Produção de estrutura com gradiente de porosidade a partir da sinterização por plasma da mistura de pós Ti-Nb-Sn

Porous structures are being widely investigated for use in biomedical implants, aiming to mechanically integrate and functionally the implant inside the bone tissue. Moreover, this structure is also important for drugs that can be stored and can induce and accelerate the process of osseointegration. With the purpose to investigate this effect, Ti, Nb and Sn metal powders, were sintered by plasma using a hollow cathode discharge. Sintering was performed in argon plasma set at 4 mbar pressure and temperatures of 500 ° C, 600 ° C and 700 ° C. Samples were also sintered in the electrical resistance furnace at 1200 ° C in order to compare plasma sintering with the conventional method. It was observed that plasma samples sintered with the hollow cathode configuration showed a gradient in porosity, while the samples sintered in the resistive furnace did not. Furthermore, differences in the microstructure of the samples were found, were a surface with higher porosity and ales porous core were obtained at different temperatures. The percolation profile of distilled water and the chemical compositions of the porous layers of the plasma treated samples were the main results obtained. Based on these results, we can conclude that this structure is particularly important for application in the biomedical field such as scaffolds for drug delivery and implants

Avaliação das propriedades das fibras de algodões coloridos naturalmente e ecologicamente corretas cultivados nos assentamentos do município de Guamaré/RN

In this work evaluate the technical characteristics of the fibers grown in settlements Guamaré, colored cotton seeds were donated existing in the Germplasm Bank of Embrapa Cotton. We sought through the breeding program, raising the resistance, fineness, length and uniformity of cotton fibers, as well as stabilize the staining of fibers in the BRS Topaz, BRS Brown and BRS Green shades and raise their productivity in the field. First, the individual selections to test progeny seeds, and thereafter the hybridization method followed by family selection to obtain variations in the color tones were performed. The BRS Topaz, BRS Brown and BRS Green varieties were produced, analyzed and compared with existing cottons in the region which is the White cotton. The properties amount of impurities and neps, length, length uniformity, short fiber content, fineness and tensile strength of the fibers were sized in Classifiber, NATI, Pressley and Micronaire devices. 10 trials each with 10 tests for all four fiber types were carried out. The White and Topaz fibers showed greater length (32-34mm) and greater resistance (7.94 lb/mg and 7.97 lb/mg respectively) and showed finesse with lower micronaire index 3,71μg/inch and 3, 73μg/inch and a low rate of short fibers. The results were very promising for the use of genetically improved cotton in the manufacturing of fabric and yarn in the textile industry. The fibers were brown colored cotton used in the manufacture of a composite fiber with thermoplastic resin

Análise da formulação em Monte Carlo dos pacotes de energia multiespectrais aplicada a meios constituídos por vapor d'água

The Monte Carlo method is accurate and is relatively simple to implement for the solution of problems involving complex geometries and anisotropic scattering of radiation as compared with other numerical techniques. In addition, differently of what happens for most of numerical techniques, for which the associated simulations computational time tends to increase exponentially with the complexity of the problems, in the Monte Carlo the increase of the computational time tends to be linear. Nevertheless, the Monte Carlo solution is highly computer time consuming for most of the interest problems. The Multispectral Energy Bundle model allows the reduction of the computational time associated to the Monte Carlo solution. The referred model is here analyzed for applications in media constituted for nonparticipating species and water vapor, which is an important emitting species formed during the combustion of hydrocarbon fuels. Aspects related to computer time optimization are investigated the model solutions are compared with benchmark line-by-line solutions

Viabilidade técnica da fabricação de compósito utilizando fibra de pneu na fabricação de blocos intertravados

This work aims to demonstrate the feasibility of a ceramic composite containing fiber in the rubber manufacturing interlocking blocks. Gravel, sand, cement, rubber and fiber: the processes of manufacture and assembly of blocks produced and the various formulations studied with different proportions between the constituent elements were addressed. Mechanical properties were determined for the different formulations, compressive strength, diametral compressive strength, water absorption and apparent density, obeying the rules related to each property. It was concluded that the addition of rubber fiber gave the concrete studied resistance lower than conventional concrete which can be verified on the microstructural analysis obtained by SEM, which revealed the presence of pores and the low adhesion between the fiber and the matrix compression (tire fiber / cement paste). The composite of more viable tire BCPB1 (1/2) fiber can be used in places requests as light squares, pavements, roads and other cycle as well as in the manufacture of the curb and gutter, by having compressive strength in about 20 MPa

Densificação e microestrutura de um compósito Mo-Cu preparado a partir de um pó de heptamolibidato de amônia e cobre

The Cu-Mo system is a composite used in the electrical industry as material for electrical contact and resistance welding electrode as well as the heat sink and microwave absorber in microelectronic devices. The use of this material in such applications is due to the excellent properties of thermal and electrical conductivity and the possibility of adjustment of its coefficient of thermal expansion to meet those of materials used as substrates in the semiconductor micoreletrônic industry. Powder metallurgy through the processes of milling, pressing shaping and sintering is a viable technique for consolidation of such material. However, the mutual insolubility of both phases and the low wettability of liquid Cu on Mo impede its densification. However, the mutual insolubility of both phases and the low wettability of liquid Cu on Mo impede its densification. The mechanical alloying is a technique for preparation of powders used to produce nanocrystalline composite powder with amorphous phase or extended solid solution, which increases the sinterability immiscible systems such as the Mo-Cu. This paper investigates the influence of ammonium heptamolybdate (HMA) and the mechanical alloying in the preparation of a composite powder HMA-20% Cu and the effect of this preparation on densification and structure of MoCu composite produced. HMA and Cu powders in the proportion of 20% by weight of Cu were prepared by the techniques of mechanical mixing and mechanical alloying in a planetary mill. These were milled for 50 hours. To observe the evolution of the characteristics of the particles, powder samples were taken after 2, 10, 15, 20, 30 and 40 hours of milling. Cylindrical samples 5 to 8 mm in diameter and 3 to 4 mm thickness were obtained by pressing at 200 MPa to the mixed powders so as to ground. These samples were sintered at 1200 ° C for 60 minutes under an atmosphere of H2. To determine the effect of heating rate on the structure of the material during the decomposition and reduction of HMA, rates of 2, 5 and 10 ° C / min were used .. The post and the structures of the sintered samples were characterized by SEM and EDS. The density of the green and sintered bodies was measured using the geometric method (weight / volume). Vickers microhardness with a load of 1 N for 15 s were performed on sintered structures. The density of the sintered structures 10 ° C / min. reached 99% of theoretical density, how the density of sintered structures to 2 ° C / min. reached only 90% of the theoretical density

Análise de tensões integrada a sistema de engenharia reversa para projeto e confecção de próteses

This work consists of the conception, developing and implementation of a Computational Routine CAE which has algorithms suitable for the tension and deformation analysis. The system was integrated to an academic software named as OrtoCAD. The expansion algorithms for the interface CAE genereated by this work were developed in FORTRAN with the objective of increase the applications of two former works of PPGEM-UFRN: project and fabrication of a Electromechanincal reader and Software OrtoCAD. The software OrtoCAD is an interface that, orinally, includes the visualization of prothetic cartridges from the data obtained from a electromechanical reader (LEM). The LEM is basically a tridimensional scanner based on reverse engineering. First, the geometry of a residual limb (i.e., the remaining part of an amputee leg wherein the prothesis is fixed) is obtained from the data generated by LEM by the use of Reverse Engineering concepts. The proposed core FEA uses the Shell's Theory where a 2D surface is generated from a 3D piece form OrtoCAD. The shell's analysis program uses the well-known Finite Elements Method to describe the geometry and the behavior of the material. The program is based square-based Lagragean elements of nine nodes and displacement field of higher order to a better description of the tension field in the thickness. As a result, the new FEA routine provide excellent advantages by providing new features to OrtoCAD: independency of high cost commercial softwares; new routines were added to the OrtoCAD library for more realistic problems by using criteria of fault engineering of composites materials; enhanced the performance of the FEA analysis by using a specific grid element for a higher number of nodes; and finally, it has the advantage of open-source project and offering customized intrinsic versatility and wide possibilities of editing and/or optimization that may be necessary in the future

Contribuição ao estudo avançado das argamassas de alto desempenho para reparos estruturais

Inúmeras estruturas de concreto no Brasil e no mundo estão atingindo o limite de sua vida útil projetada, completando um ciclo de cinco ou mais décadas de uso e operação. Além das estruturas mais antigas, existem ainda estruturas com reduzido tempo de serviço, e qualidade discutível, que já apresentam patologias em estado tão avançado que chegam a comprometer o seu desempenho. Vindo ao encontro dessas necessidades e no sentido de contribuir para o avanço científico e tecnológico do setor, este trabalho apresenta um método para dosagem, preparo e aplicação de argamassas de alto desempenho para recuperação de estruturas deterioradas, além de sugerir procedimentos para a realização desses reparos, fomentando a cultura das manutenções preventivas e desmistificando a complexidade atribuída a tais operações. Para tanto, foram realizados ensaios mecânicos, microestruturais e relacionados à durabilidade em corpos-de-prova moldados com sílica ativa e látex de estireno-butadieno. Os resultados indicaram que a adoção desses ingredientes, na composição da argamassa de reparo, provocou uma redução significativa da permeabilidade total e descontinuidade de poros, assim como promoveu uma melhor integridade dos constituintes da argamassa, traduzindo-se em uma ampliação, expressiva, das suas capacidades mecânicas. Quando comparada aos produtos industrializados da construção civil, com padrões similares, proporcionou uma economia da ordem de 85%, que permitiria recuperar, com os mesmos custos, quase cinco vezes mais estruturas comprometidas. Este estudo, de viés altamente tecnológico, vem oferecer à construção civil uma argamassa polimérica de alto desempenho, com função reparadora e custo mais acessível, que pode ser adotada em canteiros de obras, implementando ações de natureza sustentável e ainda atendendo às atuais exigências elencadas pela literatura, relacionadas à desempenho, vida útil e durabilidade das estruturas reparadas.

Efeito da moagem de alta energia na densificação e microestrutura do compósito AI2O3-Cu

The Cu-Al2O3 composite ceramic combines the phase of alumina, which is extremely hard and durable, yet very brittle, to metallic copper phase high ductility and high fracture toughness. These characteristics make this material a strong candidate for use as a cutting tool. Al2O3-Cu composite powders nanocrystalline and high homogeneity can be produced by high energy milling, as well as dense and better mechanical structures can be obtained by liquid phase sintering. This work investigates the effect of high-energy milling the dispersion phase Al2O3, Cu, and the influence of the content of Cu in the formation of Cu-Al2O3 composite particles. A planetary mill Pulverisatte 7 high energy was used to perform the experiments grinding. Al2O3 powder and Cu in the proportion of 5, 10 and 15% by weight of Cu were placed in a container for grinding with balls of hard metal and ethyl alcohol. A mass ratio of balls to powder of 1:5 was used. All powders were milled to 100 hours, and powder samples were collected after 2, 10, 20, 50 and 70 hours of grinding. Composite powders with compact cylindrical shape of 8 mm diameter were pressed and sintered in uniaxial matrix resistive furnace to 1200, 1300 to 1350 °C for 60 minutes under an atmosphere of argon and hydrogen. The heating rate used was 10°C/min. The powders and structures of the sintered bodies were characterized by XRD, SEM and EDS. Analysis TG, DSC and particle size were also used to characterize the milled powders, as well as dilatometry was used to observe the contraction of the sintered bodies. The density of the green and sintered bodies was measured using the geometric method (mass / volume). Vickers microhardness with a load of 500 g for 10 s were performed on sintered structures. The Cu-Al2O3 composite with 5% copper density reached 61% of theoretical density and a hardness of 129 HV when sintered at 1300 ° C for 1h. In contrast, lower densities (59 and 51% of the theoretical density) and hardness (110 HV and 105) were achieved when the copper content increases to 10 and 15%.

Desenvolvimento de um sistema de captura de baixo custo destinado a determinação da cinemática humana

The motion capture is a main tool for quantitative motion analyses. Since the XIX century, several motion caption systems have been developed for biomechanics study, animations, games and movies. The biomechanics and kinesiology involves and depends on knowledge from distinct fields, the engineering and health sciences. A precise human motion analysis requires knowledge from both fields. It is necessary then the use of didactics tools and methods for research and teaching for learning aid. The devices for analysis and motion capture currently that are found on the market and on educational institutes presents difficulties for didactical practice, which are the difficulty of transportation, high cost and limited freedom for the user towards the data acquisition. Therefore, the motion analysis is qualitatively performed or is quantitatively performed in highly complex laboratories. Based is these problems, this work presents the development of a motion capture system for didactic use hence a cheap, light, portable and easily used device with a free software. This design includes the selection of the device, the software development for that and tests. The developed system uses the device Kinect, from Microsoft, for its low cost, low weight, portability and easy use, and delivery tree-dimensional data with only one peripheral device. The proposed programs use the hardware to make motion captures, store them, reproduce them, process the motion data and graphically presents the data.

Análise da eficácia de um refrigerador doméstico com condensador modificado: revestimento com meio poroso dissipativo

The development of home refrigerators generally are compact and economic reasons for using simplified configuration. The thermodynamic coefficient of performance ( COP ) is limited mainly in the condenser design for reasons of size and arrangement ( layout ) of the project ( design ) and climatic characteristics of the region where it will operate. It is noteworthy that this latter limitation is very significant when it comes to a country of continental size like Brazil with diverse climatic conditions. The COP of the cycle depends crucially on the ability of heat dissipated in the condenser. So in hot climates like the northeast, north, and west-central dispel ability is highly attenuated compared to the south and southeast regions with tropical or subtropical climates when compared with other regions. The dissipation in compact capacitors for applications in domestic refrigeration has been the focus of several studies, that due to its impact on reducing costs and power consumption, and better use of the space occupied by the components of refrigeration systems. This space should be kept to a minimum to allow an increase in the useful storage volume of refrigerator without changing the external dimensions of the product. Due to its low cost manufacturing, wire on tube condensers continue to be the most advantageous option for domestic refrigeration. Traditionally, these heat exchangers are designed to operate under natural convection. Not always, the benefits of greater compactness of capacitors for forced outweigh the burden of pumping air through the external heat exchanger. In this work we propose an improvement in convective condenser changing it to a transfer mechanism combined in series with conductive pipes and wire to a moist convective porous medium and the porous medium to the environment. The porous media used in the coating was composed of a gypsum plaster impregnated fiber about a mesh of natural cellulosic molded tubular wire mesh about the original structure of the condenser , and then dried and calcined to greater adherence and increased porosity. The proposed configuration was installed in domestic refrigeration system ( trough ) and tested under the same conditions of the original configuration . Was also evaluated in the dry condition and humidified drip water under natural and forced with an electro - fan ( fan coil ) convection. Assays were performed for the same 134- refrigerant charge e under the same thermal cooling load. The performance was evaluated in various configurations, showing an improvement of about 72 % compared with the original configuration proposed in humidification and natural convection.

Síntese e imobilização de nanopartículas de ouro em fibras regeneradas via exaustão para potencial aplicação biomédica

The advancement of nanotechnology in the synthesis and characterisation of nanoparticles (NP's) has played an important role in the development of new technologies for various applications of nano-scale materials that have unique properties. The scientific development in the last decades in the field of nanotechnology has sought ceaselessly, the discovery of new materials for the most diverse applications, such as biomedical areas, chemical, optical, mechanical and textiles. The high bactericidal efficiency of metallic nanoparticles (Au and Ag), among other metals is well known, due to its ability to act in the DNA of fungi, viruses and bacteria, interrupting the process of cellular respiration, making them important means of study, in addition to its ability to protect UVA and UVB. The present work has as its main objective the implementation of an innovative method in the impregnation of nanoparticles of gold in textile substrate, functionalized with chitosan, by a dyeing process by exhaustion, with the control of temperature, time and velocity, thus obtaining microbial characteristics and UV protection. The exhausted substrates with colloidal solutions of NPAu's presented the colours, lilac and red (soybean knits) due to their surface plasmon peak around 520-540 nm. The NPAu's were synthesized chemically, using sodium citrate as a reducing agent and stabilizer. The material was previously cationised with chitosan, a natural polyelectrolyte, with the purpose of functionalising it to enhance the adsorption of colloid, at concentrations of 5, 7, 10 and 20 % of the bonding agent on the weight of the material (OWM). It was also observed, through an experimental design 23 , with 3 central points, which was the best process of exhaustion of the substrates, using the following factors: Time (min.), temperature (OC) and concentration of the colloid (%), having as a response to variable K/S (ABSORBÂNCIA/ Kubelka-Munk) of the fibres. Furthermore, it was evidenced as the best response, the following parameters: concentration 100%, temperature 70 ºC and time 30 minutes. The substrate with NPAu was characterised by XRD; thermal analysis using TGA; microstructural study using SEM/EDS and STEM, thus showing the NP on the surface of the substrate confirming the presence of the metal. The substrates showed higher washing fastness, antibacterial properties and UV radiation protection.

Influência da superfície do titânio nitretado a plasma em diferentes atmosferas na ativação de plaquetas sanguíneas

This study aimed to analyze the biological response of titanium surfaces modified by plasma Ar + N2 + H2. Titanium disks grade II received different surface treatments Ar + N2 + H2 plasma, constituting seven groups including only polished samples used as standard. Before and after treatment the samples were evaluated in terms of topography, crystal structure and wettability, using atomic force microscopy, X-ray diffraction, Raman spectroscopy and testing of the sessile drop, respectively. Rich plasma (PRP) was applied to the surfaces modified in culture plates. Images obtained by scanning electron microscopy of the adhered platelets were analyzed to verify the behavior of platelets in the different experimental conditions. We verified that the adition of H2 on plasma atmosphere resulted in more rough surfaces, with round tops. These surfaces, in contrast to that surfaces treated with high concentration of N2, are less propense to platelet aggregation and, consequently, to the formation of thrombus when applied in biomedical devices.

Reaproveitamento de condensado e vapor flash em uma planta têxtil com ênfase no setor de acabamento

This study focused object a steam generation system, steam distribution and condensate return a textile plant located in Rio Grande do Norte. The work was based on the following objectives: Knowing the use of saturated water vapor in the dyeing and finishing processes in a textile plant; To study the various aspects of a steam distribution system to identify the ways in which energy losses occur; Obtain quantitative information of the main loss in steam generation system and steam distribution and to measure the losses, water and steam system; Using the flash steam as a means of cost reduction. For it was made use of the calculation of financial gains made in their respective improvements. As a database for the development of working registers are used in industrial processes, data from utility systems, laboratory data analysis and on-line analyzers, covering the period 2013. Using the principles set conservation laws mass and energy, those data showed that the loss of water and energy in the steam system are significant and that the environmental and economic gains to be obtained with improvement actions are quite significant. Based on the data and results suggest that future studies deem the continuity approach to steam generation systems, distribution and mainly condensate return.

Estudo de um secador híbrido (solar-elétrico) para desidratação de frutas

The growing need for food is something that worries the world, which has a population that is growing at a geometric progression while their resources grows at an arithmetic progression. To alleviate this problem there are some proposals, including increased food production or reduce waste thereof. Many studies have been conducted in the world in order to reduce food waste that can reach 40% of production, depending on the region. For this purpose techniques are used to retard degradation of foods, including drying. This paper presents a design of a hybrid fruit dryer that uses solar energy and electric energy with automation of the process. To accomplish drying tests were chosen Typical fruits with good acceptability as processed fruits. During the experiments were measured temperature values at different points. Were also measured humidity values, solar radiation and mass. A data acquisition system was built using a Arduino for obtaining temperatures. The data were sent to a program named Secador de Frutas, done in this work, to plot the same. The volume of the drying chamber was 423 liters and despite the unusual size test using mirrors to increase the incidence of direct radiation, showed that the drier is competitive when compared with other solar dryers produced in Hydraulic Machines and Solar Energy Laboratory (LMHES ) UFRN. The drier has been built at a cost of 3 to 5 times smaller than industrial dryers that operate with the same load of fruit. And the energy cost to produce dried fruits was more feasible compared with such dryers that use LPG as an energy source. However, the drying time was longer.

Estudo do comportamento da sinterização de compactos de cavacos de um aço SAE 1050 obtidos sob alta pressão

From an economic standpoint, the powder metallurgy (P/M) is a technique widely used for the production of small parts. It is possible, through the P/M and prior comminution of solid waste such as ferrous chips, produce highly dense sintered parts and of interest to the automotive, electronics and aerospace industries. However, without prior comminution the chip, the production of bodies with a density equal to theoretical density by conventional sintering techniques require the use of additives or significantly higher temperatures than 1250ºC. An alternative route to the production of sintered bodies with high density compaction from ferrous chips (≤ 850 microns) and solid phase sintering is a compression technique under high pressure (HP). In this work, different compaction pressures to produce a sintered chip of SAE 1050 carbon steel were used. Specifically, the objective was to investigate them, the effect of high pressure compression in the behavior of densification of the sintered samples. Therefore, samples of the chips from the SAE 1050 carbon steel were uniaxially cold compacted at 500 and 2000 MPa, respectively. The green compacts obtained were sintered under carbon atmosphere at 1100 and 1200°C for 90 minutes. The heating rate used was 20°C/min. The starting materials and the sintered bodies were characterized by optical microscopy, SEM, XRD, density measurements (geometric: mass/volume, and pycnometry) and microhardness measurements Vickers and Rockwell hardness. The results showed that the compact produced under 2000 MPa presented relative density values between 93% and 100% of theoretical density and microhardness between 150 HV and 180 HV, respectively. In contrast, compressed under 500 MPa showed a very heterogeneous microstructure, density value below 80% of theoretical density and structural conditions of inadequate specimens for carrying out the hardness and microhardness measurements. The results indicate that use of the high pressure of ferrous chips compression is a promising route to improve the sinterability conditions of this type of material, because in addition to promoting greater compression of the starting material, the external tension acts together with surface tension, functioning as the motive power for sintering process. Additionally, extremely high pressures allow plastic deformation of the material, providing an intimate and extended contact of the particles and eliminating cracks and pores. This tends to reduce the time and / or temperature required for good sintering, avoiding excessive grain growth without the use of additives. Moreover, higher pressures lead to fracture the grains in fragile or ductile materials highly hardened, which provides a starting powder for sintering, thinner, without the risk of contamination present when previous methods are used comminution of the powder.