FEA and microstructure characterization of a one-piece Y-TZP abutment

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

Biomechanical Study in Polyurethane Mandibles of Different Metal Plates and Internal Fixation Techniques, Employed in Mandibular Angle Fractures

The aim of this study was to perform a physicochemical and morphological characterization and compare the mechanical behavior of an experimental Ti-Mo alloy to the analogous metallic Ti-based fixation system, for mandibular angle fractures. Twenty-eight polyurethane mandibles were uniformly sectioned on the left angle. These were divided into 4 groups: group Eng 1P, one 2.0-mm plate and 4 screws 6 mm long; group Eng 2P, two 2.0-mm plates, the first fixed with 4 screws 6 mm long and the second with 4 screws 12 mm long. The same groups were created for the Ti-15Mo alloy. Each group was subjected to linear vertical loading at the first molar on the plated side in a mechanical testing unit. Means and standard deviations were compared with respect to statistical significance using ANOVA. The chemical composition of the Ti-15Mo alloy was close to the nominal value. The mapping of Mo and Ti showed a homogeneous distribution. SEM of the screw revealed machining debris. For the plates, only the cpTi plate undergoes a surface treatment. The metallographic analysis reveals granular microstructure, from the thermomechanical trials. A statistically significant difference was found (P < 0.05) when the comparison between both internal fixation techniques was performed. The 2P technique showed better mechanical behavior than 1P.

COMPARISON BETWEEN MECHANICAL PROPERTIES AND MICROSTRUCTURE OF ALLOY TI-6AL4V, COLD WORK VERSUS PROTOTIPES BY DIRECT METAL LASER SINTERING

The present work aims to study the microstructure and mechanical properties of titanium alloys, widely used in the manufacture of orthopedic implants in order to compare a new manufacturing technology of implants, rapid prototyping in metals with conventional manufacturing processes. Rapid prototyping is being used in many areas of human knowledge to assist in the study and often in the manufacture of components for their own use. Nowadays with the advancement of software and equipment such as computed tomography and magnetic resonance imaging, we can reproduce any part of the human body in three-dimensional images with great perfection and it is used in the reproduction of implants, scaffolds, material aid and preparation in surgery. This work aims to do: A comparison between the microstructure of the alloy in the two manufacturing processes (prototyping and conventional), showing the grain size, the nature, form, quantity, and distribution of various ingredients or certain inclusions and study of mechanical properties of titanium in both cases.

Um estudo sobre a preparação metalográfica da liga de aluminio AA7075-T6

The increasing technological innovation and demand for materials with better properties boosts research into new materials and new alloys. To do so, aluminum alloys are being developed, among them the AA7075-T6, having many applications in aerospace and military industries, machinery and equipment, molds for plastic injection and structures. To study and understand the properties, characteristics and especially the microstructure of the material, the metallographic preparation is essential. This paper presents new methodologies to achieve the metallography of samples of scrap alloy AA7075-T6, with emphasis on methods of polishing. For the five samples, the best results were those with specific grinding, the samples only going down on the sander. For polishing, the most effective method so far has been using the polishing cloth 16.3, of ATM enterprise, solution of diamond 3 μm, solution of diamond 1 μm, and colloidal solution of OP-S. For the etching, the reactive agent used was phosphoric acid (H3PO4) 85% P.A., as 90% in the proportion of distilled water to 10% acid. The best results were obtained in the attacks of 300 and 240 seconds, revealing the grain boundaries in most areas. Methodologies need more studies and more tests, but the results have proved to be satisfactory

Caracterização microestrutural de uma estrutura tubular aeronáutica submetida a sucessivos reparos de solda TIG

This work examines the possible effects of successive repair procedures on the microstructure of welded steel SAE 4130 by TIG welding process. Discussions and results were made about the metallographic analysis , non-metallic inclusions and microhardness tests , which were conducted on samples taken from the cradle engine component after the end of its life , a model airplane T-27 Tucano , made by EMBRAER and belonging were performed FAB . The choice of such component is due to the fact that this is critical to flight safety since it provides support for the aircraft engine . Thus regions of the weld metal , base metal and heat affected , with samples of the original weld bead , free of weld bead and also with four rework procedures for TIG welding zone were analyzed . It was found that after the fourth rework there is an increase in the amount of martensite , which may weaken the material with respect to resistance to fatigue. It was also found that the regions of the heat affected zone and weld metal have higher microhardness values when compared to those found in the base metal due to favoring the formation of ferritic and tempered martensite microstructures . Moreover, a welding process promotes a region with less non-metallic inclusions than metal base , which also explains the difference in the results obtained

Aços avançados de alta resistência: avaliação da microestrutura e propriedades dos aços DP 600 E DP 780

This work aims to study the Dual-Phase 600 and 780 steels, which are part of technology development project materials for the automotive industry. It is worth underscoring the antagonistic properties as the Dual-Phase steel assemble, high mechanical strength and elongation due its microstructure, ferrite and martensite. These properties are obtained by a intercritical heat treatment which facilitates the formation of a hardness metastable microstructure shaped plates of low carbon steels. The applicability of Dual Phase steel in the structure of vehicles is huge and its production is already on a commercial scale, so the study and development of this material implies lower cost in automobile manufacturing processes. The dual phase steels DP600 and DP780 underwent tensile, hardness and metallographic analysis to evaluate and comparing its properties. The results indicate that the DP780 steel has higher strength and hardness than the DP600 steel and its microstructure consists of martensite higher fraction which accounts for the higher resistance and hardness. However, the DP600 has higher conformability to DP780 steel

Estudo da fadiga em liga de alumínio aeronáutico 7475-T761

This work will address the study of fatigue conditions with constant load in an alloy of aluminum analysis 7475 - T761, so we can better understand the conditions of the aircrafts which contain this alloy in their structures. A literature review, which was discussed the concepts of fracture mechanics, fatigue, aeronautical components, chemical analysis of aluminum alloys, fatigue problems that appears in the aircrafts, metallographic analysis, and testing of optical microscopy tensile, fatigue and microhardness, surface analysis (MEV) study of the chemical composition of the alloy in question, the main causes of crashes, was performed, completing the work, analysis of data from tensile test, hardness and fatigue together with the interpretation of images of optical microscopy and scanning electron was taken. The data indicated the high mechanical strength of the alloy, along with its microstructure indicating elongated grains and high surface contour, which shows such resistance by hindering the movement of dislocations. The grooves are clearly shown in the MEV images as well as the classic with increased fatigue loading and subsequent reduction of the number of cycles to rupture behavior shown in the graphs. Therefore we observed the optimal behavior is supported by the league when subjected to fatigue loadings

Análise metalográfica do titânio puro submetido à soldagem laser Nd: YAG e TIG

Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)

Influência da adição do nióbio no comportamento mecânico e microestrutural do aço SAE 6150

Pós-graduação em Engenharia Mecânica - FEG

Chromosomal Microstructure Diversity in Three Astyanax (Characiformes, Characidae) Species: Comparative Analysis of the Chromosomal Locations of the 18S and 5S rDNAs

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)

The changes on microstructure and electrical properties of Bi:2223/Ag composite as a function of the granulation and the content of the added silver powder

The Bi-Sr-Ca-Cu-O system has been one of the most studied superconducting ceramic materials for industry applications. The most of the studies with this aim are on silver/ceramic composites, due to the benefits and great compatibility of this metal with the oxide. In this paper we describe a systematic and comparative study on Ag/BSCCO composite, made by the citrate route, in which the ceramic pellets are sintered in the presence of silver powder using several proportions and having several granulations. It was observed that the introduction of fine (0.5 and 2 μm) silver powder in the proportions of 5 wt. % always implies in a better critical current density compared to the no silver pellet. According to the results, the silver powder in excess of 5 wt.% may not promote best electrical properties, depending on the size of the silver particles.

Caracterização microestrutural e propriedades mecânicas em pinos para transmissão mecânica de aço inoxidável martensítico e pinos fusíveis de latão em chave de alta tensão

Pós-graduação em Engenharia Mecânica - FEB

Recycling leather waste: preparing and studying on the microstructure, mechanical, and rheological properties of leather waste/rubber composite

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

Recycling leather waste: preparing and studying on the microstructure, mechanical, and rheological properties of leather waste/rubber composite

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

Structure, microstructure, and selected mechanical properties of Ti-Zr-Mo alloys for biomedical applications

New titanium alloys for biomedical applications have been developed primarily with the addition of Nb, Ta, Mo, and Zr, because those elements stabilize the β phase and they don’t cause cytotoxicity in the organism. The objective of this paper is to analyze the effect of molybdenum on the structure, microstructure, and selected mechanical properties of Ti-15Zr-xMo (x = 5, 10, 15, and 20 wt%) alloys. The samples were produced in an arc-melting furnace with inert argon atmosphere, and they were hot-rolled and homogenized. The samples were characterized using chemical, structural, and microstructural analysis. The mechanical analysis was made using Vickers microhardness and Young’s modulus measurements. The compositions of the alloys were sensitive to the molybdenum concentration, indicating the presence of α’+α”+β phases in the Ti-15Zr-5Mo alloy, α”+β in the Ti-15Zr-10Mo alloy, and β phase in the Ti-15Zr-15Mo and Ti-15Zr-20Mo alloys. The mechanical properties showed favorable values for biomedical application in the alloys presenting high hardness and low Young’s modulus compared with CP-Ti.