Tratamento térmico do titânio e suas consequências sobre as propriedades físico-químicas e de biocompatibilidade

The titanium and titanium alloys are widely used as biomaterial in biomedical device and so research have been developed aiming to improve and/or better to understand interaction biomaterial/biological environment. The process for manufacturing of this titanium implants usually involves a series of thermal and mechanical processes which have consequence on the final product. The heat treatments are usually used to obtain different properties for each application. In order to understand the influence of these treatments on the biological response of the surface, it was done, in this work, different heat treatments in titanium and analyzed their influence on the morphology, adhesion and proliferation of the pre-osteoblastic cells (MC3T3-E1). For such heat-treated titanium disks were characterized by optical microscopy, contact angle, surface energy, roughness, microhardness, X-ray diffraction and scanning through the techniques (BSE, EDS and EBSD). For the analysis of biological response were tested by MTT proliferation, adhesion by crystal violet and β1 integrin expression by flow cytometry. It was found that the presence of a microstructure very orderly, defined by a chemical attack, cells tend to stretch in the same direction of orientation of the material microstructure. When this order does not happen, the most important factor influencing cell proliferation is the residual stress, indicated by the hardness of the material. This way the disks with the highest level state of residual stress also showed increased cell proliferation

Síntese hidrotérmica assistida por micro-ondas de tiO2, e aplicação em nanocompósito

In recent decades have seen a sharp growth in the study area of nanoscience and nanotechnology and is included in this area, the study of nanocomposites with self-cleaning properties. Since titanium dioxide (TiO2) has high photocatalytic activity and also antimicrobial, self-cleaning surfaces in your application has been explored. In this study a comparison was made between two synthesis routes to obtain TiO2 nanoparticles by hydrothermal method assisted by microwave. And after analysis of XRD and SEM was considered the best material for use in nanocomposites. It was deposited nanocomposite film of poly (dimethyl siloxane) (PDMS) with 0.5, 1, 1.5 and 2% by weight of nanoparticles of titanium dioxide (TiO2) by the spraying method. The nanocomposite was diluted with hexane and the suspension was deposited onto glass substrate, followed by curing in an oven with forced air circulation. The photocatalytic activity of the nanocomposite impregnated with methylene blue was evaluated by UV- vis spectroscopy from the intensity variation of absorption main peak at 660nm with time of exposure to the UV chamber. Changes in the contact angle and microhardness were analyzed before and after UV aging test. The effect of ultraviolet radiation on the chemical structure of the PDMS matrix was evaluated by spectrophotometry Fourier transform infrared (FTIR).The results indicated that the addition of TiO2 nanoparticles in the coating PDMS gave high photocatalytic activity in the decomposition of methylene blue, an important characteristic for the development of self-cleaning coatings

Desenvolvimento e caracterização de um compósito matriz metálica (CMM): aço EUROFER97 reforçado com Carbeto de Tântalo - TaC

Steel is an alloy EUROFER promising for use in nuclear reactors, or in applications where the material is subjected to temperatures up to 550 ° C due to their lower creep resistance under. One way to increase this property, so that the steel work at higher temperatures it is necessary to prevent sliding of its grain boundaries. Factors that influence this slip contours are the morphology of the grains, the angle and speed of the grain boundaries. This speed can be decreased in the presence of a dispersed phase in the material, provided it is fine and homogeneously distributed. In this context, this paper presents the development of a new material metal matrix composite (MMC) which has as starting materials as stainless steel EUROFER 97, and two different kinds of tantalum carbide - TaC, one with average crystallite sizes 13.78 nm synthesized in UFRN and another with 40.66 nm supplied by Aldrich. In order to improve the mechanical properties of metal matrix was added by powder metallurgy, nano-sized particles of the two types of TaC. This paper discusses the effect of dispersion of carbides in the microstructure of sintered parts. Pure steel powders with the addition of 3% TaC UFRN and 3% TaC commercial respectively, were ground in grinding times following: a) 5 hours in the planetary mill for all post b) 8 hours of grinding in the mill Planetary only for steel TaC powders of commercial and c) 24 hours in the conventional ball mill mixing the pure steel milled for 5 hours in the planetary mill with 3% TaC commercial. Each of the resulting particulate samples were cold compacted under a uniaxial pressure of 600MPa, on a cylindrical matrix of 5 mm diameter. Subsequently, the compressed were sintered in a vacuum furnace at temperatures of 1150 to 1250 ° C with an increment of 20 ° C and 10 ° C per minute and maintained at these isotherms for 30, 60 and 120 minutes and cooled to room temperature. The distribution, size and dispersion of steel and composite particles were determined by x-ray diffraction, scanning electron microscopy followed by chemical analysis (EDS). The structures of the sintered bodies were observed by optical microscopy and scanning electron accompanied by EDS beyond the x-ray diffraction. Initial studies sintering the obtained steel EUROFER 97 a positive reply in relation to improvement of the mechanical properties independent of the processing, because it is obtained with sintered microhardness values close to and even greater than 100% of the value obtained for the HV 333.2 pure steel as received in the form of a bar

Estudo da viabilidade do processo de reciclagem do material descartado do sistema Zirkonzanh® de produção de próteses dentárias

At present, the material of choice for performing aesthetic dental prosthetic work is in the ceramic. Among them, the ceramic base of stabilized zirconia with 3% yttria (3Y - TZP) stand out for having excellent physical and mechanical properties. During the machining of blocks of zirconia in the laboratory to prepare the various types of prostheses, much of the material is given off in the form of powder, which is subsequently discarded. The waste of this material results in financial loss, reflecting higher final cost treatment for patients, as well as damage to the environment, thanks to the processes involved in the manufacture and disposal of the ceramic. This research, pioneered the recycling of zirconium oxide powder obtained during milling of dental crowns and bridges, we highlight the social and environmental aspects and aims to establish a protocol for the reuse of waste (powder of zirconia Zirkonzahn® system) discarded to obtain a new block of compacted zirconia to maintain the same mechanical and microstructural properties of commercial high-cost imported material. To compare with the commercial material, samples were uniaxially (20 MPa) and isostatically (100 MPa), and its mechanical and microstructural characterization was performed through tests of density, porosity, dilatometry, X-ray diffraction (XRD), hardness, fracture toughness, resistance to fracture electron microscopy (SEM) and analysis of grain size. The results observed in the samples were isostatically pressed similiares those obtained with samples from the commercial material demonstrating the viability of the process

Pastas compósitas cimento/sílica/polímero para cimentação de poços de baixa profundidade sujeitas à injeção de vapor

The production of heavy oil fields, typical in the Northeastern region, is commonly stimulated by steam injection. High bottom hole temperatures are responsible not only for the development of deleterious stresses of the cement sheath but also for cement strength retrogression. To overcome this unfavorable scenario, polymeric admixtures can be added to cement slurries to improve its fracture energy and silica flour to prevent strength retrogression. Therefore, the objective of the present study was to investigate the effect of the addition of different concentrations of polyurethane (5-25%) to cement slurries containing 40% BWOC silica flour. The resulting slurries were characterized using standard API (American Petroleum Institute) laboratory tests. In addition to them, the mechanical properties of the slurries, including elastic modulus and microhardness were also evaluated. The results revealed that density, free water and stability of the composite cement/silica/polyurethane slurries were within acceptable limits. The rheological behavior of the slurries, including plastic viscosity, yield strength and gel strength increased with the addition of 10% BWOC polyurethane. The presence of polyurethane reduced the fluid loss of the slurries as well as their elastic modulus. Composite slurries also depicted longer setting times due to the presence of the polymer. As expected, both the mechanical strength and microhardness of the slurries decreased with the addition of polyurethane. However, at high bottom hole temperatures, the strength of the slurries containing silica and polyurethane was far superior than that of plain cement slurries. In summary, the use of polyurethane combined with silica is an interesting solution to better adequate the mechanical behavior of cement slurries to heavy oil fields subjected to steam injection