Avaliação dos aspectos de processo no torneamento de madeiras tratadas termicamente

Pós-graduação em Engenharia Mecânica - FEG

Estudo da aplicação de mínima quantidade de fluido no fresamento de acabamento da liga Ti-6Al-4V

Pós-graduação em Engenharia Mecânica - FEG

Análise comparativa do uso de ferramentas de metal duro sem revestimento e revestidas com diboreto de titânio na usinagem da madeira

Pós-graduação em Engenharia Mecânica - FEB

Estudo experimental do uso de rebolos convencionais na usinagem do aço VP-50 utilizado na retificação cilíndrica, por meio de diferentes métodos de lubri-refrigeração

Pós-graduação em Engenharia Mecânica - FEB

Caracterização de juntas soldadas em PAW e GTAW de chapas finas em aço maraging 300 submetidas a vários reparos

Pós-graduação em Engenharia Mecânica - FEG

Efeito da infiltração de sílica pelo método sol-gel na resistência à flexão de bicamadas de porcelana e Y-TZP

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)

Effect of different light sources on degree of conversion, hardness and plasticization of a composite

Clinical performance of composite resins depends largely on their mechanical properties,and those are influenced by several factors,such as the light-curing mode. The purpose of this study was to evaluate the influence of different light sources on degree of conversion(DC), Knoop hardness(KHN) and plasticization(P) of a composite resin. Disc-shaped specimens (5 x 2 mm) of Esthet-X(Dentsply) methacrylate-based microhybrid composite were light-cured using quartz-tungsten-halogen (QTH) Optilight Plus(Gnatus) or light-emitting diode(LED) Ultraled(Dabi Atlante) curing units at 400 and 340 mW/cm2 of irradiance, respectively. After 24 h, absorption spectra of composite were obtained using Nexus 670(Nicolet)FT-IR spectrometer in order to calculate the DC.The KHN was measured in the HMV-2000(Shimadzu) microhardness tester under 50 g loads for 15 s, and P was evaluated by percentage reductio of hardness after 24 h of alcohol storage. Data were subjected to t-Student test(alpha=0.05).QTH device showed lower P and higher KHN$ than LED (p<0.05), and no difference between the light-curing units was found for DC (p>0.05). The halogen-curing unit with higher irradiance promoted higher KHN and lower softening in alcohol than LED.

Experimental and numerical study of heat transfer in hot machined workpiece using infrared radiation

One of the greatest problems found in machining is related to the cutting tool wear. A way for increasing the tool life points out to the development of materials more resistant to wear, such as PCBN inserts. However, the unit cost of these tools is considerable high, around 10 to 20 times compared to coated carbide insert, besides its better performance occurs in high speeds requiring modern machine tools. Another way, less studied is the workpiece heating in order to diminish the shear stress material and thus reduce the machining forces allowing an increase of tool life. For understanding the heat transfer influences by conduction in this machining process, a mathematical model was developed to allow a simplified numerical simulation, using the finite element method, in order to determine the temperature profiles inside the workpiece.

Ultra-precision face grinding with constant pressure, lapping kinematics, and SiC grinding wheels dressed with overlap factor

Several machining processes have been created and improved in order to achieve the best results ever accomplished in hard and difficult to machine materials. Some of these abrasive manufacturing processes emerging on the science frontier can be defined as ultra-precision grinding. For finishing flat surfaces, researchers have been putting together the main advantages of traditional abrasive processes such as face grinding with constant pressure, fixed abrasives for two-body removal mechanism, total contact of the part with the tool, and lapping kinematics as well as some specific operations to keep grinding wheel sharpness and form. In the present work, both U d-lap grinding process and its machine tool were studied aiming nanometric finishing on flat metallic surfaces. Such hypothesis was investigated on AISI 420 stainless steel workpieces U d-lap ground with different values of overlap factor on dressing (Ud=1, 3, and 5) and grit sizes of conventional grinding wheels (silicon carbide (SiC)=#800, #600, and #300) applying a new machine tool especially designed and built for such finishing. The best results, obtained after 10 min of machining, were average surface roughness (Ra) of 1.92 nm, 1.19-μm flatness deviation of 25.4-mm-diameter workpieces, and mirrored surface finishing. Given the surface quality achieved, the U d-lap grinding process can be included among the ultra-precision abrasive processes and, depending on the application, the chaining steps of grinding, lapping, and polishing can be replaced by the proposed abrasive process.

Influência do aporte térmico da soldagem GTAW no balanço de fases Ferrita/Austenita do Aço Inoxidável Duplex UNS S32205

Pós-graduação em Engenharia Mecânica - FEIS

Efeito das diferentes direções de aplicação de jato de fluido de corte no torneamento de um aço de difícil usinagem

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)

Avaliação in vitro do tempo de fotopolimerização com led de alta potência de bráquetes ortodônticos e remoção de adesivo remanescente sob luz ultravioleta

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)

Influência do tratamento térmico assistido por pressão nas propriedades óptica e elétrica do trióxido de tungstênio

Pós-graduação em Química - IQ

Desinfecção fotoeletrocatalítica de águas contaminadas com Candida Parapsilosis utilizando eletrodos de W/WO3 em tratamento fotoeletrocatalítico

Pós-graduação em Química - IQ

Propriedades estruturais e espectroscópicas de WO3 e WO3:Eu3+

Used as catalysts even in organic and inorganic molecules, as additives on catalysts, electrochromic films on smart windows the tungsten trioxide have been largely studied on the lasts decades, but there is just a few about it's luminescence. Using as precursors nitric acid and sodium tungstate the tungsten trioxide were been prepared thru wet process then treating on thermic and hydrothermal treatments. Where been evaluated the effects of methodology, nitric acid concentration, duration and temperature of treatments. The samples were characterized by X-ray diffraction (XRD), Raman scattering spectroscopy (RSS), Fourier transformed infrared spectroscopy, photoluminescence spectroscopy (PLS) and X-ray excited optical luminescence (XEOL). Hydrated phases of tungsten trioxide were obtained through hydrothermal treatments and the non-hydrated phases occur with thermic treatments. The acid concentration has the ability to determine the major phase formed as well the temperature determine the hydratation of the product. With lower temperatures dihydrate phase were preferable formed and with the rise of temperature, the water molecules were lost up to the fractionary hydratation and then the non-hydrated phase with higher temperatures depending on the atmosphere used on the thermal treatment. Doping the system with europium ions even substituting tungsten or in the interstices of the matrix were not been successful, as well the XEOL spectroscopy intensity were null and quite low for ultraviolet and visible excitation photoluminescence because of oxygen defect levels localized into the prohibited band.