Desenvolvimento e caracterização de formulação cosmética contendo nanopartículas de dióxido de titânio para proteção solar

O protetor solar é um produto extremamente importante para proteger a pele da radiação ultravioleta proveniente do sol e capaz de reduzir a incidência de câncer de pele. Os filtros solares são divididos em orgânicos e inorgânicos e, dentre os inorgânicos, se encontra o TiO2 que atua refletindo, espalhando e absorvendo as radiações UV, além de ser fotoestável e de baixo potencial de irritabilidade dérmica. Neste trabalho foram desenvolvidas formulações cosméticas em forma de gel contendo nanopartículas de dióxido de titânio capazes de agir como fotoprotetores físicos e que mantem a transparência ao serem aplicados sobre uma superfície, como a pele. Foram desenvolvidos xerogéis a base de nanopartículas de TiO2 com tamanho e superfície controlados. A partir dessas nanopartículas foi possível preparar formulações cosméticas contendo nanopartículas redispersas de xerogéis a base de TiO2. Esses sistemas foram avaliados por testes de citotoxicidade e foi obtido um resultado favorável para a continuidade da pesquisa, sugerindo o uso deste material em humanos sem causar danos. Foram feitas as caracterizações físico químicas e estruturais. A análise de FPS indicou amplo espectro da formulação, o potencial zeta mostrou que é possível evitar aglomerações das nanopartículas em pHs utilizados para formulações tópicas, a reologia demonstrou que as formulações apresentam comportamento de recuperação da consistência e organização do material inicial após seu desarranjo durante o cisalhamento. As caracterizações serviram para obter um conhecimento da estrutura química e física das amostras que contém as nanopartículas de dióxido de titânio, para que seja possível fazer uma análise crítica e melhor qualificar o protetor solar desenvolvido.

Obtenção e caracterização de suporte de regeneração óssea de dióxido de titânio

Due to complications caused by metallic implants in the replacement of bone tissue, the biological application of ceramics raised and became a viable alternative. The titania has the ability to promote bone tissue regeneration based on its structure, mechanical and biologically properties compatibility. The present work aims at obtaining and characterization of Titania (TiO2) porous ceramics produced by the polymeric sponge method (replica method). Polyurethane sponge with 10 ppi and 15 ppi (pores per linear inch) were used. The process differentiation is the air blower used to remove excess slurry. The ceramics sponges were dried in an oven, then pre-sintered at 1000 o C and sintered at 1450 o C. The effect of direct sintering at 1450 o C was also assessed. The percentage of solids used to prepare the slurry was 40 to 45% by weight. To increase the surface porosity of the sponge, 20% of starch was added. There was difficulty on controlling the thickness of the slurry layers on the sponge which resulted in the variation of samples mechanical resistance. Despite this, the results obtained are quite promising for the proposed use, indicating that it is possible to obtain titania sponges with an apparent porosity of around 60%, a bulk density ranging from 40 to 47% and a compressive strength resistance – that with better control of layers depositions – can vary from 1 to 4 MPa

Análise da confiabilidade do ensaio de identificação de ligas através de espectrometria por fluorescência de raios x

In chemical industry, petrochemical and oil refinery may be found situations that working pressures and very high temperatures, and alloys that comprise such equipment must have specific characteristics such. As a way to ensure that the materials are as designed, companies have some specific techniques, and one of them is X-ray fluorescence spectrometry, which allows its application in devices small and lightweight, which ensures its portability in field use. This technique however, has some shortcomings such as the impossibility of detecting carbon and other elements of low atomic number which can generate false identifications of elements that are not in the league or non-detection of existing elements. Therefore, this study investigated the reliability of this method using the apparatus Niton XL3t 800 and may conclude that their results are reliable and can be used to assist in ensuring the operational integrity of the production units of these companies

Estudo da usinagem por torneamento de ligas de alumínio

The non-ferrous materials have got so many mechanical, physical and chemical advantageous properties so that is provided to them consolidated position in industry. In this context, aluminium alloys have been seen a lot on many applications of engineering areas – specially on automotive, aeronautical and aerospace due to their main properties such as low density, high corrosion resistance, favorable structure weight / material resistance relation, among others characteristics that are mencioned through this study. This study aims to analyze the aluminium alloys behavior on a general context when they are used on turning process, taking for examples the 6262 and 7050 aluminium alloys. In this way, the analysis studies the datas obtained during the turning tests realized on 3 steps each one; those datas are concerning the medium and total rugosities – obtained with the assistance of a portable Surface Roughness Finish Tester, as well as the chips obtained during the tests - visual analysis, and the cutting tools wear – with the assistance of an optical microscope, under different conditions of application of cutting fluids (dry machining, application of coolant in abundance and MQL – Minimum Quantity of Lubricant). The results concerning this study show detailed information about influence of cutting fluids on the machining by turning of the aluminium alloys related on this work and also about aluminium alloys in general when they are used on turning processes with different conditions from one another. By this way, it was evident the MQL technique is the best one for the 6262 alloy. However, for 7050 alloy, it was evident that the dry machining is responsible for the best results

Processo de fabricação de tarugos pelo método HotTop de ligas de alumínio da série 6XXX e as não conformidades desse processamento

The goal of this work is to report some problems that occur in the in the production of aluminum billets (series 6XXX) produced by the hot top process in the Alcoa aluminum Inc. The aluminum fabrication process is described from its first stage, since the mining until the reduction, smelting and treatment of the metal. One of the plant’s final product, are billets for clients that produce profiles by extrusion. The product’s final quality highly depends on the whole production process. Therefore it’s necessary to use good practices in the treatment of the metal, follow up its fabrication and control its thermal treatment, in order to meet the required standards to satisfy the clients. The billet’s production method and its variables will be detailed through temperature and casting speed, cone of water flow, cooling rate, duration of thermal treatment, degassing and metal “in line “filtering, in other words when it’s still found in its liquid state. The non-conformities of the process were studied by metallographic analysis, both macrostutural and microstructural that will be described and discussed in this work

Estudo da fluência dos aços inoxidáveis ferríticos estabilizados ao titânio e nióbio e simulação numérica do processo no abaqus

The purpose of this research was tested a finite element model (FEM) that represented the creep of a slab during the reheating process of hot rolling. The aim is to prevent creep phenomenon changing the reheating profile with hot tensile test in Gleeble 3500, and, also, understand the former defect crisis. The goal of this work is to have a predictive tool to optimize the reheating process changing parameters (length and thickness). Then, use input parameters obtained from the tests to approximate the solution of the problem aided by Abaqus CAE. The results have showed that the ferritic stainless steel AISI 409 has a lower sensitivity to creep comparing to the stainless steel AISI 409, AISI 430Ti, AISI 441 and AISI 444

Análise da curva de resfriamento e refino de grão da liga de alumínio AA 356

The macrostructure of an alloy solidification in the raw state is of utmost importance due to its influence on mechanical properties. A structure showing columnar grains is generally undesirable in most applications of cast products and grain refining aims to suppress the formation of these grains and get a fine-grained equiaxed structure that improves the supply of liquid metal and the mechanical properties, as yield strength and tensile strength limit, as well as the tendency of formation of hot cracks. The type and size of grains formed are determined by chemical composition, cooling rate and the use of inoculum for grain refining. Titanium and boron are the major refiners in the aluminum industry and can be added to the molten metal in the form of alloys such as Al-Ti, Al-Ti-B or Al-B. In this paper we will discuss the information obtained from cooling curves and first derivative of the cooling curve to obtain the thermal parameters that influence the process of grain refining alloy AA 356.0

Modificação da superfície do titânio e de sua liga Ti-6Al-4V por recobrimento com TiO2 e hidroxiapatita

In this work, the influence of modifications of the cp-Ti and Ti 6Al 4V alloy, by treating the surface with NaOH and depositing titanium oxide and hydroxyapatite by sol-gel method, on their biocompatibility was studied. The coatings were characterized by scanning electron microscopy and X-ray diffraction which showed that the coatings on Ti 6Al 4V are better than on cp-Ti. Adhesion tests showed that adhesion strength of the coatings on cp-Ti substrate is less than on Ti 6Al 4V as well as cytotoxicity for L929 fibroblast cells is higher

Desenvolvimento de formulações multifuncionais líquido cristalinas contendo nanopartículas de dióxido de titânio e alfa-tocoferol

A destruição da camada de ozônio resulta em um preocupante aumento na incidência de radiação ultravioleta (UV) na superfície da Terra, radiação esta, responsável pela ocorrência de danos na pele e pelo aparecimento do câncer de pele, tipo mais comum de câncer. Assim, neste trabalho foram desenvolvidos sistemas líquido-cristalinos multifuncionais contendo nanopartículas de dióxido de titânio, cuja propriedade fotoprotetora é bem conhecida, e alfa-tocoferol, um composto com ação antioxidante. Com isso, pretendeu-se desenvolver uma formulação que atue como protetor solar inorgânico, bloqueando a radiação UV e impedindo sua penetração que pode causar sérios danos à pele, além de conter o alfa-tocoferol que interage com os radicais livres, diminuindo os danos causados por estes. Para tanto, inicialmente foram preparadas formulações baseadas em dois diagramas de fases, as amostras que apresentaram separação de fase foram excluídas do trabalho, e as outras foram submetidas à análise de microscopia de luz polarizadas. Através da microscopia de luz polarizada foi possível concluir que a estrutura líquido-cristalina é mantida com a incorporação dos ativos no sistema, o que posteriormente foi confirmado com a análise por SAXS. A análise do potencial zeta permitiu verificar que na faixa de pH entre 5 e 7, indicada para produtos de uso tópico, é possível evitar aglomeração das partículas, e com isso obter um visual transparente do produto. A avaliação do comportamento possibilitou concluir que todas as amostras apresentaram uma consistência ideal para aplicação do produto na pele

Comportamento fractal de superfícies de fadiga em ligas aeronaúticas

Fracture surfaces express sequences of events of energy release with crack propagation in metal alloys, the evolution of topographic features can indicate the lines of load action, failures during the use or processing. The quantitative fractography is an important tool in the study of fracture surfaces, because it allows their interpretation and characterization. In order to evaluate the effectiveness of the characterization of fracture surfaces grounded on concepts such as selfsimilarity and self-affinity, it used the 15-5PH steel that was characterized by metallographic and tensile tests. The metallography allows the microstructural characterization of this steel and proved the presence of the martensite phase in the slats form and a fine-grained, both in the radial and in the axial direction of the dowel. The tensile test (ASTM E8) of this material allowed the determination of the mechanical properties, so based on the obtained results it was possible to affirm that the 15-5PH steel has high mechanical properties and a good stretch. Besides, the specimens also underwent testing of crack propagation, standardized by ASTM E647-00, thus it was obtained the fracture surfaces for characterization under monofractal and multifractal approaches. In front of all the exposed it was possible to conclude that in all measurements the correlation between the crack tip position and the fractal dimension was established in accordance with changes in the thickness and in the fracture micromechanisms presents. Furthermore, the multifractal approach was more sensitive to these variations allowing a more detailed characterization of the morphology

Avaliação do efeito ambiental nas propriedades mecânicas e viscoelásticas de compósitos híbridos de titânio/fibra de carbono/resina epóxi

Hybrid composites combining metal plates and laminates with continuous fiber reinforced polymer, called fiber-metal (CHMF), have been particularly attractive for aerospace applications, due mainly to their high mechanical strength and stiffness associated with low density. These laminates (CHMF) consist of a sandwich structure consisting of layers of polymer composites and metal plates, stacked alternately. This setting allows you to combine the best mechanical performance of polymer composites reinforced with long fibers, to the high toughness of metals. Environmental effects should always be considered in the design of structural components, because these materials in applications are submitted to the effects of moisture in the atmosphere, the large cyclical variations of temperature around 82 ° C to -56 ° C, and high effort mechanical. The specimens of fibermetal composite were prepared at EMBRAER with titanium plates and laminates of carbon fiber/epoxy resin. This study aims to evaluate the effect of different environmental conditions (water immersion, hygrothermal chamber and thermal shock) of laminate hybrid titanium/carbon fiber/epoxy resin. The effects of conditioning were evaluated by interlaminar shear tests - ILSS, tensile, and vibration free

Estudo do comportamento térmico e reológico de amidos na conformação cerâmica de compostos multicamada com alumina, titanato de alumínio e dióxido de titânio

The project aims to develop ceramic compounds with gradients of the mechanical properties, using the molding technique with commercial starches. To understand the process of interaction between starch and ceramic powders, the proposed methodology involves viscometry tests (up to 200 °C). Viscometric assays were carried out with slurries of alumina, titania and aluminum titanate with potato starch, cassava and corn. The specimens were tested for dilatometry, thermomechanical, thermal shock, mechanical and characterization by SEM. The ceramic powders and starches were analyzed using the optical microscope to measure the size of these. It was made of th kinetics of starch gelatinization and titania with the cornstarch in theoptical microscope to observe how the grains of starch behaved in welling

Crescimento de apatita na superfície da liga Ti-25Ta empregando dois tipos de tratamento de superfície: biomimético e deposição de polímero por eletrofiação

Titanium and its alloys has been widely used as materials for metallic biomaterials implants are usually employed to restore the hard tissue function, being used for artificial joints and bones, synthetic plates, crowns, dental implants and screws . Objective of this work was the surface modification of Ti-alloy 25Ta from biomimetic surface treatment of employment and deposition of polymer by electrospinning. The league was obtained from the fusion of the pure elements in the arc furnace with controlled atmosphere. The ingots were subjected to heat treatment, cold forged and sectioned discs with 13 mm diameter and 3 mm thick. Two surface treatments was evaluated, biomimetic and electrospinning with PCL fiber. The biomimetic treatment was performed involving alkaline treatment for three molarities 1.5M, 3M and 5M with immersion in SBF. The electrospinning was performed using PCL polymer alloy surface after the alkali treatment Ti25Ta 1M. For this group the polymer coated surfaces were immersed in calcium phosphate containing solution for immobilization of apatite. The results were compared with previous studies using surface treatment group to verify hydroxyapatite formation on the sample surface and it is concluded that the best condition is biomimetic treatment with 5M alkali treatment and heat treatment at 80 ° C for 72 hours

Estudo de tempos e temperaturas de sinterização na obtenção da liga NiTi por metalurgia do pó

The nickel-titanium alloys are very attractive and so it is widely used in industry, engineering applications in general and also in biomedical and dental applications. Besides showing the shape of memory effect, biocompatibility and superelastic, the alloy commercially known as Nitinol, has excellent mechanical properties. Most devices used in Brazil have been produced nationally, but using imported material is also necessary, which shows the need of produce the alloy nationally. In this study we have investigated the influence of sintering temperatures and times to obtain nickel-titanium alloys by powder metallurgy alloys and the characterization of the precipitated intermetallic phases by using the post-mix of elemental nickel and titanium in proportion of 49.5% Ti - 50.5% Ni. The samples were sintered at 930ºC for periods of 30, 40 and 50 hours and were characterized by optical microscopy using metallography and x-ray diffraction. The results of the study show that the 50 hours sintering time was the most suitable time for obtaining the alloy, observing a low volume of precipitated intermetallic phases and absence of Ni and Ti residuals

Usinabilidade e integridade superficial de implantes dentários

Pós-graduação em Engenharia Mecânica - FEIS