Análise macro e micrográfica da liga AA-356 conforme a taxa de resfriamento

The present work aims to study the characteristics of the alloy Al - 7 % Si - 0 , 3Mg ( AA356 ) , more specifically characterize the macrostructure and microstructure and mechanical properties of the alloy ingots AA356 obtained in metal molds and sand molds for power studying the structures through the difference of cooling rates . This alloy is explained by the fact of referring league has excellent combination of properties such as low solidification shrinkage and good fluidity, good weldability , high wear resistance , high strength to weight ratio, has wide application in general engineering , and particularly in the automotive and aerospace engineering . In this work we will verify this difference in properties through two different cooling rates . We monitor the solid solidification temperatures by thermocouples building with them the cooling curve as a tool that will aid us to evaluate the effectiveness of the grain refining because it achieved with some important properties of the alloy as the latent heat of solidification fraction the liquid and solid temperatures, the total solidification time, and identify the presence of inoculants for grain refinement. Thermal analysis will be supported by the study of graphic software “Origin “will be achieved where the cooling curve and its first derivative that is the cooling rate. Made thermal analysis, analysis will be made in macrographs ingots obtained for observation of macrostructures obtained in both types of ingots and also analysis of micrographs where sampling will occur in strategic positions ingots to correlate with the microstructure. Finally will be collecting data from Brinell hardness of ingots and so then correlating the properties of their respective ingots with cooling rate. We found that obtained with cast metal ingots showed superior properties to the ingots obtained with sand mold

Usinagem da liga de níquel inconel 718 com pastilhas de cerâmica

The machining of super alloys resistant to high temperatures such as nickel alloys, inconel 718 specifically, is a very difficult job to obtain improvements in the process, due to the difficulty of machining at high cutting speeds, the use of these alloys in industries showed great developments in recent years, its application in aeronautical industry spread being used in vane turbo, compressor parts, props and set elements. The automotive, chemical, medical and others also took advantage of the great features of inconel 718 and has used the material. The high temperature resistant alloys have high machining difficulty, a fact that is associated with high cutting forces generated during machining which result in high temperatures. High levels of temperatures can cause deterioration of the cutting edge, with subsequent deformation or breakage, wear most common obtained in machining such materials are flank wear the formation of built-up edge for cutting and notch wear. The experimental part of the work consists in machining of nickel-based alloy Inconel 718 heat treated for hardness, using a tool based ceramic silicon nitride Sandvik (Si3N4) in order to compare the best results obtained in the master's thesis of SANTOS (2010) who used a tool ceramics also the basis of silicon nitride which was developed in the doctoral thesis of SOUZA (2005). Assays were performed on a CNC lathe and was noted for each cutting edge results obtained. Tests were made starting from an initial condition of the tool with cutting speed of 200 m/min, feed 0.5 mm and 0.5 mm depth of cut was reduced cutting speed for the subsequent tests with the same conditions of feed and depth of cut. The tool presented wear instant under two 200 m/min and 100 m/min, premature rupture of 50 m/min and finally cut provided with difficulty... (Complete abstract click electronic access below)

Processamento de peças em materiais compósitos para o projeto BAJA SAE

The weight of a vehicle has always been considered an extreme important factor, because it interferes in the performance, steering, consume, environmental impact, wear of components, among the others. Because of the new demand, consume reduction aim and gases emission increased the necessity to manufacture lighter vehicles, guaranteeing the complying with the gas emission international law. Besides the legal demand, the low weight will certainly be essential for the competitiveness for the next generation of vehicles. It is with this thinking the composite materials have been introduced in the automobilist industry, because those materials show an excellent relation of strength/weight, providing a reduction of consume and the increase of load capacity. Those factors justify the increase of interest of industry and the necessity of optimization of those materials and of their process. For this research, the field of application will be the Baja SAE Project, a project that is fully developed by engineering students, where they build a prototype single seat, off-road category, for use on hilly slopes with obstacle. This research aims to study two key components of the prototype are made of composite materials, analyzing all the processing. In addition, there is the analysis of the viability of this production parts to a Baja SAE vehicle, in order to increase their performance and reduce their weight without reducing the safety and robustness of the prototype. It was possible to achieve weight reduction of the steering subsystem with manufacturing the flywheel hybrid composite (carbon/glass) and the replacement of SAE 1010 steel by hybrid composite (carbon/aramid) in CVT box. The importance of this study is to obtain a good project for the vehicle of technical and scientific manner, contributing to the know-how to the team and providing a basis for optimization for upcoming projects

Desenvolvimento de um equipamento para análise de desgastes em prótese de articulação total de quadril

Pós-graduação em Engenharia Mecânica - FEG

Efeitos dos parâmetros de usinagem no acabamento superficial de materiais cerâmicos a verde

Pós-graduação em Engenharia Mecânica - FEB

Uma estréia no romance: A mocidade de Trajano

L'article Uma estréia no romance: A mocidade de Trajano veut revoir l'histoire de la publication de ce roman de 1871, renié,quelques années plus tard, par Alfredo d'Escragnolle Taunay. On y veut aussi vérifier les marques qui ce remettent à ceux de Macedo, surtout en ce qui concerne sa filiation au mélodrame (le mot pris dans son sens le plus vaste). Le regard de l'auteur sur le paysage, l'importance du rôle attribué par lui à la nature – scène idéaleopposés à la constatation des dégâts dans les rapports seigneur/esclave, surtout dans les grandes propriétés rurales, pendant le XIXe., ont, eux aussi, été objet de réflexions. Finalement, dans cet article on a essayé de remarquer la filiation idéologique du personnage Trajano à des valeurs européennes, notamment françaises.

Controlador PID utilizando microcontrolador PIC

This monograph proposes the implementation of a low cost PID controller utilizing a PIC microcontroller, and its application in a positioning system previously controlled by a dedicated integrated circuit for a positioning system. Applying the closed-loop PID control, the system instability was reduced, and its response was smoother, eliminating vibrations and mechanical wear compared to its response with the dedicated integrated circuit, which has a very limited control action. The actuator of the system is a DC motor, whose speed is controlled by the Pulse Width Modulation (PWM) technique, using a Full-Bridge circuit, allowing the shift of direction of rotation. The utilized microcontroller was the PIC16F684, which has an enhanced PWM module, with its analog converters used as reference and position feedback. The positioning sensor is a multiturn potentiometer coupled to the motor axis by gears. The possibility of programming the PID coefficients in the microcontroller, as well as the adjustment of the sampling rate, allows the implemented system achieving high level of versatility

Usinabilidade do aço DIN C45 trefilado de alta resistência

Pós-graduação em Engenharia Mecânica - FEG

Bioimperialismo e direito de propriedade intelectual: disputas pelo acesso ao cupuaçu e ao conhecimento tradicional

Pós-graduação em Ciências Sociais - FFC

Restauración onlay usando técnica semi-directa con resina compuesta: reporte de un caso

Posterior teeth restorations have changed the contemporary treatment philosophy influenced by the aesthetic demand of patients, progress of adhesive material science and techniques for preservation and rehabilitation of affected teeth by dental caries and trauma. The development of Onlay restorations with semi-direct technique in endodontically teeth treated aims to preserve the remaining surfaces, to reduce the possibility of fracture and polymerization shrinkage. In addition, better restoration adaptation and marginal seal, resistance to wear and dimensional stability are achieved. This case reports the rehabilitation of an endodontically treated permanent maxillary first molar in a 13 years old- patient who attended the Araraquara School of Dentistry, Brazil, using Miris 2 Composite resin with semi-direct technique and obtaining an aesthetic and functional restoration in a single appointment. The fundaments and clinical guidelines of the procedure are detailed, based on the review of the literature that supports this conservative treatment.

Efeito do ângulo de trabalho do ultrassom e do jato de bicarbonato sobre as superfícies ranculares

The aim of this study was to evaluate the effect of the working angle variation of the magnetoestritive ultrasonic (MU) and air polishing devices (APD) on the roughness and wear of dental root. Fifty bovine incisive teeth were used in this study. The proximal surfaces of the teeth were divided in three regions: coronal, median, and an apical. The coronal region was treated with a manual scaler, the apical region was treated with APD or with a MU and the medium region was maintained untreated to serve as a control. The teeth were divided in 11 groups according to the treatment applied: MU-0º; MU-30º; MU-45º; MU-60º; MU-90º; AP-0º; AP-30º; AP-45º; AP-60º; AP-90º; MS: manual scaler. To the statistical analysis, data submitted to the Anova and Tukey's test (p < 0.05). The manual curette promotes less roughness and higher tooth wear in comparison with the both ultrasonic and air polishing devices (p < 0.05). The angles of 45º, 60º and 90º caused higher rate of tooth wear and roughness when the MU was used (p < 0.05), while the angle of 90° caused a higher tooth wear than the angle of 30° when the APD was used (p < 0.05). The working angle variation influenced the tooth wear and roughness promoted by MU, whereas when using APD, the working angle variation influenced only the tooth wear.

Características clínicas da associação entre o bruxismo do sono e o refluxo gastroesofágico merecem atenção profissional

Introduction: Bruxism has been defined as an oral parafunctional activity that includes clenching and/or grinding the teeth while asleep or awake. In addition to sleep bruxism (SB), various other orofacial movements sporadically occur during sleep. Occasional regurgitation and heartburn due to gastroesophageal reflux (GER) are frequent in the general population. GER refers to the presence of symptoms that are secondary to the reflux of gastric content through the esophagus with or without signs of esophageal mucosal lesions. Dentists are often the first health care professionals to diagnose GER through observation of its oral manifestation. Objective: The aim of the present case reports was to discuss the diagnosis and clinical procedures followed in two patients with SB and GER, thereby contributing to the dissemination of knowledge about these two entities. We therefore recommend dentists to be alert to identifying the first signs of GER that appear in the oral cavity. Conclusion: At this point, we highlight the importance of treating the patient as a whole, in an endeavor to identify other sources of the problems that could contribute as factors aggravating these conditions.

Prótese metalocerâmica associada à prótese metaloplástica implantossuportada em paciente desdentado total

The use of different methods and materials should be considered during the planning of implant-supported prostheses. Complications such as fractures of the acrylic resin base, wear and fracture of teeth can occur frequently, creating the need for careful planning for each patient, which can make the selection of the type of treatment more complex. Thus, this article describes the oral rehabilitation of a completely edentulous patient with bimaxillary fixed implant-supported prosthesis, with complaints on aesthetics, loss of vertical dimension and fracture of acrylic resin teeth of the upper arch. After the restoration of vertical dimension, his dentures were replaced with new bimaxillary implant-supported fixed prostheses, ceramic and acrylic resin were used as veneering material for maxilla and mandible, respectively. At the end of the treatment, the patient received bimaxillary flat occlusal splints to protect the teeth and implants of possible parafunctional habits. The approach for the treatment allowed a quick and effective resolution, with aesthetic and functional outcomes very favorable for the patient.

Influência de diferentes métodos de limpeza sobre a eficiência de corte e as características morfológicas de fresas Carbide

Introduction: Currently, there are many questions regarding the cleaning methods seeking greater efficiency and less loss of burs. Aim: the aim of this study was to evaluate the influence of cleaning methods on the cutting efficiency and morphological characteristics of stainless steel burs tungsten carbide (carbide). Materials and method: Thirty burs were divided into five groups (n = 5) according with the cleaning method: L1 - steel brush, L2 - nylon brush, L3 - ultrasound  +  distilled water, L4 - ultrasound + descaling solution and L5 - no cleaning method (control). The burs were used for the cutting of bovine enamel during six periods of 12 minutes each. After each period, the burs were cleaned (except L5 ) following the protocol established for each group. The cutting efficiency was determined by mass loss and morphological characteristics. Result: The average amount of wear after 72 minutes of use were L1  = 0.3558 g; L2  = 0.4275 g; L3  = 0.4652 g; L4  = 0.4396 g e L5  = 0.4854 g; significant differences in the time of use (p  <  0.001) and cleaning method (p  <  0.001). The L1 group showed the worst performance. Regardless of the experimental group, morphological analysis revealed alterations in the cutting blades soon after the first 12 minutes, being L1 the most affected group. Conclusion: The cleaning with wire brush was the most damaging method to the cutting efficiency and to the morphology of carbide burs.

Influência do cimento obturador e agente de irrigação final na infiltração marginal em situações de sobreobturações endodônticas

Objective: The objective of this paper was to verify if the final irrigation at 17% EDTA, separately or followed by chlorhexidine digluconate at 2% interferes on the apical marginal leakage in root canal overfilling, due to the use of two root canal filling materials (Sealer 26TM or SealapexTM). Methods: Forty lower incisors extracted, with a single root canal, were biomechanically prepared, at 2.0mm beyond the radicular apex, with ProTaper SystemTM, finishing it with the F3 instrument. Irrigation was accomplished with 1.0 mL NaOCl at 2.5% at each change of equipment caliper and, in the end, with 5.0 mL normal saline solution. After achieving this procedure, the foraminal channels was standardized with a file K 25 until its DO appears in the foraminal opening. From this moment, the teeth were subdivided into two groups of 20 specimens each, because of the final irrigation method used: I – irrigation with EDTA at 17% for 3min and II – identical protocol, thus, after EDTA aspiration at17%, it was again irrigated with chlorhexidine digluconate at 2%, also kept intra-canal for 3min. Each group was again sub-divided into two sub-groups (ten teeth each), according to the cement used (Sealer 26TM or SealapexTM), and filled by using a single gutta-percha F1 (ProTaperTM, Universal Filling), in such a manner that it goes 2.0 mm beyond the radicular apex. Soon after that, the teeth were immersed in Rhodamine BTM for 72h, vacuum and after the roots have been bucolingually grooved, the leakages marked were measured with program Image ToolTM. Results and Conclusions: The leakage magnitude was similar among themselves (p > 0.05), except for group Sealapex®, thus the final use with chlorhexidine reduced apical leakage (p < 0.05).