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General chemistry, physical chemistry, Chimie générale, chimie physique, Chemistry, Chimie, Chemical industry parachemical industry, Industrie chimique et parachimique, Metallurgy, welding, Métallurgie, soudage, Condensed state physics, Physique de l'état condensé, Pollution, Sciences exactes et technologie, Exact sciences and technology, Sciences appliquees, Applied sciences, Industries chimique et parachimique, Chemical industry and chemicals, Matériaux de construction. Céramique. Verres, Building materials. Ceramics. Glasses, Industries céramiques, Ceramic industries, Céramiques lourdes, céramiques fines, Heavyclay products, whiteware, Etudes générales, General studies, Additif, Additive, Aditivo, Argile, Clay, Arcilla, Conception, Design, Diseño, Céramique, Ceramic materials, Cerámica, Dispersant, Dispersante, Défloculant, Deflocculant, Defloculante, Défloculation, Deflocculation, Defloculación, Fabrication, Manufacturing, Fabricación, Feldspath, Feldspar, Feldespato, Industrie céramique, Ceramics industry, Industria cerámica, Matière première, Raw materials, Materia prima, Mélange ternaire, Ternary mixture, Mezcla ternaria, Optimisation, Optimization, Optimización, Procédé voie humide, Wet process, Procedimiento vía húmeda, Quartz, Cuarzo, Sodium silicate, Sodio silicato, Suspension particule, Particle suspension, Suspensión partícula, and Céramique triaxiale

An optimum amount of deflocculant was determined for three-component suspensions, based on a mixture design approach. Three raw materials were used, characterized as clay, feldspar and quartz. Ten compositions were prepared using the mixture design approach. Deflocculation curves were measured for suspensions with 40 wt.% of solids, adding sodium silicate as dispersant. The optimum deflocculant amount (ODA) was determined for each suspension, corresponding to the lowest value of apparent viscosity considering two nearest experimental points. It was observed that ODA increases linearly with the increase of the clay fraction in the mixture. A response surface and polynomial regression could be used to identify the composition range that satisfies usual conditions in wet ceramics processing.

General chemistry, physical chemistry, Chimie générale, chimie physique, Chemistry, Chimie, Chemical industry parachemical industry, Industrie chimique et parachimique, Metallurgy, welding, Métallurgie, soudage, Condensed state physics, Physique de l'état condensé, Pollution, Sciences exactes et technologie, Exact sciences and technology, Sciences appliquees, Applied sciences, Industries chimique et parachimique, Chemical industry and chemicals, Matériaux de construction. Céramique. Verres, Building materials. Ceramics. Glasses, Industries céramiques, Ceramic industries, Céramiques techniques, Technical ceramics, Céramiques thermomécaniques, Structural ceramics, Pollution, Déchets, Wastes, Déchets divers et constituants particuliers des déchets, Other wastes and particular components of wastes, Céramique thermomécanique, Structural ceramic, Cerámica termomecánica, Déchet construction, Building waste, Residuo de construcción, Déchet solide, Solid waste, Residuos sólidos, Fabrication, Manufacturing, Fabricación, Industrie céramique, Ceramics industry, Industria cerámica, Matière première, Raw materials, Materia prima, Réutilisation déchet, Waste reuse, Reutilización desperdicios, Valorisation, Upgrading, and Valorización

The industry of ornamental stones processing from Espírito Santo State produces high amounts of powder waste from sawing and polishing of granite. This waste is a non-biodegradable material that when disposed generates pollution and environmental damage. Clay/waste mixtures were prepared with a kaolinitic clay and waste additions up to 10 wt%. Various bodies were prepared by uniaxial pressing and sintered in air between 850°C and 1150°C. Emphasis is given on the drying and firing properties. The results revealed that the ceramic bodies containing granite powder waste are adequate for manufacture of structural ceramic. In addition, the employed methodology is environmentally correct and can contribute to the sustainable development.

General chemistry, physical chemistry, Chimie générale, chimie physique, Chemistry, Chimie, Chemical industry parachemical industry, Industrie chimique et parachimique, Metallurgy, welding, Métallurgie, soudage, Condensed state physics, Physique de l'état condensé, Pollution, Sciences exactes et technologie, Exact sciences and technology, Sciences appliquees, Applied sciences, Industries chimique et parachimique, Chemical industry and chemicals, Matériaux de construction. Céramique. Verres, Building materials. Ceramics. Glasses, Industries céramiques, Ceramic industries, Céramiques lourdes, céramiques fines, Heavyclay products, whiteware, Carreaux céramiques, Ceramic tiles, Carreau mural, Wall tile, Loseta mural, Carreau sol, Floor tile, Loseta piso, Composition chimique, Chemical composition, Composición química, Cuisson matériau, Firing (materials), Cocción material, Céramique, Ceramic materials, Cerámica, Etude expérimentale, Experimental study, Estudio experimental, Etude théorique, Theoretical study, Estudio teórico, Matière première, Raw materials, Materia prima, Modèle régression, Regression model, Modelo regresión, Modélisation, Modeling, Modelización, Retrait, Shrinkage, and Retiro

In the development and manufacture stages of floor and wall ceramic tiles, firing shrinkage is basically determined by the combination of raw materials and frequently used as quality control parameters. This configures the ideal scenario to apply the techniques of experiments design, often used in various other areas, to model those properties of such ceramics bodies. In this work, ten formulations of three different raw materials, namely a clay mixture, potash feldspar and quartz (triaxial compositions) were selected and processed under conditions similar to those used in the ceramics industry. With the experimental results, a regression model was calculated, relating linear shrinkage with composition. After statistical analysis and verification experiments, the significance and validity of the model was confirmed. The regression model can then be used to select the best combination of those three raw materials to produce a ceramic body with specified properties.

General chemistry, physical chemistry, Chimie générale, chimie physique, Chemistry, Chimie, Chemical industry parachemical industry, Industrie chimique et parachimique, Metallurgy, welding, Métallurgie, soudage, Condensed state physics, Physique de l'état condensé, Pollution, Sciences exactes et technologie, Exact sciences and technology, Sciences appliquees, Applied sciences, Industries chimique et parachimique, Chemical industry and chemicals, Matériaux de construction. Céramique. Verres, Building materials. Ceramics. Glasses, Industries céramiques, Ceramic industries, Céramiques techniques, Technical ceramics, Céramiques électrotechniques et électroniques, Electrotechnical and electronic ceramics, Addition chrome, Chromium addition, Adición cromo, Céramique oxyde, Oxide ceramics, Cerámica óxido, Céramique électronique, Electroceramics, Cerámica electrónica, Diffraction RX, X ray diffraction, Difracción RX, Dopage, Doping, Effet composition, Composition effect, Efecto composición, Etain oxyde, Tin oxide, Estaño óxido, Etude expérimentale, Experimental study, Estudio experimental, Fabrication, Manufacturing, Fabricación, Impédance, Impedance, Impedancia, Microscopie électronique balayage, Scanning electron microscopy, Microscopía electrónica barrido, Propriété électrique, Electrical properties, Propiedad eléctrica, Relation composition propriété, Property composition relationship, Relación composición propiedad, Méthode Pechini, O Sn, and SnO2:Cr

This paper reports a study of influence of Cr concentration on the electrical properties and microstructure of SnO2-based powders doped with Mn and Nb, prepared by an organic route (Pechini method). All the samples were compacted into discs and sintered at 1300°C for 3h, resulting in ceramics with relative density varying between 78% and 98%. The powders were characterized by X-ray diffraction analysis. Impedance spectroscopy characterization indicated that the conductivity decreases as Cr concentration increases, probably due to Cr segregation at grain boundaries, which reduces grain size, increasing the number of resistive boundaries.

General chemistry, physical chemistry, Chimie générale, chimie physique, Chemistry, Chimie, Chemical industry parachemical industry, Industrie chimique et parachimique, Metallurgy, welding, Métallurgie, soudage, Condensed state physics, Physique de l'état condensé, Pollution, Sciences exactes et technologie, Exact sciences and technology, Sciences appliquees, Applied sciences, Pollution, Traitement et pollution des eaux, Water treatment and pollution, Pollution des eaux naturelles, Natural water pollution, Eaux souterraines, Groundwaters, Pollution du sol et des sédiments, Soil and sediments pollution, Décontamination. Divers, Decontamination. Miscellaneous, Composé organique, Organic compounds, Compuesto orgánico, Ammonium quaternaire composé, Quaternary ammonium compound, Amonio cuaternario compuesto, Argile organique, Organic clay, Arcilla orgánica, Carburant diesel, Diesel fuel, Carburante diesel, Composé aromatique, Aromatic compound, Compuesto aromático, Décontamination, Decontamination, Descontaminación, Eau souterraine, Ground water, Agua subterránea, Hydrocarbure, Hydrocarbon, Hidrocarburo, Pollution chimique, Chemical pollution, Polución química, Pollution eau, Water pollution, Contaminación agua, Pollution sol, Soil pollution, Polución suelo, Sorbant, Sorbent, Sorbente, Sorption, Sorción, Toluène, Toluene, Tolueno, Xylène, Xylene, and Xileno

The most common route of soil and groundwater contamination is leaking underground storage tanks (USTs), that are used by gas station, industrial, and residencial compounds. Over 418000 UST releases had been confirmed as of September 30, 2001 in the USA. There are no precise numbers for contaminated sites in Brazil, but it's easy to suppose that many exist. Contamination of soil and water by gasoline and Diesel from leaking underground storage tanks (USTs) may result in serious environmental problem. The objective of this study was to investigate the sorption of toluene, xylene and Diesel by organoclays produced from Brazilian bentonites (AM2, SVC) with hexadecyltrimethylammonium (HDTMA), as well as by a commercial peat. The test used is based on Standard Methods of Testing Sorbent Performance of Adsorbents (ASTM F 726-99) and Standard Methods of Testing Sorbent Performance of Absorbents [ASTM F 716-82 (Reapproved 1993)]. The organoclays (SVC-HDTMA and AM2-HDTMA) were characterized by X-Ray Diffraction. The data showed that the sorption capacity of the organoclays ranged from 8.5 g sorbed/g sorbent to 14 g sorbed/g sorbent. The peat sorb organic compounds equal to about 8 times its weight. The results suggest that these sorbents are effective to sorb toluene, xylene, and Diesel oil.

General chemistry, physical chemistry, Chimie générale, chimie physique, Chemistry, Chimie, Chemical industry parachemical industry, Industrie chimique et parachimique, Metallurgy, welding, Métallurgie, soudage, Condensed state physics, Physique de l'état condensé, Pollution, Sciences exactes et technologie, Exact sciences and technology, Physique, Physics, Domaines interdisciplinaires: science des materiaux; rheologie, Cross-disciplinary physics: materials science; rheology, Science des matériaux, Materials science, Autres méthodes de préparation et de traitement des matériaux, Materials synthesis; materials processing, Sciences appliquees, Applied sciences, Metaux. Metallurgie, Metals. Metallurgy, Transformation de matériaux métalliques, Production techniques, Métallurgie des poudres. Matériaux composites, Powder metallurgy. Composite materials, Poudres métalliques, Metal powders, Biomatériau, Biomaterial, Dimension pore, Pore size, Dimensión poro, Frittage, Sintering, Sinterización, Sintern, Liant, Binders, Ligante, Bindemittel, Matériau poreux, Porous material, Material poroso, Poroeser Werkstoff, Microscopie électronique balayage, Scanning electron microscopy, Microscopía electrónica barrido, Rasterelektronenmikroskopie, Microstructure, Microestructura, Mikrogefuege, Métallographie, Metallography, Metalografía, Metallographie, Métallurgie poudre, Powder metallurgy, Metalurgia polvo, Pulvermetallurgie, Porosité, Porosity, Porosidad, Porositaet, Revêtement surface, Surface coating, Titane alliage, Titanium alloy, Titanio aleación, Titanlegierung, Traitement matériau, Material processing, Tratamiento material, and 8120E

Porous structures are applied as coatings in order to improve surgical implants bone fixation by allowing the mechanical interlocking of the pores and bone. Sintered titanium porous coatings have been, used for surgical implants because they have a strong attachment of the coating to the substrate. This works reports the processing and characterization of titanium porous coatings and foam samples, for surgical implants applications. Pure titanium powders mixed with urea as a binder was used for the porous coatings and foam samples. A rod shape of Ti-6Al-7Nb alloy P/M sample was used as substrate. Coatings surfaces were analyzed via scanning electron microscopy and the porosity characterization was made by quantitative metallografic analysis. It was found that coating porosity can be controlled by adjusting the binder percent addition and powder sizes. Sintered samples exhibited a microstructure with micropores and inteconnected macropores which is suitable to be used in surgical implants.

General chemistry, physical chemistry, Chimie générale, chimie physique, Chemistry, Chimie, Chemical industry parachemical industry, Industrie chimique et parachimique, Metallurgy, welding, Métallurgie, soudage, Condensed state physics, Physique de l'état condensé, Pollution, Sciences exactes et technologie, Exact sciences and technology, Sciences appliquees, Applied sciences, Industries chimique et parachimique, Chemical industry and chemicals, Matériaux de construction. Céramique. Verres, Building materials. Ceramics. Glasses, Industries céramiques, Ceramic industries, Divers, Miscellaneous, Pollution, Déchets, Wastes, Autres déchets industriels. Boues résiduaires, Other industrial wastes. Sewage sludge, Céramique, Ceramic materials, Cerámica, Diffusion thermique, Thermal diffusion, Difusión térmica, Déchet industriel, Industrial waste, Desperdicio industrial, Effet température, Temperature effect, Efecto temperatura, Industrie céramique, Ceramics industry, Industria cerámica, Industrie pétrolière, Oil industry, Industria petrolera, Matière première, Raw materials, Materia prima, Propriété thermique, Thermal properties, Propiedad térmica, Relation composition propriété, Property composition relationship, Relación composición propiedad, Réutilisation déchet, Waste reuse, Reutilización desperdicios, Valorisation, Upgrading, and Valorización

In Campos oil Basin (Brazil), which is responsible for more than 80% of the national petroleum production, it is generated a great amount of wastes from deep crude oil extraction related activities. Particularly, the oil sludge waste has been intensely studied in order to search alternatives for the reuse of the waste in treated form in the ceramic industry. The present work focuses on the photoacoustic thermal characterization of sintered ceramic bodies containing up to 5 wt% added waste. Specimens were uniaxially pressed at 25 MPa, and sintered between 850°C and 1000°C. The results of thermal diffusivity indicate that the use of petroleum waste in structural ceramic up to 5 wt% does not cause significant changes in the structure or composition of the clay/waste system, resulting in great advantages in waste minimization.

General chemistry, physical chemistry, Chimie générale, chimie physique, Chemistry, Chimie, Chemical industry parachemical industry, Industrie chimique et parachimique, Metallurgy, welding, Métallurgie, soudage, Condensed state physics, Physique de l'état condensé, Pollution, Sciences exactes et technologie, Exact sciences and technology, Sciences appliquees, Applied sciences, Genie chimique, Chemical engineering, Séparations mécaniques liquide-liquide et fluide-solide, Liquid-liquid and fluid-solid mechanical separations, Divers, Miscellaneous, Distribution concentration, Concentration distribution, Distribución concentración, En discontinu, Batchwise, En discontinuo, Liquide solide, Liquid solid, Líquido sólido, Rayonnement gamma, Gamma radiation, Radiación gama, Rayonnement haute énergie, High energy radiation, Radiación alta energía, Système biphasique, Biphasic system, Sistema bifásico, Sédimentation, Sedimentation, and Sedimentación

The behavior of an isothermal and non-reaction solid-liquid system can be model using a mathematical model based on the Mixtures' Theory of Continuum Mechanics. The knowledge of the constitutive equations of this phenomenon, as pressure on the solids and medium permeability, is very important in the design and performance evaluation of the continuous thickeners or filters. In this work the batch sedimentation phenomena of a kaolin aqueous suspensions was investigated. The technique consists on measuring of the gamma rays attenuation when they cross the physical media as a function of the local concentration at several vertical positions in a reservoir. Using the experimental data and local concentration as a function of the attenuation curve, it is possible to determine the constitutive equations. The results were satisfactory, allowing simulations of this phenomenon for steady and transient regimes in future papers.

General chemistry, physical chemistry, Chimie générale, chimie physique, Chemistry, Chimie, Chemical industry parachemical industry, Industrie chimique et parachimique, Metallurgy, welding, Métallurgie, soudage, Condensed state physics, Physique de l'état condensé, Pollution, Sciences exactes et technologie, Exact sciences and technology, Sciences appliquees, Applied sciences, Genie chimique, Chemical engineering, Séparations mécaniques liquide-liquide et fluide-solide, Liquid-liquid and fluid-solid mechanical separations, Filtration, Céramique, Ceramic materials, Cerámica, Electrocinétique, Electrokinetics, Electrocinética, Electroosmose, Electroosmosis, Electro-osmosis, Filtration, Filtración, Filtre, Filter, Filtro, Méthode électrochimique, Electrochemical method, Método electroquímico, Nettoyage, Cleaning, and Limpieza

Preliminary results of the use of electroomosis technique for removal of organic contaminants in ceramic filtration porous structure are presented. The method employed provokes the migration of chemical residue and waste retained or adsorbed on the pore surfaces by applying a controlled tension within an electrochemical system. Porous ceramics have been the most common filtration medium employed within a broad range of applications. Conventional cleaning of a ceramic medium is not entirely effective for organic contaminants since they cannot be excluded by size, but retained through chemical affinity to the oxide surface. Under the influence of an electrical current, adsorbed molecules underwent shear stress due to the diffuse moving layer. In their ionic state the specimens are dragged and thus move towards the opposite charged electrode. Phenol was chosen as a standard contaminant and tests carried out using commercial ceramic filtration candles. Relative contaminant concentration was assessed by optical densities (UV-Vis spectroscopy). The results show that removal is proportional for up to 58% of the contaminant in diluted condition.

General chemistry, physical chemistry, Chimie générale, chimie physique, Chemistry, Chimie, Chemical industry parachemical industry, Industrie chimique et parachimique, Metallurgy, welding, Métallurgie, soudage, Condensed state physics, Physique de l'état condensé, Pollution, Sciences exactes et technologie, Exact sciences and technology, Physique, Physics, Domaines interdisciplinaires: science des materiaux; rheologie, Cross-disciplinary physics: materials science; rheology, Science des matériaux, Materials science, Autres méthodes de préparation et de traitement des matériaux, Materials synthesis; materials processing, Sciences appliquees, Applied sciences, Metaux. Metallurgie, Metals. Metallurgy, Transformation de matériaux métalliques, Production techniques, Métallurgie des poudres. Matériaux composites, Powder metallurgy. Composite materials, Poudres métalliques, Metal powders, Acier inoxydable 316, Stainless steel-316, Acier inoxydable austénitique, Austenitic stainless steel, Densité, Density, Dimension particule, Particle size, Frittage, Sintering, Matériau poreux, Porous materials, Métallurgie poudre, Powder metallurgy, Perméation, Permeation, Permeación, Pressage froid, Cold pressing, Pulvérisation jet, Atomizing, Pulverización a chorro, Zerstaeuben, and 8120E

Filters of austenitic stainless steel are usually obtained from non-spherical, mostly atomized powders by cold pressing and sintering. The required controlled permeation rates are provided by using powders with a narrow range of particle size. Apparent density can be adjusted by the particle size, shape and distribution. This paper discusses the relationships between apparent density (ranging from 1.5 to 3.1 g/cm3) and permeability of the sintered samples. Commercial 316 stainless steel water atomized powders and a high apparent density water atomized powder were used as raw material. Samples were pressed to get green densities around 5 g/cm3. Sintering was carried out under vacuum at 1230°C. Shrinkage after sintering was measured.

General chemistry, physical chemistry, Chimie générale, chimie physique, Chemistry, Chimie, Chemical industry parachemical industry, Industrie chimique et parachimique, Metallurgy, welding, Métallurgie, soudage, Condensed state physics, Physique de l'état condensé, Pollution, Sciences exactes et technologie, Exact sciences and technology, Sciences appliquees, Applied sciences, Metaux. Metallurgie, Metals. Metallurgy, Transformation de matériaux métalliques, Production techniques, Traitements de surface, Surface treatment, Autres traitements de surface, Other surface treatments, Cinétique, Kinetics, Cinética, Kinetik, Commande processus, Process control, Control proceso, Prozesssteuerung, Effet surface, Surface effect, Efecto superficie, Oberflaecheneinfluss, Fer alliage, Iron alloy, Hierro aleación, Eisenlegierung, Frittage, Sintering, Sinterización, Sintern, Modèle mathématique, Mathematical model, Modelo matemático, Mathematisches Modell, Modélisation, Modeling, Modelización, Métal transition alliage, Transition metal alloy, Metal transición aleación, Uebergangsmetallegierung, Nitruration, Nitriding, Nitruración, Nitrieren, Perméation, Permeation, Permeación, Porosité, Porosity, Porosidad, Porositaet, Poudre métallique, Metal powder, Polvo metálico, Metallpulver, Précipitation, Precipitation, Precipitación, Ausscheidung, Simulation ordinateur, Computer simulation, Simulación computadora, and Elektronenrechnersimulation

Mathematical modelling has been developed to improve processes control and has helped theories about complex systems to be written. Nitriding is a multivariable system that needs the convergence of efforts to allow its improvement. Computer simulation is an important tool to give a simultaneous evaluation of all variables and respective effects in the result of the process. Surface conditions have an important effect in the interaction between gases and metals. Its influence can only be studied under two-dimensional and 3-D simulations. The presence of oxides and other barrier have a critical influence on the kinetic and on the result of the process. Secondary reactions such as precipitation and nitride layer formation also affect the process. Particularly, porosities can have an important effect by enhancing the gas permeation inside the sintered material. Depending on the variables that might be deleterious to the process, the simulations give some indications how to proceed and how to control these process variables. This work show, through simulation tools, how variables such as gas atmosphere, temperature, powder surface conditions, porosity and alloy composition will affect the final result of the nitriding process of sintered and non-sintered powders. A methodology was developed using numerical methods and systemic algorithms.

General chemistry, physical chemistry, Chimie générale, chimie physique, Chemistry, Chimie, Chemical industry parachemical industry, Industrie chimique et parachimique, Metallurgy, welding, Métallurgie, soudage, Condensed state physics, Physique de l'état condensé, Pollution, Sciences exactes et technologie, Exact sciences and technology, Physique, Physics, Etat condense: structure electronique, proprietes electriques, magnetiques et optiques, Condensed matter: electronic structure, electrical, magnetic, and optical properties, Propriétés et matériaux magnétiques, Magnetic properties and materials, Etudes de matériaux magnétiques particuliers, Studies of specific magnetic materials, Aimants permanents, Permanent magnets, Aimant permanent, Permanent magnets, Composition chimique, Chemical composition, Fer alliage, Iron alloys, Grosseur grain, Grain size, Microstructure, Métal transition alliage, Transition element alloys, Praséodyme alliage, Praseodymium alloys, Procédé HDDR, HDDR process, Propriété magnétique, Magnetic properties, Recuit, Annealing, and 7550W

Permanent magnets were produced from annealed alloys using the hydrogenation, disproportionation, desorption and recombination (HDDR) process. The influence of Pr concentration on the magnetic properties of these magnets was studied. Under the present processing conditions Pr has a significant influence on the magnetic behaviour of these magnetic materials. Microstructural examinations revealed that free iron was completed eliminated from all studied alloys with annealing and the grain size changed somewhat with praseodymium content. It has also been shown that to obtain bonded magnets with optimum magnetic properties the praseodymium content in these alloys should be around 13.5 at%.

General chemistry, physical chemistry, Chimie générale, chimie physique, Chemistry, Chimie, Chemical industry parachemical industry, Industrie chimique et parachimique, Metallurgy, welding, Métallurgie, soudage, Condensed state physics, Physique de l'état condensé, Pollution, Sciences exactes et technologie, Exact sciences and technology, Sciences appliquees, Applied sciences, Genie mecanique. Construction mecanique, Mechanical engineering. Machine design, Organes de machines, Machine components, Frottement, usure, lubrification, Friction, wear, lubrication, Anneau, Ring, Anillo, Carter, Crankcase, Carter (motores), Chaîne fabrication, Production line, Línea fabricación, Contrainte contact, Contact stress, Tensión contacto, Epaisseur couche, Layer thickness, Espesor capa, Frottement, Friction, Frotamiento, Huile lubrifiante, Lubricating oil, Aceite lubricante, Lubrifiant, Lubricant, Lubricante, Lubrification, Lubrication, Lubricación, Moteur combustion interne, Internal combustion engine, Motor explosión interna, Métal, Metal, Métallurgie poudre, Powder metallurgy, Metalurgia polvo, Pression dynamique, Dynamic pressure, Presión dinámica, Recherche développement, Research and development, Investigación desarrollo, Segment piston, Piston ring, and Segmento pistón

The two major working characteristics of the oil control ring are: 1) to scrape the lubricant oil from the cylinder wall to the direction of the crankcase, and 2) to maintain a sufficient amount of lubricant oil to the compression rings above it in order to sustain a suitable lubricant film thickness between the rings and the cylinder. The oil control ring efficiency is the outcome of the combination of the following parameters: conformability, sort of the contact between the ring and the cylinder, contact pressure, and oil scraping dynamics. This work shows the development of an original oil control ring named Monoland, conceived by powder metallurgy design, having high conformability and optimized contact pressure that provides a superior oil scraping efficiency even with decreasing the friction losses. These qualities were achieved as an effect of an extensive product advance program established by Mahle Metal Leve Research and Development Center and Mahle Metal Leve Miba Sinterizados, which involved steps beginning from.the product concept to the production streamline and passing through an extensive product validation program.

General chemistry, physical chemistry, Chimie générale, chimie physique, Chemistry, Chimie, Chemical industry parachemical industry, Industrie chimique et parachimique, Metallurgy, welding, Métallurgie, soudage, Condensed state physics, Physique de l'état condensé, Pollution, Sciences exactes et technologie, Exact sciences and technology, Physique, Physics, Domaines interdisciplinaires: science des materiaux; rheologie, Cross-disciplinary physics: materials science; rheology, Science des matériaux, Materials science, Matériaux particuliers, Specific materials, Autres matériaux, Other materials, Sciences appliquees, Applied sciences, Industries chimique et parachimique, Chemical industry and chemicals, Matériaux de construction. Céramique. Verres, Building materials. Ceramics. Glasses, Industries céramiques, Ceramic industries, Céramiques techniques, Technical ceramics, Céramiques électrotechniques et électroniques, Electrotechnical and electronic ceramics, Cermets, ceramic and refractory composites, Analyse thermique différentielle, Differential thermal analysis, Análisis térmico diferencial, Argent, Silver, Plata, Bismuth Calcium Cuivre Strontium Oxyde Mixte, Bismuth Calcium Copper Strontium Oxides Mixed, Bismuto Calcio Cobre Estroncio Óxido Mixto, Bismuth oxyde, Bismuth oxide, Bismuto óxido, Calcium oxyde, Calcium oxide, Calcio óxido, Citrate, Citrato, Composite matrice céramique, Ceramic matrix composite, Compuesta matriz ceramica, Cuivre oxyde, Copper oxide, Cobre óxido, Cuprate, Cuprates, Céramique oxyde, Oxide ceramics, Cerámica óxido, Céramique électronique, Electroceramics, Cerámica electrónica, Diffraction RX, X ray diffraction, Difracción RX, Etude expérimentale, Experimental study, Estudio experimental, Fabrication, Manufacturing, Fabricación, Frittage, Sintering, Sinterización, Matériau composite, Composite material, Material compuesto, Propriété électrique, Electrical properties, Propiedad eléctrica, Relation composition propriété, Property composition relationship, Relación composición propiedad, Strontium oxyde, Strontium oxide, Estroncio óxido, Supraconducteur haute température, High temperature superconductor, Supraconductor alta temperatura, and Composite Bi2223 Ag

The Bi-Sr-Ca-Cu-O system has been one of the most studied superconducting ceramic materials for industry applications. The most of the studies with this aim are on silver/ceramic composites, due to the benefits and great compatibility of this metal with the oxide. In this paper we describe a systematic and comparative study on Ag/BSCCO composite, made by the citrate route, in which the ceramic pellets are sintered in the presence of silver powder using several proportions and having several granulations. It was observed that the introduction of fine (0.5 and 2 μm) silver powder in the proportions of 5 wt. % always implies in a better critical current density compared to the no silver pellet. According to the results, the silver powder in excess of 5 wt.% may not promote best electrical properties, depending on the size of the silver particles.

General chemistry, physical chemistry, Chimie générale, chimie physique, Chemistry, Chimie, Chemical industry parachemical industry, Industrie chimique et parachimique, Metallurgy, welding, Métallurgie, soudage, Condensed state physics, Physique de l'état condensé, Pollution, Sciences exactes et technologie, Exact sciences and technology, Physique, Physics, Domaines interdisciplinaires: science des materiaux; rheologie, Cross-disciplinary physics: materials science; rheology, Science des matériaux, Materials science, Matériaux particuliers, Specific materials, Autres matériaux, Other materials, Sciences appliquees, Applied sciences, Industries chimique et parachimique, Chemical industry and chemicals, Matériaux de construction. Céramique. Verres, Building materials. Ceramics. Glasses, Industries céramiques, Ceramic industries, Céramiques techniques, Technical ceramics, Céramiques thermomécaniques, Structural ceramics, Cermets, ceramic and refractory composites, Composite matrice céramique, Ceramic matrix composite, Compuesta matriz ceramica, Contrainte, Constraint, Coacción, Céramique oxyde, Oxide ceramics, Cerámica óxido, Céramique thermomécanique, Structural ceramic, Cerámica termomecánica, Cérium oxyde, Cerium oxide, Cerio óxido, Diffraction RX, X ray diffraction, Difracción RX, Dureté Vickers, Vickers hardness, Dureza Vickers, Dureté superficielle, Surface hardness, Dureza superficial, Essai flexion, Bending test, Ensayo flexion, Etude expérimentale, Experimental study, Estudio experimental, Matériau composite, Composite material, Material compuesto, Microscopie électronique balayage, Scanning electron microscopy, Microscopía electrónica barrido, Microstructure, Microestructura, Polymorphisme, Polymorphism, Polimorfismo, Propriété mécanique, Mechanical properties, Propiedad mecánica, Relation structure propriété, Property structure relationship, Relación estructura propiedad, Réseau quadratique, Tetragonal lattices, Transformation phase, Phase transformation, Transformación fase, Ténacité, Fracture toughness, Tenacidad, Zirconium oxyde, Zirconium oxide, Zirconio óxido, and Composite ZrO2 CeO2

CeO2- ZrC2 ceramics are considered a candidate material for applications as structural high performance ceramics, In this work are presented and discussed the tetragonal-to-monoclinic stress-induced transformation influence on the mechanical properties in these ceramics. Sintered ceramics were fabricated from powders mixtures containing ZrC2 and 8 to 14 CeO2 % mol. SEM observations were used to study de ceramic microstructures and X-rays diffraction to identification and determination of tetragonal and monoclinic phases. It was adopted the 4-point bending tests, Vickers surface hardness and fracture toughness technique to the determination of the mechanical parameters. The results showed that the mechanical properties were strongly dependent of the CeO2content, the microstructure and the fraction of tetragonal-to-monoclinic stress-induced transformation.

General chemistry, physical chemistry, Chimie générale, chimie physique, Chemistry, Chimie, Chemical industry parachemical industry, Industrie chimique et parachimique, Metallurgy, welding, Métallurgie, soudage, Condensed state physics, Physique de l'état condensé, Pollution, Sciences exactes et technologie, Exact sciences and technology, Sciences appliquees, Applied sciences, Physicochimie des polymeres, Physicochemistry of polymers, Polymères minéraux et organominéraux, Inorganic and organomineral polymers, Préparation, Preparation, Aluminosilicate, Aluminosilicates, Aluminosilicato, Etude expérimentale, Experimental study, Estudio experimental, Kaolin, Caolín, Polycondensation, Condensation polymerization, Policondensación, Polymère aluminium, Aluminum polymer, Polímero aluminio, Polymère minéral, Inorganic polymer, Polímero inorgánico, Polymère silicium, Silicon polymer, Polímero silicio, Polymère tridimensionnel, Three dimensional polymer, Polímero tridimensional, Propriété mécanique, Mechanical properties, Propiedad mecánica, Propriété rhéologique, Rheological properties, Propiedad reológica, Préparation, Preparation, Preparación, Relation mise en oeuvre propriété, Property processing relationship, Relación puesta en marcha propiedad, Résistance compression, Compressive strength, Resistencia compresión, Géopolymère, and Métakaolin

Geopolymers are inorganic materials with ceramic characteristics that can be synthesized at room temperature from the setting of slurries. Their structure consists of aluminosilicate units that polymerize in alkaline environment. The setting rate and mechanical behavior of geopolymers strongly depends on the SiO2:Al2O3 molar ratio, polymeric precursor and polymerization cation. The present work reports the synthesis and characterization of 3.5:1 (SiO2:Al2O3) structural geopolymers prepared using either metakaolin (GPMK) or kaolin (GPK) as geopolymeric precursor in potassium hydroxide solution. GPMK depicted quick setting whereas GPK set only after 4 hours. The rheological characterization of the slurries revealed that plastic viscosity and yield point of GPK were 0.40 Pa.s and 14.2 Pa, respectively, whereas GPMK set instantly. The compressive strength of both geopolymers were measured after 24 hours and resulted in similar results, i.e., 4.6 MPa for GPMK and 4.4 MPa for GPK. The strength of both geopolymers was compatible to values typical of structural materials.

General chemistry, physical chemistry, Chimie générale, chimie physique, Chemistry, Chimie, Chemical industry parachemical industry, Industrie chimique et parachimique, Metallurgy, welding, Métallurgie, soudage, Condensed state physics, Physique de l'état condensé, Pollution, Sciences exactes et technologie, Exact sciences and technology, Chimie, Chemistry, Chimie minerale et origine de la vie, Inorganic chemistry and origins of life, Préparations et propriétés, Preparations and properties, Corps simples et composés non métalliques (oxydes, hydroxydes, hydrures, sulfures, carbures, ...), Elements and non-metal compounds (oxides, hydroxides, hydrides, sulfides, carbides, ...), Ammonium Niobium Oxalate Mixte, Ammonium Niobium Oxalate Mixed, Amonio Niobio Oxalato Mixto, Basse température, Low temperature, Baja temperatura, Diffraction RX, X ray diffraction, Difracción RX, Etude expérimentale, Experimental study, Estudio experimental, Niobium carbure, Niobium carbide, Niobio carburo, Réacteur chimique, Chemical reactor, Reactor químico, Réaction gaz solide, Gas solid reaction, Reacción gas sólido, Synthèse chimique, Chemical synthesis, Síntesis química, C Nb, and NbC

The reaction of oxalic precursor {(NH4)3[NbO(C2O4)3]H2O}, was prepared from the Nb2O5, to niobium carbide (NbC) were performed in a rotating cylinder reactor scale-lab designed to niobium carbide powders synthesis at low temperature (1173 K). The NbC was prepared by a oxalic precursor and as well of commercial niobium pentoxide under flowing CH4- H2 mixtures. The reactor was heated through a bi-partied electric furnace with programmable temperature. The reaction overall time was determined from the curve of methane absorption evolution by gas chromatograph (FID) analysis. The preliminary results showed that the conversion function depends on the rotation, temperature, mixture flow, CH4/H2 ratio and heating rate. The niobium carbide was characterized through X-ray diffraction and compared to the commercial products. The reaction of oxalic precursor {(NH4)3[NbO(C204)3]H20} to niobium carbide (NbC) in 3% (v/v) CH4/H2 yielded smallest grain size as well smaller overall time when compared with obtained direct by commercial Nb2O5, however it had small mass conversion due the solid carryover not controlled.

General chemistry, physical chemistry, Chimie générale, chimie physique, Chemistry, Chimie, Chemical industry parachemical industry, Industrie chimique et parachimique, Metallurgy, welding, Métallurgie, soudage, Condensed state physics, Physique de l'état condensé, Pollution, Sciences exactes et technologie, Exact sciences and technology, Physique, Physics, Domaines interdisciplinaires: science des materiaux; rheologie, Cross-disciplinary physics: materials science; rheology, Science des matériaux, Materials science, Nanomatériaux et nanostructures : fabrication et caractèrisation, Nanoscale materials and structures: fabrication and characterization, Nanopoudres, Nanopowders, Autres méthodes de préparation et de traitement des matériaux, Materials synthesis; materials processing, Machining, milling, Carbure, Carbides, Composé minéral, Inorganic compounds, Métal transition composé, Transition element compounds, Aire superficielle, Surface area, Broyeur boulet, Ball mill, Molino bolas, Concassage, Crushing, Diffraction RX, XRD, Etude expérimentale, Experimental study, Fabrication, Haute énergie, High energy, Alta energía, Microscopie électronique balayage, Scanning electron microscopy, Nanomatériau, Nanostructured materials, Poudre ultrafine, Ultrafine powder, Polvo ultrafino, Traitement mécanique, Mechanical treatment, Tratamiento mecánico, Tungstène carbure, Tungsten carbides, C W, Mécanochimie, Mechanochemistry, and WC

One possible route for the production of nanometric powders is the reactive high-energy milling. For a variety of systems of highly exothermic reactions, the milling can lead to self-sustaining reactions, with the reaction being observed after an induction or ignition time, which produces a temperature increase in the reactants. In this work, WC powder was obtained by reactive high energy-milling, performed in a SPEX 8000 shaker/mill. During milling the highly exothermic displacement reaction of reduction of the WO3 by Mg was performed in presence of carbon to produce WC and MgO. The material to ball mass ratio was fixed in 4:1 and the ignition time of the reaction was determined. In order to characterize the transformations from reactant powders to reaction products, the milling was stopped at given times before, immediately after and after the reaction; the powders obtained were characterized by X-ray diffraction, scanning electron microscopy and specific surface area. Depending on the amount of carbon, W and the W2C were also observed as reaction products. The complete formation of WC was achieved with addition of an excess of carbon.

General chemistry, physical chemistry, Chimie générale, chimie physique, Chemistry, Chimie, Chemical industry parachemical industry, Industrie chimique et parachimique, Metallurgy, welding, Métallurgie, soudage, Condensed state physics, Physique de l'état condensé, Pollution, Sciences exactes et technologie, Exact sciences and technology, Chimie, Chemistry, Chimie generale et chimie physique, General and physical chemistry, Etat colloïdal et états dispersés, Colloidal state and disperse state, Poudres, Powders, Citrate, Citrato, Composé quaternaire, Quaternary compound, Compuesto cuaternario, Lanthane Oxyde, Lanthanum Oxides, Lantano Óxido, Manganèse Oxyde, Manganese Oxides, Manganeso Óxido, Métal alcalinoterreux Composé, Alkaline earth metal Compounds, Metal alcalino-térreo Compuesto, Préparation, Preparation, Preparación, Strontium Oxyde, Strontium Oxides, and Estroncio Óxido

La0.8Sr0.2Mn03±δ(LSM) powders were prepared by a Pechini-type polymerizable complex process and by amorphous citrate technique. Both processes involve the complexation of the LSM cations from their nitrates or carbonates. The aim of this work is to determinate the differences between the powers obtained by these techniques. The powders synthesized by the Pechini-type process were calcined between 500 °C and 1100 °C. The powders prepared by amorphous citrate technique were calcined at 900 °C. No contamination of either of the powders was observed by X ray fluorescence analysis. X ray diffraction results showed that a perovskite-type structure phase was obtained. BET results showed that the specific surface areas of the powders prepared by the polymerizable complex process and the amorphous citrate route were 6.6 m2g-1 and 5.7 m2g-1, respectively.

General chemistry, physical chemistry, Chimie générale, chimie physique, Chemistry, Chimie, Chemical industry parachemical industry, Industrie chimique et parachimique, Metallurgy, welding, Métallurgie, soudage, Condensed state physics, Physique de l'état condensé, Pollution, Sciences exactes et technologie, Exact sciences and technology, Chimie, Chemistry, Chimie generale et chimie physique, General and physical chemistry, Etat colloïdal et états dispersés, Colloidal state and disperse state, Poudres, Powders, Coordinat organique, Organic ligand, Ligando orgánico, Décomposition thermique, Thermal decomposition, Descomposición térmica, Lanthanide Complexe, Lanthanide Complexes, Lantánido Complejo, Luminescence, Luminiscencia, Poudre, Powder, Polvo, Stabilité thermique, Thermal stability, Estabilidad térmica, Terbium III Complexe, Terbium III Complexes, and Terbio III Complejo

This work deals with the synthesis and thermal decomposition of complexes of general formula: Ln(β-dik)3L (where Ln=Tb+3, β-dik=4,4,4-trifluoro-l-phenyl-1,3-butanedione(btfa) and L=1,10-fenantroline(phen) or 2,2-bipiridine(bipy). The powders were characterized by melting point, FTIR spectroscopy, UV-visible, elemental analysis, scanning differential calorimeter(DSC) and thermogravimetry(TG). The TG/DSC curves were obtained simultaneously in a system DSC-TGA, under nitrogen atmosphere. The experimental conditions were: 0.83 ml.s-1 carrier gas flow, 2.0±0.5 mg samples and 10°C.min-1 heating rate. The CHN elemental analysis of the Tb(btfa)3bipy and Tb(btfa)3phen complexes, are in good agreement with the expected values. The IR spectra evinced that the metal ion is coordinated to the ligands via C=O and C-N groups. The TG/DTG/DSC curves of the complexes show that they decompose before melting. The profiles of the thermal decomposition of the Tb(btfa)3phen and Tb(btfa)3bipy showed six and five decomposition stages, respectively. Our data suggests that the thermal stability of the complexes under investigation followed the order: Tb(btfa)3phen < Tb(btfa)3bipy.