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In Brazil, ceramic plates are widely used in the construction industry for both small and large constructions in view of their advantages compared with other coating systems [1]. These advantages include ease of maintenance, durability, impermeability, and ease of cleaning. Despite these favorable characteristics, problems occur due to aging of a building. The most common of these problems is the loss of adhesion of ceramic tiles with facades [2]. It is commonly observed that after a few years of use the plates begin to loosen, thereby endangering individuals and properties.

Metal matrix composites (MMCs) are relatively new materials on science and materials engineering. In this work was used single-walled carbon nanotube (SWNT) as reinforcement in an aluminum matrix. For this purpose, 0.75% (by weight) of SWNT was dispersed with isopropanol using ultrasonication and mixed with particles of aluminum powder. The samples with and without SWNT were dried and compacted at room temperature with a pressure of 400 MPa for obtain a billet with 4,8x4,8x25,0 mm3. These compacted billet were subjected to Equal-Channel Angular Extrusion - ECAE (Φ=90 °) at room temperature. The influence of the presence of SWNT, of the number of extrusion passes (0, 1, and 3 passes), of the extrusion route (A or BC) and of the use of back pressure (0-65 MPa) in densification and hardness of the composite was evaluated. Optical microscopy was used to characterize the morphology of the aluminum grains, the dispersion of SWCNT and present pores in the samples. The results indicated that the density and hardness of the samples are increased with the increase in the number of extrusion passes and the use of back pressure. The microstructures showed alignment of the aluminum grains and of the CNT clusters in a direction close to the shear imposed by the ECAE process and increase of the dispersion because of the necking and defragmentation of the CNT clusters.

This work presents a study about thermal properties of a ceramic material based on NdBaCu system sintered with barium carbonate. These specialized ceramics are manufactured under special conditions and due to its unique electrical and thermal properties are frequently used by the electronic industry. Ceramics containing neodymium-barium-copper (NdBaCu) exhibit high conductivity at low temperatures. In this work, the ceramic samples were sintered with different percentage of barium carbonate, cupric and neodymium oxide and were characterized with Termogravimetric Analysis (TGA), Differential Scanning Calorimetric (DSC), Thermal Dilatometric Analysis (TDA) and X-Ray Diffraction Analysis (DRX). The results showed that the electrical conductivity of NdBaCu system is dependent on the calcination temperature. In turn, the complete calcination is dependent on the barium percentage and the thermal treatment conditions.

The gas separation is a very expensive step in the chemical industry and unquestionable relevance. In this work, was verified the efficiency of the use of type A-zeolites in the separation of CO2 in a gas mixture containing 25% CO2, 4% O2 and 71% N2. These concentrations are similar to the effluent gases from combustion processes. To this end, was synthesized type A-zeolites using commercial kaolin and mounted to an adsorption column to test the effectiveness of zeolites in the adsorption of CO2. The synthesized zeolites had surface area equal to 66.22 m2/g. The CO2 concentration was determined by gas chromatography with TCD detector. After adjusting the data to the Langmuir model, it was obtained the kinetic parameters of adsorption. Based on these parameters was found the ability of the zeolite to adsorb CO2, using a column of 0.461285 mg/g. The adsorption results have proved promising and showed maximum adsorption of 78.4% after a time of 10 seconds.

The use of waste to development of products has been an increasingly routine practice today. In this work was used rice husk ash from combustion boiler for energy for synthesis of sodium silicate. The silicate was obtained by means of ash fusion with sodium hydroxide at a temperature of 1200°C for 2 hours. For the synthesis of 4A-zeolite was performed hydrothermal reaction of sodium silicate, previously obtained with sodium aluminate and sodium hydroxide. The zeolite obtained was characterized by X-ray fluorescence, X-ray diffraction and scanning electron microscopy. The results have indicated the formation of 4A-zeolite.

This work evaluates fluorinated thin films and their composites for sensor development. Composites were produced using 5 µm starch particles and plasma films obtained from organic fluorinated and silicon compounds reactants. Silicon wafers and aluminum trenches were used as substrates. Film thickness, refractive index and chemical structure were also determined. Scanning electron microscopy shows conformal deposition on aluminum trenches. Films deposited on silicon were exposed to vapor of volatile organic compounds and CV curves were obtained. A qualitative model (FemLab 3.2® program) was proposed for the electronic behavior. These environmentally correct films can be used in electronic devices and preferentially reacted to polar compounds. Nonetheless, due to the difficulty in signal recovery, these films are more effective in one-way sensors, in sub-ppm range.

The aim of this work was production of tetraethoxysilane (TEOS) plasma polymerized thin films and optimization of their physical-chemical characteristic for sensor development. The films were analyzed using several techniques. It was possible to produce composites (graphite clusters imbibed by silicon oxide film) made from only one reactant (TEOS). Deposition rate can vary significantly, reaching a maximum of 30 nm/min; cluster formation and their size widely depending on deposition parameters. The film surface was hydrophobic but can be wetted by organic compounds, probably due to carbon radicals. These films are good candidates for sensor development.

This work aims to obtain plasma thin film composites with hydrophobic/hydrophilic alternated regions, which are useful for the production of miniaturized mixers. These regions were acquired by two different strategies: either the codeposition of TEOS and HFE plasma thin films or the exposition of TEOS plasma films to ultraviolet radiation (UVA and UVC). These films were characterized by several chemical and physical techniques. The refractive indexes vary from 1.4 to 1.7; infrared and photoelectron spectroscopy detect Si-O-Si and CHn species. Silicone-like structures with high or low number of amorphous carbon microparticles and with fluorinated organic clusters were produced. Cluster dimensions were in the 1-5 mm range and they are made of graphite or COF (carbon/oxygen/fluorine) compounds. Scanning electron and optical microscopy showed rough surfaces. Water contact angles were 90º; however, for TEOS films that value changed after 6 hr of UVC exposure. Moreover, after UV exposure, organic polar compounds could be adsorbed in those films and water was not. The passive mixer performance was simulated using the FemLab 3.2® program and was tested with 20 nm thick films on a silicon wafer, showing the capacity of these films to be used in such devices.

This work describes the production and characterization of a selective membrane useful for electronic devices. The membrane was a composite made by a thin film of plasma-polymerized HFE (methyl nonafluoro(iso)butyl ether) immersed in plasma-polymerized HMDS (hexamethyldisilazane) film, a third phase being 5 µm starch particles included in this matrix. The film was deposited on silicon substrates and its physical, chemical and adsorption characteristics were determined. Infrared and x-ray photoelectron spectroscopy analyses showed fluorine and carboxyl groups on the bulk and the surface, respectively. SEM results indicate the film is conformal even if starch is present. Optical microscopy analysis showed good resistance toward acid and base solutions. Quartz crystal microbalance indicated adsorption of polar organic compounds on ppm range. This thin film is environment-friendly and can be used as a protective layer or in electronic devices due to adsorption of volatile organic compounds.

In this work, microstructural changes in coatings deposited by hypersonic thermal spraying technique (HVOF) were subjected to adhesive wear tests. Materials subjected to wear lose efficiency, increase costs and direct or indirect way can stop large production systems. The mechanisms involved in this type of wear can be minimized by the microstructural changes that in many cases reduces or stops the loss of material. To perform this assessment coatings compounds of Cr3C225 (80 Ni-20 Cr) e Al2O3.TiO2 (87-13) investigated had similar hardness values (1000 HV) and chemical characteristics. Were subjected to the ASTM G99 using commercial hard metal pin 2 mm, load 50N force and tangential velocity of 0.5 m/s. Worn surfaces and debris were analyzed by optical microscopy, scanning electron microscope and mass loss. The results show high resistance sprayed coatings worn surfaces and debris were fragile nature with little loss of material during the tests.

Some materials have been applied in many surrounding conditions as sensors, electronic devices and other applications. Inexpensive and reliable temperature and flow measurement are important in many applications including, for example, environmental monitoring and control, indoor air conditioning, weather forecasting, automotive and aerospace systems. Special ceramics are an example of such materials. Neodymium-Barium-Copper is a special ceramic that has high electrical conductivity and airflow sensor characteristics. This property is influenced by high energy milling of the powder, when it is not sintered. To evaluate the influence of this type of milling it was carried out an analysis of particle size as a function of milling time. SEM images and granulometric analysis showed significant reduction of particle size with the increase of milling time. For longer times of milling the mixture of precursor powders is favored, resulting in better homogeneity of the ceramic. This is reflected in the properties of airflow sensor.

The present work studied the adsorption of ions of iron and manganese of the effluent from coal acid mine drainage (AMD), located in South of the Santa Catarina using for this purpose type 4A zeolite. Were tested the Langmuir adsorption isothermal model. Tests of adsorption of heavy metals were performed by varying the adsorption time and the ratio of the volume of effluent and the amount of adsorbent. The results showed the efficiency of kinetic adsorption of iron and manganese ions by the zeolite.

This study aims to evaluate the behavior of thermally sprayed coatings with the HVOF technique (High Velocity Oxygen Fuel), subject to tribological testing of reciprocal movement with the SAE 52100 flat steel pin, in accordance with ASTM G 133. The carbon with Cr2C3-25NiCr and WC-12Co were evaluated under conditions of intense surface fatigue. The microstructure and surface modifications were analyzed by optical microscopy and scanning electron microscopy. By using these techniques were possible to compare the modifications of the coatings under repeated loading conditions, and to expand the knowledge about wear mechanisms, mainly the adhesive one, present in several mechanical components, particularly in bearing and internal combustion engines. The coatings tested showed lower wear rate when compared to SAE52100 steel and equivalent behavior among the different loading conditions applied.

The aim of this work was to produce, to characterize and test selective membranes based on derivatives from organic fluorinated/silicon compounds. The produced composites presented silicon and fluorinated species on the surface. The morphology of these non uniform surfaces showed big domains in the micrometer scale but a closer view reveals structures also in the nanometer range. Contact angle measurements showed a mildly hydrophobic and organophilic surface. Polymeric tapes treated with this composite showed an increase on permeation rate for the organic compounds. An acrylic device that employed this modified polymeric tape was manufactured and used for sample pretreatment during chemical analysis.

The aim of this work was the production of a large surface area of hexamethyldisilazane (HMDS) plasma-deposited thin films and their applicability in a miniaturized structure useful for preliminary analysis of organic mixtures. The HMDS plasma films were produced with different surface areas and morphologies, and all films adsorbed polar and non-polar organic compounds. A low cost miniaturized structure was manufactured in glass using a Milling cutter and covered with HMDS plasma films. Good agreement was observed between simulation and experimental results on those microstructures. The observed different performance between pure and mixtures of organic compound samples suggests that the proposed system is a simple setup that could be useful for rough analysis of a fuel.

The machinery used in coal thermoelectrical plants usually is submitted to erosive wear. The erosive wear occurs mainly in the metallic pipe set of heat exchangers due the flow of hot gases carrying erosive particles. Jorge Lacerda’s thermoelectrical complex at Capivari de Baixo city holds seven power units, where two units use approximately 20 000 ASTM A178 heat pipes. The set is submitted to a semester maintenance schedule (preventive and corrective) where the damaged pipes are changed. So, in this work a set of erosive wear accelerated tests according ASTM G76 were performed in order to develop and specify materials and methods to diminish the erosive action caused by the combustion gases over the heat pipes. Specimens were coated with WC12Co and Cr3C2-25NiCr alloys using the HVOF technique and the coated specimens were tested at 450°C, the heat pipes working temperature. Silica was used as abrasive material at 30° and 45° impact angles, simulating a harder erosive condition than the real condition. The best performance coating at laboratory scale was later used in field condition. The results showed the coated specimen performance is better than the ASTM A178 alloy. The erosion resistance of the Cr3C2-25NiCr and WC12Co coatings is eight times higher than the uncoated alloy, and the coatings also presented a better corrosion resistance. This feature is important, because despite the erosive action the circulating gases also present a large amount of sulfur in their composition. Sulfur at lower temperatures forms H2SO4, causing intense corrosion of the pipes located at the heat exchangers colder parts. Based on the results and considering the coating costs the Cr3C2-25NiCr alloy was selected to coat a set of pipes mounted at the region of the heat exchanger with the most intense erosive wear. At the moment these coated tubes are in field operation and under observation regarding their performance in comparison with the uncoated pipes located at the same heat exchanger. The real operation conditions of the coated pipes will be estimated from the field life cycle analysis, and after all the cost-benefit of the studied coating.

Films produced by plasma polymerization of ethyl ether and methyl or ethyl acetate show good adsorption characteristic for polar and non-polar organic compounds. These films when used in microchannels machined in a 3D-structure present some preconcentration of organic compounds. Therefore, the aim of this work is to investigate the physical-chemical preconcentration mechanisms on this structure. The test molecules used were n-hexane and 2-propanol. Quartz crystal microbalance and mass spectrometry were used to measure preconcentration. Two different procedures for reactant injection on the structure were used: a continuous flow during several minutes or a small amount injected on a single pulse and in a few seconds. The microchannels were also modified by the introduction of small ceramic particles for enhancement of the flow dispersion. It was possible to notice for all films a similar kinetic of retention. The main removal mechanism is adsorption. Although all films can provide the removal of the adsorbents molecules, the most important characteristic for the adsorption and/or retention is the surface condition. Thus, the retention of polar compound can be troubled if a non-polar compound was used previously. The most promising films for retention are ethyl ether and ethyl acetate when n-hexane and 2-propanol are used as test molecules. The results using n-hexane or 2-propanol point out the use of low-cost microchannels for preconcentration development.