Materials Science Forum Vols. 727-728

Abstract: The membrane separation process, although is recently, is increasing in applications such as purification, fractioning and concentration of substances in several industries. The membranes to gas separation present specific advantages when compared with conventional separation process (such as, cryogenic distillation and adsorption). Composite membrane has been widely applied in gas separation. The interest in the nanotechnology development in the last decade allows the increase in the nanocomposite area due to the special properties presented by these materials. In the nanocomposite the nanometric particles are dispersed in the polymer matrix. The polymer matrix used in this work was a polyetherimide (PEI), which is the most popular polymers for the preparation of membrane due to its solvent resistance and high selectivity. These membranes were obtained from polyetherimide (PEI) with bentonite clay from Paraiba/Brazil, by solvent evaporation method, and applied to gas permeability. The membranes were characterized by permeability to O₂, CO₂ and water vapor. The results present in this study show good expectation.

Abstract: Metallic oxide materials with AB₂O₄ structure are very interesting for technological applications. Nickel ferrite (NiFe₂O₄), for example, attracts considerable attention due to its chemical stability and mechanical hardness. These characteristics make it a suitable material for magnetic and magneto-optical applications. The properties of NiFe₂O₄ have a strong dependence on the crystallite size and microstructure. Due to this dependence, it is necessary to develop effective methods that allow controlling these variables. The aim of this work is to investigate the effect of time, temperature of isothermal treatment and choice of organic precursor during the production of NiFe₂O₄ samples employing the proteic sol-gel method have on crystallite size and microstructure. Two kinds of organic precursors were used: coconut water and pectin extracted from aple peel. Temperatures of 873 and 1173 K; 2, 4, 6, 8, 24 and 30 hours of isothermal treatment were also used. The samples produced were analyzed employing X-ray Diffraction.

Abstract: Industrialized component wastes, regularly discarded by the society, are increasingly contributing to the environmental pollution. The glass of these lamps is contaminated with mercury, which a serious hazard due to conventional recycling by melting with other glasses. A possible solution could be its incorporation into a clay body to fabricate common fired ceramics such as bricks and tiles. The objective of this work is to characterize a type of glass to be incorporated into a clayey ceramic. The glass analyzed was obtained from fluorescent lamps, which was passed through mercury decontamination process and ground into powder. This glass powder was tested for X-ray fluorescence, DTA/DTG, optical microscopy, scanning electron microscopy and optical dilatometry. The results showed that the glass presents sintering and softening points around 650 °C and 800 °C, respectively. The chemical analysis indicated the presence of impurities in considerable amounts in the composition of the fluorescent lamp glass waste.

Abstract: Ceramic fibers are characterized by their light weight, high degree of purity, low heat storage, low thermal conductivity, thermal shock resistance and superior corrosion resistance in high-temperature environments. In addition, they can be produced extensively in substitution to all materials used in the coating of almost all heating equipment as well as contributing to the reduction of energy consumption. Such characteristics make them ideal in the coating of distributors, mufflers, heating ovens, among others, as highly demanded by the mining and metallurgical industries, among others. After use in the process of industrial production, generated waste will lose their insulation capacity and thus require safe disposal. The present work focuses specifically on ceramic and glass wools aiming at an evaluation of their recycling prospect of incorporation into cement mortars and concrete. This residues were pulverized and displayed ~30µm average particle size. The scan electronic microscopy (SEM) presented elongated, thin and straight particles, which is very different than flocular structure of cement. The X-rays diffraction revealed amorphous structure for glass wool and crystalline structure for ceramics wool. The chemical analysis showed high concentrations of Al₂O₃ and silica in both residues, with higher percentage of calcium oxide in glass wool.

Abstract: Cationic surfactants, such as quaternary ammonium cations, have been used, in order to ameliorate the oil sorption capacity of inorganics materials, such as clays. Clays modified with quaternary ammonium cations (organoclays) have better performance in sorption, remove oil and grease from water at seven times the rate of activated carbon, as well as they can be used like perforation fluids of oil wells to the oil base, lubricants, among others industries. This work aims characterize the Cloisite 30B using various techniques: X-Ray Diffraction (XRD), Specific Surface Area (BET) and Cation Exchange Capacity. Different organic solvents, namely gasoline, diesel and kerosene were used in order to investigate the clays compatibility after orgophilization.

Abstract: The growing interesting in the use of silicon carbide in automotive components, biomaterials, energy, among others, which demand the production of parts with complex geometry that are difficult to obtain by conventional compaction techniques, motivates the search for developing new conformation processes. Within this context, this paper investigates the production of pieces of silicon carbide through the gelcasting process and subsequent green machining of these parts. Three systems of monomers were studied: MAM-NVP-MBAM, MAM-PEG (DMA) and MAM-HMAM. The effect of the concentration of monomers, concentration of chemical initiator and the ratio of chain-forming and crosslinker monomers on the cutting force during machining and surface roughness were evaluated. These data are compared with values of flexural strength and hardness of samples produced under the same conditions. Through a statistical analysis it was determined the best formulation for the production of parts of SiC with favorable characteristics of green machining.

Abstract: The aim of this work is to characterize by electrochemical, physicochemical and morphological analysis the hybrid films applied on galvanized steel by dip-coating process. Preliminaries studies showed that a monolayer of silane is not enough to increase the corrosion resistance protection of the substrate. In this context, the galvanized steel was coated with a double and triple layer of hybrid film obtained from a sol constituted by silane precursors 3 - (trimetoxisililpropil) methacrylate (TMSPMA) and tetraethoxysilane (TEOS) with addition of cerium nitrate at a concentration of 0.01M. The hybrid films were cured for 20 minutes at 60°C in each application of the film. The results showed that a double and triple layer of hybrid film increase the barrier effect contributing to corrosion protection of galvanized steel.

Abstract: The characteristics of siloxane-PMMA hybrid films permit the obtaining of coatings with thickness of few microns without cracking. Besides, the methacrylate groups (MMA) can be easily polymerizated by UV irradiation or thermal treatments. These hybrids can also be applied in anti-corrosive coatings for metals and alloys, replacing chromates which exhibit high toxicity. In this context, the aim of this work is to study the behavior of tinplate coated with a siloxane-PMMA hybrid film by dip-coating process and cured by thermal cure process. The systems were characterized by electrochemical, morphological and physicochemical analysis. Preliminary results showed that the systems studied presented a regular and adherent siloxane-PMMA hybrid film, which increased the corrosion resistance of tinplate substrates.

Abstract: In this research, glass beads with size range between 1.68 and 2mm were coated with 5 polymeric suspensions. The suspensions formulations differ in relation to their employment and physical properties (solids concentration, surface tension and rheology), generating different characteristics of wettability and adhesion with the nucleus. The aim of this study was to evaluate particle coating in a spouted bed through analysis of particle growth in terms of solid surface energy, wettability, and adhesion before and after the formation of the first layer of polymeric film on the particle. The solid-suspension and film-suspension systems were characterized by contact angle and surface energy. The operating conditions were fixed for all suspensions: 1.5 kg of beads, air velocity of 0.369 m/s, air temperature of 60 °C, suspension flow rate of 4 ml and atomizing pressure of 10 psig. Analyzing particle growth kinetics, different behaviors were observed and related not only to glass-suspension wettability, but also to polymeric film-suspension surface properties.

Abstract: Studies show that calcium phosphate coatings on titanium implants improve osseointegration at the implant-bone interface, due to the mineral biocompatibility. Titanium implants can be coated with calcium phosphates by a biomimetic precipitation method. This work studied a biomimetic method under a simplified solution with calcium and phosphorus ions. As substrates, commercially dense titanium sheet and macroporous titanium samples produced by powder metallurgy were used, both ASTM F67 grade 2. The substrates were submitted to chemical and heat treatment and then immersed in the solution for 10 days. Samples characterization was performed by Optical Microscopy (OM), Scanning Electron Microscopy/Energy Dispersive Spectroscopy (SEM/EDS), low angle X-ray Diffractometry (XRD) and Fourier Transform Infrared Spectroscopy (FTIR). Powder metallurgy successfully produced macroporous titanium substrates. Calcium phosphate coatings were deposited on both substrates, confirmed by FTIR bands. Such results indicated the potential of this methodology for calcium phosphate coatings on titanium substrates.