oil. The oil used in this study was characterized by the determination of some properties, like iodine number, acid number and viscosity. A transesterification was done to transform the triglycerides into their corresponding methyl esters of fatty acids. These was submitted the molecular distillation process, for present as an efficient alternative to separation and purification of these substances, using high vacuum and low temperatures. Of the esters fractions that was obtained, were analyzed by gas chromatography. The experimental design technique was used to evaluate the influence of the temperature variation of evaporation and condensation system on the percentage obtained residue. The evaporator temperature proved to be the most influential variable on the studied response. The optimized conditions for the answer was studied at 100 °C for evaporator temperature and 10 °C for the condenser temperature. The graph of "split ratio" showed that for the lowest flow feed (1 mL/min) and higher evaporator temperature (110 °C) was obtained in the largest fraction of distillate. It also used the study of the influence of evaporator temperature on the concentration of unsaturated compounds. The best operating conditions for temperature was 90 °C reached 82.21 % of unsaturated compounds. Elimination curves of the unsaturated compounds present in the distillate stream were obtained. The simulation results of the molecular distillation process of sunflower oil showed the concentration profiles for three different feed flow rates. The speed, temperature and thickness profiles of the liquid film were obtained. The speed of the film increases as the fluid flows through the walls of the evaporator, reaching a maximum on length of 0.075 m. The film thickness decreases on the route, since many compounds are volatilized. The result of the temperature profile had to be consistent with the literature reproduced, being constant after reaching the maximum operating temperature in the length of 0.15 m. This study allowed characterizing and focusing, through experimental analysis, unsaturated compounds and observing the sunflower oil´s behavior through process simulation.

Estudo da obtenção de cerâmica composta de alumina e beta alumina sódica utilizando-se resíduo cerâmico de velas de ignição e pó químico de extintores de incêndio

Ceramic materials the alumina base are large industrial applications. They are required for these products, specific characteristics obtained by following strict criteria during the manufacturing process. However, after life, not always these products are reused by a suitable waste management process. In ceramist context, advance research aimed at the reuse of waste aimed at obtaining ceramics and composite materials, with marked reduction of conventional raw materials. Aiming to generate scientific, technological and environmental contribution, this work studied to obtain a composite of alumina ceramic (Al2O3) and sodium beta alumina (NaAl11O17 ), and as starting materials the residue of the ceramic insulator of spark plugs, as a source alumina (Al2O3) powder and unusable sodium bicarbonate (NaHCO3) of fire extinguishers, as a source of sodium oxide (Na2O). The final ceramic product was obtained from a conventional mixture of sodium aluminum oxide in appropriate molar proportions. Sample spark plugs were obtained, discarded by lifetime, specific to a manufacturer, which, after passing through mechanical stress (grinding, magnetic purification, washing, drying and grinding the high energy), which resulted in residue powder with ceramic content of 84.34 % alumina (Al2O3), found by FRX chemical analysis, the phases present and identified by DRX. The dry chemical fire extinguisher, baking soda-based (NaHCO3) with expired, was obtained through direct collection of the waste generated during maintenance. Subjected to heat treatment at 120 °C , the NaHCO3 powder was decomposed in sodium oxide ( Na2O), which, subjected to chemical analysis (FRX) and mineralogical (DRX) revealed a content of 86.62 % sodium oxide (Na2O) . In the following steps the experimental procedure, chemical formulations were made on a molar basis of the starting material (1:9, 1:10 and 1:11 de Na2O/ Al2O3) inclusion of additives, milling parameters, sieve analysis, dilatometry, conformation of specimens, sintering in firing steps at 800 °C , 1000 °C and 1.200 °C with varying stays 30 , 60 and 120 minutes in each of the levels. The characterization of the final product was made by the following physical tests: water absorption, porosity, linear shrinkage, mineralogical analysis by DRX and microstructural analysis by MEV. A higher formation of sodium beta alumina (NaAl11O17), in sintered specimens in levels of 1.200 °C and 120 minutes, despite the prevailing coexistence of alpha phase alumina (Al2O3). From the results obtained opens up prospects for the reuse of waste studied in this work, the potter context and in other technological areas.

Estudo da obtenção de cerâmica composta de alumina e beta alumina sódica utilizando-se resíduo cerâmico de velas de ignição e pó químico de extintores de incêndio

Ceramic materials the alumina base are large industrial applications. They are required for these products, specific characteristics obtained by following strict criteria during the manufacturing process. However, after life, not always these products are reused by a suitable waste management process. In ceramist context, advance research aimed at the reuse of waste aimed at obtaining ceramics and composite materials, with marked reduction of conventional raw materials. Aiming to generate scientific, technological and environmental contribution, this work studied to obtain a composite of alumina ceramic (Al2O3) and sodium beta alumina (NaAl11O17 ), and as starting materials the residue of the ceramic insulator of spark plugs, as a source alumina (Al2O3) powder and unusable sodium bicarbonate (NaHCO3) of fire extinguishers, as a source of sodium oxide (Na2O). The final ceramic product was obtained from a conventional mixture of sodium aluminum oxide in appropriate molar proportions. Sample spark plugs were obtained, discarded by lifetime, specific to a manufacturer, which, after passing through mechanical stress (grinding, magnetic purification, washing, drying and grinding the high energy), which resulted in residue powder with ceramic content of 84.34 % alumina (Al2O3), found by FRX chemical analysis, the phases present and identified by DRX. The dry chemical fire extinguisher, baking soda-based (NaHCO3) with expired, was obtained through direct collection of the waste generated during maintenance. Subjected to heat treatment at 120 °C , the NaHCO3 powder was decomposed in sodium oxide ( Na2O), which, subjected to chemical analysis (FRX) and mineralogical (DRX) revealed a content of 86.62 % sodium oxide (Na2O) . In the following steps the experimental procedure, chemical formulations were made on a molar basis of the starting material (1:9, 1:10 and 1:11 de Na2O/ Al2O3) inclusion of additives, milling parameters, sieve analysis, dilatometry, conformation of specimens, sintering in firing steps at 800 °C , 1000 °C and 1.200 °C with varying stays 30 , 60 and 120 minutes in each of the levels. The characterization of the final product was made by the following physical tests: water absorption, porosity, linear shrinkage, mineralogical analysis by DRX and microstructural analysis by MEV. A higher formation of sodium beta alumina (NaAl11O17), in sintered specimens in levels of 1.200 °C and 120 minutes, despite the prevailing coexistence of alpha phase alumina (Al2O3). From the results obtained opens up prospects for the reuse of waste studied in this work, the potter context and in other technological areas.

Caracterização de um compósito utilizando cimento com agregado de resíduo plástico e resíduo de gesso

The demand for environmental comfort in construction systems within the insulation and thermal comfort, plus the advent of new laws regulating the minimum requirements of comfort, disposal of solid industrial waste, construction waste, the requirements of consumers by adopting construction methods "cleaner", encouraged the development of this work. Aims technologically characterize the composite proposed in three types of samples (10%, 30% and 50% of thermoset plastic industrial waste) and raw materials: gypsum waste, cement and plastic thermosetting industrial waste in order to produce the composite with properties of thermal insulation: conductivity, thermal diffusivity, specific heat and resistivity. The physical, structural and morphological properties of the raw materials were investigated by thermogravimetry analysis (TG / DSC), X-ray diffraction (DRX), X-ray fluorescence (FXR) and scanning electron microscopy (MEV). Obtaining mechanical properties through the compression strength test. The analysis results indicate characteristics suitable for cement matrix composite production with the addition of thermosetting plastic industrial waste and gypsum waste, with potential application of these materials in composites with properties of thermal insulation. Finally, assessing what proportion showed up with better performance. Considering the analysis and testing carried out.

Caracterização de um compósito utilizando cimento com agregado de resíduo plástico e resíduo de gesso

The demand for environmental comfort in construction systems within the insulation and thermal comfort, plus the advent of new laws regulating the minimum requirements of comfort, disposal of solid industrial waste, construction waste, the requirements of consumers by adopting construction methods "cleaner", encouraged the development of this work. Aims technologically characterize the composite proposed in three types of samples (10%, 30% and 50% of thermoset plastic industrial waste) and raw materials: gypsum waste, cement and plastic thermosetting industrial waste in order to produce the composite with properties of thermal insulation: conductivity, thermal diffusivity, specific heat and resistivity. The physical, structural and morphological properties of the raw materials were investigated by thermogravimetry analysis (TG / DSC), X-ray diffraction (DRX), X-ray fluorescence (FXR) and scanning electron microscopy (MEV). Obtaining mechanical properties through the compression strength test. The analysis results indicate characteristics suitable for cement matrix composite production with the addition of thermosetting plastic industrial waste and gypsum waste, with potential application of these materials in composites with properties of thermal insulation. Finally, assessing what proportion showed up with better performance. Considering the analysis and testing carried out.

Análise microestrutural de misturas cerâmicas de grês porcelanato com adição de chamote de telhas cerâmicas

MELO, Maxymme Mendes de ; PINHEIRO, Andrea Santos ; NASCIMENTO, R. M. ; MARTINELLI, Antonio Eduardo ; DUTRA, Ricardo Peixoto Suassuna ; MELO, Marcus Antônio de Freitas . Análise microestrutural de misturas cerâmicas de grês Porcelanato com adição de chamote de telhas cerâmicas. Cerâmica (São Paulo. Impresso), v. 55, p. 356-364, 2009

Avaliação da potencialidade de uso do resíduo proveniente da indústria de beneficiamento do caulim na produção de piso cerâmico

FORMIGA, Felipe Lira et al. Avaliação da Potencialidade de Uso do Resíduo Proveniente da Indústria de Beneficiamento do Caulim na Produção de Piso Cerâmico. Cerâmica Industrial, v. 14, p. 41-45, 2009.

Cerâmica de Santo Antônio do Potengi: entre tradição e modernidade

In the Rio Grande do Norte, the craftsmanship is generating of economy, it involves a significant number of people and is diversified in its raw materials and particular type. As reference of the craft local, the ceramics supplied the primary necessities in the utilitarian domestic servants, acquired piety in the religious figures, were toy in infantile amusements and, finally, gained status of pure ornament. By its historical representation, the district of Santo Antônio do Potengi is considered the most important center of manufacture of craftpottery in the State. The work of the potters continues in that locality anchored between the familiar inheritance and the participation each more influential time of the public politics destined to the sector situation verified for visible alterations in the shape of the pottery from the decade of 1990 with the implantation of a cooperative destined to the collective production. We observe in this passage, that such actions in the measure where they objectify to structuralize conditions ideal to support the artisan making, do not benefit in significant way the social development them craftsmen. It is important not to lose of sight that exists some involved dimensions in this process and that these surpass the common interest for the object and the consequent economic connotation of its commercialization. They are knowledge that imply in the access to raw materials, in the peculiar of the formal aspects and productive methods, in the contextual relations organized to defend the survival of the activity

Influência do teor de calcário no comportamento físico, mecânico e microestrutural de cerâmicas estruturais

There are ores of clay in Piauí State that are used for red structural ceramics, which are naturally contaminated with calcareous vein. This is one thing that impedes its exploration in an adequate way, especially for tile production. The present work aims at verifying the influence of the calcareous contents in the technological structural ceramics area, seeking to determine a maximum permissible calcareous proportion/contents in the ceramic mass using the patterns of the local industry production. For the consecution of this paper, it was characterized the clay and calcareous material by FRX, DRX, TGA and DTA. It was also configurated by extrusion and burnt in the temperatures of 850°C, 900°C, 950°C and 1000°C pieces of the corpus with 0, 5, 10, 15 e 20% of calcareous proportion. After that, it was carried out technological samples of linear retraction, water absortion, apparent porosity, specific apparent mass and mechanic resistance. The results showed the possibility of using calcareous in the ceramic mass and in some cases the technological properties got better

Estudo da adição de argila expandida na formulação de concretos leves

Lightweight concrete has been the subject of several studies towards the development of new building materials. Emphasis has been given on the particle size effect and nature of aggregates used as raw materials. The present study includes an analysis of the materials that make this kind of concrete, analyzes of mechanical properties such as compressive and tensile strength, in addition to assessments of the interface concrete aggregate/matrix interface, porosity and absorption profile of chloride ions in lightweight concrete based on expanded clay. The experiments were carried out by molding cylindrical samples 100 mm in diameter and 200 mm in height. The dosage experiments were performed without additives or with the addition of minerals: (T1) 1: 2.01: 1.10: 0.78 (T2) 1: 2.00: 1.32 : 0.62 - (T3) 1 :1.93 :1.54: 0.47 (cement : sand : expanded clay 0500 : expanded clay 1506).The water to cement ratio was set to 0.43. Expanded clay minerals with different average particle sizes were used, i.e., 9.5 mm/0500 and 19 mm/1506. The larger aggregate was coated by a glassy layer, yielding lower water absorption characteristics to the concrete. The results showed that the use of light expanded clay aggregates is a technically interesting solution to the production of lightweight concrete for construction applications