Abstract:Dedico esta teseAo meu Deus, por ter dado energia às pessoas que estão à minha volta, e por tornar possível este momento.À minha doce e adorável mamãe Mariza, pelo carinho e amor inesgotável dedicado a toda família e pela serenidade e força de vontade em um momento quando não havia mais esperança.Ao meu amado pai Manoel, por ter escolhido o melhor caminho para que eu chegasse a este momento. Pai, você é um herói, por isso eu te amo tanto.Aos meus irmãos, Maristela, Guilherme e Mauricio, pela companhia e carinh… Show more
“…It has also piqued the interest of the automotive [2,3] and biomedical [4,5] sectors. However, due to its elevated melting point (1670 °C) and high chemical reactivity, it is challenging to process this alloy with traditional manufacturing methods like casting [6,7]. Yet, the additive manufacturing (AM) technology of powder bed fusion (PBF) has proven to be highly efficient for processing titanium alloys and producing parts with comparable or even superior mechanical properties [8].…”
While the electron beam powder bed fusion (EB-PBF) process is recognized for generating parts with high surface roughness, the impact of wall thickness remains relatively understudied and shows inconsistent literature results. This study addresses this gap by performing a full factorial Design of Experiments (DoE) to examine Ti-6Al-4V specimen surfaces built in three distinct orientations (vertical, upskin, and downskin) and six wall thickness levels (0.5, 1.0, 2.0, 2.5, 3.0, and 4.0 mm). Findings reveal orientation-dependent effects of wall thickness on surface roughness, particularly for thicknesses below 1.0 mm. Vertical surfaces show increased roughness with decreasing wall thickness, in which 0.5 mm-thick specimens exhibited the highest Ra roughness values. In contrast, no particular trend was observed for upskin surfaces, with 0.5 mm specimens displaying roughness values comparable to the 2.0 to 4.0 mm range of specimens. Yet, downskin surfaces of 0.5 mm specimens showed significantly lower Ra roughness compared to their thicker counterparts, a trend opposite of that of vertical surfaces. These behaviors may relate to scanning strategies and electron beam parameters, particularly when building smaller cross-sectional areas.
“…It has also piqued the interest of the automotive [2,3] and biomedical [4,5] sectors. However, due to its elevated melting point (1670 °C) and high chemical reactivity, it is challenging to process this alloy with traditional manufacturing methods like casting [6,7]. Yet, the additive manufacturing (AM) technology of powder bed fusion (PBF) has proven to be highly efficient for processing titanium alloys and producing parts with comparable or even superior mechanical properties [8].…”
While the electron beam powder bed fusion (EB-PBF) process is recognized for generating parts with high surface roughness, the impact of wall thickness remains relatively understudied and shows inconsistent literature results. This study addresses this gap by performing a full factorial Design of Experiments (DoE) to examine Ti-6Al-4V specimen surfaces built in three distinct orientations (vertical, upskin, and downskin) and six wall thickness levels (0.5, 1.0, 2.0, 2.5, 3.0, and 4.0 mm). Findings reveal orientation-dependent effects of wall thickness on surface roughness, particularly for thicknesses below 1.0 mm. Vertical surfaces show increased roughness with decreasing wall thickness, in which 0.5 mm-thick specimens exhibited the highest Ra roughness values. In contrast, no particular trend was observed for upskin surfaces, with 0.5 mm specimens displaying roughness values comparable to the 2.0 to 4.0 mm range of specimens. Yet, downskin surfaces of 0.5 mm specimens showed significantly lower Ra roughness compared to their thicker counterparts, a trend opposite of that of vertical surfaces. These behaviors may relate to scanning strategies and electron beam parameters, particularly when building smaller cross-sectional areas.
“…O Titânio (Ti) é um elemento abundante na crosta terrestre, embora de difícil obtenção [1,2]. É muito utilizado em diversas áreas como por exemplo na fabricação de peças para motores, na fabricação de foguetes e produtos aeroespaciais, na produção de catalisadores para reações de polimerização de compostos organometálicos, na produção de ligas com outros metais, na produção de tintas e papeis, e em especial em diversas aplicações área biomédica.…”
Resumo Neste presente estudo foi utilizada a técnica de elipsometria espectroscópica a fim de se caracterizar as propriedades ópticas do filme fino de óxido anódico de Titânio formado espontaneamente. As propriedades desse óxido são relevantes consideradas as diversas aplicações do titânio, dentre as quais as biológicas. A elipsometria é uma técnica não destrutiva, porém indireta, apropriada para obtenção de propriedades ópticas e dielétricas, após modelagem. Usando essa técnica, obtivemos além das propriedades ópticas, a espessura do óxido formado de forma natural sobre o substrato de Titânio. Palavras-chave: Titânio; Óxido de titânio; Elipsometria STUDY OF THE OPTICAL PROPERTIES OF THE THIN FILM OF TITANIUM ANODIC OXIDE BY ELLIPSOMETRY Abstract In this present study, the spectroscopic ellipsometry technique was used in order to characterize the optical properties of the spontaneous titanium anodic oxide thin film. The properties of this oxide are relevant considering the various applications of titanium, among which the biological ones. Ellipsometry is a non-destructive, but indirect, technique suitable for obtaining optical and dielectric properties, after modeling. Using this technique, we obtained besides the optical properties, the thickness of the oxide formed of natural form on the substrate of Titanium.
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